Lois Roth

A Grading System for Lymphocytic Plasmacytic Colitis in Dogs

Colonic mucosal samples were obtained every 4 weeks for 13 months from 6 clinically normal dogs and from 47 dogs with a clinical diagnosis of chronic inflammatory bowel disease. All samples were graded on a scale of 0–5, based upon the quantity of lymphocytes and plasma cells in the lamina propria, epithelial changes, and the presence of ulcers and erosions. A grade of ≤2.0 was considered normal and was assigned to 77 of 78 samples from clinically normal dogs and 28 of 48 samples from dogs with diarrhea. A transient increase in cellulaiity was noted in 1 sample from 1 control dog. Nineteen dogs with clinical disease had obvious histologic abnormalities. The grading scheme described provides the pathologist with an objective criterion for the microscopic evaluation of colonic mucosal samples obtained by endoscopic techniques and offers clinicians a method of assessing the dogs progress and response to therapy.

Cocaethylene hepatotoxicity in mice

Cocaethylene is a novel metabolite of cocaine formed in the presence of ethanol. When administered to ICR male mice in dosages ranging from 10 to 50 mg/kg, i.p., cocaethylene was found to produce dose-dependent hepatic necrosis in the midlobular zone (zone 2). Severity of the lesion was maximal 12-24 hr after administration. A transient but significant decrease in hepatic glutathione content was observed 1 hr after cocaethylene administration. Pretreatment with the cytochrome P450 inhibitors cimetidine (200 mg/kg, i.p., in divided doses) or SKF 525A (50 mg/kg, i.p.) diminished toxicity. Pretreatment of mice with the esterase inhibitor diazinon (10 mg/kg, i.p.) increased cocaethylene hepatotoxicity, as did pretreatment with the cytochrome P450 inducing agents phenobarbital (80 mg/kg/day, i.p., for 3 days) or beta-naphthoflavone (40 mg/kg/day, i.p., for 3 days). Phenobarbital pretreatment also caused a shift in the morphologic site of necrosis from midzonal to peripheral lobular (zone 1) regions. The type of hepatic lesion produced by cocaethylene, its morphologic distribution (including the shift with phenobarbital treatment), the potency of cocaethylene in producing this effect, and the apparent requirement of oxidative metabolism for hepatoxicity were all remarkably similar to observations with its parent compound, cocaine, in this and earlier studies. This suggests that these compounds produce liver toxicity through the same or similar mechanisms.

Evaluation of low sodium : potassium ratios in dogs

The results of general chemistry profiles of canine patients from Angell Memorial Animal Hospital, Boston, Massachusetts, during 1993 were reviewed for low (<24) serum sodium: potassium (Na:K) ratios. Thirty-seven dogs had low Na:K ratios. The medical records for 34 these patients were available and sufficiently complete to identify conditions that were associated with low Na:K ratios. Of these 34 dogs, 8 (24%) had hypoadrenocorticism, and 14 had renal disease. Twenty-two of the 34 (65%) had Na:K ratios between 24 and 20. Of these 22 dogs, 9 (41%) had renal or urinary tract disease, and 2 (9%) had hypoadrenocorticism. Other diagnoses in this group included pancreatic disease (3), disseminated neoplasia (3), circulatory disturbance (2), pyometra (1), mushroom poisoning (1), and behavior problem (1). Eight of 34 dogs had Na:K ratios between 19.9 and 15. Of these 8 dogs, 4 (50%) had urinary tract disease, 2 had hypoadrenocorticism, 1 had pancreatic disease, and 1 had severe anemia and hypoproteinemia due to severe parasitism. All of the 4 dogs with Na:K ratios < 15 had hypoadrenocorticism, and 1 of these 4 had concurrent renal failure. In all dogs, serum potassium concentration was above the laboratorys reference range, but sodium was below the laboratorys reference range in only 18 dogs (53%). Two of the 8 (25%) dogs with hypoadrenocorticism had serum sodium concentrations within the laboratorys reference range. In this population, low Na:K ratios were invariably associated with hyperkalemia but not always with hyponatremia. Although numerous conditions were associated with a low Na:K ratio, renal disease was the most common. Hypoadrenocorticism was present in only 13% of dogs with Na:K ratios between 24 and 15 but was present in all dogs with Na:K ratios < 15.

Traumatic Reticulitis in Cattle: A Review of 60 Fatal Cases

Sixty fatal cases of traumatic reticulitis in cattle were reviewed. Fifty-nine cases were caused by fragments of wire. A nail perforated the reticulum of 1 animal. Common clinical signs included decreased milk production, anorexia, fever, and weight loss. Abnormal or muffled heart sounds associated with pericarditis and epicarditis was the most common sequela, occurring in 40 cases. Fibrous adhesions found at necropsy in all cases suggest that initial clinical signs are difficult to recognize and in most cases it takes weeks to months for abnormalities to be observed.

