California Veterinary Diagnostic Laboratory System, Fresno Branch

University of California, Davis

2789 South Orange Avenue

Fresno, CA 93725

Tele: 559-498-7740

Fax: 559-485-8097

E-mail: hprasad@cvdls.ucdavis.edu

1. Avian Inflammation

• Reaction is rapid in birds, 36 hours

• Leakage of fibrin and fibrinogen common in early exudate

• Intense granulomatous reaction (12 hours)

• Coagulum of eosinophilic debris, degranulating heterophils, macrophages and giant cells

• Macrophages, heterophils and thrombocytes are active phagocytes

• Pus is caseous but liquefaction can occur
• Birds respond with granulomatous inflammation to many insults
• Acute inflammatory reaction in birds involve edema, congestion and vascular changes mediated by basophils and mast cells

• 1-3 hours: basophils, heterophils and monocytes
• 2-6 hours: basophils degranulate and die
• 6-12 hours: lymphocytes, monocytes, macrophages
• 12-36 hours: lymphocytes, macrophages, giant cells
• Acute reaction peak by 12 hours (when giant cells appear)

• 36-72 hours: regeneration and repair
• Fibroblasts, secondary lymphoid follicles, plasma cells
• Chronic reaction with caseation, macrophages, giant cells, granuloma formation

• Cells involved in inflammation

• Heterophils: have lance-shaped granules, lack myeloperoxidase and alkaline phosphatase, have b -glucuronidase and acid phosphatase
• Very phagocytic
• Granules tend to round up in tissues, difficult to identify
• Eosinophils: have spherical granules

• Function is not known, delayed type IV hypersensitivity?
• Associated with eosinophilic enteritis in turkeys due to ascarids

• Basophils: contain histamine, involved in acute inflammation
• Thrombocytes: small round to oval cells with clear cytoplasm and small round nucleus (looks like small lymphocyte), phagocytic
• Monocytes: precursors to cells of MPS, phagocytic, can fuse to form multinucleated giant cells
• Make monokines; IL-1, IL-2, TNF, G-CSF, gamma intf.
• Lymphocytes: various morphologies involved in subacute inflammation including plasma cells

1. Avian Bacterial Diseases

1. Colibacillosis

• Disease of great economic significance in poultry
• Any one of the syndromes in poultry caused by E. coli
• Colisepticemia, air sac disease (CRD), peritonitis, coligranuloma, salpingitis, omphalitis/yolk sac infection, cellulitis, osteomyelitis/synovitis, swollen head syndrome and panophthalmitis
• Enteritis with AAEC, eae gene present
• Ceca most commonly involved
• Common in turkeys, others; chickens, pigeons, quail, partridges, pheasants, ducks, ostriches, etc.
• Septicemia and enteritis in psittacines and other birds?

1. Salmonellosis

• Large group of acute, subacute or chronic diseases caused by one or more members of bacterial genus Salmonella
• Pullorum disease in poultry, S. pullorum
• Typhoid disease in poultry, S. gallinarum
• Paratyphoid in poultry, ducks, pigeons, wild birds, psittacines, passerines, etc.
• 10-20 species: S. typhimurium, S. enteritidis, S. heidelberg, S. anatum, S derby, S. bredeney, etc.
• Arizonosis in turkey poults, S. arizonae
• Also in chicks, ducklings, psittacines, passerines, etc.
• Lesions
• Pullorum/Typhoid
• In chicks: Septicemic lesions of omphalitis, hepatitis, peritonitis, necrotic typhlitis, pericarditis, splenitis, pneumonia, synovitis, nephritis, opthalmitis, etc.

• In adults: oophoritis, salpingitis, peritonitis, orchitis

• Paratyphoid
• S. typhimurium most important
• In different species of birds: similar to acute septicemic lesions of pullorum and typhoid,
• In pigeons: brain, bone, and gonads often involved
• S. enteritidis can cause septicemic lesions in chicks
• Important in egg-associated food poisoning
• Arizonosis, in turkey poults
• Septicemic lesions, meningitis, ophthalmitis

1. Chlamydiosis

• Naturally occurring contagious systemic disease of various species of birds
• Chlamydophila psittaci, six serotypes (A, B, C, D, E and F)
• Diagnosed in 139 avian species, 15 orders and 30 families
• Psittacines, 25% of the reported host species, others; pigeons, passerines, wild and feral birds, rheas, turkeys, pheasants, etc.
• Chickens relatively resistant
• Clinical signs: vary greatly, species and age of bird, and strain of Chlamydia
• Respiratory signs, oculonasal discharge, diarrhea often greenish colored, swelling above eye (turkeys), conjunctivitis (pigeons), etc.
• Lesions: airsacculitis, pericarditis, pneumonia, hepatitis, splenitis, enteritis, conjunctivitis, nasal adenitis (turkeys), synovitis, encephalitis, nephritis, etc.
• Chlamydia-taxonomy (Int. J Syst. Bact. April 1999)

• Chlamydophila psittaci
• Obligate nonmotile, coccoid intracellular bacteria
• Depends on host cells for ATP metabolites
• Multiply within membrane-bound inclusions, in the cytoplasm of host cells
• Have a non-synchronous multimorphic developmental cycle:
• Spore-like, non-vegetative elementary body (EB), uniformly spherical particle of 300nm diameter
• Ingestion by host cell, fusion of bacterial endosome with host lysosomes?
• EB undergoes conversion to metabolically active reticulate body (RB), 800-1200nm
• RB replicate by binary fission, within a membrane bound vacuole, the chlamydial inclusion
• Intermediate bodies (IB) can also be seen
• Mature to infectious EB’s which infect other cells by lysis of host cells or by extrusion of chlamydial inclusion

1. Clostridial diseases

• C. perfringens (type A most common) - necrotic enteritis in poultry, ratites, psittacines, etc.
• C. colinum - ulcerative enteritis in poultry, especially in quail (quail disease), toucans, ratites, etc.
• C. difficile - entero/typhlocolitis in ratites (ostrich)
• Liver may have foci of necrosis and inflammation with the above clostridial diseases
• C. septicum - gangrenous dermatitis in poultry, especially chickens (C. perfringens can also cause)
• C. botulinum - limberneck in poultry

1. Mycobacteriosis

• Chronic progressive disease of a variety of species of birds with unthriftiness, loss of weight, diarrhea, etc.
• M. avium - wide host spectrum, poultry, pigeons, raptors, ratites, wild birds, psittacines , passerines, etc.
• M. genavense - psittacines, passerines?
• M. tuberculosis - psittacines, others?
• M. bovis - psittacine, others?
• Lesions
• Poultry, pigeons, raptors, ratites; grossly pale yellow or grey nodules in liver, spleen, intestine, bone marrow, lung, heart, etc.
• micro: caseous necrosis surrounded by multinucleated giant cells and fibrosis
• Psittacines, passerines, touracos; grossly pale mottling or diffuse enlargement of liver, spleen, intestine, lung, heart, eyelid, skin, etc.
• micro: diffuse or focal infiltration of foamy macrophages with myriads of acid fast bacilli in the cytoplasm, necrosis is unusual

1. Mycoplasmosis

• Important economic diseases of poultry caused by
• M. gallisepticum
• M. synoviae
• M. meleagridis
• M. iowae
• 14-20 or more Mycoplasma sp. are known

• Isolated from chickens, turkeys, pigeons, raptors, ratites, wild birds, psittacines, passerines, etc.
• Pathogenic significance?

• M. gallisepticum (MG) – Disease called chronic respiratory disease (CRD) in chickens and infectious sinusitis in turkeys. Other birds susceptible include, quail, pheasants, partridges, peafowl, finches, etc.
• Egg transmitted also
• Respiratory disease with swollen infraorbital sinus, tracheitis, airsacculitis, conjunctivitis, etc.
• Primarily of lymphocytic inflammation
• MG can cause decreased egg production in layers
• Some strains of MG can cause neurological signs in turkeys due to vasculitis in the brain
• M. synoviae (MS) - in chickens, turkeys, geese, quail, partridge, ducks, etc.
• Egg transmitted also
• Subclinical infection of respiratory disease, sinusitis, tracheitis, air sacculitis, conjunctivitis
• It can cause severe synovitis, ulceration
• Lymphocytic inflammation, proliferation of synovial cells
• Some strains of MS can cause neurological signs in turkeys, (chickens?) due to vasculitis in the brain
• Disseminated vasculitis in synovium, eye, kidney, skeletal muscle, heart, lung, etc., can be seen in turkeys
• M. melagridis - affects turkeys
• Egg transmitted also
• Airsacculitis in day-old poults
• Decreased hatchability, swelling of hock joint, bowing of tarsometatorsus (TS-65 syndrome), deformation of cervical vertebrae (wry neck)

• M. iowae - affects turkeys
• Egg transmitted also
• Causes decreased hatchability and embryo mortality

1. Turkey Coryza (Bordetellosis)

• Caused by Bordetella avium
• Upper respiratory tract infection primarily of young turkey poults; swollen sinus, collapsed trachea, watery eyes
• Tracheitis: deciliation, squamous metaplasia, and lymphoplasmacytic inflammation
• Decrease of GAGS (?) in the cartilage, effect of toxin ?
• B. avium can be a significant pathogen in young broiler chickens, ratites, passerines and psittacines (lock jaw?)

