Pharmacokinetics of sulfamethoxazole and trimethoprim in donkeys, mules, and horses

OBJECTIVE: To compare serum disposition of sulfamethoxazole and trimethoprim after IV administration to donkeys, mules, and horses. ANIMALS: 5 donkeys, 5 mules, and 3 horses. PROCEDURE: Blood samples were collected before (time 0) and 5, 15, 30, and 45 minutes and 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 8, 10, and 24 hours after IV administration of sulfamethoxazole (12.5 mg/kg) and trimethoprim (2.5 mg/kg). Serum was analyzed in triplicate with high-performance liquid chromatography for determination of sulfamethoxazole and trimethoprim concentrations. Serum concentration-time curve for each animal was analyzed separately to estimate noncompartmental pharmacokinetic variables. RESULTS: Clearance of trimethoprim and sulfamethoxazole in donkeys was significantly faster than in mules or horses. In donkeys, mean residence time (MRT) of sulfamethoxazole (2.5 hours) was less than half the MRT in mules (6.2 hours); MRT of trimethoprim in donkeys (0.8 hours) was half that in horses (1.5 hours). Volume of distribution at steady state (Vdss) for sulfamethoxazole did not differ, but Vdss of trimethoprim was significantly greater in horses than mules or donkeys. Area under the curve for sulfamethoxazole and trimethoprim was higher in mules than in horses or donkeys. CONCLUSIONS AND CLINICAL RELEVANCE: Dosing intervals for IV administration of trimethoprim-sulfamethoxazole in horses may not be appropriate for use in donkeys or mules. Donkeys eliminate the drugs rapidly, compared with horses. Ratios of trimethoprim and sulfamethoxazole optimum for antibacterial activity are maintained for only a short duration in horses, donkeys, and mules.     

Conservative management of minimally displaced radial fractures in three horses

Minimally displaced, spiral, radial fractures were diagnosed in three adult horses. Two horses had open fractures and in one horse the fracture was closed. A diagnosis was made on radiographs taken 24 h, 5, and 9 days after the fracture. There was minimal displacement of the fracture fragments despite the considerable time which had elapsed between fracture and diagnosis and an unfavourable prognosis with internal fixation, so conservative therapy was the preferred method of treatment. One horse developed a sequestrum and draining sinus, which was treated surgically under general anaesthesia 3 months after diagnosis of the fracture. Other complications were minimal and transient. Two horses were being used for pleasure riding 12 months after fracture and one horse was pasture sound at 8 months.     

The behaviour of male lambs transported by sea from New Zealand to Saudi Arabia

The behaviour of two pens of mixed British breed male sheep transported by ship from New Zealand to Saudi Arabia was studied. One of the groups was carried above decks (n = 128) and one below decks (n = 116). Observations were conducted four to five times daily throughout the 24-day voyage. Over the whole voyage the most common activities were standing, lying and feeding. Overall, the animals adapted reasonably well to the shipboard environment, with most gaining weight. The mortality rate in the study pens averaged 2.5%, which was similar to that of the total shipment and average for this type of voyage. The behavioural measures appeared to provide sensitive indices of changes in the welfare of the sheep. An increase in lying activity, panting and drinking and a decrease in feeding during the latter part of the voyage were indicative of increasing heat stress. Plunging at the feed and water troughs led to loss of footing and increased the likelihood of smothering. This activity occurred after periods without feed or without water. Plunging also occurred when sheep moved towards the ventilators. Other factors associated with reduced well-being were the high stocking density which, combined with a wet faecal pad, limited movement towards feed or water and increased the likelihood of smothering.     

Effects of dietary levels of essential oil extracts from Moringa oleifera and Artemisia afra on kidney histology,haemato‐immunological parameters and disease resistance in Clarias gariepinus

This experiment investigated the effect of dietary supplementation with essential oils from Artemisia afra and Moringa oleifera on haemato‐immunological parameters and resistance in Clarias gariepinus (African Sharptooth catfish) (Burchell, 1822) challenged with Aeromonas hydrophila. The experiment lasted for 45 days. Prior to and postchallenge, white blood cells significantly increased (p < .05) from the 3% to 12% M. oleifera and A. afra supplementation. Pre‐challenge, no significant differences (p > .05) in red blood cells, haemoglobin and haematocrit were observed between the control and M. oleifera supplementation, while in the A. afra supplementation, RBC and HCT significantly increased from the 6% to 12%. Postchallenge, RBC, HGB and HCT were significantly lower (p < .05) in the control and the 3% and 6% M. oleifera and A. afra supplementation. Both pre‐ and postchallenge, nitro‐blue tetrazolium levels significantly increased (p < .05) from the 3% to 12% M. oleifera supplementation while no significant differences (p > .05) were observed in lysozyme activity between the control and treatment groups. In A. afra, NBT and lysozyme activities increased significantly (p < .05) from the 6% to 12% supplementation pre‐ and postchallenge. Survival rate increased from the 3% to 12% in M. oleifera and A. afra supplementation groups. Significant kidney histological alterations were noted in the control and the 3% and 6% supplementation of both plants postchallenge, while no major histological changes were observed between treatment groups and the control pre‐challenge. The results demonstrate that EO from M. oleifera and A. afra can improve immunity and enhance survival in C. gariepinus.     

