DISEASES OF WILDLIFE
AFIP REVIEW OF GROSS MORBID ANATOMY OF ANIMALS
C.L. DAVIS, DVM FOUNDATION
MARCH 22, 1999
John R. Fischer
Southeastern Cooperative Wildlife Disease Study
College of Veterinary Medicine
The University of Georgia
Athens, GA 30602
I. General considerations
A. The same diseases and lesions generally occur in wild and domestic animals
B. There is a smaller number of diseases seen only in wild animals
C. Some diseases are observed ONLY in captive or farmed "wild" animals and are not reported in free-ranging wildlife
D. This review will cover diseases reported in free-ranging and captive wild birds and mammals of North America
E. Numerous persons contributed materials for this presentation and their help is greatly appreciated
F. An excellent reference on wildlife diseases is the second edition of the Field Manual of Wildlife Diseases in the Southeastern United States, W.R. Davidson and V.F Nettles, eds. This new edition contains over 400 pages of information on common wildlife diseases including approximately 130 color plates of gross lesions. The book may be ordered from the American Association for Vocational Instructional Materials at 1-800-228-4689. The cost is $20.00 plus shipping and handling.
II. Diseases of wild birds
A. Viral diseases
1. Avian pox
Etiology: Genus Avipoxvirus. Some viruses are adapted to a single avian species, others infect more than one species.
Species: Virtually all orders of birds including galliforms - turkeys, quail, grouse; passeriforms - songbirds; anseriforms - ducks and geese; falconiforms and strigiforms - raptors (J Wildlife Diseases 33:323-327, 1997); columbiforms - pigeons and doves.
Lesions: Multifocal to coalescing, proliferative and necrotizing dermatitis (epithelial hyperplasia with ballooning degeneration and large intracytoplasmic inclusions) in dry form; oral cavity and esophagus affected in wet form. Restricted to non-feathered portions of body (face and legs).
2. Duck plague, duck viral enteritis (DVE)
Affected species: Ducks and geese. Seen in domestic and semi-wild ducks, occasionally in wild ducks.
Lesions: Acute, hemorrhagic, multifocal, fibrinonecrotic, ulcerative enteritis sometimes in characteristic annular bands at gut-associated lymphoid tissue. Multifocal necrotizing hepatitis, stomatitis, esophagitis, splenitis.
3. Herpesvirus of raptors
Etiology: Probably pigeon herpesvirus
Affected species: Pigeons. Raptors including hawks and owls may become infected via ingestion of prey species.
Lesions: Multifocal necrotizing hepatitis and splenitis as well as pharyngitis, esophagitis, and tracheitis.
4. Marble spleen disease, pheasant adenovirus
Etiology: Avian adenovirus (group II)
Affected species: Pen-raised pheasants (Avian Diseases 40:306-311, 1996; Avian Diseases 39:68-73, 1995). Also may occur in other farmed gamebirds, turkeys, chickens.
Lesions: Splenomegaly with multifocal necrotizing splenitis. Pulmonary hemorrhage also may occur.
Note: Quail bronchitis is caused by avian adenovirus (type 1); bobwhite quail (mostly pen-raised birds) have catarrhal conjunctivitis, tracheitis, bronchitis, and airsacculitis.
B. Bacterial diseases
1. Avian cholera, fowl cholera, avian pasteurellosis
Etiology: Pasteurella multocida
Affected wild species: waterfowl, gulls, crows, recent reports in raptors (Avian Diseases 41:203-213, 1997; Avian Diseases 40:908-918, 1996)
Lesions are those of peracute septicemia: Multifocal hepatic necrosis is the classic lesion. Multifocal ecchymoses or petechiae in epicardium and catarrhal enteritis may occur. In raptors - septicemic lesions plus esophageal abscesses in Buteo hawks
2. New duck disease, duck septicemia
Etiology: Riemerella anatipestifer
Affected species: Very rare in wild waterfowl (more frequently reported in captive waterfowl and domestic birds)
Lesions: Fibrinous or exudative polyserositis - pericarditis, perihepatitis, airsacculitis. Meningitis and multiple thromboses may be observed microscopically.
