Lisa M. Miller

Liver Histopathology and Liver and Serum Alanine Aminotransferase and Alkaline Phosphatase Activities in Epileptic Dogs Receiving Phenobarbital

Phenobarbital (PB) therapy is frequently associated with elevated serum alanine aminotransferase (ALT) and alkaline phosphatase (AP) activities in dogs without clinical signs of liver disease. The goal of this study was to determine if increased serum ALT and AP activities in clinically healthy PB-treated epileptic dogs are due to hepatic enzyme induction or to subclinical liver injury. Liver biopsies were obtained from 12 PB-treated dogs without clinical signs of liver disease but with elevated serum ALT and/or AP activities or both. Liver biopsies were obtained from eight healthy control dogs not receiving PB. Biopsies were evaluated histopathologically (all dogs) and liver homogenates were assayed for ALT (all dogs) and AP (six treated dogs, all controls) activities. As a positive control, liver cytochrome P4502B, an enzyme known to be induced by PB, was measured by benzyloxyresorufin-O-dealkylase activity and immunoblotting (five treated dogs, all controls). Serum AP isoenzyme analyses were performed. Results showed that ALT and AP activities in liver homogenates were not increased in treated dogs compared with controls, whereas the positive control for induction, CYP2B, was dramatically increased in treated dogs. Histopathological examination of liver biopsies revealed more severe and frequent abnormalities in treated dogs compared to controls, but similar types of abnormalities were found in both groups. Serum AP isoenzyme analyses in treated dogs demonstrated increased corticosteroid-induced and liver isoenzyme activities compared to controls. Results do not support induction of ALT or AP in the liver as the cause of elevated serum activities of these enzymes due to PB.

Pathological Findings in Dogs Naturally Infected with Angiostrongylus Vasorum in Newfoundland and Labrador, Canada

Fifty-six dogs from St. Johns, Newfoundland, Canada, were evaluated for Angiostrongylus vasorum infection. Small numbers of nematodes were found within pulmonary arteries of 6 dogs. Larvae were identified in fecal samples in 2 of 6 dogs. All 6 dogs had multifocal granulomatous pneumonia and sometimes foci of chronic thrombosis, which varied from very mild to severe. One dog had extensive pulmonary lesions resulting in cor pulmonale. Right heart failure was characterized by right ventricular hypertrophy, hepatic congestion, ascites, and hydrothorax. Microscopically, in most cases, eggs, larvae, and sometimes intravascular adults, were present within lung tissue sections. Small foci of granulomatous inflammation with and without larvae were present in kidney and brain in 4 dogs. An additional dog, diagnosed antemortem with angiostrongylosis via fecal examination, was also examined. Pathological findings consisted of severe pyogranulomatous interstitial pneumonia with myriad eggs, larvae, and numerous intravascular pulmonary adult nematodes with extensive arterial thrombosis. Five hundred and seventy-two adult worms were removed from pulmonary arteries. Foci of granulomatous inflammation, often associated with larvae and/or eggs, were present in tracheobronchial lymph nodes, adrenal gland, brain, and kidneys. Severe seizuring noted antemortem was attributed to several large, discrete areas of acute hemorrhagic infarction within the cerebrum and cerebellum. Natural A. vasorum infection in domestic dogs in eastern Newfoundland causes lung pathology of variable severity, which in some cases, may progress to cor pulmonale and which may be associated with extrapulmonary lesions and clinical signs.

Berberine and plant stanols synergistically inhibit cholesterol absorption in hamsters.