1. Infectious Coryza

• Disease primarily of young chickens caused by Haemophilus paragallinarum
• Pheasants and guinea fowl are also susceptible
• Upper respiratory tract infection; swollen sinus (sinusitis/rhinits), facial edema, conjunctivitis
• Occasionally tracheitis, bronchitis and airsacculitis

1. Fowl Cholera

• Also called avian cholera, pasteurellosis
• Septicemic disease of birds with high mortality and morbidity
• Etiology: P. multocida
• Most common in turkeys, chickens, wild waterfowl
• Other birds such as geese, quail, pheasants, raptors, psittacines, passerines, zoo birds, etc., are susceptible

• Lesions

• Acute: petechiae on viscera, consolidated lungs (common in turkeys), enlarged liver with foci of necrosis, pericarditis, airsacculitis, cellulitis, endocarditis, etc.
• Mucoid enteritis in waterfowl
• Peritonitis and oophoritis in breeders
• Chronic: swollen wattles, synovitis, otitis, osteomyelitis of cranial bones, sinusitis, conjunctivitis, etc.
• Esophageal abscesses in raptors

1. Erysipelas

• Acute septicemic disease of primarily turkeys
• Etiology: Erysipelothrix rhusiopathiae
• Chickens, emus, pheasants, ducks, grebes, geese, chukars, raptors, psittacines, zoo birds, etc.
• Lesions
• Acute cases: hemorrhages over epicardium, abdominal fat, skin, muscle, congested and enlarged spleen, foci of hepatic necrosis
• Chronic cases: vegetative endocarditis and arthritis

1. Pseudotuberculosis

• Chronic contagious disease of psittacines, canaries, finches, poultry, raptors, wild birds, etc.
• Yersinia pseudotuberculosis
• Birds often found dead, loss of weight, digestive and respiratory signs can be seen
• Lesions
• Pale yellow nodules of caseous granulomas in liver, spleen, intestine, lung, airsacs, bone, muscle, etc.
• Lesions can be confused with mycobacteriosis or coligranuloma

1. Riemerella anatipestifer

• Previously classified as Pasteurella anatipestifer
• Disease called new duck disease, goose influenza
• Disease of young domestic ducks, geese and turkeys
• Respiratory signs, ocular discharge, diarrhea, neurological signs, as much as 10% mortality
• Fibrinosuppurative airsacculitis, pericarditis, perihepatitis, meningitis, uveitis, etc.
• Skin and joints may be involved

1. Ornithobacterium rhinotracheale

• Recently described Gram negative bacillus associated with respiratory disease in poultry, primarily turkeys and broiler chickens
• It has been isolated from layer-type chickens, pheasants, partridges, pigeons, psittacines, etc.
• Consolidated lungs (similar to fowl cholera), tracheitis, airsacculitis, sinusitis, peritonitis, hepatic necrosis, etc.

1. Staphylococcosis

• Systemic infection of birds caused by S. aureus
• Less commonly by S. epidermidis and S. hyicus
• S. aureus most common in turkeys and broiler chickens, but has been isolated from a variety of bird species
• Lesions: omphalitis, synovitis, arthritis, osteomyelitis, green liver, gangrenous dermatitis, cellulitis, endocarditis, abscesses (bumblefoot), etc.

1. Streptococcosis

• Systemic infection of a variety of birds caused by species of genus Streptococcus
• S. zooepidemicus, septicemia in chickens, turkeys, pigeons, wild birds, etc.
• Valvular endocarditis with secondary infarcts in heart, liver, spleen, etc.
• Others: osteomyelitis, arthritis, tenosynovitis, salpingitis
• S. bovis, septicemia in turkeys, pigeons, etc.
• S. faecium, septicemia in ducklings and goslings
• Enterococcus hirae, encephalomalacia with vascular thrombosis and meningitis in broiler chicks

1. Miscellaneous bacteria

• Pseudomonas aeruginosa, Klebsiella pneumoniae - can cause localized or systemic infection in poultry and other birds
• Bacillus anthracis - been reported in ostriches as a cause of septicemia
• Listeria monocytogenes - can cause septicemia and encephalitis in chickens
• Campylobacter jejuni - been associated with enteritis and hepatic necrosis in ostriches
• Lawsonia intracellulare - associated with enteritis in ratites
• Megabacteria ? - associated with proventriculitis in psittacines, ostriches, etc.
• Eubacterium tortuosum - granulomas in liver and spleen, broiler chickens and turkeys
• Clostridium piliformis (Tyzzer’s disease) - hepatic necrosis in psittacines
• Spirochetosis:
• Borrelia anserina, septicemia in poultry and canaries
• Serpulina hyodysenteriae associated with typhlitis in rheas, in poultry?
• Serpulina piloscholi in ceca of pheasants, disease?

1. Avian Fungal diseases

• One of the most common fungal diseases of poultry, water fowl, psittacines, passerines, ratites, raptors, zoo birds (penguins), etc.
• Aspergillus fumigatus and A. flavus most common
• Others: A. niger, A. terreus, A. glaucus, etc.
• Respiratory signs (brooder pneumonia in poultry), unthrifty, diarrhea, neurological signs, ocular involvement, etc.
• Lesions
• Pale yellow nodules in lungs, air sac, syrinx, sinus, liver, brain, cloudy cornea, etc.
• White plaques with fuzzy green or grey or blue material (conidiophores-fruity bodies) on air sacs, pleura, etc.
• Fibrinosuppurative or granulomatous pneumonia, airsacculitis, syringitis, sinusitis, encephalitis, ophthalmitis, vasculitis (aortic rupture), hepatitis, osteomyelitis, pericarditis, etc.

1. Candidiasis

• Common mycosis of the upper digestive tract
• Also called thrush, crop mycosis, moniliasis
• Young birds most susceptible
• Candida albicans most common etiology
• Poultry, psittacines, passerines, ratites, raptors, pigeons, water fowl, etc.
• Oral cavity, esophagus and crop involved with white proliferative plaques
• Proventriculus, gizzard, intestine less often involved
• Systemic and ocular candidiasis have been described

1. Zygomycosis

• In ostriches, psittacines, water fowl, canaries involving proventriculus and gizzard and air sacs in a pigeon
• Mucor sp, Absidia sp. and Rhizopus sp. isolated
• necrotizing lesions with granulomatous reaction

1. Favus (avian ringworm)

• Due to Microsporum gallinae, dermatophyte of chickens with white powdery material on head, face and eyelids
• Acanthosis, hyperkeratosis and dermatitis

1. Dactylariosis

• Due to D. gallopava in turkeys and quail
• Fibrinosuppurative encephalitis and ophthalmitis

1. Crpytococcosis

• Due to C. neoformans in psittacines, pigeons, pheasant and experimental infection in chickens
• Sinusitis, encephalitis, hepatitis, pneumonia, etc.

