MAGNETIC RESONANCE IMAGING OF THE BRAIN OF NORMAL NEONATAL FOALS

Magnetic resonance imaging (MRI) was performed on gthe brain of 5 normal, anesthetized, neonatal (age 3-to-6 days) Quarter Horse foals. The objectives of the study were to develop a technique for imaging the brain of neonatal foals, and to ascertain their normal brain anatomy. Interavenous propofol was administered for induction and maintenance of general anesthesia. Using spin echo MR techniques, T1 weighted sagittal and transverse views, and spin density and T2 weighted transverse views were successfully made of each foal. MR images provided excellent visualization of many anatomic struictures of the brain and head. MRI of the bgrain is feasible for selected neonantal equine patients.     

Prolongation of xylazine/ketamine induced recumbency time with temazepam in horses

Short term anaesthesia induced with xylazine and ketamine was compared to a combination of xylazine, ketamine and temazepam (a benzodiazepine) in six adult horses. Duration of recumbency was significantly prolonged when temazepam was administered with xylazine and ketamine. No significant differences in heart rate, respiratory rate, blood pressure or arterial pH, pCO2 and pO2 were seen between the xylazine and ketamine combination plus temazepam, and xylazine and ketamine combination only treated horses.     

Halothane-sparing effect of benzodiazepines in ponies

The halothane-sparing effect of 2 benzodiazepines, diazepam and temazepam, were investigated in ponies by measuring the minimum alveolar concentration (MAC) for halothane before and after drug administration. The MAC value for halothane decreased 29% and 16% when either 0.044 mg/kg of diazepam or 0.044 mg/kg of temazepam, respectively, was administered intravenously. Heart rate, respiratory rate, systolic and mean arterial blood pressure, and expired CO2 were also measured. No differences were present in these variables before and after drug administration nor were differences noted between the benzodiazepines.     

Serological study of leptospiral infections and endogenous uveitis among horses and ponies in the United Kingdom

The prevalence of antibody titres to a range of 20 leptospira antigens in the serum of horses and ponies with no ophthalmic abnormalities and with ophthalmoscopic evidence of endogenous uveal inflammatory disease was determined using a microscopic agglutination technique. Titres against leptospira antigens were observed in 13 out of 138 (9.1 per cent) animals with no ophthalmic abnormalities, and in three out of 27 (11.1 per cent) animals with anterior uveitis. Serovar sejroe was common to all seropositive animals with anterior uveitis. The results show that leptospira infection is not a major factor in the aetiology of equine anterior uveitis in the UK, but suggests that the organism may be associated with some cases of recurrent anterior uveitis.     

Cardiovascular and pharmacokinetic effects of isoxsuprine in the horse

Isoxsuprine (0.6 mg/kg) administered IV to 6 standing horses produced substantial, transient decreases in systemic blood pressure, systemic vascular resistance, and stroke volume. It also produced substantial, transient increases in heart rate, cardiac output, and purposeful movement. Plasma concentrations of isoxsuprine peaked soon after the drug was administered IV and then decreased over a 12-hour period in a biexponential manner, with distribution and elimination half-lives of 14 minutes and 2.67 hours, respectively. Total body clearance and steady-state volume of distribution were calculated to be 53.8 ml/min/kg and 10.5 L/kg, respectively. When a recommended therapeutic dosage regimen (0.6 mg/kg 2 times a day, per os) was used in 4 of these horses, changes were not detected. Isoxsuprine was not detected in plasma after the drug was given orally. We conclude that 0.6 mg of isoxsuprine/kg given orally every 12 hours is not likely to produce cardiovascular changes in the resting horse and that this is probably because plasma concentrations are not high enough to do so.     

The mucolytic effect of Sputolosin in horses with respiratory disease

The effect of the mucolytic drug Sputolosin on the clinical signs of respiratory disease among 28 matched pairs of horses was examined. Compared with the untreated group, the treated group showed a significant decrease in the frequency of coughing and a decreased time to resolution of both cough and nasal discharge. The results indicate that the drug is potentially useful in the management of respiratory disease characterised by an abnormal or increased production of mucus.     

Neutron activation analysis using dysprosium as a tracer to measure spray drift

Neutron activation analysis was used to determine the level of dysprosium (Dy) in spray deposits within and up to 100 m downwind from plots of winter wheat treated with an Ulvamast (Mk2) sprayer. Spray was collected on filter papers positioned horizontally 0, 0·45 and 0·75 m above the ground at 10, 30 and 100 m downwind and 36 m upwind within the sprayed plots. The minimum detectable quantity of dysprosium was found to be 1·62 × 10^?3 μg for a filter paper matrix. The concentration of dysprosium on ground collecting surfaces was significantly higher than at other sampling heights. Deposits within the sprayed areas were significantly higher than at all sampling points downwind. There was no significant difference between the deposits measured at different distances downwind or between the samples taken at different heights above the ground. Samples from the field can be sent for neutron activation analysis to the Imperial College Reactor, which has suitable facilities. This technique has the advantages of sensitivity, safety in the field, speed of analysis and reasonably low cost when compared with other quantitative techniques which require expensive solvents for extraction.