The present study was conducted to determine the efficacy and underlying mechanism of berberine (BBR), plant stanols (PS) and their combination on plasma lipids. Male Golden Syrian hamsters were randomly divided into 4 groups (n=15/group) and fed a cornstarch-casein-sucrose-based diet containing 0.15% cholesterol and 5% fat. Three treatment groups were supplemented with 0.17% (equivalent to 100mgkg(-1)d(-1)) BBR, 1% PS, or a combination of both (BBRPS) for 4wk. At the end of the study, plasma lipids were analyzed with enzymatic methods, cholesterol absorption and synthesis using stable isotope tracer methodology, and gene and protein expressions in the liver and small intestine using real-time PCR and Western blot, respectively. BBR and PS significantly lowered plasma total- and nonHDL-cholesterol levels, and BBRPS markedly improved cholesterol-lowering efficacy compared to BBR or PS alone. Further examinations revealed that BBR and PS both inhibited cholesterol absorption and by contrast, increased cholesterol synthesis, and exerted a synergistic action when they were combined. Plasma total or nonHDL-cholesterol levels were significantly correlated with cholesterol absorption rates. BBR upregulated sterol 27-hydroxlase gene expression and BBRPS increased both cholesterol-7alpha-hydroxylase and sterol 27-hydroxlase gene expressions. BBR and PS also synergistically decreased plasma triacylglycerides. These findings suggest that the cholesterol-lowering action of BBR might involve a combination of inhibition of cholesterol absorption and stimulation of bile acid synthesis. The combination of BBR and PS improves cholesterol-lowering efficacy through a synergistic action on cholesterol absorption, in addition to synergistically reducing plasma triacylglycerols in hamsters.

Necrotizing Fasciitis: A Review

Necrotizing fasciitis is a rapidly spreading, bacterial, soft-tissue infection reported in both humans and dogs. A review of the pathophysiology, clinical findings, diagnosis, and treatment of necrotizing fasciitis is presented, with the goal of familiarizing veterinarians with this uncommon but potentially fatal condition. A case report highlighting the fulminant course of this disease is also included.

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.

Peripheral nerve sheath tumor of the diaphragm with osseous differentiation in a one-year-old dog

A 12-month-old, spayed female German shepherd dog was referred to the Veterinary Teaching Hospital for repair of a diaphragmatic hernia. Abdominal exploration revealed an intact diaphragm, but thoracic exploration revealed a large mass originating from the diaphragm. Resection of the mass was incomplete and required reconstruction of the diaphragm. On histopathology, the mass was composed mainly of spindle-shaped cells with occasional areas of osseous and chondroid tissue. The tumor was diagnosed as a peripheral nerve sheath tumor (PNST) with chondro-osseous differentiation. The dog was released four days after surgery; however, she began having difficulty breathing seven days after discharge, and the owners elected euthanasia. A necropsy was not performed. This is the first known report of a PNST originating in the diaphragm of a dog.

Efficacy of Milbemax (milbemycin oxime + praziquantel) in the treatment of dogs experimentally infected with Crenosoma vulpis

Crenosoma vulpis, the fox lungworm, infects wild and domestic canids and is a cause of chronic respiratory disease in dogs in North America and Europe. The objective of this study was to determine the efficacy of milbemycin oxime (0.5mg/kg)/praziquantel (5mg/kg) (Milbemax; Novartis Animal Health, Inc.) against C. vulpis infection in a randomized, blinded, placebo-controlled study using experimentally infected dogs. Sixteen beagles (8 males, 8 females) were each given 100 infective third-stage larvae of C. vulpis. Fecal samples were examined for first-stage larvae by quantitative Baermann examination pre-exposure and at days 21, 28, 35, 42 and 49 post-infection (PI). All of the dogs were shedding larvae in the feces at 21 days PI. The dogs were randomly assigned to one of two groups. At 28 days PI, Group 1 (4 males, 4 females) received placebo only while Group 2 (4 males, 4 females) received a single treatment of milbemycin oxime (0.5mg/kg) and praziquantel (5mg/kg). The 16 dogs were euthanized and necropsied at 49 days PI. Lungs were removed, assessed for gross lesions (graded on a subjective scale 0-3 with 0 being normal) and C. vulpis were collected by lung-flush and counted. Samples of lung tissue were preserved for evaluation of histopathology and the lesions graded on a subjective scale (0-3 with 0 being normal). Gross and histopathology lesions were detected in all 8 untreated Group 1 dogs with mean subjective lesion scores of 1.8 ± 0.7 (range 1-3) and 3.0 ± 0.0 (range 3), respectively. Gross lesions were observed in 3/8 and histopathology lesions in all 8 of the treated Group 2 dogs with mean subjective lesion scores of 0.4 ± 0.5 (range 0-1) and 1.3 ± 0.4 (range 1-2), respectively. The mean (geometric) number for adult C. vulpis recovered in untreated dogs was 48.3 (range 25-70) compared with 0.65 (range 0-2) in animals treated with Milbemax. The resulting efficacy against C. vulpis was 98.7%. The number of C. vulpis was significantly lower for treated dogs than the burden in the untreated group (p=0.0002). A single dose of Milbemax (milbemycin oxime 0.5mg/kg+praziquantel 5mg/kg) was highly effective for the treatment of patent C. vulpis infection in dogs. A dosing interval for the prevention of clinical disease in dogs exposed to natural infections has not been established.

