Metabolic responses to ammonium acetate infusion in exercising horses.

The relationship between elevated plasma ammonia (NH3) levels, fatigue development and muscle metabolism were examined in horses during a submaximal fatigue test. Eight Quarter Horse mares were intravenously infused prior to exercise with either sodium acetate (control) or ammonium acetate (AMINF), and exercised to fatigue on an 11% grade treadmill, carrying 27 kg of lead. Time to fatigue was not different (P greater than 0.05) between groups. Intramuscular NH3 and lactate increased (P less than 0.001) during exercise; however, the treatment did not (P greater than 0.05) affect either. A treatment by exercise interaction (P less than 0.01) occurred for plasma NH3. The reciprocal relationship between changes in plasma and intramuscular alanine (ala) and glutamate (glu) indicated activation of the glucose-alanine cycle. Plasma glutamine (gln) increased (P less than 0.001) during exercise; however intramuscular gln was not (P greater than 0.05) altered. The excretion of urea-N was depressed as a result of exercise while the orotic acid/creatinine ratio did not (P greater than 0.05) change. The amino acids and urinary metabolites were not (P greater than 0.05) affected by treatment. These results did not show any metabolic evidence for a role of increased plasma NH3 levels in fatigue development. However this study did provide insight into other aspects of nitrogen metabolism during exercise in the horse.     

What is your diagnosis? Peritoneal fluid from an Arabian horse after colic surgery

A 16-year-old castrated male Arabian horse was presented to the Purdue University Veterinary Teaching Hospital with a 4-hour history of colic. Initial examinations provided strong evidence for small intestinal obstruction. Abdominal surgery revealed a strangulating lipoma, and 25 feet of small intestine were resected. Postoperatively, the horse developed obstructive ileus due to adhesion formation, which required a second laparotomy. During and after surgery, the abdomen was lavaged with sodium carboxymethylcellulose (CMC). One week after the second surgery, evaluation of peritoneal fluid revealed an inflammatory exudate, with many macrophages containing amorphous to granular, pink to magenta phagocytosed material. Extracellular aggregates of the material were also observed. The material was consistent with CMC. To our knowledge, this report is the first to demonstrate the phagocytosis of CMC by peritoneal fluid macrophages.     

Cytomorphologic differentiation of benign and malignant mammary tumors in fine needle aspirate specimens from irradiated female Sprague-Dawley rats.

BACKGROUND: Fine needle aspiration (FNA) offers a rapid and minimally invasive means to distinguish malignant from benign neoplasms. However, few studies have been published regarding the cytopathology of mammary tumors in rats despite widespread use of the rat model for breast cancer formation and inhibition. OBJECTIVE: The purpose of this study was to determine the diagnostic accuracy of FNA cytology and to develop distinguishing cytologic criteria for the diagnosis of radiation-induced benign and malignant mammary tumors in rats. METHODS: In a study of radiation-induced mammary carcinogenesis, 100 Sprague-Dawley rats with cutaneous masses were randomly chosen for FNA. The aspirates were smeared, fixed, and stained with a modified Papanicolaou procedure for diagnostic evaluation. Cytologic and histologic diagnoses (benign vs malignant) were compared, and diagnostic accuracy was calculated using the histologic diagnosis as the criterion standard. FNA smears were scored semiquantitatively on a scale of 1-4 for cellularity, atypia, nuclear size, chromatin pattern, nuclear membrane thickness, nucleoli, and mitoses. The background was evaluated for necrosis, hemorrhage, inflammation, and mucosecretory material. Cytomorphologic features were compared statistically between benign and malignant tumors, based on the histologic diagnosis. RESULTS: The sensitivity of FNA was 92.3% and specificity was 89.4% for the detection of malignancy. However, 14% of specimens, all fibroadenomas by histology, had insufficient cells for cytologic evaluation, for an overall accuracy rate of 78.0%. Malignant tumors had significantly higher scores for all cytomorphologic features, and were significantly more likely to contain cell clusters and necrotic debris. CONCLUSIONS: FNA is an accurate method for differentiating benign and malignant rat mammary tumors.     

Risk factors for umbilical hernia in Holstein heifers during the first two months after birth

OBJECTIVE: To determine risk factors associated with identification of an umbilical hernia during the first 2 months after birth in Holstein heifers. DESIGN: Case-control study. ANIMALS: 322 Holstein heifers born in a single herd (45 with an umbilical hernia and 277 without). PROCEDURE: Risk factors that were examined included sire, whether the dam had a history of umbilical hernia, milk yield, duration of gestation, whether the dam had a history of dystocia, whether the heifer had a twin, birth weight, total serum protein concentration, and whether the heifer had an umbilical infection. Logistic regression was used to analyze risk factors. RESULTS: Heifers born to sires with > or = 3 progeny with an umbilical hernia were 2.31 times as likely to develop an umbilical hernia as were heifers born to sires with < or = 2 progeny with an umbilical hernia. Heifers with umbilical infection were 5.65 times as likely to develop an umbilical hernia as were heifers without umbilical infection. CONCLUSIONS AND CLINICAL RELEVANCE: Sire and umbilical infection were associated with risk of an umbilical hernia during the first 2 months of life in Holstein heifers. Attributable proportion analysis indicated that the frequency of umbilical hernias in Holstein heifers with umbilical infection would have been reduced by 82% if umbilical infection had been prevented.