3. Avian tuberculosis, mycobacteriosis
Etiology: Mycobacterium avium
Affected species: All avian species are susceptible. More frequently reported among wild species closely associated with domestic stock and in scavengers.
Lesions: Multifocal granulomas with central caseous necrosis (tubercles) - liver most commonly affected in waterfowl, also seen in spleen, lung, and intestines. Infrequent lesions in bones and marrow. Chronically affected birds are emaciated.
4. Avian salmonellosis
Etiology: Salmonella spp.
Affected species: Most avian orders from waterfowl to songbirds. Often seen as songbird epornitics at bird feeders in winter.
Lesions: Focally extensive or diffuse fibrinonecrotic esophagitis, ingluvitis. Multifocal caseonecrotic to granulomatous lesions may occur in skeletal muscle, heart, other tissues.
5. Mycoplasmal conjunctivitis, house finch conjunctivitis
Etiology: Mycoplasma gallisepticum (MG)
Affected species: Almost exclusively in house finches, occasionally in American goldfinches. First recognized in DC area in early 1994, disease now extends over entire eastern U.S. and Canada.
Lesions: Unilateral or bilateral exudative conjunctivitis often with mucopurulent nasal discharge, rarely with infraorbital sinusitis. Microscopic lesion is lymphoplasmacytic inflammation with epithelial hyperplasia in conjunctivae, cornea, nasal turbinates, and trachea (Avian Diseases 40:335-341, 1996; Vet Path 32:592, 1995, Abstract 186; J Wildlife Diseases 34:289-296, 1998).
Mycoplasmal conjunctivitis notes: Keratoconjunctivitis in chickens associated with MG (Vet Path 32:11-18, 1995). Conjunctivitis associated with Mycoplasma sturni in a European starling (J Wildlife Diseases 33:336-339, 1997) and in blue jays and northern mockingbirds (J Wildlife Diseases 34:403-406, 1998).
6. Infectious sinusitis, infraorbital sinusitis
Etiology: Mycoplasma gallisepticum
Affected species: Three reports in wild turkeys, all closely associated with domestic poultry.
Lesions: Serous to fibrinous infraorbital sinusitis.
7. Quail disease, ulcerative enteritis
Etiology: Clostridium colinum
Affected species: Pen-raised bobwhite quail, other captive gamebirds and domestic poultry
Lesions: Initially hemorrhagic enteritis in duodenum followed in survivors by multifocal to coalescing necrotizing, ulcerative enterocolitis and typhlitis. Acute, multifocal, necrotizing hepatitis may occur.
8. Chlamydiosis, psittacosis, ornithosis, parrot fever
Etiology: Chlamydia psittaci
Affected species: Waterfowl, herons, gulls, and pigeons are most commonly affected wild birds.
Lesions: Splenomegaly most common; less common - fibrinous polyserositis, hepatomegaly and focal hepatic necrosis, pulmonary edema, conjunctivitis, infraorbital sinusitis.
Etiology: Escherichia coli
Affected species: Infrequent in wild turkeys
Lesions: Multifocal to coalescing granulomatous hepatitis, enteritis, typhlitis
C. Protozoal diseases
1. Histomoniasis, blackhead
Etiology: Histomonas meleagridis - protozoa within the ova of cecal worms (Heterakis gallinarum) are ingested by birds
Affected species: Wild turkey, grouse, quail, chukar partridge. Subclinical carriers include pheasant and chicken.
Lesions: Multifocal, necrotizing hepatitis (often with sunken, dark central area surrounded by a pale raised rim resulting in characteristic target or bullseye appearance); fibrinonecrotic, ulcerative typhlitis often with cecal cores or plugs
2. Trichomoniasis, crop canker
Etiology: Trichomonas gallinae
Affected species: Doves and pigeons, raptors ("frounce"), other wild birds
Lesions: Focally extensive caseous necrosis of oral cavity, esophagus, crop. May see multifocal granulomatous pneumonia, hepatitis, myocarditis. Emaciation in chronic cases.