Lesions Associated with Postweaning Multisystemic Wasting Syndrome in Pigs from Prince Edward Island, Canada

Postweaning multisystemic wasting syndrome (PMWS) is a recently recognized swine disease originally reported in western Canada.2,9 Retrospective postmortem studies revealed that this condition first appeared in 1991, but it was not recognized as a specific disease until 1996.9 A similar syndrome has been described recently in pigs from the United States4,11 and Europe.1 The etiology of this syndrome is still under investigation, but porcine circovirus (PCV), a member of the family Circoviridae that includes chicken anemia virus, psittacine beak and feather disease virus, and a newly described pigeon circovirus,15 is thought to play an important role in the pathogenesis of this condition. The purpose of this paper is to describe and illustrate the most common microscopic findings associated with PMWS in pigs and to report the presence of PMWS in swine herds from Atlantic Canada. Six pigs, 5–12 weeks of age, from four swine herds located in Prince Edward Island were submitted to the Atlantic Veterinary College for postmortem examination. Five pigs were alive and one (pig no. 3) had been found dead in its pen. Pig nos. 2 and 3 and pig nos. 5 and 6 were herdmates. All pigs had a history of weight loss, dyspnea, and/or scouring, first noticed 1 or 2 weeks after weaning. Blood samples were obtained from live pigs prior to euthanasia. Complete postmortem examination was performed, and tissues were selected for histopathology, bacteriologic culture, and virologic analysis. Tissues for histopathology were fixed in 10% neutral buffered formalin, embedded in paraffin, cut at 5 mm, and stained with hematoxylin and eosin. In two cases, formalin-fixed tissue was fixed in 2% glutaraldehyde and postfixed in 1% osmium tetroxide, dehydrated in a graded series of ethanol, and infiltrated and embedded in epon/araldite for sectioning and examination by transmission electron microscopy. Thin sections were stained with a saturated solution of uranyl acetate and Sato lead stain. Tissues from five pigs (nos. 1, 2, 3, 5, and 6) were sent to the Veterinary Services Branch of Manitoba Agriculture for the detection of pathogenic PCV by polymerase chain reaction (PCR).8 Porcine reproductive and respiratory syndrome (PRRS) serology was done on serum of two pigs by an indirect fluorescent antibody test (IFAT) that was developed in house. Gradual dilutions of the test serum were made and reacted with PRRS virus (PRRSV)-infected MARC cells, washed, mounted, and evaluated by fluorescent microscopy. Lungs from three pigs and lymph nodes from two others were tested for the pres-

Coronary Arterioventricular Anomaly in a Calf

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Histopathology of the Swim Bladder of the Cisco Due to the Presence of the Nematode Cystidicola farionis Fischer

Abstract Histopathological changes in the swim bladders of ciscos Coregonus artedii due to infection with the nematode Cystidicola farionis included invasion of the subepithelium by histiocytic inflammatory cells, varying degrees of epithelial atrophy, and the occurrence of round granular cells in submucosal connective tissue.