Productivity of sheep and goats under three management systems at Bamenda,Cameroon

The productivity of sheep and goats was examined under three management systems. A regime by which each animal received five doses of fenbendazole in a year gave similar results in terms of survival and liveweight gain to monthly dosing. Sheep kept by traditional methods without anthelmintic treatment survived and grew less well than goats. In contrast goats grew better and produced more young under traditional management although they were in general lighter than sheep.     

Ultrastructural features of Cowdria ruminantium in midgut epithelial cells and salivary glands of nymphal Amblyomma hebraeum

Colonies of Cowdria ruminantium were studied in midgut epithelial cells and salivary gland acini of nymphal Amblyomma hebraeum that were infected experimentally as larvae. Colonies were found in both tissues and studied with light and electron microscopy. Colonies observed within gut cells frequently contained 2 types of the organism: electron-dense and reticulated forms. The morphology of colonies from salivary glands, as seen with light microscopy, varied from compact, densely-staining, small colonies to larger ones in which individual organisms were apparent. With electron microscopy, most organisms in salivary glands were reticulated and appeared to be dividing by binary fission. In both types of host cells, colonies often contained a dense inclusion to which reticulated organisms were adhered.     

Evaluation of the Krupin-Denver valve implant in normotensive and glaucomatous beagles

The Krupin-Denver valve was implanted unilaterally in 2 normotensive and in 6 glaucomatous Beagles. The fellow eye of each dog had an external trabeculectomy. Before and after surgery, all dogs were evaluated serially by gonioscopy, biomicroscopy, tonometry, and tonography. The valve implant remained patent in 2 normotensive and in 2 glaucomatous Beagles throughout the 12 months of observation. Valve function was lost in 4 glaucomatous Beagles 4 to 6 weeks (3 dogs) and 6 months (1 dog) after implantation. Light microscopic and scanning electron microscopic evaluations of early loss of implant function revealed occlusion of the lumen and/or valve mechanism by inflammatory debris and cells. The late loss of valve function was related to chronic inflammatory response and fibrosis about the valve mechanism and tubing within the sclera.     

Propofol as an intravenous anaesthetic agent in dogs

Studies in dogs with an emulsion formulation of the intravenous anaesthetic, propofol, showed that induction of anaesthesia was smooth and it was possible to maintain anaesthesia by intermittent injection. The mean dose for induction of anaesthesia in unpremedicated dogs was 5.95 mg/kg body-weight. When no premedication was administered anaesthesia was maintained by a total dose of approximately 0.806 mg/kg/minute. Premedication with between 0.02 and 0.04 mg/kg of acepromazine reduced the mean induction dose by about 30 per cent and the maintenance dose by more than 50 per cent. In 68 unpremedicated dogs given one dose, recovery was complete in a mean time of 18 minutes and after maintenance of anaesthesia by intermittent injection in 65 dogs the mean recovery time was 22 minutes from administration of the last dose. Premedication with acepromazine did not produce statistically significant increases in these recovery times. The quiet, rapid and complete recovery proved to be most valuable in cases where the animal had to be returned to the owners' care with the minimum of delay.     

Phenylbutazone inhibition of equine platelet function.

Nonsteroidal anti-inflammatory drugs impair platelet aggregation and secretion in man, pigs, and rabbits and inhibit platelet thromboxane/prostaglandin synthesis. The present investigation studied the effects of phenylbutazone on platelet aggregation and bleeding times in the horse. Aggregation responses to adenosine diphosphate and collagen were markedly impaired 15 minutes and 2 hours after treatment, but 4 hours after treatment, platelet responses approximated those prior to treatment. The in vivo effect of phenylbutazone correlated with its plasma concentrations. Phenylbutazone, like aspirin, appeared to exert its effect by inhibiting thromboxane/prostaglandin synthesis, because thrombin-induced malondialdehyde formation was inhibited. However, unlike aspirin, free arachidonate-induced malondialdehyde synthesis was reduced but not eliminated, which suggested that phenylbutazone may have more than one site of action. Although collagen-induced platelet aggregation was impaired, a response was still present, and bleeding times were not altered by phenylbutazone treatment. To account for these findings, it is proposed that equine platelets can respond to collagen by thromboxane/prostaglandin independent pathways. The physiologic and pathophysiologic importance of these findings is discussed.     

Histology of the hair cycle in male beagle dogs

A detailed histologic study of the hair follicles of male Beagle dogs was made to determine changes in microscopic structure associated with the three stages in the hair cycle. Observed changes are that the bulbs of hair follicles in anagen are more closely associated with adipose tissue than they are in telogen. This is due to the deeper penetration of the follicles into the subcutaneous tissue during anagen. The hair germ cells of telogen were presumed to arise from the stratum basale of the matrix cells rather than from the outer root sheath cells. During telogen, the dermal papilla is separated from the club hair, but remains in close proximity to it. There is no connecting stalk as is reported for other animals.     

Effect of incubation temperature or maternal antibody on virus growth and mortality of embryonated chicken eggs inoculated with the B1 strain of lentogenic Newcastle disease virus

The effects of incubation temperature on virus growth and mortality patterns were studied in antibody-free chicken eggs inoculated with the B1 strain of Newcastle disease virus. Embryo mortality patterns did not differ much between 37, 39, and 41 C of incubation, although virus growth curves were higher at 39 C and 41 C than at 37 C. Below 35 C, embryo mortality was delayed, although from 48 hours after incubation the virus growth curves were similar to those at 37 C. In eggs with and without maternal antibody, virus titers were maximum 48 hours after incubation, although slightly higher in antibody-free eggs than in eggs with antibody whether the eggs were alive or dead. Eggs with maternal antibody had delayed mortality patterns.     

Hemodynamic effects of xylazine in the calf

The hemodynamic effects of sedative level doses of xylazine in five chronically instrumented calves were studied. These effects included immediate and prolonged reductions in heart rate, cardiac output, arterial blood pressure, and left ventricular dp/dt max. Stroke volume showed an initial decrease in value with a return in 15 minutes to base-line values. Total peripheral resistance, end-diastolic left ventricular pressure, end-diastolic left ventricular volume, and left ventricular residual fraction were increased after drug administration. The results indicate that a depressed myocardium results from xylazine administration. With one exception (the absence of a hypertensive response), these effects largely parallel, both quantitatively and qualitatively, those seen with this drug in other species. Sedation by xylazine is produced in cattle at doses which are small compared to those which is required for sedation in other species. These same small doses in cattle also cause hemodynamic changes.