3. Sarcocystosis, sarcosporidiosis, rice breast
Etiology: Sarcocystis spp. (S. rileyi most common in N.A. waterfowl)
Affected species: Wild ducks most frequently, also geese, swans, and songbirds as well as some mammals and reptiles.
Lesions: Multiple, cylindrical, off-white, protozoal cysts in pectoral and other skeletal muscles sometimes with mineralization.
Etiology: Toxoplasma gondii
Affected species: Recent reports in wild turkeys (J Wildlife Diseases 31:255-258, 1995) and barred owls (Avian Diseases 41:738-740, 1997), additional avian species
Lesions: Multifocal necrosis of liver, spleen, kidney, lung, etc. Microscopically the inflammatory infiltrates are predominated by macrophages with plasma cells, lymphocytes, and neutrophils.
D. Ectoparasitic diseases
1. Scaly leg mites
Etiology: Knemidokoptes mutants, K. jamaicensis
Affected species: Upland game birds such as wild turkeys and quail, passerine birds such as robins (J Wildlife Diseases 35:1-7, 1999) and grackles
Lesions: Hyperkeratotic dermatitis of legs with scaling and crusting
E. Helminthic diseases
1. Crop worms, crop capillariasis
Etiology: Capillaria contorta, C. annulata
Affected species: Quail, turkeys, grouse, pheasants, partridges
Lesions: Severe infestations cause esophageal and ingluvial hypertrophy and hyperplasia with catarrhal to fibrinous inflammation.
2. Proventriculus worms
Etiology/affected species: Eustrongylides in fish-eating birds such as herons, egrets, mergansers; Tetrameres spp. in ducks, quail
Lesions: Eustrongylides penetrates proventricular wall and incites marked fibrosis around nematode on serosal surface. Worms are bright red. Tetrameres spp. often subclinical, worms also are bright red.
3. Gizzard worms, stomach worms, ventricular nematodiasis
Etiology: Amidostomum spp and Epomidostomum spp.
Affected species: Geese, ducks, swans, coots
Lesions: Focal, hemorrhagic, ulcerative ventriculitis
4. Tracheal worms, gapeworms
Etiology: Syngamus trachea
Affected species: Wild turkey, grouse, quail, other wild and domestic galliformes, many passerines
Lesions: Catarrhal tracheitis to complete tracheal obstruction by nematodes
5. Pericloacal trematodes
Etiology: Collyriclum faba
Affected species: Passerine birds such as grackles
Lesions: Pericloacal cysts with two flukes/cyst (trematodiasis), severe infestation may obstruct cloaca
F. Fungal diseases
Etiology: Aspergillus fumigatus most common
Affected species: Probably all avian species are susceptible; frequently seen in waterfowl and loons likely immunocompromised due to stress of migration, crowding, climate, etc.
Lesions: Multifocal granulomatous pneumonia; multifocal to coalescing granulomatous airsacculitis and serositis with intralesional fungi
F. Toxicologic diseases
1. Lead poisoning
Source: Spent shot in wetlands most common, fishing sinkers less common
Affected species: Ducks (J Wildlife Diseases 34:673-687, 1998), geese (Vet Path 30:522-528, 1993), swans, loons, and shorebirds; secondary poisoning of raptors (eagles and hawks) feeding on poisoned waterfowl or gunshot animals
Lesions: Impactions of esophagus, proventriculus, or gizzard due to vagal paralysis; emaciation in chronic cases; acute renal tubular necrosis; biliary stasis; gall bladder distention; bile staining of gizzard mucosa and liver; hydropericardium.
G. Miscellaneous diseases/lesions/processes
1. Visceral gout, visceral urate deposition
Etiology: Secondary to numerous processes
Affected species: All avian species
Lesions: Chalky, urate deposits in kidneys and on surfaces of heart, liver, mesentery, air sacs, muscles, etc.