1. Rhinosporidiosis

• Due to R. seeberi in swans
• Granulomatous conjunctivitis

1. Others fungal diseases

• Histoplasmosis - due to H. encapsulatum
• Granulomatous iridocyclitis in experimental infection of chickens
• Penicillium
• Penicillium griseofulvum, systemic infection in a toucanet
• P. cyclopium, beak infection in a macaw

• Trichosporon

• Trichosporon beigelii, granulomatous pneumonia, myocarditis, hepatitis in a macaw

• Curvularia
• Curvularia geniculata, mycetoma in a parrot
• Scedosporium
• Scedosporium prolificans isolated from feet of an ostrich with severe hyperkeratosis
• Geotrichum and Paecilomyces
• Geotrichum candidum and Paecilomyces variota have been isolated with disease

1. Avian Viral diseases

1. Marek’s Disease

• One of the most common and well studied diseases of young chickens
• Quail and turkeys are also susceptible
• Etiology: cell-associated herpesvirus
• Pathogenesis: virus replicates in feather follicle epithelium, infection through respiratory route, viremia, infection of B cells, cytolysis, infection of activated T cells, cytolysis, immunosuppression, infection of other organs like nerves (paralysis & blindness), latency, transformation of T cells (CD4), lymphoma
• Lesions
• Gross: bursal and thymic atrophy, swollen peripheral nerves, enlarged organs with pale white tumors in liver, spleen, kidney, lung, proventriculus, intestine, heart, gonads, thymus, irregular/gray iris, prominent feather follicles, etc.
• Microscopic: lymphoid necrosis and depletion in bursa, and thymus, neuritis, encephalomyelitis, pleomorphic lymphocytic lymphoma in various organs
• Intranuclear inclusion bodies in feather epithelium
• Arteriosclerosis can be produced with MD virus

1. Leukosis/Sarcoma Group

• Genus, ALV- related viruses of family Retrovirus
• Six subgroups; A, B, C and D (exogenous viruses), E (endogenous) & J (recombinant)
• A, B and J are common in the field, C and D are rare
• Various oncogenes been identified (see table 1)
• They can produce a variety of neoplasms in chickens
• Influenced by strain of virus, virus dose, route of inoculation, age of host, genotype and sex of host
• Neoplasms: sarcoma’s (fibro, osteochondro, myxo, histio, lympho, hemangio), meningioma, mesothelioma, erythroblastosis, myeloblastosis, nephroblastoma, granulosa cell tumor, hepatocellular carcinoma, glioma, (osteopetrosis), etc.
• Lymphoid Leukosis

• Disease of semimature and mature chickens
• Etiology: retrovirus of leukosis/sarcoma group
• Exogenous viruses, subgroups A,B, C and D
• Transmission
• Horizontal, transient viremia, immunity, LL rare
• Egg transmission, chronic viremia, immune tolerance, LL common
• B cell lymphoma in various organs, bursa of Fabricius, liver, spleen, kidney, gonads, etc.

• Osteopetrosis
• thickening of long bones
• Effect of virus on osteoblasts
• Myelocytomatosis
• Neoplastic disease primarily of broiler breeders and broilers
• Etiology: retrovirus, subgroup J (leukosis/sarcoma group)
• Lesions: liver, spleen, kidney, sternum, etc., with nodules made up immature granulocytes
• Hemangiosarcoma, histiocytoma, myxoma, carcinomas in liver, fibrosarcoma, lymphoma, ganglioneuroma, renal tumors, etc., have also been associated with subgroup J virus
• Reticuloendotheliosis
• Includes runting syndrome, chronic lymphoma and acute reticulum cell sarcoma
• Primarily in chickens and turkeys
• Etiology: retrovirus of REV group, distinctly different from leukosis/sarcoma group
• Lesions
• In runting syndrome: thymic and bursal atrophy, neuritis, lymphoma (similar to Marek’s disease)
• In chronic lymphoma: bursal and visceral lymphoma (similar to Lymphoid Leukosis)
• In acute reticulum cell sarcoma: enlarged liver, spleen, kidney, heart, gonads, etc.

1. Infectious laryngotracheitis

• Acute viral respiratory disease of primarily chickens
• Pheasants and peafowl are also susceptible
• Etiology: herpesvirus
• Lesions: oculonasal discharge, trachea with hemorrhage and/or fibrinous exudate
• Conjunctivitis, tracheitis and sinusitis, syncytia formation and intranuclear inclusion bodies

1. Infectious Bronchitis

• Highly contagious viral respiratory disease of young chickens
• Drop in egg production and egg quality in layers
• Etiology: coronavirus, many serotypes, and great antigenic variation among strains of virus
• Lesions: catarrhal tracheitis, conjunctivitis, bronchitis, and airsacculitis
• Fibrinosuppurative inflammation in cases complicated with E. coli
• Interstitial nephritis with nephrotropic strains

1. Avian Paramyxoviruses

• Newcastle Disease
• Acute viral disease of chickens, turkeys, pigeons, doves, pheasants, ratites, psittacines, cormorants, etc.
• 236 species of birds comprising 27 orders
• Etiology: avian paramyxovirus - 1, isolates vary greatly in pathogenicity to chickens
• Lentogenic: mild or inapparent infection in chickens
• Mesogenic: cause disease and mortatlity in young chickens
• Velogenic (viscerotropic and neurotropic): lethal infection of chickens of all ages
• Clinical signs
• Vary with strain, respiratory, digestive, ocular, neurological, sudden death
• In mature chickens, egg production and quality problems (mesogenic strain)
• Lesions
• In pigeons: enteritis, pancreatitis, nephritis, encephalitis, respiratory system rarely involved
• In chickens; tracheitis, pneumonia, enteritis, conjunctivitis, encephalitis, myocarditis, lymphoid necrosis
• Velogenic; hemorrhages in conjunctiva, trachea, oral cavity, esophagus, proventriculus, ceca, rectum
• Disseminated vasculitis, lymphoid necrosis and depletion, mucosal necrosis and ulceration
• Inclusions are rare
• In a recent case, discrete eosinophilic intranuclear and intracytoplasmic inclusions in conjunctiva, esophagus, lung, brain, adrenal ganglia of a pheasant and in the brain of a chicken with a lentogenic type NDV
• Eosinophilic intranuclear inclusions in hepatocytes in doves associated with lentogenic type of NDV

• Other Avian Paramyxoviruses

• PMV - 2 (Yucaipa):
• Respiratory disease in young turkeys and drop in egg production in layers, chickens are susceptible
• PMV - 3, two strains, turkey and psittacine
• Turkey; egg production drop in turkeys
• Psittacine; neurological and digestive problems in psittacines and passerines
• Encephalitis with intranuclear and intracytoplasmic inclusion bodies in neurons and glial cells
• Myocarditis, pancreatitis with intranuclear inclusions
• PMV -5 (Kunitachi):
• Enteritis and mortality in budgerigars and lorikeets

1. Avian Influenza

• Acute viral disease of poultry; turkeys and chickens and psittacines, passerines, ratites, etc.
• It has been isolated from many species of birds
• Waterfowl may serve as reservoir
• Etiology: type A influenza virus of family Orthomyxoviridae
• Numerous subtypes based on surface antigens, hemagglutinin (13) and neuraminidase (9)
• Viruses of H5 (H5N2) and H7 (H7N1) subtypes are considered pathogenic, H1N1 (swine flu) in turkeys
• H4N8, H4N6, H3N8 in exotic birds
• H5N1 in chickens and humans, Hong Kong, 1997
• Clinical signs: vary greatly, respiratory, digestive, ocular, neurological, sudden death, etc.
• Drop in egg production in layers
• Lesions: vary greatly in pathogenicity
• Mildly pathogenic: catarrhal tracheitis, sinusitis, airsacculitis, conjunctivitis, pneumonia, etc.
• Highly pathogenic: hemorrhagic lesions in skin of face, comb & shanks and GI tract, interstitial pneumonia & nephritis, encephalitis, conjunctivitis, myocarditis, adrenalitis, pancreatitis, myositis, lymphoid necrosis, vasculitis and thrombosis, etc.

