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)

Etiology: Herpesvirus

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.


9. Coligranuloma

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.


4. Toxoplasmosis

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

1. Aspergillosis

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



3. Amyloidosis

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

Etiology: Hepadnavirus

Affected species: Woodchucks

Lesions: Chronic-active, diffuse hepatitis with possible progression to hepatoma/hepatic carcinoma

4. Rabies

Etiology: Rhabdovirus

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

Etiology: Leporipoxvirus

Affected species: Cottontail rabbit

Lesions: Single to multifocal, cutaneous, fibromatous masses


6. Squirrel fibroma

Etiology: Leporipoxvirus

Affected species: Gray squirrels, woodchucks

Lesions: Multifocal and sometimes coalescing, cutaneous, fibromatous masses



7. Deer fibroma, infectious cutaneous fibroma

Etiology: Papovavirus

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


4. Staphylococcosis

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


6. Tuberculosis

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).


7. Brucellosis

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).

9. Dermatophilosis

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

1. Adiaspiromycosis

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


6. Myiasis

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.


2. Paragonimiasis

Etiology: Paragonimus kellicotti

Affected species: Muskrat, bobcat, other wild species

Lesions: Encysted pairs of flukes in lungs, usually subclinical infection


3. Echinococcosis

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.


7. Heartworms

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


8. Elaeophorosis

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


13. Lungworms

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



2. Besnoitiosis

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; myoglobinuric nephropathy may develop