Recommended guidelines for submission, trimming, margin evaluation, and reporting of tumor biopsy specimens in veterinary surgical pathology.

Neoplastic diseases are typically diagnosed by biopsy and histopathological evaluation. The pathology report is key in determining prognosis, therapeutic decisions, and overall case management and therefore requires diagnostic accuracy, completeness, and clarity. Successful management relies on collaboration between clinical veterinarians, oncologists, and pathologists. To date there has been no standardized approach or guideline for the submission, trimming, margin evaluation, or reporting of neoplastic biopsy specimens in veterinary medicine. To address this issue, a committee consisting of veterinary pathologists and oncologists was established under the auspices of the American College of Veterinary Pathologists Oncology Committee. These consensus guidelines were subsequently reviewed and endorsed by a large international group of veterinary pathologists. These recommended guidelines are not mandated but rather exist to help clinicians and veterinary pathologists optimally handle neoplastic biopsy samples. Many of these guidelines represent the collective experience of the committee members and consensus group when assessing neoplastic lesions from veterinary patients but have not met the rigors of definitive scientific study and investigation. These questions of technique, analysis, and evaluation should be put through formal scrutiny in rigorous clinical studies in the near future so that more definitive guidelines can be derived.

Prospective characterization of the clinicopathologic and immunologic features of an immunodeficiency syndrome affecting juvenile llamas.

The clinicopathologic and immunologic features of 15 llamas affected with juvenile llama immunodeficiency syndrome (JLIDS) are described. Healthy adult (n = 10) and juvenile (n = 10) llamas served as controls. JLIDS llamas were characterized by wasting, and clinically apparent, repeated infections were frequently observed. The median age at which a health problem was first perceived was 11.6 months. All 15 affected llamas died or were killed, and JLIDS was confirmed at necropsy. The median duration of illness was 3.5 months. Lymphocyte blastogenesis assays showed suppressed responses (particularly to Staphylococcus sp. Protein A) in JLIDS llamas. No evidence of retroviral infection was detected. Mild, normocytic, normochromic, non-regenerative anemia, low serum albumin concentration and low to low-normal globulin concentrations were typically found on initial clinical evaluation. Lymph node biopsies showed areas of paracortical depletion. All llamas affected with JLIDS had low serum IgG concentrations, pre-vaccination titers against Clostridium perfringens C and D toxoids of < or = 1:100, and no titer increase following vaccination.

Retrovirus-like activity in an immunosuppressed dog: pathological and immunological findings.

A putative retrovirus was isolated from a dog with a severe, acquired immunodeficiency-like syndrome. The haematological abnormalities and immunological deficiencies included anaemia, leucopenia (lymphopenia and neutropenia), thrombocytopenia, decreased humoral immunity, and ineffective T-cell responses in-vitro. The necropsy findings included generalized lymphoid depletion, severe bone marrow hypoplasia, plasmacytic infiltrates in lymphoid and non-lymphoid organs, and severe secondary infections. Supernates of peripheral blood mononuclear cell cultures from the affected dog contained an agent with manganese-dependent reverse transcriptase (RT) activity that sedimented at a density of 1.122 g/ml. RT activity was also found post-mortem in extracts prepared from the bone marrow, lymph nodes, and small intestine. The lymph nodes and small intestine expressed a 3.8 kb mRNA that was recognized by a bovine leukaemia virus (BLV) pol DNA probe by Northern blotting. DNA isolated from the lymph nodes and small intestine from the affected dog showed distinct band patterns by Southern analysis, suggesting an exogenous retrovirus. The retrovirus could be propagated in normal canine peripheral blood mononuclear cells or short-term canine lymphocyte cell lines in-vitro, and was cytopathogenic for cells of canine, but not human, origin. These results suggest the existence of a pathogenic canine retrovirus capable of producing disease of the type associated with retroviruses in other species.

Hepatic lipidosis in anorectic, lactating holstein cattle: a retrospective study of serum biochemical abnormalities.

