peer reviewed

peer reviewed | OBJECTIVE: To characterize the cardiovascular response to i.v. administration of serotonin (5-hydroxytryptamine [5-HT]) in calves. ANIMALS: 5 healthy unsedated Friesian calves. PROCEDURE: 41 5-HT administrations were performed: II slow infusions (duration, 5 minutes) and 30 bolus infusions (duration, 5 seconds). Cardiovascular function values were recorded before, during, and after the infusion. RESULTS: Slow infusion of 5HT first resulted in a brief period of severe bradycardia, then in sustained tachycardia with a concomitant increase in cardiac output. Systemic initial hypotension concomitant with bradycardia, then a pressor phase associated with an increase in systemic vascular resistance, and finally, a long-lasting hypotensive phase associated with decreased systemic vascular resistance. Pulmonary hypertension was associated with increased pulmonary vascular resistance, reflecting intense pulmonary vasoconstriction. Bolus infusion at increasing dosages resulted in dose-dependent bradycardia and systemic hypotension, followed by dose-dependent systemic hypertension. Unlike with slow infusion, neither the second tachycardiac nor the third systemic hypotensive phases were evident. CONCLUSIONS: 5-HT induces dose-dependent cardiovascular responses, including a reflex response followed by pulmonary and systemic vasoconstriction, in healthy calves. CLINICAL RELEVANCE: Determining the type of serotonergic receptors responsible for these responses may help to determine whether 5-HT is involved in the mechanisms underlying brisket disease in cattle.

peer reviewed | OBJECTIVE--To characterize the hemodynamic effects of medetomidine (1 mg/m2 of body surface area; dosage, 39 to 46 micrograms/kg of body weight, IM) and midazolam (1 mg/kg of body weight, i.v.) combined with butorphanol (0.1 mg/kg, i.v.), buprenorphine (10 micrograms/kg, i.v.) or saline solution. Reversibility of these effects by atipamezole (2.5 mg/m2; dosage, 97.5 to 115 micrograms/kg, IM) was evaluated. DESIGN--2 treated groups and 1 control group, without repetition. ANIMALS--15 clinically normal dogs (3 groups of 5). PROCEDURE--Medetomidine was administered at time 0; midazolam and butorphanol, buprenorphine, or saline solution at time 20; and atipamezole at time 60. Heart rate, systemic and pulmonary arterial pressures, central venous pressure, body temperature, cardiac output, and arterial and mixed venous blood gas tensions and pH were measured. Cardiac index, stroke index, systemic and pulmonary vascular resistances, and left and right stroke work indexes were calculated. RESULTS--Body temperature, heart rate, cardiac index, and stroke index were significantly decrease below baseline values in some groups. Central venous pressure, pulmonary capillary wedge pressure, and systemic vascular resistance were significantly increased above baseline in all groups. Arterial and venous PO2 and pH decreased in all groups and PCO2 increased, but these changes were more pronounced when buprenorphine was administered. Arterial pressure decreased after atipamezole administration. CONCLUSION--The combinations seemed to result in cardiorespiratory depressant effects of similar importance and most of these effects, which are related to medetomidine, were reversed by atipamezole.

A NYVAC vaccinia vector containing genes for pseudorables virus glycoproteins gII and gp50 was administered to pigs to determine if it would have a greater protective effect than a vector containing the gene for gp50 alone. Both NYVAC vectors protected pigs similarly from virulent pseudorabies virus challenge.

A rabbit serosal scarification model was utilized to compare the ability of four drugs, previously administered peri-operatively to horses undergoing exploratory celiotomy, to prevent the development of postoperative intestinal adhesions. The substances compared were 32% Dextran 70 (7 mL/kg), 1% sodium carboxymethylcellulose (7 mL/kg), trimethoprim-sulfadiazine (30 mg/kg), and flunixin meglumine (1 mg/kg). The first two were administered intra-abdominally following surgery, while the latter two were administered systemically in the peri-operative period. Fibrous adhesions were evident in all animals in the untreated serosal scarification group. No significant difference in the number of animals with adhesions was found between the untreated control group and any treatment group, nor among the treatment groups. Microscopic examination of adhesions collected at postmortem examination revealed fibers consistent with cotton, surrounded by a giant-cell reaction and ongoing acute inflammation. The source of the fibers was likely the cotton laparotomy sponges used to scarify the intestinal surface, since the pattern in the granuloma and sponge fibers appeared similar under polarized light. Though consistent intestinal adhesion formation was produced in the rabbit, the presence of foreign body granulomas may prevent consideration of this model for future research. The drugs tested were ineffective in preventing the formation of postoperative small intestinal adhesions in this model.