:: Pathology Case Study

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Two adult Great horned owls (Bubo virginianus), were submitted to a local veterinary clinic in Williston, North Dakota, by the North Dakota Game and Fish Department in late March of 2003. The birds were found 25 yards apart in a treed area near a farmstead. They were taken to a local veterinary clinic where radiographs for evidence of gunshot-related death were negative. The referring veterinarian performed necropsies on the owls. Both birds, one determined to be a male and one a female, showed similar gross lesions, severe multifocal hepatic and splenic necrosis. Fresh and fixed tissues were submitted to the North Dakota State University Veterinary Diagnostic Laboratory where they were processed through routine histopathology (10% neutral buffered formalin, Hematoxylin and Eosin, 5 micron sections). Histopathology of liver showed severe, multifocal hepatic and splenic necrosis with numerous eosinophilic intranuclear inclusion bodies. Cultures of liver from both owls yielded no growth (male) and E. coli (female). Fluorescent antibody examination of frozen sections of liver and spleen was negative for bovine herpesvirus 1, equine herpesvirus 1, canine herpesvirus, pseudorabies virus, and feline herpesvirus 1, but positive for bovine herpesvirus 4 and weakly positive for infectious laryngotracheitis virus. EM examination of liver homogenate showed typical herpesvirus particles. Herpesvirus hepatitis is sporadically reported in owls and falcons. Owl and falcon herpesviruses are very closely related to the pigeon strain. Restriction typing indicates that these three varieties are extremely difficult to differentiate. The speculated mode of transmission in this case is bird to bird, and likely occurred when the owls fed on pigeons carrying the virus.

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Bison Research at NDSU North Dakota Veterinary Diagnostic Laboratory

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:: Dyer NW, Ward ACS., J. Vet Diagn Invest 10:360-362 (1998), Pneumonic
pasteurellosis associated with Pasteurella hemolytica serotype A6 in American
bison (Bison bison).

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:: Ward ACS, Dyer NW, Fenwick B F. Pasteurellaceae isolated from Tonsillar
samples of Commercially-Reared American bison (Bison bison) Can J Vet Res
1999;63:161-165.

Abstract: As commercial producers of American bison (Bison bison) become more numerouse, concerns relative to bison health management increase. Since loss due to respiratory disease associated with Pasteurella and related Pasteurellaceae is a major concern for cattle producers, a study was conducted to determine what types of Pasteurellaceae are carried by bison to evaluate the potential of pneumonic pasteurellosis in bison herds where management practices are comparable to those used for cattle. Tonsillar biopsies, collected in May (n = 29) and August (n = 25) 1997 from 24- to 30-month-old bison bulls, at the time of slaughter were cultured for Pasteurellaceae. Pasteurella spp. were isolated from all the samples collected in May. These included isolates identified as P.haemolytica, trehalosi, testudinis, and multocida subsp. multocida a and
multocida b. Actinobacillus spp. and Haemophilus somnus were also isolated from some samples. Pasteurella spp., haemolytica, trehalosi, and multocida subsp. multocida a multocida b and septica, plus 2 nonspeciated indole-positive biotypes, U2 and U16, were isolated from the second group of tonsil samples. Most of these organisms, including P. haemolytica, P. multocida subsp., and H. somnus are associated with disease in domestic livestock and should be regarded as potential pathogens for bison , particularly in animals which become stressed by management practices commonly used with cattle such as herding, crowding, and shipping.

:: Ward ACS, Dyer NW, Corbeil LB. Characterization of Putative Haemophilus
somnus Isolates from Tonsils of American bison (Bison bison) Can J Vet Res 1999;
63: 166-169.

Abstract: Three Haemophilus somnus isolates (2a, 3a, and 27b) and one
H. somnus-like (13b) isolate from tonsils of commercially reared American bison
were compared with 2 known H. somnus isolates from cattle, namely, 2236, shown to cause respiratory disease, and 129Pt, from the prepuce of an asymptomatic bull. All H. somnus isolates , but not the H. somnus-like isolates, required CO2 for growth. Biochemical utilization profiles were identical for bison and bovine H. somnus isolates with the exception of a- fucosidase production by isolate 3a. Isolate 27a varied from 2a, 2336 and 129Pt by hemolysis of bovine erythrocytes. Isolate 13b hemolyzed sheep but not bovine or bison erythrocytes and varied from other isolates in biochemical utilization tests. Outer membrane protein profiles of 2a, 3a and 27a were almost identical with those of bovine isolate 2336 and similar to that of 129Pt, but quite different from that of 13b. Western blots of bison isolates were similar to that of the virulent bovine 2336 isolate, including detection of high molecular mass antigens above 100 kDa and the 76 kDa antigens associated with bovine IgG2 Fc binding characteristic of virulent strains, as well as antigens of approximately 78, 60 and 40 kDa. Producers and veterinarians should be aware that H. somnus may be carried by bison and may have potential for causing diseases in bison similar to those described in cattle and sheep.

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:: Stoltenow CL, Solemsaas K, Rupprecht C, Niezgoda M, Yager P. Rabies in an American Bison from North Dakota Journal of Wildlife Diseases 36(1), 2000,
pp. 169-171.