The association between hepatic lipidosis (HL) and disease in 59 anorectic, ketotic, lactating Holstein heifers and cows was investigated. Severe HL, as determined by histologic evaluation of liver tissue, was present in 46 animals; only half of these animals required intensive treatment for ketosis, and only half had serum biochemical evidence of liver disease, as determined by the presence of a last value of 2-fold or greater than the upper limit of the reference ranges for at least 2 of the 4 serum tests: gamma-glutamyl transferase, aspartate aminotransferase, and sorbitol dehydrogenase activities and bile acid concentrations. Most cattle with biochemical evidence of liver disease and severe HL had been lactating for 14 or more days. Cows that required intensive treatment inconsistently had serum biochemical evidence of liver disease. Although cattle with severe HL had significantly higher serum bilirubin concentrations and aspartate aminotransferase and sorbitol dehydrogenase activities than cattle with less severe lipidosis, the specificity of abnormally high serum sorbitol dehydrogenase activity or bilirubin concentration for severe lipidosis was only 8%. Abnormally high serum aspartate aminotransferase activity was 83% sensitive and 62% specific for severe lipidosis. Serum glucose and total carbon dioxide concentrations were significantly lower in cattle with severe lipidosis than in those with mild or moderate lipidosis, and low serum glucose or total carbon dioxide concentrations were rare in cattle without severe lipidosis. From these data, we conclude that the use of a single biochemical or histopathologic criterion to define severity of disease or degree of liver compromise in anorectic, ketotic cows results in the misidentification of many animals.

Association of hepatic necrosis with trimethoprim sulfonamide administration in 4 dogs.

Hepatic necrosis in association with trimethoprim-sulfonamide (TMS) combination therapy was diagnosed in 4 dogs based on history, clinical presentation, and examination of histopathologic specimens collected postmortem. Duration of TMS therapy prior to onset of clinical signs ranged from 4 to 30 days. The dose of TMS ranged from 18 mg/kg to 53 mg/kg bid. Despite supportive medical therapy, all dogs died or were euthanized due to hepatic failure. This report highlights the potential for hepatotoxicity during TMS therapy. Duration of therapy, type of TMS combination, and dose did not appear related to the development of toxicity. The low number of dogs affected suggests an idiosyncratic drug reaction.

Effects of enalapril versus placebo as a treatment for canine idiopathic glomerulonephritis.

A blinded, multicenter, prospective clinical trial assessed the effects of enalapril (EN) versus standard care in dogs with naturally occurring, idiopathic glomerulonephritis (GN). Twenty-nine adult dogs with membranous (n = 16) and membranoproliferative (n = 13) GN were studied. Dogs were randomly assigned to receive either EN (0.5 mg/kg PO q12-24h; n = 16) or placebo (n = 14) for 6 months (1 dog was treated first with the placebo and then with EN). All dogs were treated with low-dose aspirin (0.5-5 mg/kg PO q12-24h) and fed a commercial diet. At baseline, serum creatinine (SrCr), systolic blood pressure (SBP), and glomerular histologic grade were not different between groups, but the urine protein/creatinine ratio (UP/C) was greater in the EN group compared with the placebo group (8.7 +/- 4.4 versus 4.7 +/- 2.3). After 6 months of treatment, the change in UP/C from baseline was significantly different between groups (EN = -4.2 +/- 1.4 versus 1.9 +/- 0.9 in the placebo group). When data were adjusted for changes in SrCr (SrCr X UP/C) a similar significant reduction was noted ( 2.2 +/- 15.2 versus 8.4 +/- 10.1). The change in SBP after 6 months of treatment also was significantly different between groups (EN = -12.8 +/- 27.3 versus 5.9 +/- 21.5 mm Hg in the placebo group). Response to treatment was categorized as improvement (assigned a value of 2), no progression (assigned a value of 1), and progression (assigned a value of 0). Response was significantly better in the EN group (1.4 +/- 0.8) compared with the placebo group (0.3 +/- 0.5). These results suggest that EN treatment is beneficial in dogs with naturally occurring idiopathic GN.

Feline inflammatory polyps: historical, clinical, and PCR findings for feline calici virus and feline herpes virus-1 in 28 cases.

Inflammatory polyps are associated with significant aural or nasopharyngeal disease in cats. It has been proposed that chronic viral infection may induce the masses. Ventral bulla osteotomy (VBO) is usually recommended for definitive therapy but removal of masses from the nasopharynx or external ear canal by traction/avulsion is also used. A retrospective study of 28 cats with inflammatory polyps was conducted to correlate recurrence with mode of therapy. Tissues from 41 polyps were assayed for feline calicivirus and feline herpesvirus-1 by RT-PCR and PCR, respectively. Of the 14 cats initially treated by traction/avulsion, recurrence was detected in five of nine cats with radiographic evidence of bulla disease but none of the cats with normal bullae. Traction/avulsion is a reasonable treatment for inflammatory polyps if the bullae are radiographically normal. Failure to detect feline calicivirus and feline herpesvirus-1 suggests that tissue persistence of these viruses is not associated with the development of inflammatory polyps.

