Beth A. Valentine

Survey of Equine Cutaneous Neoplasia in the Pacific Northwest

A retrospective study examined data regarding equine cutaneous and mucocutaneous neoplasms submitted to the Veterinary Diagnostic Laboratory at Oregon State University in a 3.5-year period. A total of 536 neoplasms were identified, accounting for 30% of the total equine pathology submissions. Sarcoid, squamous cell carcinoma, melanocytic tumors, papillomas, and mast cell tumors were the most common neoplasms, constituting 87.5% of all cutaneous neoplasms. Sarcoids represented 51.4% of all neoplasms and 15.18% of total equine accessions. Sarcoid was most common in paints, quarter horses, and Arabians, and was the only common tumor in donkeys and mules. Mean age at diagnosis of equine sarcoid was 9 years. Squamous cell carcinoma constituted 18.3% of all neoplasms and 5.41% of total equine accessions. Ocular squamous cell carcinoma was most common in paints and quarter horses, and penile/preputial squamous cell carcinoma was most common in appaloosas and quarter horses. The mean age of horses with ocular squamous cell carcinoma (13 years) and squamous cell carcinoma of the skin (15 years) was significantly less (P < 0.5) than that of horses with squamous cell carcinoma of the penis and prepuce (21 years) or vulva, anal, and perianal skin (19 years). Findings suggest that equine sarcoid and squamous cell carcinoma occur more frequently in the Pacific Northwest than in the northeastern United States.

Pathological changes associated with white striping in broiler breast muscles

White striping is a condition in broiler chickens characterized grossly by the occurrence of white striations, seen parallel to the direction of muscle fibers, on broiler breast fillets and thighs. Based on visual evaluation of the intensity of white striping, breast fillets can be categorized into normal (NORM), moderate (MOD), and severe (SEV) categories. This study was undertaken to evaluate the details of changes in histology as well as proximate composition occurring in the fillets with respect to the 3 degrees of white striping. In experiment 1, representative breast fillets for each degree of white striping (n = 20) were collected from 45-d-old broilers, approximately 2 h postmortem. From each fillet, 2 skeletal muscle samples were obtained and fixed in 10% neutral buffered formalin. To identify and differentiate the histological changes, slides were prepared and stained using hematoxylin and eosin, Massons Trichrome, and Oil Red O stains. In experiment 2, samples with 3 degrees of white striping were collected from 57-d-old birds for conducting proximate analysis. Major histopathological changes observed in the MOD and SEV samples consisted of loss of cross striations, variability in fiber size, floccular/vacuolar degeneration and lysis of fibers, mild mineralization, occasional regeneration (nuclear rowing and multinucleated cells), mononuclear cell infiltration, lipidosis, and interstitial inflammation and fibrosis. Microscopic lesions were visually scored for degeneration and necrosis, fibrosis, and lipidosis. The scale used to score the samples ranged from 0 (normal) to 3 (severe). There was an increase (P < 0.05) in mean scores for degenerative or necrotic lesions, fibrosis, and lipidosis as the degree of white striping increased from NORM to SEV. The results from the histopathological study were supported by the findings from proximate analysis confirming that the fat and protein contents of muscle increased (P < 0.05) and decreased (P < 0.05), respectively, as the degree of white striping increased. In conclusion, the histopathological changes occurring in white striping indicate a degenerative myopathy that could be associated with increased growth rate in birds.

Canine Laryngeal Rhabdomyoma

Three canine laryngeal tumors were diagnosed as oncocytomas by light microscopy, but were determined to be rhabdomyomas following ultrastructural and immunocytochemical examination. Tumors consisted of large eosinophilic cells interspersed with smaller dark cells. Large tumor cells had a granular, intensely eosinophilic cytoplasm. Scattered through the tumors were a few elongated cells with cytoplasmic cross striations and multiple nuclei. Tumor cells from all three dogs contained numerous mitochondria and bundles of myofibrils with electron-dense Z-lines typical of striated muscle cells. Intracellular myoglobin and desmin were detected in the tumors by immunocytochemistry. Comparisons are made with a previous report of canine laryngeal oncocytomas.

Incidence of Polysaccharide Storage Myopathy in Draft Horse-Related Breeds: A Necropsy Study of 37 Horses and a Mule

Skeletal muscle samples from 38 draft horse–related animals 1–23 years of age were evaluated for evidence of aggregates of glycogen and complex polysaccharide characteristic of equine polysaccharide storage myopathy (EPSSM). Cardiac muscle from 12 of these horses was also examined. Antemortem serum levels of creatine kinase (CK) and aspartate aminotransferase (AST) from 9 horses with EPSSM and 5 horses without EPSSM were compared. Skeletal muscle from 17 horses contained inclusions of periodic acid–Schiff (PAS)-positive, amylase-resistant complex polysaccharide. Similar inclusions were also present in the cardiac muscle of 1 horse. A vacuolar myopathy with aggregates of PAS-positive, amylase-sensitive glycogen was seen in 8 other horses, and these findings are also considered diagnostic for EPSSM. Antemortem serum activities of CK and AST were often higher in EPSSM horses than in horses without EPSSM. Using the presence of amylase-resistant complex polysaccharide as the criterion for diagnosis of EPSSM, the incidence in this population was 45%. Inclusion of horses with aggregates of glycogen but no amylase-resistant complex polysaccharide as representative of the range of pathologic findings in horses with EPSSM resulted in a 66% incidence in this population.