1. Avian Encephalomyelitis

• Viral disease of young (1-3 weeks) chickens, turkeys, pheasants and coturnix quail
• Neurological signs (epidemic tremor)
• Drop in egg production in layers
• Egg transmitted
• Etiology: enterovirus (family Picornaviridae)
• Lesions: neuronal swelling, chromatolysis, lymphocytic perivascular cuffing, lymphocytic foci in muscular layer of proventriculus and gizzard, pancreatitis
• A few survivors can develop cataract

1. Avian Pox

• Slow spreading viral disease of chickens, turkeys, quail, pigeons, canaries, raptors, psittacines, ostrich, peacock, waterfowl, etc.
• 60 species of wild birds
• Etiology: poxvirus of genus Avipoxvirus, many strains
• Fowl pox, turkey pox, pigeon pox, canary pox, quail, mynah, psittacine, junco, sparrow, starling, etc.
• Signs: cutaneous, respiratory, digestive, ocular
• Septicemic form in canaries, 70 - 90% mortality
• Lesions
• Gross:
• Dry pox or cutaneous form: proliferative skin lesions on face, eyelids, beak, feet, legs, vent, etc.
• Wet pox or diphtheritic form: yellow raised plaques in sinus, trachea, oral cavity esophagus/crop, conjunctiva, etc.
• Micro:
• Proliferation of epithelial cells, ballooning degeneration with eosinophilic intracytoplasmic inclusion bodies (pathognomonic)
• Desquamative pneumonia in canaries
• Some avipoxviruses are oncogenic, wart-like growth

1. Infectious Bursal disease

• Acute viral disease of young chickens (1-6 weeks) and secondary immunosuppression
• Turkeys and ducks, subclinical infection
• Etiology: birnavirus
• Lesions: enlarged and edematous bursa of Fabricius some times with hemorrhages and atrophy in later stages, hemorrhages in skeletal muscle, thymic atrophy with virulent IBD
• Lymphoid necrosis and depletion
• Secondary infections with inclusion body hepatitis, gangrenous dermatitis, bursal cryptosporidiosis, etc.

1. Chicken Infectious Anemia

• Viral disease of young chickens characterized by aplastic anemia and immunosuppression
• Chicks 1-3 weeks of age most susceptible
• Vertically transmitted
• Etiology: circovirus
• Hematology: anemia, hematocrit less than 27% (N 35%), leukopenia, thrombocytopenia
• Due to cytotoxic effect of virus on bone marrow precursor cells
• Lesions: pale bone marrow, severe thymic atrophy, atrophy of bursa, hemorrhages in skeletal muscles
• Lymphoid necrosis and depletion, bone marrow hypoplasia
• Gangrenous dermatitis, colibacillosis, aspergillosis, viral infection, etc.
• Eosinophilic (red) intranuclear inclusions in mononuclear cells of thymus, spleen, bone marrow, bursa, lung, etc. in some cases
• True nature of these inclusions not known

1. Duck Viral Enteritis

• Acute viral disease of primarily adult ducks, geese and swans characterized by high mortality
• Etiology: herpesvirus
• Lesions: hemorrhages on heart, liver, gizzard, fibrinonecrotic lesions in esophagus, rectum, cloaca, bursa, annular band of hemorrhage and necrosis in intestine, ceca, and thymic atrophy
• Necrosis, inflammation and intranuclear inclusions in liver, intestine, thymus, gland of Harder, conjunctiva, etc.
• Esophagitis and bursal necrosis with intranuclear and intracytoplasmic inclusions in mucosal cells

1. Duck virus hepatitis

• Peracute viral infection of ducklings (< 5 weeks) characterized by high mortality
• Etiology:
• DVH - 1, enterovirus
• DVH - 2, astrovirus
• DVH - 3, enterovirus (unrelated to DVH1)
• Lesions: petechiae or ecchymotic hemorrhages and necrosis in liver, minimal inflammation

1. Parvovirus Infection

• Goose parvovirus (Derzsy’ disease): highly contagious disease of young geese and Muscovy ducks
• Serofibrinous pericarditis and perihepatitis
• Myocarditis with intranuclear inclusions

• Muscovy duck parvovirus

• Serologically related to goose parvovirus
• Causes locomotor problems with high mortality in 1-3 weeks-old ducks, loss of weight , pale leg muscles, serofibrinous pericarditis and perihepatitis
• Myositis, myocarditis, encephalomyelitis, neuritis, etc.
• Ascites, round hearts in ducks recovered infection

1. Avian Adenoviruses

• Three groups:
• Group I - quail bronchitis, inclusion body hepatitis and hydropericardium syndrome in chickens, also disease in turkeys, pigeons, psittacines, raptors, etc.
• Group II - hemorrhagic enteritis virus of turkeys (HEV), marble spleen disease of pheasants (MSD) and splenomegaly of chickens
• Group III - egg drop syndrome of chickens
• Quail bronchitis
• High mortality in young bobwhite quail associated with bronchopneumonia, tracheitis, hepatitis, pancreatitis, bursal necrosis, intranuclear inclusions
• Inclusion body hepatitis of chickens, also in turkeys, guinea fowl, pigeons, psittacines, etc.
• In chickens usually secondary to immunosuppression caused by IBDV, CIAV
• Liver enlarged and mottled red/pale, foci of necrosis, inflammation and intranuclear inclusion bodies, also pancreatitis
• Similar lesions seen in turkey poults, guinea fowl, pigeons
• Hepatitis, enteritis, bronchitis, pancreatitis, nephritis, encephalitis, etc., associated with intranuclear inclusions in psittacines
• Hemorrhagic enteritis virus (HEV) of turkeys and Marble spleen disease (MSD) of pheasants
• Caused by group II adenovirus
• Guinea fowl, psittacines, (partridge) susceptible
• Young turkeys (4-12 weeks) and pheasants (3-8 months)
• With HEV, intestinal hemorrhage and enlarged mottled white spleen and immunosuppression
• Intranuclear inclusions in mononuclear cells of spleen and intestine, renal epithelial cells in HEV
• In pheasants mottled white enlarged spleen, MPS cell hyperplasia, intranuclear inclusions

1. Poult Enteritis

• Disease of young turkeys, multiple etiologies
• Viruses include coronavirus (blue comb disease), enterovirus, rotavirus, astrovirus, etc.
• Diarrhea, loss of weight, mortality 1 - 55%, small intestine and ceca distended with watery or frothy contents, caseous exudate in bursa, thymic atrophy
• Increased cellularity of lamina propria, necrosis of cells in lamina propria, villus atrophy, lymphoid necrosis in thymus and bursa (virus?)

1. Herpesviruses

• Probably diverse group of viruses which infect a variety of psittacines
• Three diseases are known
• Pacheco’s disease
• Acute viral disease of a variety of psittacines (common in 1980’s in US)
• Lesions:
• enlarged liver occasionally with petechiae, enlarged spleen, fluid filled intestine, diptheretic membrane in oral cavity, esophagus, etc.
• liver necrosis with or without inflammation, enteritis, stomatitis, esophagitis, pancreatitis, conjunctivitis, splenic and bursal necrosis, nephritis with intranuclear inclusion bodies
• syncytia formation with inclusions in liver
• Amazon tracheitis, disease characterized by tracheitis, bronchitis, rhinitis, laryngitis with syncytia formation and intranuclear inclusions
• Virus has some cross reactivity with ILT virus of chickens
• Budgerigar herpesvirus, rare disease associated with decreased hatchability and "feather duster" plumage

• Other herpesviruses
• Pigeon herpesvirus
• Common in young squabs characterized by hepatitis, pancreatitis, esophagitis associated with intranuclear inclusions
• Conjunctivitis, enteritis, myocarditis, encephalitis, laryngitis, splenitis, etc. can also be seen
• Raptors and budgies susceptible
• Finch herpesvirus (cytomegalovirus)
• Disease of primarily Gouldian finches characterized by high mortality, conjunctivitis, tracheitis, bronchitis, associated with cytomegalic cells and inclusions
• Others herpes viruses of owls, falcons, eagles, cranes, etc.
• Hepatitis associated with inclusion bodies

1. Psittacine Beak and Feather Disease

• Viral disease of many species of psittacines characterized by chronic feather and beak dystrophy
• Acute immunosuppression and sudden death in young birds due to secondary bacterial septicemia and fungal infections
• Etiology: circovirus
• Clinical signs: dystrophic feathers first noticed of the powder down, progress to contour feathers, followed by primary, secondary tail and crest feathers, almost symmetrical
• Lesions
• Gross: abnormal and loss of feathers, sloughing of claws, beak necrosis, necrosis of oral mucosa, liver, bursa, thymus, etc.
• Microscopic: pterylitis and pulpitis associated with botryoid inclusions in macrophages, also in bursa, bone marrow, thymus, beak, claws, liver, pancreas, thyroid, testes, etc.
• Intranuclear inclusions in feather epithelium, intestine, esophagus, hepatocytes