Serodiagnosis of paratuberculosis in sheep by use of agar gel immunodiffusion.

An agar gel immunodiffusion (AGID) test was used over a 3-year period to examine 1,871 serum samples from sheep representing 5 Mycobacterium paratuberculosis-infected flocks and 4 flocks presumed to be uninfected. Of 1,032 sheep, 31 had positive AGID test results (scoring 1 to 5), and 23 of these 31 were necropsied. Infection with M paratuberculosis was confirmed by 1 or more of the following findings: observation of typical lesions on histologic examination of sections of ileum or ileocecal lymph nodes, observation of clumps of acid-fast bacteria in mucosal smears of ileum, and isolation of the organism from feces or tissue. False-positive results on AGID testing were not found in sheep from flocks known to have exposure to Corynebacterium pseudotuberculosis. Diarrhea in infected sheep was observed infrequently; chronic, severe weight loss was the most common sign observed. On histologic examination of tissues from 20 infected sheep, 16 (80%) had diffuse lesions of the ileum and 13 (65%) had acid-fast bacteria in areas of ileal inflammation; 4 had discrete granulomas and peripheral lymphocytic infiltrates in the ileum. Sheep with diffuse lesions tended to have higher mean scores on AGID testing and examination for acid-fast bacteria, compared with those from sheep with more discrete lesions. Bacteriologic culture yielded M paratuberculosis from only 3 sheep with paratuberculosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities in oxygenation, coagulation, and fibrinolysis in colonic blood of horses with experimentally induced strangulation obstruction.

OBJECTIVE: To measure arterial and venous blood gas, coagulation, and fibrinolysis variables in blood from isolated segments of control and ischemic large colons for the purpose of identifying variables for rapid, indirect assessment of colonic mucosal injury. DESIGN: Variables were determined at specific intervals during the 4-hour study (3 hours of ischemia and 1 hour of reperfusion). ANIMALS: Seven clinically normal horses between 2 and 15 years old. PROCEDURES: Horses underwent laparotomy and occlusion of the lumen and vasculature of the mid-portion of the pelvic flexure of the large colon. During ischemia of 1 randomly-chosen colonic segment, variables were measured to determine colonic mucosal damage and were compared with histologic scores of colonic biopsy specimens. RESULTS: Significant (P < 0.05) differences from control values were observed over time for venous pH, PCO2, PO2, oxygen saturation, oxygen content, arteriovenous oxygen difference, and lactate and glucose concentrations. Mean histologic scores of biopsy specimens obtained from ischemic colons were significantly (P < 0.05) greater (indicating greater damage) than those from control colons, and increased significantly (P < 0.05) with duration of ischemia. CONCLUSIONS: Venous lactate, oxygen saturation, and PO2 values were the most significant predictors of the severity of histologic damage within the ischemic colons (R2 = 0.661). CLINICAL RELEVANCE: Venous blood gas and lactate values in the large colon are good predictors of the amount of intestinal damage incurred during 3 hours of ischemia, and may be clinically useful for the rapid determination of colonic viability.

Effects of dietary n-3 fatty acid supplementation versus thromboxane synthetase inhibition on gentamicin-induced nephrotoxicosis in healthy male dogs.

