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The safety of synthetic levothyroxine sodium tablets (Thyro-Tabs® Canine; LLOYD, Inc.) in dogs was evaluated in a randomized, sham-dose controlled, parallel-group study. Young, healthy, euthyroid Beagle dogs were randomized into four groups (four females and four males per group) and received single daily doses of 0×, 2× (0.044 mg/kg), 6× (0.132 mg/kg), or 10× (0.22 mg/kg) the labeled starting dose of 0.022 mg kg-1 day-1 for 182 days. Every 2 weeks, physical examinations, electrocardiology examinations, and sample collections for thyroid panel, hematology, serum biochemistry, coagulation panel, and urinalysis were performed. At the end of the study, the dogs were euthanized and full necropsies performed. The most overt finding was the expected dose-dependent increase in serum concentrations of total and free thyroxine with dose-dependent suppression of the hypothalamic-pituitary-thyroid axis as evidenced by decreased serum thyroid-stimulating hormone concentrations, decreased thyroid+parathyroid/body weight ratios, and a trend for decreased pituitary weight/brain weight ratios. Clinical signs of thyrotoxicosis (excitation, tachypnea, tachycardia) in the treated dogs were sporadic with no dose-response relationship. Other findings statistically associated with levothyroxine treatment were generally mild and not clinically important. In summary, doses of levothyroxine sodium up to 10× the labeled starting dose were well tolerated in healthy dogs.

Carotid endarterectomy by the eversion technique allows for all of the benefits of conventional endarterectomy but obviates the need for a distal suture line on the smaller internal carotid artery, and thus batching. Carotid artery reanastomosis onto the bifurcation can be quickly and simply performed with almost no risk of closure-related restenosis, given the anastomosis is on the larger of 2 arteries. In our experience of over 3,000 eversion carotid artery endarterectomies, the restenosis rate has been less than 1% judged by rigorous duplex follow-up. In this article, the technique and utility of eversion carotid endarterectomy is discussed.

To test effectiveness of IV administration of tolazoline hydrochloride in reversing xylazine hydrochloride-induced sedation in calves.Prospective study.12 female and 12 male Friesian-cross calves from 5 to 7 months old.Calves were assigned to 1 of 4 treatment groups. Calves were given xylazine (0.3 mg/kg [0.14 mg/lb] of body weight, IM). Twenty minutes later, calves were treated with saline (0.9% NaCl) solution (1 ml/50 kg [1 ml/110 lb], IV) or tolazoline (1, 2, or 4 mg/kg [0.45, 0.9, or 1.8 mg/lb], IV). Behavioral and physiologic measurements included elapsed time from xylazine administration to recumbency, arousal and standing times after reversal drug administration, heart rate, and respiratory rate.Mean (+/- SD) recumbency time for all calves was 5.4 +/- 1.8 minutes. Compared with administration of saline solution, all 3 doses of tolazoline significantly decreased arousal and standing times. Mean arousal time for calves receiving saline solution was 27.8 +/- 11.5 minutes. Administration of tolazoline at 1, 2, and 4 mg/kg resulted in mean arousal times of 4.7 +/- 3.8, 0.9 +/- 0.5, and 0.7 +/- 0.3 minutes, respectively. Mean standing time for calves receiving saline solution was 38.8 +/- 2.8 minutes. Administration of tolazoline at 1, 2, and 4 mg/kg resulted in mean standing times of 14.0 +/- 11.0, 3.0 +/- 1.2, and 2.4 +/- 1.1 minutes, respectively.For routine use, tolazoline doses of 1 to 2 mg/kg should suffice. In cattle, IV administration of tolazoline reverses pharmacologic effects of xylazine, thereby hastening recovery from xylazine-induced sedation.

A computerized pattern recognition system has been developed that is capable of identifying 40 separate spontaneously occurring behavioral acts of the primateMacaca fascicularis. The system, called PROBE (pattern recognition of behavioral events), is described in detail. In its present stage of development, PROBE classifies behavioral activity with a reliability comparable to trained human observers. The potential applications for and improvements to the PROBE system are discussed.

Twenty healthy ponies were given i.v. 1.1 mg/kg of xylazine from 2 manufacturers and the pharmacokinetic parameters calculated from the disposition curves. The disposition curves for the 2 commercial preparations were not different. Yohimbine, an antagonist of the pharmacologic effects produced by xylazine, did not alter the disposition of xylazine in the plasma. A single i.v. bolus of xylazine was completely described in 17 of 20 animals by the biexponential equation: Cp = 1.30e(-0.3955t) + 0.58e(-0.033t) where Cp represents the concentration of xylazine in the plasma at time t (min). The t1/2 beta was 75 +/- 13 min and whole body clearance was 18.9 +/- 1.5 (ml/min.kg).

Sulfamethazine (110 mg/kg of feed) was fed to 4 groups of pigs for 10 days. Each group was then fed withdrawal rations containing 0, 1.1, 11.0, or 110.0 mg/kg of feed for 10 days before slaughter. A 5th group was fed a sulfamethazine-free diet only. Fat, kidney, liver, and muscle from each pig were analyzed by several laboratories, using the Tishler Bratton-Marshall (BM) and gas liquid chromatographic (GLC) methods. Mean background (BG) amounts of sulfamethazine, as measured in control tissues, were essentially negligible using GLC; however, BM BG values (mean +/- SD), expressed as milligrams of sulfamethazine per kilogram of edible animal tissue (ppm) were: fat 0.019 +/- 0.003, kidney 0.048 +/- 0.012, liver 0.053 +/- 0.034, and muscle 0.018 +/- 0.017. Regression of tissue sulfamethazine on feed sulfamethazine, as measured by GLC and BM adjusted for BM-BG values, yielded essentially linear plots. Values obtained by GLC and corrected BM were highly correlated, but the variability was higher, using GLC. The linear model predicted that the dietary sulfamethazine required to produce 0.1 ppm in liver as measured by the BM, BM-BG, and GLC were 1.6, 2.8, and 3.4 ppm, respectively. The concentrations necessary to produce 0.1 ppm in muscle were 5.3, 6.2, and 5.5 ppm. The thin-layer chromatographic method of screening swine plasma was a good predictor of tissue sulfamethazine values.

Although the exact cause of DVT is not known, venous thrombosis and its sequelae remain important clinical problems. Pulmonary embolism is a significant cause of morbidity and mortality in the hospitalized population, and the postthrombotic syndrome affects a large portion of the general population. While specific screening tests are not readily available to detect those patients who are likely to develop DVT, certain clinical risk factors have been identified that predispose to thrombosis. These groups include patients undergoing a wide variety of surgical procedures, patients with cardiac disease or cancer, pregnant or postpartum women, and individuals with previous history of DVT. The diagnosis of thrombosis is based on clinical findings and must be confirmed with appropriate laboratory tests. While contrast venography remains the gold standard, noninvasive tests have become increasingly more accurate. The recent use of real-time B-mode ultrasonic imaging and duplex sonography for the diagnoses of DVT has been shown to be efficacious. The postthrombotic syndrome with its associated chronic pain and ulcerations remains a significant clinical problem. The general diagnosis of this condition is readily made on clinical grounds in the advanced state. However, exact knowledge of the location and cause of the venous pathology can only be obtained using objective diagnostic tests. Older noninvasive and invasive tests may diagnose the presence of venous obstruction, valvular incompetence, and also may document venous hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)