1. Papovavirus

• Two genera are known to cause disease in psittacines and passerines
• Papillomavirus
• Polyomavirus
• Papillomavirus
• It has been associated with cutaneous papillomas in wild finches (Fringilla) and an African Grey Parrot
• No virus has been associated with papillomas of cloaca, conjunctiva, tongue, larynx, oral cavity, crop/esophagus, etc., in psittacines
• Polyomavirus
• Causes Budgerigar fledgling disease (BFD)
• One of the most common diseases of psittacines (disease of 90’s?) and passerines
• Antibodies to BFDV been detected in chickens, but chickens are resistant to infection
• Etiology: polyomavirus, different strains such as psittacine, passerine, etc., may exist
• Variety of psittacines, finches and canaries are susceptible
• Young psittacines are highly susceptible with very high mortality (30 - 100%), also adults
• Feather dystrophy in budgerigars, acute death, digestive, neurological, respiratory, etc.
• Lesions
• Gross: variation among psittacines and also passerines
• In most of psittacines feather dystrophy, hemorrhages in skin, subcutis, skeletal muscle, heart, intestine, liver enlarged and mottled red or with white foci, splenomegaly, pale kidneys, ascites, lung congestion, pale carcass, etc.
• In passerines, liver enlarged and mottled white, serosal or subserosal hemorrhage of intestine, pale myocardium, etc.
• Microscopic: hemorrhages in various organs, necrosis in spleen, bursa, thymus and bone marrow, midzonal or random necrosis in liver, myocarditis, enteritis, nephritis, membranous glomerulopathy, pancreatitis, conjunctivitis, encephalomyelitis, ganglionitis (spinal), etc.
• Bluish karyomegalic inclusions in various tissues; epidermis, feather follicle epithelium, esophagus, kidney, macro/lympho of spleen, bursa, thymus, bone marrow, liver, etc., hepatocytes, myocytes, endothelial cells, glial cells, Purkinje cells, etc.

1. Proventricular Dilation Syndrome (PDD)

• A common chronic disease of psittacines
• Characterized by dilation of proventriculus, anorexia, regurgitation, passing of undigested seeds in feces, diarrhea, neurological signs, loss of weight, etc.
• Etiology: not known, presumed to be a virus
• Lesions
• Gross: dilated thin proventriculus in 70% of cases, distended duodenum, etc.
• Microscopic: lymphoplasmacytic ganglioneuritis of splanchnic nerves of crop/esophagus, proventriculus, gizzard, intestine, adrenalitis, myocarditis, neuritis, encephalomyelitis, choroiditis, etc. (see table 2)

1. Miscellaneous Viral Diseases

• Turkey viral hepatitis
• Disease of young turkeys
• Etiology: picornavirus
• Liver and pancreas with foci of necrosis and inflammation
• Viral arthritis
• Disease primarily of young chickens and turkeys
• Etiology: reovirus
• Joints enlarged with fluid, proliferative synovitis
• Turkey Rhino Tracheitis (TRT) of turkeys, Swollen Head Syndrome (SHS) of chickens
• Highly contagious respiratory diseases
• Etiology: pneumovirus (Paramyxoviridae)
• Lesions: swollen sinuses, sinusitis, tracheitis, rhinitis, conjunctivitis
• Avian nephritis
• Highly contagious disease of chickens
• Etiology: picornavirus
• Nephritis and secondary visceral urate deposition

• Arboviruses
• Eastern Equine Encephalomyelitis virus
• Causes neurological signs and encephalitis in pheasants, partridges, finches and turkeys
• In young turkeys and chickens, myocarditis, lymphoid necrosis in bursa and thymus
• Hemorrhagic enteritis and splenic necrosis in emu’s
• Western Equine Encephalomyelitis virus
• Encephalitis, myocarditis, hemorrhagic leiomyositis of intestine associated with vasculitis in emu
• Encephalitis in pigeon and neuro signs in turkeys
• Highland J virus:
• Encephalitis and myocarditis in partridges and young turkeys
• Associated with precipitous drop in egg production in turkeys
• Hepadna virus in ducks (hepatitis B virus):
• Common but no significant clinical disease or lesions
• Bunya virus (Turlock-like):
• Associated with encephalomyocarditis in an ostrich chick

1. Avian Parasitic diseases

• Protozoa: coccidia, histomonas, cryptosporidia, sarcocystis, toxoplasma, atoxoplasma, amoeba, microsporidia, trichomonas, leucocytozoon, malaria, haemoproteus, giardia, cochlosoma, spironucleus (Hexamita), balantidium, trypanosomes, hemoporozoa, etc.
• Nematodes: Ascarids, Capillaria, Syngamus, Tetrameres, Heterakis, Baylisascaris, etc.
• Cestodes: Raillietina, Davainea, Hymenolepis, etc.
• Trematodes: Prosthogonimus, Schistosomes, etc.
• Arthropods: mites, fleas, lice, etc.

1. Protozoa

• Common disease of many species of birds caused by species of genera primarily Eimeria and Isospora and are quite host specific
• Chickens: disease of universal importance
• Eimeria tenella (ceca), E. acervulina (upper small int.), E. maxima and E. necatrix (mid small intestine)
• Hemorrhagic, mucoid, necrotic, proliferative enteritis
• Numerous coccidia in different stages of development
• Turkeys: common, less severe than in chickens
• E. adenoides (ceca), E. meleagrimitis (mid small intestine)
• Mucoid, hemorrhagic, necrotic enteritis
• Geese: E. truncata occurs in kidney
• Nephritis and urate deposits
• E. anseris causes enteritis
• Ducks: renal coccidia due to E. boschadis, etc.
• Quail, partridges, and pheasants: various species of Eimeria causes enteritis
• In quail coccidiosis is commonly associated with ulcerative enteritis caused by Cl. colinum
• Pigeons: E. labbeana causes enteritis
• Psittacines:
• Species of Eimeria, E. dunsingi and Isospora can cause enteritis in budgerigars, lories, parakeets, parrots, etc.
• Passerines:
• Finches: Isospora lacazei has been associated with enteritis
• Cranes:
• E. gruis and E. reichenowi causes granulomatous enteritis, hepatitis, splenitis, pneumonia, myocarditis, etc. in whooping and sandhill cranes

• Also called black head, a common protozoal disease of turkeys and partridges
• Also in chickens, peafowl, quail, pheasants, rhea, etc.
• Etiology: Histomonas meleagridis
• Cecal worm, Heterakis gallinarum and earth worms act as accessory hosts
• Lesions: saucer shaped depressions or white foci in liver and fibrinonecrotic mucosa and thickened wall of ceca
• Granulomatous hepatitis and typhlitis associated with spherical protozoa, 8 - 21 um in diameter

• Common protozoa of various species of birds
• Chickens, turkeys, quail, ratites, ducks, pheasants, peafowl, psittacines, passerines, etc.
• C. baileyi, C. meleagridis and probably others
• Infect various body systems
• Cloaca, bursa of Fabricius and trachea most common
• Nasal cavity, sinus, bronchus, air sac, conjunctiva
• Proventriculus, intestine, ducts of pancreas, salivary and esophageal glands and bile duct
• Ureter, collecting tubules of kidney
• Inflammation and hyperplasia of epithelium

• Systemic protozoal disease of psittacines caused by S. falcatula
• Opossum is the definitive host, cowbirds and grackles are intermediate hosts
• Old World psittacines highly susceptible
• Young new world psittacines, canaries, finches, pigeons are susceptible, gallinaceous birds and anseriformes are resistant
• Sarcocystis with encephalitis has been described in a golden eagle, capercailles and chickens
• S. riley causes sarcocystosis in skeletal muscle of ducks, innocuous incidental finding
• Lesions
• Pulmonary edema, congestion, liver may be enlarged and mottled white, splenomegaly
• Lymphoplasmacytic interstitial pneumonia, edema and schizonts in capillaries
• Myocarditis, hepatitis, splenitis, nephritis, encephalomyelitis, neuritis, myositis, uveitis, etc., associated with schizonts
• Mature cysts in the heart and skeletal muscle
• Generally no reaction to cysts in muscles

• Sporadic disease of various species of birds
• It has been described in passerines (canaries), chickens, psittacines, pigeons, ducks, penguin, Japanese quail, chukar partridges, etc.
• Turkeys, pheasants, Bob White quail, owls resistant
• Etiology: T. gondii
• Lesions: encephalomyelitis, ophthalmitis, pneumonia, myocarditis, hepatitis, splenitis, neuritis, myositis, enteritis, adrenalitis, etc. associated with zoites and cysts
• Optic nerve; may be enlarged and yellow with necrotizing and granulomatous neuritis in chickens