2. Steatitis in herons
Etiology: Unknown, possible nutritional deficiency
Affected species: Great blue heron
Lesions: Severe multifocal steatitis, especially of abdominal fat
Etiology: Secondary to numerous disease processes
Affected species: All avian species
Lesions: Enlargement /pallor of tissues including spleen, liver, kidney due to amyloid deposition; splenic thrombosis
III. Diseases of wild mammals
A. Viral diseases
1. Canine distemper
Etiology: Canine morbillivirus.
Affected species: Raccoon (J Vet Diagn Invest 10:194-196, 1998); canids including gray fox, coyote; mustelids including black-footed ferret, skunk; large cats in Africa and in zoo collections (J Vet Diagn Invest 6:277-288, 1994).
Lesions: Interstitial pneumonia, mucopurulent conjunctivitis and rhinitis, diarrhea, hyperkeratosis of foot pads. Microscopic lesions as in domestic animals including pneumonia, encephalitis, lymphoid depletion, intranuclear and intracytoplasmic inclusion bodies. May be secondary toxoplasmosis or bacterial infections.
2. Parvoviral disease
Etiology/affected species: Canine parvovirus - coyotes, wolves (J Wildlife Diseases 33:321-322, 1997); feline panleukopenia parvovirus - bobcat; mink enteritis virus - farmed mink; raccoon parvovirus - raccoons (usually in captivity)
Lesions: Segmental, hemorrhagic, necrotizing enteritis with crypt depletion; lymphoid depletion (lymphadenopathy, thymic atrophy, etc.). Secondary infections may occur in these immunocompromised animals.
Aleutian disease of farmed mink: Characterized in adults by plasmacytosis, hypergammaglobulinemia, immune complex-mediated glomerulonephritis and arteritis. Lesions of immune complex disease - hepatosplenomegaly and lymphadenopathy due to lymphoplasmacytic/histiocytic infiltrates, glomerulonephritis. In young mink - acute interstitial pneumonia (Vet Path 31:216-218, 1994)
3. Woodchuck hepatitis
Affected species: Woodchucks
Lesions: Chronic-active, diffuse hepatitis with possible progression to hepatoma/hepatic carcinoma
Affected species: All species susceptible. Primary terrestrial species varies with region - skunk, raccoon (J Vet Diagn Invest 10:194-196, 1998), gray fox, red fox, coyote. Bats - human cases in U.S. most frequently associated with silver-haired bat rabies strain.
Lesions: No gross lesions. Microscopic encephalomyelitis with neuronal cytoplasmic inclusions, especially hippocampus in carnivores, Purkinje cells in herbivores
5. Shope fibroma
Affected species: Cottontail rabbit
Lesions: Single to multifocal, cutaneous, fibromatous masses
6. Squirrel fibroma
Affected species: Gray squirrels, woodchucks
Lesions: Multifocal and sometimes coalescing, cutaneous, fibromatous masses
7. Deer fibroma, infectious cutaneous fibroma
Affected species: White-tailed deer; other wild ruminants probably are infected by species-specific papovaviruses
Lesions: Multiple proliferative cutaneous masses, sessile to pendulous, most often on head or hindquarters. Superficial necrosis with secondary bacterial infection may occur. Microscopic lesion consists of cutaneous fibroproliferative mass with epithelial hyperplasia.
8. Hemorrhagic disease of deer
Etiology: Bluetongue and Epizootic Hemorrhagic Disease orbiviruses (several serotypes)
Affected species: Primarily white-tailed deer with other deer and wild ruminant species also affected (J Wildlife Diseases 31:30-36, 1995)
Lesions: Pathogenesis characterized by viral infection and damage of vascular endothelium with loss of vascular integrity.
Peracute form - subcutaneous edema of head and neck, pulmonary edema, hydropericardium, hydrothorax, hydroperitoneum;
Acute form - peracute lesions plus multifocal hemorrhages of heart (pulmonary artery) and gastrointestinal tract, erosive and ulcerative glossitis, stomatitis, rumenitis, and omasitis;
Chronic form - ulcerative glossitis and rumenitis with rumen papillae atrophy and mucosal scarring, interruptions in hoof wall.