OBJECTIVE: To evaluate the protective effects of dietary n-3 fatty acid supplementation versus treatment with a thromboxane synthetase inhibitor (TXSI) in dogs given high-dose gentamicin. DESIGN: Clinicopathologic and renal histopathologic changes induced by gentamicin (10 mg/kg of body weight, IM, q 8 h, for 8 days) were compared in dogs fed an n-3 fatty acid-supplemented diet containing a fatty acid ratio of 5.7:1 (n-6:n-3), dogs treated with CGS 12970 (a specific TXSI given at 30 mg/kg, PO, q 8 h, beginning 2 days prior to gentamicin administration), and control dogs. The TXSI-treated and control dogs were fed a diet with a fatty acid ratio of 51.5:1 (n-6:n-3). Both diets were fed beginning 42 days prior to and during the 8-day course of gentamicin administration. ANIMALS: Eighteen 6-month-old male Beagles, 6 in each group. RESULTS: After 8 days of gentamicin administration, differences existed among groups. Compared with n-3-supplemented and control dogs. TXSI-treated dogs had higher creatinine clearance. Both TXSI-treated and n-3-supplemented dogs had higher urinary prostaglandin E2 and E3 (PGE2/3) and 6-keto prostaglandin F1a (PGF1a) excretion, compared with control dogs. Urinary thromboxane B2 (TXB2) excretion was higher in n-3-supplemented and control dogs, compared with TXSI-treated dogs. Urine PGE2/3-to-TXB2 and PGF(in)-to-TXB2, ratios were increased in TXSI-treated dogs, compared with n-3-supplemented and control dogs, and these ratios were increased in n-3-supplemented dogs, compared with control dogs. In addition, TXSI-treated and n-3-supplemented dogs had lower urinary protein excretion, compared with control dogs. Proximal tubular necrosis was less severe in TXSI-treated dogs, compared with control dogs. CONCLUSION: Treatment with CGS 12970 prior to and during gentamicin administration prevented increases in urinary TXB2 excretion and reduced nephrotoxicosis. CLINICAL RELEVANCE: Increased renal production/excretion of thromboxane is important in the pathogenesis of gentamicin-induced nephrotoxicosis.

Effects of embedded tungsten-bismuth-tin shot and steel shot on mallards (Anas platyrhynchos).

We assessed the potential for embedded steel and tungsten-bismuth-tin (TBT) shot to adversely affect health of mallards (Anas platyrhynchos). Ducks were implanted with three number four steel (n = 19) or TBT (n = 20) shot pellets in their pectoral muscles. None of seven hematology parameters measured differed in response to treatment (P > or = 0.17). At necropsy 1, 2, 4, and 8 wk posttreatment, we observed only localized tissue reactions to embedded steel or TBT shot. Reactions differed grossly: after wk 1, embedded steel shot were enveloped in 0.5 to 2 mm grayish capsules, whereas TBT shot were surrounded by thinner (< 0.5 mm), translucent capsules. Corrosion of steel shot was apparent. Microscopic lesions associated with steel shot were characterized by moderate to severe histiocytic and lymphocytic inflammation and considerable particle deposition, whereas histiocytic inflammation was mild and particle deposition minimal in TBT lesions. Overall scores of inflammation at steel shot implant sites were greater (P < or = 0.043) than at TBT sites during wk 1 and 8. Inflammation at steel implant sites was relatively consistent over the 8-wk period, but decreased (P = 0.0017) at TBT sites by wk 8. Weights of steel shot recovered from muscle tissue declined logarithmically (R2 = 0.978, P = 0.0014) over 8 wk, but TBT shot weights remained unchanged (P = 0.255). Embedded TBT shot, as compared to steel, resisted corrosion and induced comparatively mild inflammatory responses in mallard muscle tissue. However, inflammatory reactions to both embedded steel and TBT shot were localized and had no detectable systemic effects on mallard health under experimental conditions.

Spongiform encephalopathy in free-ranging mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus) and Rocky Mountain elk (Cervus elaphus nelsoni) in northcentral Colorado.

Between March 1981 and June 1995, a neurological disease characterized histologically by spongiform encephalopathy was diagnosed in 49 free-ranging cervids from northcentral Colorado (USA). Mule deer (Odocoileus hemionus) were the primary species affected and accounted for 41 (84%) of the 49 cases, but six Rocky Mountain elk (Cervus elaphus nelsoni) and two white-tailed deer (Odocoileus virginianus) were also affected. Clinical signs included emaciation, excessive salivation, behavioral changes, ataxia, and weakness. Emaciation with total loss of subcutaneous and abdominal adipose tissue and serous atrophy of remaining fat depots were the only consistent gross findings. Spongiform encephalopathy characterized by microcavitation of gray matter, intraneuronal vacuolation and neuronal degeneration was observed microscopically in all cases. Scrapie-associated prion protein or an antigenically indistinguishable protein was demonstrated in brains from 26 affected animals, 10 using an immunohistochemical staining procedure, nine using electron microscopy, and seven using Western blot. Clinical signs, gross and microscopic lesions and ancillary test findings in affected deer and elk were indistinguishable from those reported in chronic wasting disease of captive cervids. Prevalence estimates, transmissibility, host range, distribution, origins, and management implications of spongiform encephalopathy in free-ranging deer and elk remain undetermined.