• Common coccidian infection of canaries and finches, (previously called Lankesterella)
• Also in mynah’s, sparrows, grosbeaks
• Etiology: A. serini (Isospora serini), A. adiei
• Lesions
• Liver enlarged with white foci, splenomegaly
• Enteritis, hepatitis, myocarditis with arteritis, splenitis, myositis, etc.
• Schizonts in cytoplasm of macrophages
• Lankesterella-like coccidia associated with pneumonia in a Northern Cardinal

• It can be a significant disease of psittacines
• It has been reported in a variety of lovebirds, budgerigars, parrots, cockatiels, etc.
• Also reported in ostrich
• Encephalitozoon hellum, others?
• Lesions: granulomatous nephritis, necrosis and inflammation in liver, enteritis, pneumonia, etc. associated with Gram positive organisms

• A common infection of pigeons and raptors
• Also in canaries, finches, doves, psittacines, ducks, poultry, wild birds, etc.
• Etiology: T. gallinae

• Lesions
• Granulomatous stomatitis, pharyngitis, esophagitis, ingluvitis, and enteritis
• Hepatitis, pericarditis, airsacculitis, tracheitis, pneumonia, meningoencephalitis
• Sinusitis, rhinitis, episcleritis

• Disease of anseriformes, turkeys, raptors, wild birds and columbiformes
• Black flies (Simuliidae) are vectors
• Etiology: L. simondi in anseriformes, L. smithi in turkeys, L. marchouxi in columbiformes, L. toddi in falconiformes, L ziemanni in owls
• Infect both white and red blood cells
• Lesions
• Disseminated characteristic megaloschizonts in endothelial cells of liver, spleen, heart, brain, eye with hepatitis, myocarditis, encephalitis, etc.
• L. caulleryi, which causes severe disease in young chickens in south and eastern Asia, is classified as Akiba caulleryi
• Vectors are biting midges of genus Culicoides
• Lesions are similar to ducks
• Leucocytozoon-like infection has been described in budgerigars, parakeets and a buzzard
• Myositis, myocarditis and hemorrhages in skin, pericardium, pancreas, hepatosplenomegaly, etc.

• Hemoprotozoal infection of canaries, penguins and raptors caused by species of Plasmodium
• Ducks, pigeons, chickens, grouse, pheasants, sparrows, blackbirds, robin, etc. are susceptible
• Three species of Culicoides are vectors
• Etiology: P. relictum, P. elongatum, P. circumflexum, etc.
• Infect red blood cells and cells of MPS
• Lesions: anemia, interstitial pneumonia, hepatitis, splenitis, encephalitis, etc.
• Brown-black pigment (malaria pigment) in RBC, MPS Cells

• Hemoprotozoa of some significance primarily in columbiformes
• Common in raptors, water fowl, passerines, etc.
• Also seen in psittacines
• Etiology: H. columbae in pigeons and doves
• Biting flies of hippoboscids and Culicoides are vectors
• Infects red blood cells and endothelial cells
• Lesions: anemia, hepatitis, splenitis, myositis, pneumonia, etc.
• Schizonts and megaloschizonts can be seen

• Giardia psittaci cause of enteric disease in budgerigars
• Others: cockatiels, love birds, parrots, conures, many wild birds, herons , egrets, sparrows, etc.
• H. meleagridis an enteric protozoa of turkeys
• Others: pheasants, quail, partridge, ostrich, pea fowl, etc.
• Lesions
• Emaciation, fluid filled intestine, catarrhal enteritis

• Cochlosoma anatis, a flagellate enteric protozoon of small intestine is associated with catarrhal enteritis in turkeys
• Entamoeba gallinarum common in large intestine of turkeys, significance?
• Others: Chilomastix gallinarum in turkeys, Balantidium spp. in ostriches, Wenyonella philiplevinei in ducks, Blastocystis sp. in pheasants, etc.

• Hemosporozoa of undetermined taxonomy
• Disseminated myositis associated with cysts and high mortality in BW quail in California
• Also hepatitis, splenitis, myocarditis, nephritis, etc. associated with cysts, encephalomyelitis
• Large protozoan cysts of undetermined spp. associated with hepatitis, splenitis, pneumonia in canaries, conures, love birds, oropendola, etc.
• Amoeba of undetermined spp. associated with meningoencephalitis in a cockatiel
• Others: trypanosomes, aegyptianella, etc.

1. Nematodes

• Common intestinal parasitism of many birds
• Chickens, turkeys, pigeons, partridges, raptors, psittacines (Australian parakeets), passerines, etc.
• Etiology: Ascaridia galli (chicken), A. dissimilis (turkey), A. columbae, A. hermaphrodita, species of Porrocaecum and Contracaecum, etc.
• Lesions: loss of weight, intussusception, mild enteritis if in large numbers
• Eosinophilic enteritis in turkeys
• Granulomas in livers due to larval migration
• Bile duct hyperplasia and pericholangitis associated with larvae in bile ducts in parakeets

• Significant disease primarily of upper digestive tract in many species of birds
• Quail, pheasants, partridges, guinea fowl, turkeys, pigeons, chickens, raptors, ducks, pscittacines, etc.
• Etiology: C. contorta, C. annulata, etc.
• Lesions: hyperplastic mucosa, fibrinonecrotic esophagitis, ingluvitis, etc.
• C. obsignata, C. caudinflata may cause enteritis in galliformes and columbiformes

• Common condition in a variety of birds
• Chickens, emus, ostriches, psittacines, raptors, quail, partridges, wild birds, etc.
• Etiology: Baylisascaris procyonis (raccoon) and occasionally B. columnaris (skunk)
• Lesions: non-suppurative encephalomyelitis
• Larvae of Chandlerella quiscali, a filarid nematode of grackle has been associated with encephalitis in emu

• Common tracheal worm (gape worm) of pheasants
• Others: turkeys, geese, quail, peafowl, chickens
• Etiology: Syngamus trachea
• Lesions: granulomatous tracheitis and occasionally bronchitis
• Cyathostoma bronchialis can cause bronchitis and pneumonia in geese
• Also been associated with tracheitis in emus

• Dispharynx nasuta, Cyrnea colini, Tetrameres americana, Cheilospirura hamulosa and species of Acuaria, Synhimantis, Habronemia, Amidostomum, Hadjelia, etc.
• Occur in pigeons, chickens, quail, ducks, turkeys, pheasants, psittacines, passerines, etc.
• Lesions: proventriculitis and ventriculitis
• Geopetitia aspiculata (Habronemia) causes severe proventriculitis in passeriformes and others
• Libyostrongylus douglassii causes severe proventriculitis in ostriches

• Heterakhis isolonche: fibrous and granulomatous typhlitis in pheasants
• Trichostrongylus tenuis: enteritis in young grouse and geese
• Oxispirura mansoni: conjunctivitis in galliformes
• Thelazia sp. have been associated with conjunctivitis in psittacines
• Pelecitus calamiformis(filarid): tenosynovitis associated with adult nematodes in parrots
• Microfilariae are common in psittacines, especially cockatoos, not pathogenic
• Microfilariae associated with severe pneumonia in magpies
• Paronchocerca ciconarum (filarid): myocardial degeneration with adult nematodes in a Marabou Stork
• Cardiofilaria - heart worm in psittacines

1. Cestodes

• Common intestinal tapeworms of many species of birds
• Chickens, turkeys, ducks, geese, pigeons, psittacines, passerines, wild birds, etc.
• Etiology and lesions:
• Davainea proglottina (smallest); enteritis in chickens
• Raillietina echinobothridia: granulomatous enteritis in chickens
• Species of Raillietina, Hymenolepis, Amoebotaenia, etc. are common in psittacines and finches
• Pathogenic in large numbers, obstruction, enteritis, etc.

1. Trematodes

• Schistosomiasis: common in waterfowl
• Dendritobilharzia sp.
• Medial hypertrophy of vessels in the intestinal wall
• Rarely hepatitis, encephalitis, nephritis, enteritis
• Dicroceliidae: been associated with dilated bile ducts and severe cholangiohepatitis in cockatoos and an amazon parrot
• Gigantobilharzia sp. associated with hemorrhagic ulcerative colitis and cloacitis in a nanday conure
• Sphaeridiotrema globulus: causes severe ulcerative hemorrhagic enteritis in swans and cygnet and chickens (experimental)
• Philophthalmus gralli: associated with conjunctivitis in ostriches
• Collyriclum faba cause cysts in the skin of poultry, wild birds including robins
• Prosthogonimus sp. oviduct fluke of poultry
• Tanaisia bragai in collecting tubules of kidney in poultry, pigeons, etc.