NOTE: A newly recognized adenoviral disease with similar lesions was reported in deer in 1996 in California. Intranuclear inclusion bodies were present in addition to the above-described lesions (J Wildlife Diseases 33:801-811, 1997; Vet Path 33:125-132, 1996).
9. Malignant catarrhal fever
Etiology: Gammaherpesviruses - "Ovine herpesvirus-2" in sheep-associated form (most common in captive wild ruminants); Alcelaphine herpesvirus-1 in wildebeest-associated form seen in zoo collections of ruminants
Affected species: Captive white-tailed deer and bison - very rarely reported in free-ranging wild ruminants
Lesions: Multifocal fibrinonecrotic, erosive to ulcerative inflammation of epithelial surfaces - conjunctivitis, nasal dermatitis, rhinitis, stomatitis, esophagitis, rumenitis, abomasitis, enteritis; corneal edema/opacity; multifocal whitish, nodular masses consisting of extensive perivascular proliferations of lymphoblastic/lymphocytic cells. Fibrinoid vascular necrosis also is observed microscopically. Chronic form of disease in cattle characterized by obliterative arteriopathy (J Vet Diag Invest 7:108-121, 1995) also observed in bison (J Vet Diagn Invest 10:255-262, 1998).
10. Additional viral diseases of domestic animals that may occur in wild animals, captive animals, or under experimental conditions
Lesions are similar or identical to those of domestic animals
Infectious canine hepatitis: Adenovirus - affected species include canids (coyote, wolf, fox), skunks
Bovine viral diarrhea (pestivirus), infectious bovine rhinotracheitis (herpesvirus), vesicular diseases - foot and mouth disease (picornavirus), rinderpest and peste des petits ruminants (morbillivirus). Natural and experimental disease in white-tailed deer and other ruminants
11. Additional viral infections without gross lesions in wild animals
Hantavirus (Sin Nombre and Blackwater canal viruses) - inapparent infections in wild rodent reservoirs including the deer mouse (Peromyscus maniculatus) and cotton rat (Sigmodon hispidus)
B. Bacterial Diseases
1. Lyme Disease
Although wildlife is involved in the natural history of Borrelia burgdorferi, disease is not reported in wild animals
2. Tularemia, rabbit fever
Etiology: Francisella tularensis
Affected species: Cottontails, jackrabbits, and other lagomorphs; rodents including muskrat, beaver; occasional cases in numerous mammalian species
Lesions: Classic lesion in rabbits is multifocal necrotizing hepatitis and splenitis; necrotizing lymphadenitis with abscessation of mesenteric nodes; fibrinopurulent pneumonia; necrotizing enteritis; fibrinous peritonitis
3. Tyzzer's disease (Errington's disease of muskrats)
Etiology: Clostridium piliformis
Affected species: Wild muskrats, captive coyotes and other species, experimental infection of cottontail rabbits
Lesions: Focally extensive necrotizing and hemorrhagic typhlocolitis; multifocal necrotizing hepatitis
Etiology: Staphylococcus aureus
Affected species: Primarily cottontail rabbit
Lesions: Abscessation of lymph nodes, especially axillary, cervical, inguinal, or mandibular.
5. Brain abscess
Etiology: Primarily Actinomyces pyogenes; other bacteria include Staphylococcus spp., Streptococcus spp., Pasteurella multocida
Affected species: Most common in white-tailed deer, especially in males and associated with antler pedicels
Lesions: Abscesses of brain and meninges, sometimes seen as diffuse, suppurative leptomeningitis
Etiology: Mycobacterium bovis
Affected species: Free-ranging white-tailed deer (J Wildlife Diseases 33:749-758, 1997) and coyotes (J Wildlife Diseases 34:632-635, 1998) in Michigan and in bison in Canada; captive deer and elk
Lesions: Multifocal granulomatous inflammation of tissues including lymph nodes of head, thorax, abdomen; lung, pleura, and liver. Lesions in elk may be granulomatous to pyogranulomatous with abundant purulent material (Vet Path 32:215-220, 1995).
a. Etiology: Brucella abortus
Affected species: Free-ranging elk and bison in the Greater Yellowstone Area; bison in Wood Buffalo National Park of Canada
b. Etiology: Brucella suis biotype 4
Affected species: Barren ground caribou and reindeer
Lesions: Necrotizing placentitis; caseous to granulomatous inflammation of epididymis, testes or other tissues
Note: Vaccination trials of B. abortus strains 19 and RB51 have been conducted in bison (J Wildlife Diseases 33:146-151, 1997; J Wildlife Diseases 34: 825-829, 1998) with varying effects on dam, fetus, calves.