COMPUTED TOMOGRAPHY AND BLOOD GAS ANALYSIS OF ANESTHETIZED BLOODHOUNDS WITH INDUCED PNEUMOTHORAX

Increasingly severe degrees of pneumothorax were produced in 6 adult anesthetized bloodhounds. Computed tomography (CT) of the thorax was performed on each dog to evaluate the effects of pneumo thorax on thoracic and on pulmonary cross-sectional area (TA and PA). Arterial PO₂ (PaO₂) and PCO₂ (PaCO₂), heart rate (HR), and mean arterial blood pressure (MAP) were determined and related to the severity of pneumothorax. Volumes of air equal to 1, 1.5 and 2 times functional residual capacity of the lung produced approximately 33%, 40%, and 50% reductions in pulmonary area respectively. These amounts of atelectasis correspond to a radiographically "moderate" degree of pneumothorax. As severity of pneumothorax increased, thoracic area consistently increased, PaO₂ consistently decreased, and PaCO₂ consistently increased, with all being statistically significant relationships (p<0.0001); but HR and MAP were variable and showed no statistical correlation to the degree of pneumothorax (p>0.2).     

The selection of antigens for the diagnosis, prognosis and evolutive study of parasitic diseases

The hypothesis is set forth that schizodeme (kDNA) typing of Trypanosoma cruzi, and possible other parasites, may be used to resolve the problem associated with the protean clinical manifestations of the disease. kDNA typing of T. cruzi clones may turn out to be useful in: (1) diagnosis; (2) prognosis; (3) production of species (generic) vaccines; (4) the study of autoimmunity. We recommend that an international culture bank of schizodeme-type T. cruzi be established.     

Estimation of the total sulfur amino acid requirement and the effect of betaine in diets deficient in total sulfur amino acids for the weanling pig.

Four experiments were conducted to determine whether betaine (BET) could replace dietary methionine (MET) in diets for weanling pigs. Pigs in each experiment were allotted to treatments on the basis of weight in a randomized complete block design. Each treatment was replicated four (Exp. 4), five (Exp. 1 and 2), or six (Exp. 3) times with five or six pigs per replicate. In Exp. 1, pigs were fed a diet formulated to be deficient in total sulfur amino acids (TSAA) (negative control; NC) or the NC + 0.05 or 0.10% MET or BET during Phase 1 and 0.035 or 0.07% MET or BET during Phase 2. Growth performance was not affected (P > 0.10) by dietary treatments, indicating that the diets were not deficient in TSAA. In Exp. 2, graded levels of TSAA (0.74, 0.79, 0.84, 0.89, or 0.94%) were fed. Overall ADG was increased (0 vs added MET, P < 0.07) in pigs fed TSAA levels of 0.79% or greater, but gain:feed was not affected (P > 0.10) by diet. Overall ADFI was increased (linear, P < 0.08) and plasma urea N (PUN) was decreased (quadratic, P < 0.01) as the level of TSAA was increased. Most of the change in ADG, PUN, and ADFI occurred between 0.74 and 0.84% TSAA. Thus, the 0.74% TSAA diet was used in Exp. 3 as the NC. In Exp. 3, the diets included the following: 1) NC, 2) NC + 0.05% MET, 3) NC + 0.10% MET, 4) NC + 0.039% BET, or 5) NC + 0.078% BET. The addition of MET resulted in increased (linear, P < 0.10) ADG, ADFI, and gain:feed, but MET decreased PUN (linear, P < 0.05). Daily gain, ADFI, and TSAA intake were not different (P > 0.10) between pigs fed 0.05% MET or 0.039% BET, but gain:feed was decreased (P < 0.01) in pigs fed 0.039% BET compared with pigs fed 0.05% MET. In Exp. 4, a 2 x 2 x 2 factorial arrangement of treatments was used (MET, 0 or 0.072%; cystine, 0 or 0.059%; or BET, 0 or 0.057%). Overall ADG and gain:feed were increased (P < 0.10) in pigs fed MET. The intake of TSAA was increased (P < 0.05), and PUN was decreased (P < 0.10) in pigs fed MET or cystine. Overall ADFI was increased in pigs fed BET or MET independently but not affected when BET and MET were fed together (BET x MET, P < 0.10). The addition of BET to TSAA-deficient diets resulted in increased ADG, which was due to an increase in ADFI (TSAA intake). Thus, BET did not spare MET in this experiment.