Abstract: In North Dakota (USA) during April 1998, a ranched female bison
(Bison bison) was found dead. At gross necropsy, there was profound hair loss and consolidated lung lobes. Intracytoplasmic neuronal inclusions suggestive of Negri bodies were observed in the brain stem and hippocampus, and a diagnosis of rabies was confirmed by the fluorescent antibody test. Antigenic typing demonstrated the occurrence of a rabies virus variant associated with skunks from the upper midwestern USA. This case of a rabid bison was one of only four such instances recorded from the USA over the past 40 yr, and is the first case report of rabies in a bison that reports clinical, pathologic, and antigenic findings. Although rabies in bison is rare, veterinarians and wildlife managers that work closely with such non-traditional species are reminded of the dangers that zoonoses such as rabies present.

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:: N.W. Dyer, A.C.S. Ward, G.C. Weiser, D.G. White. Seasonal incidence and
antibiotic susceptibility patterns of Pasteurellaceae isolated from American bison (Bison bison) The Canadian Journal of Veterinary Research, 2001; 65:7-14.

Abstract: Ninety pharyngeal tonsils were collected from 2-year-old American bison (Bison bison) bulls and sampled for members of the Pasteurellaceae family.
Particular attention was paid to seasonal incidence and antimicrobial resistance in serotypes and biovariants. Multiple strains of Pasteurella haemolytica (39%), P. trehalosi (68%), P. multocida (34%) and Haemophilus somnus (13%) were cultured from 86 out of the 90 (96%) tonsil samples. Pasteurella trehalosi was the most and evenly distributed of the organisms recovered. Pasteurella haemolytica was found in fewer numbers than P. trehalosi, but showed an increase in number of isolates recovered with each sampling period. Pasteurella multocida, both A and D capsular types, was recovered from all sampling periods. No serotype pattern was observed in any of the naimal groups sampled. One hundred twenty-seven of 147 (86%) of the isolates were resistant to at least 1 antibiotic, 95/147 (65%) to at least 2 different antibiotics, and 16/147 (11%) to at least 3 antibiotics. The most common resistance pattern observed was to neomycin and spectinomycin (73/147) (49%).

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:: N.W. Dyer. Haemophilus somnus bronchopneumonia in American bison (Bison
bison) J Vet Diagn Invest 13:419-421 (2001).

Abstract: Immunoperoxidase assays were performed on 21 archived formalin-fixed, paraffin-embedded tissues from from American bison (Bison bison) with
bronchopneumonia. Seven of the 21 bison had positive staining from Haemophilus somnus in alveolar exudate, visceral pleura, lung parenchyma, and chronic necrotic lesions, and H. somnus was isolated from tissues from 1 of these 7 animals. Results suggest that H. somnus is a respiratory pathogen in bison.

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:: E.A. Sausker, N.W. Dyer. Polymerase chain reaction and DNA sequencing for
detection of ovine herpesvirus 2 in American bison (Bison bison) J Vet Diagn
Invest 14:40-46 (2002).

Abstract: Serum samples were collected at slaughter from 226 24-30-month-old ranch-raised, clinically normal American bison (Bison bison) bulls from North Dakota, Minnesota, Kansas, and Manitoba to assess the presence of antibiodies to ovine herpesvirus 2 (OHV-2). Antibodies to OHV-2 were detected by competitive inhibition enzyme-linked immunosorbent assay in 10 of 226 (4.40%) samples. Polymerase chain reaction (PCR) analysis of sera positive for OHV-2 DNA demonstrated a 238 kilobase fragment. The nucleotide sequence of the PCR-positive samples in comparison to the reported OHV-2 nucleotide sequence resulted in a homology range of 82.8-95.4%.

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:: E.A. Sausker, N.W. Dyer. Seroprevalence of OHV-2, BVDV, BHV-1, and BRSV
in ranch-raised bison (Bison bison) J Vet Diagn Invest 14:68-70 (2002).

Abstract: Serum samples were collected at slaughter from 226 24-30 month-old American bison (Bison bison) bulls from Kansas, Minnesota, North Dakota, and Manitoba and assayed for antibiotics to ovine herpesvirus type-2 (OHV-2), bovine viral diarrhea virus (BVDV), bovine herpesvirus type-1 (BHV-1), and bovine respiratory syncytial virus (BRSV). Antibodies were detected by serum neutralization for BVDV, BHV-1, and BRSV, while antibodies to OHV-2 were detected by competitive inhibition-ELISA (CI-ELISA). Detectable antibodies were found against all viruses: 10 of 226 (4.40%) against OHV-2, 125 of 226 (55.3%) against BVDV, 99 of 226 (43.8%) against BHV-1, and 208 of 226 (92.0%) against BRSV. Titers from 93.6% of the BVDV positive animals, 79.8% of the BHV-1 positive animals, and 98.1% of the BRSV-positive animals were = 1.25. These data indicates that a low percentage of bison sampled are seropositive for BVDV,
BHV-1, and BRSV.


Carrington Research Extension Center Bison Research Page

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