8. Pneumonia complex of bighorn sheep
Etiology: Multifactorial including Pasteurella multocida, lungworms (Protostrongylus spp.), stress
Affected species: Bighorn sheep
Lesions: Cranioventral, fibrinous pleuropneumonia similar to bovine respiratory disease complex
Note: Pneumonic pasteurellosis of bison due to P. hemolytica serotype A6 (J Vet Diagn Invest 10:360-362, 1998).
Etiology: Dermatophilus congolensis
Affected species: Deer and other wild and domestic animals
Lesions: Multifocal to coalescing alopecia with crusting to pustular dermatitis
10. Additional bacterial diseases with lesions similar to those of domestic animals
Anthrax: Bacillus anthracis; in deer and other wild ruminants as well as additional species - splenomegaly
Johne's disease: Mycobacterium avium subsp. paratuberculosis; in deer and other ruminants - granulomatous enteritis and lymphadenitis
Leptospirosis: Leptospira interrogans serovars; lesions generally are not apparent in infected animals including raccoons, skunks, deer.
Plague: Yersinia pestis; in ground squirrels, prairie dogs, other wild species; septic lesions include suppurative lymphadenitis, multifocal hepatic necrosis, multifocal necrotizing pneumonia (J Wildlife Diseases 33:720-732, 1997).
Enteric yersiniosis: Yersinia pseudotuberculosis; in captive deer, elk; microabscesses of small intestine and lymph nodes associated with numerous bacteria (J Vet Diag Invest 7:78-81, 1995)
C. Fungal disease
Etiology: Emmonsia (Chrysosporium) crescens
Affected species: Numerous wild animals including skunks, rodents
Lesions: Multifocal to miliary granulomatous pneumonia
D. Ectoparasitic diseases
1. Sarcoptic mange, scabies
Etiology: Sarcoptes scabiei
Affected species: Wild canids, especially red fox (J Wildlife Diseases 34:600-611 & 620-624, 1998) and coyote
Lesions: Multifocal to generalized alopecia with crusting (hyperkeratotic) to pustular dermatitis; emaciation in generalized cases
2. Demodectic mange
Etiology: Demodex spp. are typically host species-specific
Affected species: Deer - Demodex odocoilei; other wildlife species
Lesions: Mild to severe alopecia with dermal thickening and pustules (folliculitis)
3. Chiggers (Trombidiosis)
Etiology: Eutrombicula spp. and Neotrombicula spp.
Affected species: Reported in white-tailed deer (Vet Path 34:350-352, 1997).
Lesions: Mild alopecia and exudative dermatitis around muzzle and eyes associated with orange granular material (larval mites). Chronic eosinophilic dermatitis with attached larval mites with stylosomes (feeding tubes) penetrating epidermis and dermis
4. Ear mites
Etiology: Psoroptes cuniculus
Affected species: White-tailed deer, mule deer, domestic rabbits
Lesions: Heavily infested deer have hyperkeratosis of external ear canal and concave surface of pinnae with excess wax and necrotic debris
Note: Psoroptic mange in elk and bighorn sheep is caused by Psoroptes sp. and is characterized by alopecia and hyperkeratotic dermatitis
5. Tick infestations
Etiology: Varies with region and host species
White-tailed deer: In southeastern and midwestern U.S. severe Amblyomma americanum infestations cause alopecia and exudative dermatitis, especially in periorbital areas
Moose: "Ghost moose" disease is caused by heavy infestations of Dermacentor albipictus; alopecia may be bilaterally symmetrical with hyperkeratosis, emaciation
Tick paralysis of songbirds usually is caused by Ixodes brunneus and no lesions are apparent
a. Cutaneous warbles, bots, wolves
Etiology: Cuterebra spp.