1. Arthropods

• Most common ectoparasites of a variety of species of birds
• Chickens, canaries, finches, psittacines, pigeons, turkeys, pheasants, wild birds, etc.
• Etiology (see table 3): species of Dermanyssus, Onithonyssus, Knemidocoptes, Sternostoma, etc.
• Lesions
• Anemia
• Hyperkeratosis, acanthosis, epidermitis, dermatitis
• Blockage, granulomatous tracheitis, airsacculitis, pneumonia
• Cysts in skin, poor feather growth, loss of feathers, etc.

1. Avian toxicosis

• Generally ducklings, turkey poults and pheasants are more susceptible
• Aflatoxins (B1, B2, G1and G2): B1 most toxic, liver has congestion, necrosis, fatty change, karyomegaly, numerous mitotic figures, bile duct hyperplasia, fibrosis, etc.
• Immunosuppression, myocardial, kidney degeneration, etc.
• Model for hepatocarcinogenesis
• Citrinin, Ochratoxins, Oosporein: renal tubular necrosis and visceral urate deposition
• In addition vacuoles, bile duct hyperplasia, etc. in liver associated with citrinin and ochratoxins
• Trichothecenes (T2, DAS): radiomimetic effect, oral, proventricular and gizzard erosions, lymphoid necrosis and depletion, hepatic necrosis, etc.
• Fumonisins: hepatic necrosis, biliary hyperplasia, widening of growth plates, myodegeneration, etc.
• Moniliformin: myocardial degeneration, hepatic necrosis
• Fusarochromanone: tibial dyschondroplasia
• Cyclopiozonic acid: skeletal muscle, heart, liver, GI degeneration
• Zearalenone: mycotoxin with estrogen activity
• Cystic oviduct with inflammation, cysts in vent, etc.
• Ergotism: beak and toe necrosis

1. Heavy metals

• Lead: one of the most commonly reported toxic compounds of waterfowl and companion birds
• Lesions: hemorrhagic enteritis, myocardial degeneration, hyalinosis of cerebral vessels with hemorrhage, nephrosis, demyelination of nerves, etc.
• Acid fast intranuclear inclusions in renal tubular epithelial cells
• Zinc: common in companion birds, waterfowl
• Lesions: gizzard erosion, pancreatic acinar necrosis, enteritis, nephrosis
• Iron: seen in a variety of birds
• Lesions: hepatic necrosis, hemolysis of RBC

1. Ionophore toxicity

• Ionophores widely used as anticoccidials in poultry
• Toxicity most common in turkeys and chickens
• Also described in quail, guinea fowl, etc.
• Monensin, Lasalocid, Salinomycin, Narasin
• Various compounds interact and influence toxicity
• Lesions: degeneration of skeletal muscles (pectoral muscles not affected) and occasionally heart
• In addition demyelination and axonal degeneration of peripheral nerves and spinal cord have been associated with lasalocid toxicity

1. Selenium, salt, calcium

• Selenium: pulmonary congestion and edema in an ostrich chick
• Salt: causes right heart hypertrophy, dilation and ascites in turkey poults and broiler chicks and occasionally encephalomalacia
• Water high in salinity causes conjunctivitis, cataracts and hyperemia of brain in wild adult waterfowl
• Cystic testes in poultry?
• Calcium: nephrosis in young poultry

1. Vitamins

• Vitamin D: common in psittacines
• Soft tissue mineralization, proventriculus, heart, air sacs, etc.
• Vitamin A: conjunctivitis and rickets in chickens
• Hepatic degeneration, Ito-cell hyperplasia?

1. Gases; PTFE, Ammonia, CO

• Polytetrafluoroethylene (PTFE): Teflon coated pans when overheated release toxic gases
• Seen in companion birds, also in free flying birds
• Pulmonary congestion and edema
• Carbon monoxide: pulmonary congestion and edema, bright red colored blood
• Ammonia: conjunctivitis, corneal erosions and ulcers and sinusitis and tracheitis in poultry

1. Rodenticides

• Diphacinone, Brodifoucum: blood in abdominal cavity, hemorrhage in liver
• Zinc phosphide: hydropericardium, pulmonary edema, congestion and hemorrhage in liver, congestion in kidney

1. Antibiotics

• Gentamicin, Amikacin - nephrosis
• Sulfa drugs - disseminated hemorrhages, nephrosis
• Tetracyclines - nephrosis
• Furazolidone - round heart, hepatocellular vacuoles

1. Plants

• Avocado and oleander: myocardial degeneration
• Oak: nephrosis
• Coffee senna: degeneration of muscles
• Parsley: photosensitization, dermatitis

1. Others

• Organo-phosphates - acute and delayed neurotoxicity
• Acute, inhibition of acetyl cholinesterase, no lesions
• Delayed, axonal degeneration in peripheral nerves and spinal cord, chicken is the (test) animal model
• Nitrate, Nitrite: Brown mucus membranes, methemoglobinuria
• Arsenilic acid, nitro-phenyl-arsenic acid: demyelination of peripheral nerves
• Quaternary Ammonium: erosions and ulcers in upper GI tract
• Domoic acid (marine neurotoxin):
• In pelicans and cormorants
• Hemorrhage and necrosis in skeletal muscles

1. Avian Metabolic diseases

• In male mature buff Cochin chickens (Dr. D. Webb, IL)
• Severely enlarged cystic thyroid glands with follicles lined by flattened epithelial cells
• Genetics suspected

1. Hemochromatosis

• Abnormal accumulation of iron in tissues associated with tissue disturbance such as cirrhosis
• Most common in mynahs, toucans, crows, starlings, ducks, fruit doves, horn bills, psittacines, etc.
• Hepatic degeneration, fibrosis, myocardial degeneration, ascites, etc.
• Genetics, nutrition, hemorrhagic syndromes, starvation, etc.

1. Diabetes mellitus

• It has been described in psittacines, toco toucans and a red-tailed hawk
• Glucagon is the major glucose - regulating hormone in granivorous birds
• Carnivorous birds are similar to mammals
• Lesions
• Hyperplasia of islet cells
• Enlarged islets with eosinophilic cytoplasm in toco toucans
• Islet cell tumor

1. Amyloidosis

• Accumulation of amorphous eosinophilic material in various tissues
• Liver, spleen, intestine, adrenal, kidney, synovium, heart, pancreas, thyroid, skin, brain, lung, etc.
• Commonly associated with chronic infections
• Most common in ducks and finches
• Also in other water fowl, game birds, turkeys, psittacines, ratites, canaries, flamingoes, touracos, pigeons, doves, etc.
• Lesions
• Gross: ascites (water belly) in commercial ducks, firm enlarged and waxy liver sometimes with nodules, enlarged mottled white spleen, pale or brownish kidneys, etc.
• Microscopic: interstitial accumulation of amyloid in liver with hepatocellular atrophy in severe cases, kidney, adrenal, thyroid, pancreas, spleen, in the lamina propria of intestine and proventriculus, in subepithelium of synovium, bronchus, in myocardium, brain, skin, vessels, etc.
• Severe hepatic capsular fibrosis and nodules made up of hyperplastic hepatocytes

1. Gout (visceral and articular)

• Uric acid is the end product of protein and purine metabolism (uricotelic) in birds, where as in mammals’ urea is the end product (ureotelic)
• Birds lack the enzyme carbamyl phosphate synthetase to dispose of ammonia and the enzyme uricase to decarboxylate uric acid to allantoin
• Gout is a metabolic condition where abnormal accumulation of white chalky or white semifluid-like urates in soft tissues of various organs in the body
• Gout occurs as two distinct syndromes, visceral and articular gout
• These two syndromes differ in age of onset, frequency, sex predilection, gross and microscopic lesions, pathogenesis and causes
• Great deal of confusion exists between the two syndromes because urate deposition takes place in joints in visceral gout also
• Term "visceral gout" should be replaced with the term "visceral urate deposits"
• See table 4 to help clarify differences between the two syndromes

1. Hepatic Lipidosis

• Common in some psittacines, budgerigars, amazons, rose breasted cockatoos, shell parakeets, etc.
• Diet, environment, toxicities, hormones, genetics (shell parakeets) influence lipidosis
• Lesions: obesity, hepatic lipidosis, and lipidosis in liver and other organs in shell parakeets

