Suspected tolazoline toxicosis in a llama.

Clinical signs of tolazoline toxicosis developed in a 4-year-old llama that received 2 doses of tolazoline hydrochloride to reverse xylazine-induced sedation. The full first dose (4.3 mg/kg [2.0 mg/lb] of body weight) was erroneously injected i.v., and the second dose was administered half i.v., half i.m. 45 minutes later, because the llama became weak and recumbent. Signs of anxiety, hyperesthesia, profuse salivation, and tachypnea were the first detectable clinical signs of tolazoline toxicosis. Convulsions, hypotension, gastrointestinal tract hypermotility, and diarrhea also developed. The llama was treated successfully with i.v. administration of diazepam, phenylephrine, and lactated Ringer's solution supplemented with potassium chloride and oxygen administered via nasal insufflation. We suggest that the maximum dose of tolazoline administered at any one time to llamas not exceed 2 mg/kg (0.91 mg/lb). Furthermore, tolazoline should be administered slowly i.v. or i.m. to reduce the risk of adverse reactions.

Effect of feed rate and drill speed on temperatures in equine cortical bone.

OBJECTIVE: To examine the amount of heat generated in equine cortical bone by a 6.2-mm drill, using low- and high-speed and controlled feed rate drilling. SAMPLE POPULATION: 10 metacarpal bones harvested from five 2-year-old draft-type horses. PROCEDURE: Drilling on metacarpal bones was done using a machine shop mill with which the feed rate and drill speed could be precisely controlled. Bones were drilled, using 6 combinations of feed rate (1, 2, and 3 mm advance/s) and drill speed (317 and 1,242 revolutions/min [rpm], with maximal temperatures recorded by thermocouples placed 1, 1.5, and 2 mm from the drill. Maximal temperatures were evaluated for the effect of feed rate, drill speed, cortical thickness, and distance from the drill, using linear regression analysis. RESULTS: Increasing feed rate from 1 to 2 and from 2 to 3 mm/s significantly decreased mean maximal temperature. Increasing drill speed from 317 to 1242 rpm significantly increased mean maximal temperature. Increasing cortical thickness significantly increased mean maximal temperature, and increasing the distance from the drill hole significantly decreased mean maximal temperatures. CONCLUSIONS: On the basis of our results, we recommend using low drill speeds while applying sufficient axial force to advance the drill as rapidly as possible through the bone. CLINICAL RELEVANCE: Results of using this in vitro model suggest that temperatures at the drill-bone interface may be sufficiently high to result in significant thermal necrosis when drilling equine cortical bone.

External skeletal fixation for treatment of comminuted fractures in wapiti: 5 cases.

External skeletal fixators were used successfully to treat severely comminuted fractures in 5 wapiti.

Influence of preoperative complete blood cell counts on surgical outcomes in healthy horses: 102 cases (1986-1996).

OBJECTIVE: To assess the value of CBC as a preoperative test in healthy horses undergoing cryptorchidectomy. DESIGN: Retrospective study. ANIMALS: 117 horses. PROCEDURE: Medical records were reviewed to identify horses that had had cryptorchidectomy. Of the 117 horses identified, 102 were found that did not have a known medical condition believed to adversely affect surgery. Preoperative CBC was assessed in terms of abnormalities detected and effects of these abnormalities on development of complications during and after surgery and patient management. RESULTS: Of 102 CBC performed, 55 contained abnormalities. Mild neutrophilia was detected in 40 horses. Of the remaining 15 horses with abnormal CBC, 8 had abnormalities that were considered potentially important. Changes in patient management and development of surgical complications were not associated with these 8 horses. Surgical complications were defined as intraoperative changes in blood pressure, excessive blood loss, development of postanesthetic myopathies, and postoperative wound or respiratory tract infections. Surgical complications developed in 17 horses. Of these, 6 horses had an abnormal CBC that was indicative of mild neutrophilia. Positive and negative predictive values of preoperative CBC on development of perioperative complications were 0.11 and 0.77, respectively. CLINICAL IMPLICATIONS: On the basis of findings in our study, determination of preoperative CBC does not predict development of complications during or after surgery and does not alter patient management.