Affected species: Rabbits, gray squirrels and other rodents
Lesions: Nodular skin swelling with intralesional fly larva
b. Nasal bots
Etiology: Cephenemyia spp.
Affected species: White-tailed deer and other wild cervids
Lesions: Intrapharyngeal fly larva with no associated lesions
E. Helminthic diseases
1. Giant liver fluke
Etiology: Fascioloides magna
Affected species: White-tailed deer are considered the definitive hosts; other wild ruminants including moose, elk, bison, and exotic deer are susceptible to infection
Lesions: In deer liver there may be multiple encapsulated cystic structures containing two or more flukes and reddish-brown fluid. Fluke migration in liver may cause subacute hepatitis with fibrosis and accumulation of blackish "fluke pigment" in hepatic parenchyma, fibrotic tissue, and lymph nodes.
Etiology: Paragonimus kellicotti
Affected species: Muskrat, bobcat, other wild species
Lesions: Encysted pairs of flukes in lungs, usually subclinical infection
a. Echinococcus granulosus - Canids are definitive hosts and ungulates are intermediate hosts.
"Hydatid disease" - single or multiple hydatid cysts in lung, liver, other organs of ungulates
b. E. multilocularis - Canids/felids are definitive hosts (red fox is the major host), rodents are intermediate hosts.
"Alveolar hydatid disease" - multiple, progressive, invasive masses of hydatid cysts in liver, lung, other tissues
4. Larval cestode infestations
a. Taenia pisiformis - Wild and domestic canids are definitive hosts, rabbits are the major intermediate host.
Multiple cysticerci in rabbit abdominal cavity or on serosal surfaces, occasional hepatic fibrosis due to larval migration; subclinical
b. Taenia hydatigena - Wild and domestic canids are definitive hosts, wild and domestic ungulates are intermediate hosts.
Multiple cysticerci attached to or within abdominal viscera; subclinical
5. Meningeal worm of white-tailed deer (brain worm)
Etiology: Parelaphostrongylus tenuis
Affected species: White-tailed deer are unaffected definitive hosts; other ungulates affected including moose, elk, other deer species
Lesions: None in white-tailed deer; in affected species there is multifocal cavitation with nonsuppurative to eosinophilic inflammation of spinal cord and brain often with intralesional worms or larvae
6. Raccoon and skunk roundworms
Etiology: Baylisascaris procyonis - raccoon; B. columnaris - skunk
Affected species: Raccoons and skunks are unaffected definitive hosts; aberrant hosts including rabbits, woodchucks, other mammals and birds are clinically affected
Lesions: Larval roundworm migration most frequently causes neurologic disease without gross lesions. Microscopically there may be multifocal cavitation with eosinophilic encephalomyelitis and intralesional larvae.
Etiology: Dirofilaria immitis
Affected species: Wild canids including coyotes, wolves, foxes; also occasional reports in black bear, river otter
Lesions: Cardiomegaly (especially right-sided) with lesions of congestive heart failure, caval syndrome
Etiology: Elaeophora schneideri
Affected species: Mule deer is unaffected definitive host; white-tailed deer, elk, moose, domestic sheep (sorehead)
Lesions: Worms are in carotid arteries and branches - oral food impactions, mandibular degeneration and tooth loss in white-tailed deer; ocular, cutaneous and brain infarctions in elk and moose (J Vet Diagn Invest 10:82-84, 1998). Microscopically there is verminous arteritis with thrombosis.