1. Hemorrhagic fatty liver syndrome (chickens)

• Condition of obese layer-type chickens
• Fat in abdominal cavity, fatty livers, ruptured livers

1. Atherosclerosis

• Very common in psittacines especially amazons
• Others: ducks, geese, chickens, turkeys, ostriches, flamingoes, herons, vultures, falcons, pigeons, etc.
• Etiology: diet, environment, genetics, virus, age, etc.
• Marek’s disease virus (herpesvirus) can induce atherosclerosis in chickens
• White Carneaux pigeon used as model
• Lesions
• Thickened walls or plaques in brachiocephalic, carotid, abdominal aorta, etc., coronary arteries rarely involved
• Thickening of intima and media with lipid laden cells

1. Mucopolysaccharidosis type IIIB (emu)

• Also called Sanfilippo B syndrome
• First description in any animal
• Deficiency of N-acetyl-a -D-glucosaminidase
• Probably inherited as a autosomal recessive trait
• Signs and lesions
• Sudden death, neurological signs
• Ruptured liver or subcutaneous hemorrhages
• Accumulation of membrane bound substance in neurons of nervous tissue and visceral organs

1. Aortic aneurism/rupture

• Most common in turkeys, also in ostriches and emus
• Longitudinal slit cranial to kidneys or at the origin of aorta
• Medial degeneration and loss of elastic fibers
• Genetics, hypertension, low copper, vasa vasorum defect?
• Coronary artery aneurysm (turkeys)
• In male turkeys, 15 -16 weeks-old, 1.5-3.5% mortality
• Hemopericardium, hemorrhage across base of heart, medial degeneration of coronary artery, rupture
• Genetics, hypertension, low copper, increased body weights?

1. Round heart disease (turkeys)

• Also called spontaneous cardiomyopathy
• Common condition in young commercial turkeys
• Dilated ventricles, chronic passive congestion of liver
• Cause is not known, genetics?

1. Ascites syndrome (chickens)

• Common condition in broiler chickens
• Right heart hypertrophy, dilation, passive congestion of liver and ascites
• Rapid growth coupled with insufficient pulmonary capillary capacity aggravates pulmonary hypertension leading to right heart failure

1. Tibial dyschondroplasia (TD)

• Common condition in broiler chickens and turkeys and ducks
• Abnormal masses of cartilage below the growth plate primarily in the proximal tibiotarsus but occurs also in the tarsometatarsus
• Presence of prehypertrophic cartilage with no vascular channels
• Etiology: multifactorial, nutrition, genetics, mycotoxin, etc.
• Similar picture as TD can be seen grossly in the long bones of ratites but it is not TD nor is pathologic
• It is normal embryonic cartilage which gets resorbed by 6-8 weeks of age

1. Deep pectoral myopathy

• Seen in well muscled broilers and turkeys
• Green discoloration of primarily supracoracoideus muscle due to ischemic necrosis

1. Perirenal hemorrhage

• Seen in rapidly growing turkeys, 8-14 weeks of age
• Hemorrhage over portion or entire kidney
• Underlying vascular and cardiac problems?

1. Xanthomatosis

• Common in psittacines and occasionally in chickens
• Yellow subcutaneous swelling or nodules in the body cavity
• Giant cells, lymphocytes, macrophages with cholesterol clefts

1. Auto immune thyroiditis (chicken)

• Occurs spontaneously in obese strain of chicken
• Used as model to study Hashimoto’s thyroiditis
• Birds have long and silky feathers, large amount of abdominal fat
• Thyroids become small gradually as the bird matures and atrophies
• Lymphocytic infiltration with few macrophages and lymphoid nodules, loss of architecture, thyroid gland
• Antibodies to thyroglobulin
• Hyperlipidemia, low T3 and T4 and IgA deficiency

1. Diseases of Malnutrition

• In non-commercial poultry, psittacines, etc.
• Etiology: vitamin A deficiency
• Lesions: pustule-like nodules in upper GI tract, exudate in conjunctiva, nasal cavity, nephrosis, opaque dry cornea, hyperkeratosis of plantar surfaces
• Microscopic: squamous metaplasia of epithelium, hyperkeratosis

1. Polyneuritis

• Rarely seen in poultry
• Etiology: vitamin B1 (thiamin) deficiency
• Lesions: prominent peripheral nerves with edema and infiltration of mononuclear cells
• Malacia of the brain in fish eating birds

1. Rickets/osteomalacia

• Rickets in younger birds and osteomalacia in older birds
• In poultry, ratites, psittacines, zoo birds, etc.
• Etiology: deficiency or imbalance of calcium, phosphorus and vitamin D3
• Lesions: soft and pliable beak, claws and keel, beading of ribs, enlarged epiphysis, fractures of long bones, enlarged parathyroid glands
• Microscopic:
• Calcium deficiency - lengthened proliferation of Prehypertrophic Zone and short Degenerating Hypertrophied Zone (DHZ)
• Phosphorus deficiency/calcium excess: lengthened DHZ
• Vitamin D3 deficiency - similar to calcium deficiency

1. Encephalomalacia

• In young chickens, turkeys, pheasants, geese, ducks, etc.
• Etiology: vitamin E deficiency
• Lesions: soft and enlarged cerebellum, petechiae, hemorrhages especially in turkey poults
• Microscopic: malacia, hemorrhage, vascular thrombosis, demyelination in brain
• Occasionally spinal cord involved, poliomyelomalacia
• Yellow fat disease in wild birds: herons, etc.
• Fat is brownish yellow, steatitis

1. Muscular dystrophy/exudative diathesis

• In chickens, quail, turkeys, ducks, etc.
• Etiology: vitamin E/Selenium deficiency
• Lesions
• Subcutaneous green-tinged fluid
• Pale streaks in skeletal muscles, gizzard
• Degeneration of skeletal muscle, heart, gizzard, pancreatic acinar necrosis

1. Curled-toe paralysis

• Seen in chicks, turkey poults, ducklings
• Etiology: vitamin B2 (riboflavin deficiency)
• Lesions: swelling of peripheral nerves, axon and myelin degeneration, Schwann cell proliferation, etc.

1. Perosis/slipped tendon (chicks, poults)

• Etiology: manganese and choline deficiency
• Lesions: deformity of hocks, enlargement of condyle, bowing of tarsometatarsus, slipping of gastrocnemius tendon
• Deficiency of pantothenic acid, biotin, folic acid, niacin can cause similar lesions
• In addition dermatitis can be seen in birds deficient in biotin and pantothenic acid and poor feathering and anemia in niacin deficiency

1. Goiter

• Common in psittacines especially in budgerigars
• Also seen in pheasants, geese, chickens, etc.
• Etiology: Iodine deficiency
• Lesions: enlarged thyroid glands, some times cystic
• Microscopic: severe hyperplasia of follicle epithelium with papillary projections, pale or lack of colloid, hemorrhage and severe effacement of the gland in extreme cases

1. Neoplasia

• Most common in chickens and psittacines especially budgerigars among birds

• Birds in the order Passeriformes have the lowest incidence
• In chickens most are caused by viruses such as retroviruses and herpesvirus (Marek’s Disease)
• Etiology is not known in other species of birds
• Incidence in budgerigars range from 16 to 24 %
• Some of the common tumors in psittacines include renal tumors, fibrosarcoma, lymphoma, papilloma, tumors of gonads, gastric carcinoma, leiomyosarcoma, pituitary adenoma, etc.

Table 1: Oncogenes originally identified through their presence in transforming retroviruses

Abbreviations: EGF-R, epidermal growth factor; PDGF, platelet-derived growth factor; TH-R, thyroid hormone receptor; TF, nuclear transcription factor. Chicken genes are shown in bold.

Ref: R. A. Weiss. The oncologist´s debt to the chicken. Avian Path. 27:S8-S15, 1998.

Table 2. Relative frequency of microscopic lesions in various organs of psittaciformes diagnosed of having PDS

* Incidental findings not included.

Ref: Shivaprasad et al., Pathology of proventricular dilation syndrome, Vet Path 34:500, 1997.

Table 3. Mites in Birds

* Most common

Table 4: Differences between Visceral Gout and Articular Gout in Birds

Ref: Shivaprasad, H. L. An overview of anatomy, physiology and pathology of urinary system in birds, AAV Proceedings, pp. 201-205, 1998