Prevalence of Neoplasia in Llamas and Alpacas (Oregon State University, 2001–2006)

Prevalence and type of neoplastic disease were determined in 551 camelid submissions (368 alpacas [Lama pacos], 180 llamas [Lama glama], and 3 cases in which species was not identified) over a 5-year period. Forty neoplasms were identified in 38 animals (6.9%). Prevalence of neoplasia in llamas was higher (11%) than in alpacas (4.9%). Mean age of camelids with neoplasia was 9.42 ± 4.9 years. Mean age of alpacas with neoplasia (5.48 ± 3.7 years) was significantly less than of llamas with neoplasia (12.53 ± 3.2 years; P < 0.001). Cutaneous and mucocutaneous fibroma/fibropapilloma was most common (10 animals), followed by cutaneous and mucocutaneous squamous cell carcinoma (6 animals), disseminated lymphoma (5 animals), and fibrosarcoma (4 animals). Four of 5 animals with lymphoma were alpacas, aged 0.21 to 4 years. Lymphoma occurred in 1 aged llama (15 years). Disseminated carcinoma and adenocarcinoma occurred in 4 llamas and 2 alpacas, and included biliary (2), gastrointestinal (2), mammary gland (1), and unknown (1) origin. Mean age of camelids with any type of carcinoma or adenocarcinoma (12.36 ± 2.8 years) was significantly greater than that of camelids with lymphoma (4.24 ± 6.2 years; P = 0.02). Results indicate that neoplasia is relatively common in camelids and that there are differences between llamas and alpacas as regards prevalence of neoplasia, tumor types, and age at diagnosis.

Coccidioidomycosis in dogs and cats: A review

The dimorphic fungi Coccidioides immitis and Coccidioides posadasii are the causative agents of coccidioidomycosis. Dogs and cats residing in and visiting endemic areas are at risk of exposure to infectious arthrospores. The primary infection is pulmonary and frequently results in chronic cough. Disseminated disease is common and causes cutaneous, osseous, cardiac, ocular, nervous system, or other organ disease. Radiographic changes include a variable degree of interstitial pulmonary infiltration, hilar lymphadenopathy, and osseous lesions. Serological titers support the diagnosis, but definitive diagnosis relies on identification of Coccidioides in cytological or tissue samples. Coccidioidomycosis should be considered in any dog or cat that has been potentially exposed during the previous 3 years and is presented with chronic illness, respiratory signs, lameness, lymphadenopathy, nonhealing cutaneous lesions, or neurological, ocular, or cardiac abnormalities.

Cryptococcus gattii with bimorphic colony types in a dog in Western Oregon: additional evidence for expansion of the Vancouver Island outbreak

Cryptococcus gattii was isolated from a 1.5-year-old dog with systemic cryptococcosis in Oregon. The dog had no link to Vancouver Island or British Columbia, Canada. Samples from a nasal swab and from a granulomatous mass within the cranial cavity were pooled for culture. Colonies on Sabouraud dextrose agar were mucoid and exhibited bimorphic morphology, melanin-pigmented and unpigmented. Pigmented colonies were encapsulated budding spherical yeast, whereas unpigmented colonies were of unencapsulated ovoid budding yeast. In addition to defective melanin production, the unpigmented colony type exhibited defective mating. Genetic analysis by high-resolution multilocus sequence typing revealed that the 2 isolates are genetically identical at 8 unlinked loci tested and that the 2 isolates are both the VGIIa Vancouver Island major genotype. Findings are consistent with expansion of the Vancouver Island outbreak onto the mainland Pacific Northwest region of the United States.

Malignant round cell neoplasia in llamas and alpacas.

Malignant round cell neoplasia was identified in 12 llamas and 12 alpacas aged 0–23 years. Mean age of affected alpacas (3.1 years) was significantly less than that of affected llamas (8.0 years). Tumor cell morphology varied from large and often pleomorphic (11 tumors) to small and often homogeneous (13 tumors). Neoplastic lesions were multicentric in 12 cases. Other sites were gastric (5 cases), intra-abdominal (perirenal; 4 cases), intrathoracic (2 cases), and cervical (1 case). Immunohistochemistry with antibodies to CD79α, BLA36, and CD3 identified B-cell lymphoma (12 cases) and T-cell lymphoma (6 cases). Six tumors did not express any lymphoid marker and were further immunostained for neuron-specific enolase (NSE), synaptophysin, S-100, glial fibrillary acidic protein (GFAP), and chromogranin A. All 6 of these tumors were negative for GFAP and chromogranin A but expressed 1 or more of the neural markers NSE, synaptophysin, and S-100 and were classified as primitive malignant round cell tumors (PMRCT). Tumor types could not be distinguished on the basis of animal age, gross pathologic appearance, tumor morphology, or tumor location. All animals with lymphoma and 5 with PMRCT died or were euthanatized. One alpaca with a focal cervical PMRCT lived for at least 20 months after diagnosis. Results of this study indicate that malignant round cell tumors in llamas and alpacas are a heterogeneous group that cannot be distinguished on the basis of signalment, postmortem findings, or routine light microscopic findings. Immunohistochemistry is a valuable diagnostic procedure when evaluating malignant round cell neoplasia in llamas and alpacas.

