Effect of Intravenous Administration of Cobalt Chloride to Horses on Clinical and Hemodynamic Variables.

BACKGROUND: Cobalt chloride (CoCl2 ) is administered to racehorses to enhance performance. The purpose of this study was to evaluate the clinical, cardiovascular, and endocrine effects of parenterally administered CoCl2 . OBJECTIVES: To describe the effects of weekly intravenous doses of CoCl2 on Standardbred horses. ANIMALS: Five, healthy Standardbred mares. METHODS: Prospective, randomized, experimental dose-escalation pilot. Five Standardbred mares were assigned to receive 1 of 5 doses of CoCl2 (4, 2, 1, 0.5, or 0.25 mg/kg) weekly IV for 5 weeks. Physical examination, blood pressure, cardiac output, and electrocardiography (ECG) were evaluated for 4 hours after administration of the first and fifth doses. Blood and urine samples were collected for evaluation of cobalt concentration, CBC and clinical chemistry, and hormone concentrations. RESULTS: All mares displayed pawing, nostril flaring, muscle tremors, and straining after CoCl2 infusion. Mares receiving 4, 2, or 1 mg/kg doses developed tachycardia after dosing (HR 60-126 bpm). Ventricular tachycardia was noted for 10 minutes after administration of the 4 mg/kg dose. Increases in systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and mean arterial pressure (MAP) occurred after administration of all doses (4, 2, 1, 0.5, and 0.25 mg/kg). Profound hypertension was observed after the 4 mg/kg dose (SAP/DAP, MAP [mmHg] = 291-300/163-213, 218-279). Hemodynamics normalized by 1-2 hours after administration. ACTH and cortisol concentrations increased within 30 minutes of administration of all CoCl2 doses, and cardiac troponin I concentration increased after administration of the 4 and 2 mg/kg doses. CONCLUSIONS AND CLINICAL IMPORTANCE: The degree of hypertension and arrhythmia observed after IV CoCl2 administration raises animal welfare and human safety concerns.

Cost comparison of anesthetic regimens in the dog and cat.

Comparative costs of anesthetic regimens for the dog and cat were calculated. Various combinations of currently popular sedatives, tranquilizers, and anti-muscarinics (preanesthetic drugs), and anesthetic induction and maintenance drugs were studied. The preanesthetic drug affected overall anesthetic cost through its own cost, its effect on the amount of anesthetic drug necessary for intubation, and its effect on the amount of anesthetic necessary to maintain anesthesia. The combination of acetylpromazine-thiamylal-halothane was the least expensive regimen for both the dog and cat, whereas drug combinations that included isoflurane as the maintenance drug were the most expensive. In the cat, induction of anesthesia by use of N2O, O2, and halothane in a plexiglas chamber was more expensive than by the use of thiamylal.

Change of inhalation anesthetic agents for management of ventricular premature depolarizations in anesthetized cats and dogs.

Ventricular premature depolarizations (VPD) were found in 27 cats and 14 dogs during inhalation anesthesia. For animals receiving halothane, the anesthetic agent was changed to enflurane (n = 22) or isoflurane (n = 15). After the change to enflurane, the VPD reverted to normal sinus rhythm (n = 19) or decreased in frequency (n = 3). After the change to isoflurane, the VPD reverted to normal sinus rhythm (n = 14) or decreased in frequency (n = 1). For 4 cats receiving enflurane, the inhalant agent was changed to halothane, which caused an increased frequency of VPD (n = 3) or reversion to normal sinus rhythm (n = 1). It was concluded that cats and dogs with VPD during inhalation anesthesia with halothane would benefit from a change to enflurane or isoflurane.

Studies to determine the optimal dose of medetomidine for the dog.

This study was designed to determine optimal doses of medetomidine which, when given intravenously or intramuscularly, produce analgesia/anesthesia or tranquility in dogs. Forty-eight mature, mongrel, healthy dogs weighing between 5 and 40 kg were randomized to one of four categories according to the dose of medetomidine given: zero, low, medium, high. Low dose was 280 micrograms/m2* given i.v. or 375 micrograms/m2 given im Medium dose was 750 micrograms/m2 given iv or 1000 micrograms/m2 given im High dose was 1220 micrograms/m2 given iv or 1625 micrograms/m2 given im Dogs were given the compound iv; then at least 2 weeks (100 half-lives) later, it was given i.m. Parameters measuring analgesic/anesthetic effects or ataractic effects were monitored during a control period, and at 1/4, 1/2, 1, 2, 3, 4, 5, and 6 h after dosing. A positive (ideal) response was determined by comparing a score based upon the parameters measured to observations of an ideal response made by the investigators. The numbers of dogs, receiving each dose that manifested ideal responses at 1/2 h and returned to normal enough to be left unattended at 3 h, were determined; and the optimal dose was based upon the lowest dose that produced the desired response and the highest dose that permitted the dogs to be left unattended by 3 h. Doses of medetomidine of 750 micrograms/m2 given i.v. and 1000 micrograms/m2 given i.m. were considered to be optimal of the 3 non-zero doses used.(ABSTRACT TRUNCATED AT 250 WORDS)