Doxorubicin alone or in combination with asparaginase, followed by cyclophosphamide, vincristine, and prednisone for treatment of multicentric lymphoma in dogs: 121 cases (1987-1995).

OBJECTIVE: To determine response rate and remission as well as survival times for dogs with multicentric lymphoma treated first with doxorubicin alone or in combination with asparaginase and then with cyclophosphamide, vincristine sulfate, and prednisone (CVP) and to identify prevalence of toxicoses associated with this protocol and factors associated with prognosis. DESIGN: Retrospective case series. ANIMALS: 121 dogs. PROCEDURE: Variables evaluated for prognostic value were initial response rate to chemotherapy, age, breed, sex, body weight, histologic grade, clinical stage and substage, previous corticosteroid treatment, and serum calcium concentration. RESULTS: Median overall remission and survival times for all 121 dogs were 205 and 237 days, respectively. Response rate (complete or partial response) was 88%. Ten dogs were hospitalized because of toxicoses associated with doxorubicin, and 19 dogs were hospitalized because of toxicoses associated with CVP. Asparaginase favorably influenced the initial response rate, but did not significantly influence overall remission of survival times. Initial response rate to chemotherapy, body weight, clinical substage, and serum calcium concentration was found to have prognostic value. CLINICAL IMPLICATIONS: For dogs with multicentric lymphoma, treatment with doxorubicin alone or in combination with asparaginase and then with CVP resulted in an acceptable response rate and low prevalence of toxicoses.

Multifocal myositis associated with Sarcocystis sp in a horse.

Multifocal myositis was diagnosed in a 7-year-old Quarter Horse gelding on the basis of history and findings on physical examination, serum biochemical analysis, electromyography, and microscopic examination of frozen sections of muscle biopsy specimens. Histologic examination of the muscle specimen revealed multifocal accumulations of histiocytes, lymphocytes, and plasma cells, with attendant myofiber degeneration and necrosis. Parasitic cysts with morphologic characteristics of Sarcocystis sp were found in regions of myocyte degeneration and necrosis, and in regions of normal muscle. Based on a tentative diagnosis of Sarcocystis sp-induced myositis, the horse was treated with trimethoprim/sulfamethoxazole and pyrimethamine for 28 days, phenylbutazone for 5 days, and paddock rest for 30 days. At the end of treatment, the horse had gained 35 kg, its appetite had returned to normal, and muscle mass was returning to normal. Sarcocystis fayeri is the only Sarcocystis sp reported in equine muscle in the United States and is rarely associated with acute myositis or muscle atrophy. The development of clinical signs in this horse could have been the result of an underlying immunosuppression or infection with a particularly pathogenic strain or large infective dose of S fayeri.

Evaluation of mitoxantrone for the treatment of lymphoma in dogs.

Mitoxantrone was administered to 74 dogs with lymphoma at a dosage of 5.0 mg/m2 of body surface, IV, every 3 weeks. Thirty-four dogs had failed to respond to prior treatment with chemotherapeutic agents, which included doxorubicin (33 dogs). The remaining 40 dogs had not received prior treatment. Complete remission was determined in 19 of 74 dogs (26%), 10 of which had not received prior treatment. The median duration of remission for these 10 dogs was 94 days (range, 49 to 440 days, with 2 dogs still alive at 370 and 440 days, respectively). Nine dogs that had received prior treatment had complete remission that lasted for a median of 126 days (range, 42 to 792 days, with 1 dog still alive at 792 days). The combined remission rate (complete remission plus partial remission) was 41%. Toxicosis was minimal, developing in only 9 dogs and requiring hospitalization of 2 dogs. We concluded that the complete remission rate ascertained when mitoxantrone was the only treatment administered was low, compared with treatments that involved other chemotherapeutic agents; however, the combined remission rate of 41% indicated that mitoxantrone may be beneficial in the treatment of lymphoma in dogs.

Evaluation of prognostic factors for dogs with synovial sarcoma: 36 cases (1986-1991).