Note: Recent publication regarding Elaeophora elaphi in portal vein of red deer in Spain (Vet Path 32:250-257, 1995)
9. Abdominal worm
Etiology: Setaria yehi
Affected species: White-tailed deer and most other North American cervids
Lesions: Usually no lesions; worms free or encysted on serosal surfaces of abdominal viscera
10. Subcutaneous worm
Etiology: Dracunculus insignis
Affected species: Raccoons primarily, also mink, otters, and foxes
Lesions: Subcutaneous and muscular swelling with eosinophilic inflammation on lower portions of limbs
11. Filarial dermatitis
Etiology: Filaria taxideae
Affected species: American badger, striped skunk
Lesions: Ulcerative dermatitis (subepidermal vesiculobullous filarial dermatitis) in badgers - especially in sparsely-haired inguinal area (Vet Path 30:343-351, 1993) and over dorsal head, neck and thorax of skunk (J Wildlife Diseases 33:873-876, 1997)
12. Tracheal worm
Etiology: Filaroides osleri
Affected species: Wild canids including coyote and wolf
Lesions: Multifocal, nodular, granulomatous tracheobronchitis with intralesional nematodes
Etiology/affected species: Dictyocaulus viviparus - white-tailed and mule deer, elk, moose, other ruminants; Protostrongylus stilesi and P. rushi - bighorn sheep and native goats
Lesions: Catarrhal tracheobronchitis with intraluminal nematodes; associated with bighorn sheep pneumonia complex
14. Esophageal worm
Etiology: Spirocerca lupi
Affected species: Wild canids including coyote, wolf
Lesions: Multifocal, nodular, eosinophilic granulomatous esophagitis and/or aortitis with fibrosis; possible progression of esophageal nodules to sarcoma
15. Gullet worms (gongylonemiasis)
Etiology: Gongylonema pulchrum - esophagus and oral cavity; G. verrucosum - rumen, omasum
Affected species: Wild ruminants including white-tailed deer and elk; black bears
Lesions: Mucosal or submucosal nematodes in above tissues with characteristic zipper pattern; no inflammation
16. Stomach worms
Etiology: Physaloptera spp., Gnathostoma spp.
Affected species: Raccoons, opossums, wild carnivores and omnivores
Lesions: Nematodes attached to gastric mucosa cause multifocal erosive to ulcerative, sometimes nodular gastritis; usually incidental finding
17. Abomasal worms
Etiology: Haemonchus contortus; other species usually not grossly apparent
Affected species: Deer, especially captive animals; other ruminants including elk, sheep, goats
Lesions: Parasitism and malnutrition syndrome of deer is characterized by emaciation, anemia, numerous abomasal worms grossly apparent with H. contortus.
18. Giant kidney worm
Etiology: Dioctophyma renale
Affected species: Primarily mink (J Vet Diagn Invest 10:111-113, 1998), other mustelids, canids
Lesions: Large, red nematode in right kidney, rare in left kidney or abdominal cavity; total replacement of renal parenchyma with cystic cavity containing worm
F. Protozoal diseases
1. Sarcocystosis, sarcosporidiosis
Etiology: Sarcocystis spp.
Affected species: Rabbits, rodents and other herbivores are intermediate hosts, carnivores are definitive hosts
Lesions: Multiple protozoal cysts in skeletal musculature of intermediate hosts
Etiology: Besnoitia spp.
Affected species: Opossums; caribou and reindeer (J Wildlife Diseases 33:319-326, 1995)
Lesions: In opossums there are multiple protozoal cysts in connective tissues throughout the body. In caribou and reindeer the protozoal cysts also are associated with or are within blood vessels resulting in cutaneous infarction
G. Miscellaneous diseases
1. Chronic wasting disease
Etiology: Prion protein suspected
Affected species: Cervids including elk, mule deer, and white-tailed deer in Colorado, Wyoming
Lesions: Emaciation, excess salivation. Microscopic lesions of spongiform encephalopathy of gray matter with intracytoplasmic neuronal vacuolation, neuronal degeneration and loss, astrocytic hypertrophy and hyperplasia, amyloid plaques, lack of inflammatory response. (Vet Path 30:36-45, 1993; J Wildlife Diseases 33:1-6, 1997; J Wildlife Diseases 34:532-538, 1998).
2. Capture myopathy
Etiology: Associated with physical restraint of capture, possible role for nutritional deficiencies
Affected species: Virtually all avian and mammalian wildlife.
Lesions: Focally extensive pallor of skeletal muscle due to degeneration and necrosis, gastrocnemius muscle rupture may occur;