Methyphenidate-induced hepatotoxicity in mice and its potentiation by β-adrenergic agonist drugs

Abstract Methyphenidate hydrochloride, when adminitered as a single 75 to 100 mg/kg i.p. dose, was found to produce hepatic necrosis in male ICR mice. Peak hepatotoxicity, as measured by serum ALT elevation, ooccurred 16 hours post-treatment while maximal histopathological evidence of hepatotoxicity occurred 24–48 hours after the methylphenidate dose. Liver injury measured by either method was essentially nonexistent for dosages ⩽ 50 mg/kg in male mice, and was only minimally evident in female mice at the highest dosage testable. Co-treatment of mice with either α 1 -or α 2 -madrenergic agonist drugs had no meaningful effect on methylhenidate-induced hepatotocitity. In contrast, the β-adrenergic agonist drug isoproterenol produced a striking potentiation of the liver injury, and shifted the apparent threshold for toxicity approximately 5- to 10-fold. Co-adminitration of methyphenidate with the mixed α/gb-adrenergic agonist dobutamine or with the β2- selective agonists metaproterenol, ritodrine or terbutaline produced a similar prtentiation of toxicity. Parallel tests with β-adrenergic antagonists revealed that the potentiation by isoproterenol could be significantly diminished by a single dose of the non-selective β-adrenoreceptor blocking drug nadolol or the b 2 -selective antagonist ICI-118,551, but not the b 1 -selective antagonist metoprolol. Collectively, these observations suggest that potentiation of methylpenidate hepatotoxicity occurs through stimulation of b 2 -adrenoreceptors. Mice co-treated with isoproterenol were found to have substantially higher serum and liver methylphenidate levels following the methylphenidate dose, and significant increases were also observed in the area-under-the curve (AUC) for methylphenidate in both tissues of isoproterenol co-treatedd mice. The results of this study suggest that β 2 -adrenergic agonist drugs are capable of potentiating methylphenidate-induced hepatotoxicity in mice by increasing hepatic methylphenidate concentrations.

Rhabdomyoma of the ear pinna in four cats

Four cases of rhabdomyoma of the ear pinna in white eared adult cats are reported. The lesions were raised, non-ulcerated, red-purple, discoid nodules on the convex surface of the pinna. Histologically, the nodules consisted of interlacing bundles of spindle-shaped cells that occasionally had cross striations. Lesions have not recurred 2-3 years following surgical excision. Although a specific cause for tumour development was not found, the similarity among these cases suggests that common factors played a role in the development of the lesions.

Pulmonary hamartoma in a calf

A pulmonary hamartoma was found in a 5 weeks over term Jersey Holstein cross bull calf. A 36 x 22 x 22 cm, spongy, pale pink mass with a distinct lobulated pattern was continuous with the left caudal lung lobe and compromised other thoracic viscera. The mass was non-cystic and uniformly consisted of soft, pink tissue. Histologically, the mass consisted of a disproportionate number of bronchiolar and alveolar structures, arranged in a haphazard pattern. Ascites, localized subcutaneous oedema, and chronic passive congestion of the liver were additional findings.

Comparison of Three Diagnostic Tests for Dirofilaria Immitis in a Low-Incidence Area

was obtained, tests were repeated by a different technologist. Microfilaria identification using the alkaline phosphatase technique was done to differentiate between D. immitis and Dipetalonema reconditum on all samples in which microfilariae were observed. Clinical follow-up was obtained for 11 of the 12 dogs that had any positive test result by reviewing the medical record or discussing the case with the clinician. The results of the laboratory tests are summarized in Table 1. Samples from 1,347/1,359 dogs (99.12% of samples submitted) were negative for microfilariae and adult D. immitis antigen using both commercial kits. Microfilariae, subsequently identified as D. immitis, were observed in blood samples from 7 dogs. Four of these dogs also had adult D. immitis antigen detected by both kits. Two microfilaremic dogs were negative for D. immitis adult antigen with both kits. Blood from 1 dog that was positive for microfilariae was serologically positive for adult antigen with only 1 of the commercial kits. Five dogs were serologically positive for adult D. immitis antigen but negative for microfilariae. The 5 dogs that had positive tests for adult D. immitis antigen but negative filter tests were considered otherwise healthy. They had no evidence of circulatory or respiratory compromise. Adulticide treatment was recommended for each of these dogs, but owners chose to administer ivermectin or milbemycin oxime monthly to their pets. Owners were advised to observe their dogs carefully and to restrict their pets’ exercise for at least 2 days following the administration of the monthly heartworm preventative. Adverse reactions were not reported in any of these dogs. Six of the 7 dogs that tested positive for D. immitis microfilariae underwent treatment for the elimination of adult D. immitis and microfilariae, regardless of the results of the adult antigen test. Additional information could not be obtained for 1 dog that was positive on all 3 tests. Treatment in 1 dog that had positive results with all 3 tests was initiated as an emergency procedure when the dog developed acute respiratory distress. Two dogs that were microfilaremic were adult antigen negative using both kits, and 1 microfilaremic dog was antigen negative with 1 kit but antigen positive with the other. Such results are likely to occur if the adult worm burden is low. In these cases, the sensitivity of the tests for detection of adult antigen is decreased. 2,3,6,8,9 Based on physical examination and radiographs, the clinicians strongly suspected that 2 of these 3 dogs had few adult D. immitis in their right ventricles, and the dogs were treated with adulticides before beginning preventative therapy. The presence of adult D. immitis infection in the right ventricle in the third dog was questionable, yet the owner preferred to have the dog treated with adulticide before preventative therapy was begun. Although the number of infected dogs detected in this study was small, infection in 5 of 12 animals would have gone undetected if only a filter test, accompanied by acid phos