Medical records of 36 dogs with synovial sarcoma confirmed by microscopic examination of H&E-stained sections of tissue were selected for retrospective analysis from dogs admitted between 1986 and 1991 to participating institutions of the Veterinary Cooperative Oncology Group. Metastasis was evident at the time of diagnosis in 8 (22%) dogs, and 15 (41%) dogs ultimately developed metastatic tumors. Median survival time for all dogs, as determined by life-table analysis, was 17 months. For dogs that were subsequently treated and became tumor free, the median disease-free interval was 30 months. Nine dogs had previously had localized excision attempted, but all had recurrence of the tumor locally (median, 4.5 months). Of 29 dogs that underwent amputation, including the 9 with localized recurrence, 2 had tumor recurrence on the amputation stump. Most dogs had survival time and disease-free interval of > 36 months after amputation. Four dogs that had received chemotherapy for tumors of advanced clinical stages did not respond to treatment. One dog that had received locally applied radiotherapy after localized excision did not have evidence of tumor recurrence 2 years after radiotherapy. Clinical stage, histologic grade, and a positive result for tests that used cytokeratin immunohistochemical staining significantly (P < 0.05) influenced survival time and disease-free interval. Analysis of data for the study reported here suggested that histologic criteria can be an excellent predictor of dogs that are likely to have tumor recurrence after amputation and that would most likely benefit from aggressive treatment with adjuvants.

Mycobacterium paratuberculosis infection in two llamas.

Mycobacterium paratuberculosis was diagnosed in 2 llamas by bacteriologic culturing and DNA probe testing of fecal and intestinal specimens. Diarrhea and weight loss were observed in both animals. Lesions in the gastrointestinal tracts of the 2 llamas were similar to pathologic changes reported in cattle infected with M paratuberculosis.

Immunodeficiency syndrome associated with wasting and opportunistic infection in juvenile llamas: 12 cases (1988-1990).

Immunodeficiency was diagnosed as the cause of severe debilitating disease characterized by weight loss, failure to grow, and persistent infections that failed to respond to treatment in 12 young llamas. The llamas were affected after maternal-acquired immunity had decreased; failure of passive transfer of immunoglobulins thus was not suspected. Areas of lymph nodes containing T lymphocytes were hypocellular, suggesting T-cell involvement. High serum immunoglobulin concentrations were not found, despite the existence of infectious disease, suggesting at least secondary B-cell involvement. Results of lymphocyte blastogenesis assays were suggestive of B- and T-cell involvement. It was not possible to determine whether the condition was inherited or acquired.

Monitoring and detection of acute viral respiratory tract disease in horses.

OBJECTIVE: To develop a system to monitor and detect acute infections of the upper respiratory tract (i.e., nares, nasopharynx, and pharynx) in horses and to assess the association among specific viral infections, risk factors, and clinical signs of disease. DESIGN: Prospective study. ANIMALS: 151 horses with clinical signs of acute infectious upper respiratory tract disease (IURD) from 56 premises in Colorado. PROCEDURE: Health management data, blood samples, and nasal or nasopharyngeal swab samples were obtained for 151 horses with clinical signs of acute IURD. Of these horses, 112 had an additional blood sample obtained during convalescence and were considered to have complete sample sets. Samples were tested for evidence of respiratory tract infection by use of ELISA, virus isolation, and serologic testing of paired serum samples. RESULTS: Viral infections were identified in 65 horses with complete sample sets; influenza virus infection was identified in 43 horses, equine herpesvirus (EHV) infection in 18, and mixed influenza virus and EHV infections in 4. On 14 premises, samples were obtained from more than 1 affected horse. Viral infections were identified in horses on 11 of 14 premises. Equine herpesviruses were isolated from 10 horses. A relationship was not found between vaccination history and identification of EHV or influenza virus infections. An infection with EHV was less likely to be identified in horses with initial (acute) antibody titers > 1:16 to EHV. CLINICAL IMPLICATIONS: Influenza virus (specifically, A/equine/2) was the most common virus associated with acute IURD. Use of multiple diagnostic tests and obtaining samples from more than 1 horse in an outbreak may improve detection of viral infections.

Salmonellosis in captive black rhinoceroses (Diceros bicornis).

Salmonellosis caused by Salmonella enterica subspecies arizonae (formerly known as Salmonella arizonae) was diagnosed in three of five captive black rhinoceroses (Diceros bicornis) at the Denver Zoological Gardens. Two of the three animals died despite supportive treatment. The other two rhinoceroses remained asymptomatic and were negative for Salmonella spp. after serial fecal cultures. The source for the salmonellosis was never identified.