Paul E. Hanna

Comparison of Bacterial Culture, Histopathology, and Immunohistochemistry for the Diagnosis of Johne's Disease in Culled Dairy Cows:

Paired samples of formalin-fixed, paraffin-embedded ileum and lymph node from 204 culled dairy cows were investigated for evidence of infection by Mycobacterium avium subsp. paratuberculosis. Of the samples, 151 were from animals that were tissue-culture positive for M. avium subsp. paratuberculosis, and 53 were from animals that were tissue and fecal culture negative. From the culture-positive animals, M. avium subsp. paratuberculosis was isolated from 78 samples of ileum and from 107 samples of lymph node. Ziehl-Neelsen acid-fast and immunoperoxidase stained slides were examined for 15 minutes each. Acid-fast organisms were identified in 7 of 78 (8.97%) and 6 of 106 (5.61%) culture-positive ileum and lymph node samples, respectively. Immunohistochemical (IHC) analysis of the same tissues identified infection in the ileum of 9 of 78 (11.54%) and in the lymph node of 5 of 106 (4.67%) culture-positive tissues. All tissues from culture-negative animals tested negative when using acid-fast and IHC staining. The sensitivity of these 2 tests in detecting M. avium subsp. paratuberculosis in culled dairy cows was not significantly different, and the tests exhibited substantial to almost perfect agreement. Both tests were much less sensitive than bacterial culture, detecting less than 6% of tissues positive compared with culture.

Predicting within-herd prevalence of infection with bovine leukemia virus using bulk-tank milk antibody levels

Enzootic bovine leukosis (EBL) is an economically important infection of dairy cattle caused by bovine leukemia virus (BLV). Estimating the prevalence of BLV within dairy herds is a fundamental step towards pursuing efficient control programs. The objectives of this study were: (1) to determine the prevalence of BLV infection at the herd level using a bulk-tank milk (BTM) antibody ELISA in the Maritime region of Canada (3 provinces); and (2) to develop appropriate statistical models for predicting within-herd prevalence of BLV infection using BTM antibody ELISA titers. During 2013, three monthly BTM samples were collected from all dairy farms in the Maritime region of Canada (n=623) and tested for BLV milk antibodies using a commercial indirect ELISA. Based on the mean of the 3 BTM titers, 15 strata of herds (5 per province) were defined. From each stratum, 6 herds were randomly selected for a total of 90 farms. Within every selected herd, an additional BTM sample was taken (round 4), approximately 2 months after the third round. On the same day of BTM sampling, all cows that contributed milk to the fourth BTM sample were individually tested for BLV milk antibodies (n=6111) to estimate the true within-herd prevalence for the 90 herds. The association between true within-herd prevalence of BLV and means of various combinations of the BTM titers was assessed using linear regression models, adjusting for the stratified random sampling design. Herd level prevalence of BLV in the region was 90.8%. In the individual testing, 30.4% of cows were positive. True within-herd prevalences ranged from 0 to 94%. All linear regression models were able to predict the true within-herd prevalence of BLV reasonably well (R(2)>0.69). Predictions from the models were particularly accurate for low-to-medium spectrums of the BTM titers. In general, as a greater number of the four repeated BTM titers were incorporated in the models, narrower confidence intervals around the prediction lines were achieved. The model including all 4 BTM tests as the predictor had the best fit, although the models using 2 and 3 BTM tests provided similar results to 4 repeated tests. Therefore, testing two or three BTM samples with approximately two-month intervals would provide relatively precise estimates for the potential number of infected cows in a herd. The developed models in this study could be applied to control and eradication programs for BLV as cost-effective tools.

Onchocerca lupi Nematodes in Dogs Exported from the United States into Canada

The Onchocerca lupi nematode is an emerging helminth capable of infecting pets and humans. We detected this parasite in 2 dogs that were imported into Canada from the southwestern United States, a region to which this nematode is endemic. We discuss risk for establishment of O. lupi in Canada.

Cutaneous Phaeohyphomycosis Caused by Exophiala attenuata in a Domestic Cat.

Abstract A 7-year-old female-spayed, domestic short-haired cat was presented to her veterinarian with a mass on the hind paw. Histopathologic examination of a tissue biopsy revealed nodular pyogranulomatous panniculitis with intralesional pigmented fungal hyphae. A dematiaceous fungal isolate was isolated with a micromorphological phenotype consistent with the anamorphic genus Exophiala: budding cells, torulose mycelium and annellidic conidiogenesis from simple conidiophores consisting of terminal and lateral cells that tapered to a short beak at the apex. Sequence homology of the internal transcribed spacer region of the rDNA gene confirmed the identification of the isolate as Exophialaattenuata. Reported here is the first confirmed case of feline phaeohyphomycosis caused by E. attenuata in North America. Similar to historical cases of feline phaeohyphomycosis caused by Exophiala spp., there was no history or postmortem evidence to suggest the patient was in an immunocompromised state (e.g., suffering from FeLV or FIV). Although aggressive surgical excision of local lesions is recommended prior to drug treatment when dealing with subcutaneous phaeohyphomycosis, surgery followed by itraconazole treatment did not resolve the E. attenuata infection in this cat.