Thrombotic Endocarditis in 10 Alpacas

BACKGROUND A description of the clinical signs and necropsy findings in 10 alpacas with thrombotic endocarditis. ANIMALS Clinical cases admitted to 2 veterinary referral hospitals between May 1998 and December 2006. METHODS A retrospective study was performed by searching hospital records to identify alpacas diagnosed with endocarditis. RESULTS Common clinical findings included sternal recumbency, tachycardia, tachypnea, and abdominal distension. Heart sounds were recorded as normal in 7 of 10 alpacas. Pleural and pericardial effusion and ascites were often present. Complete blood cell counts often suggested inflammation, and liver enzyme activity was often increased. When echocardiography was performed, a soft tissue density was imaged within the right ventricle. All alpacas died or were euthanized. Necropsy revealed mural endocarditis with right ventricular or biventricular fibrinous thrombi obliterating the ventricular lumina with no valvular involvement in 6 of 10 affected animals. Bacteria were not consistently identified as a cause for the endocarditic lesions. Eight of the 10 alpacas had evidence of hepatic fluke infestation. CONCLUSIONS AND CLINICAL IMPORTANCE Valvular and mural thrombotic endocarditis should be included in the list of differential diagnoses for hepatomegaly, abdominal distension, and other signs of right-sided congestive heart failure in alpacas. The prognosis of this disease is grave.

A comparison of microscopic ink characteristics of 35 commercially available surgical margin inks.

OBJECTIVE To compare microscopic characteristics of commercially available surgical margin inks used for surgical pathology specimens. STUDY DESIGN Prospective in vitro study. SAMPLE POPULATION Thirty-five different surgical margin inks (black, blue, green, orange, red, violet, and yellow from 5 different manufacturers). METHODS Inks were applied to uniform, single-source, canine cadaveric full-thickness ventral abdominal tissue blocks. Tissue blocks and ink manufacturers were randomly paired and each color was applied to a length of the cut tissue margin. After drying, tissues were fixed in formalin, and 3 radial slices were obtained from each color section and processed for routine histologic evaluation, yielding 105 randomly numbered slides with each manufacturers color represented in triplicate. Slides were evaluated by 5 blinded, board-certified veterinary anatomic pathologists using a standardized scoring scheme. Statistical analyses were performed to evaluate for ink manufacturer effects on scores, correlation among different subjective variables, and pathologist agreement. RESULTS Black and blue had the most consistently high scores whereas red and violet had the most consistently low overall scores, across all manufacturers. All colors tested, except yellow, had statistically significant differences in overall scores among individual manufacturers. Overall score was significantly correlated to all other subjective microscopic scores evaluated. The average Spearman correlation coefficient among the 10 pairwise pathologists overall ink scores was 0.60. CONCLUSIONS There are statistically significant differences in microscopic ink characteristics among manufacturers, with a notable degree of inter-pathologist agreement.Objective To compare microscopic characteristics of commercially available surgical margin inks used for surgical pathology specimens. Study Design Prospective in vitro study. Sample Population Thirty-five different surgical margin inks (black, blue, green, orange, red, violet, and yellow from 5 different manufacturers). Methods Inks were applied to uniform, single-source, canine cadaveric full-thickness ventral abdominal tissue blocks. Tissue blocks and ink manufacturers were randomly paired and each color was applied to a length of the cut tissue margin. After drying, tissues were fixed in formalin, and 3 radial slices were obtained from each color section and processed for routine histologic evaluation, yielding 105 randomly numbered slides with each manufacturers color represented in triplicate. Slides were evaluated by 5 blinded, board-certified veterinary anatomic pathologists using a standardized scoring scheme. Statistical analyses were performed to evaluate for ink manufacturer effects on scores, correlation among different subjective variables, and pathologist agreement. Results Black and blue had the most consistently high scores whereas red and violet had the most consistently low overall scores, across all manufacturers. All colors tested, except yellow, had statistically significant differences in overall scores among individual manufacturers. Overall score was significantly correlated to all other subjective microscopic scores evaluated. The average Spearman correlation coefficient among the 10 pairwise pathologists overall ink scores was 0.60. Conclusions There are statistically significant differences in microscopic ink characteristics among manufacturers, with a notable degree of inter-pathologist agreement.