Histological Characterization of Dilated Cardiomyopathy in the Juvenile Toy Manchester Terrier

Dilated cardiomyopathy (DCM), the most common form of cardiomyopathy in the dog, most often occurs in certain breeds. The objective of this study was to describe a rapidly progressive form of DCM that has been recently recognized in juvenile Toy Manchester Terrier dogs (TMTs). The clinical history and gross findings were reviewed in a group of 14 TMTs, and histologic sections of heart were examined in 12 of those 14 TMTs with DCM. Histochemical and histomorphometric analyses were employed to compare the heart in TMTs affected by DCM with that of control dogs. TMTs ranged in age from 10 to 58.3 weeks, with males and females being equally affected. Affected TMT hearts contained foci of degeneration and loss of myofibers with fibrosis and mild lymphoplasmacytic infiltrates. Less prominent features included foci of acute myofiber degeneration and necrosis with or without intralesional mineralization and mild to moderate suppurative and lymphoplasmacytic infiltrates. Morphometric quantification demonstrated that the right ventricle was more severely affected (P ≤ .05) than the left ventricle with variable involvement of the interventricular septum. Immunohistochemistry for canine parvovirus was negative in all heart samples. However, the absence of parvoviral antigen does not rule out a possible viral or autoimmune cause. The presence of these myocardial lesions among closely related dogs suggests a genetic contribution to this disease process in the TMT.

Failure of oral taurine supplementation to influence skin-flap survival in rats

Taurine was given orally to rats to determine its influence on survival of subdermal plexus skin flaps. Flaps were raised on the dorsum of 40 rats divided into groups given 0, 10, 30, or 100 mg/kg taurine daily starting 2 days before and continuing 14 days after surgery. No significant difference was found between groups for percentage of distal flap necrosis, although mean area of necrosis was less for the 30 mg/kg group. Oral taurine did not result in significant elevation of plasma taurine concentrations at day 16 of administration, although the 30 mg/kg group maintained a higher mean value. Analysis of skin taurine concentrations in flaps failed to detect significant differences between groups at each of three zones (proximal-normal, middle-transition, and distal-sloughed). All groups, except the 10 mg/kg group, had significantly lower taurine concentrations in the distal zone than in the normal and transition zones. In each group there was a trend toward lower taurine concentration from proximal to distal, suggesting that loss of tissue taurine may occur with tissue necrosis. Subjectively, no differences in skin histopathology were noted, but less severe skin lesions were more common in the 10 mg/kg group. Daily oral taurine supplementation rates of 10, 30, or 100 mg/kg appear not to significantly affect survival of subdermal plexus skin flaps in rats.

Treatment of Hydropsical Conditions Using Transcervical Gradual Fetal Fluid Drainage in Mares With or Without Concurrent Abdominal Wall Disease

&NA; Hydropsical conditions are exceedingly rare in the horse. However, when they occur, they are true emergencies due to the severe enlargement of the pregnant uterus, which can result in clinical signs, such as an enlarged round abdomen, dyspnea, reluctance to walk, and colic, and may lead to the development of abdominal wall disease. The pathogenesis of hydropsical conditions is not fully elucidated, but they have been associated with placentitis and fetal abnormalities. This report describes six cases of hydropsical conditions in mares with or without concurrent abdominal wall disease. Five out of six cases were hydrallantois, and of these five, two mares had abdominal wall disease; the remaining one out of six cases was hydramnios. All mares were treated by termination of the pregnancy through gradual fluid drainage transcervically over a number of hours, and their fetuses were delivered vaginally. All fetuses were euthanized immediately after vaginal delivery. Of the six mares, two had signs of placentitis, two were confirmed seropositive for leptospirosis, and two were euthanized (one because of a vaginal tear that communicated through the peritoneum and one mare that developed abdominal wall rupture and laminitis). The remaining 4 mares were available for follow‐up; three mares were not rebred, and one mare became an embryo donor, with a successful embryo recovery. We reported the prevalence of leptospira involvement in two out of six cases of hydrallantois and also described the clinical outcome of the mares after treatment with slow fetal fluid drainage.

Vaginal leiomyosarcoma in a cow from Uberlândia, Minas Gerais, Brazil

The clinical, pathological, and immunohistochemical findings associated with a vaginal leiomyosarcoma in a 12-year-old, Senepol breed of cow from Uberlândia, Minas Gerais are described. The animal had a large ulcerative neoplastic growth that originated between the base and the left-lateral vaginal wall. Histopathology revealed a tumor formed by muscle-like cells that demonstrated cellular pleomorphism, anisokaryosis, prominent and multiple nucleoli, with rare tumor giant cells. The neoplastic growth invaded adjacent adipose tissue, and contained areas of hemorrhage with discrete accumulations of inflammatory cells. By immunohistochemistry, most neoplastic cells expressed actin, while immunoreactivity to desmin was weakly expressed. These findings support a diagnosis of leiomyosarcoma, and represent the first description of a bovine vaginal leiomyosarcoma from Brazil.