MAGNETIC RESONANCE IMAGING OF THE NORMAL EYE AND ORBIT OF THE DOG AND CAT

Magnetic resonance (MR) images of the normal eye and orbit of the dog and cat were acquired. T1-weighted, proton-density, and T2-weighed images were obtained in the oblique dorsal, straight sagittal, and oblique sagittal planes. Signal intensity for the various orbital structures differed among the three resonance techniques. T1-weighted images provided the greatest contrast of the retrobulbar structures. T-1 weighted images also had the highest signal to noise ratio, thereby providing the best anatomic detail. Anatomic components of the globe, retrobulbar structures and ocular adnexa were easily seen in all MR sections. The oblique dorsal and oblique sagittal planes were superior for evaluating the optic nerve in its entirety.     

Lamb morbidity in three housed flocks in south-west England during two lambing seasons—farmer versus veterinary monitoring

A 2 year investigation into diseases of early-born, housed lambs was carried out from 1989 to 1991. The mortality, morbidity and sub-clinical disease of housed lambs from three flocks were studied. This paper describes the collection and analysis of morbidity data.

Morbidity was assessed using two techniques. In the first year, a cohort of approximately 80 lambs per flock was observed at regular (7 or 14 day) intervals from birth to slaughter at 10–26 weeks of age. Each lamb was examined using a routine clinical examination carried out by two out of three members of a trained team of veterinarians.

The technique used was thought to be objective and accurate. However, because there was a small proportion (10–12%) of lambs examined there was a lack of information on severely sick lambs and only diseases of prevalence greater than 3.5% had a 95% probability of being identified. This led to a change im the method of data collection in the second year when the whole flock of lambs was observed by farmers and lambs which they considered sick were presented for treatment.

Seventeen clinical entities were detected in the first year; these were primarily mild conditions. In lambs from Cohorts A, B and C, the mortality rates were 11.8%, 10.5% and 1.3%, respectively. In the second year, 16 diseases were observed. Lambs presented by the farmers were overtly sick; 15.3% from Flock A and 29.2% from Flock B died. There were no sick lambs presented by Farmer C. In the second year, sick lambs were observed but the objectivity of the study was considered to have decreased from the first year. Evidence of this came from the inter-observer bias between farmers. There was a significant difference in the proportion of sick lambs presented by Farmers A and B but there was no significant difference in the proportion of lambs which subsequently died (1.6% and 1.8 %) of lambs born in Cohorts A and B, respectively) and which had been presented for treatment, suggesting that Farmer A selected less severely sick lambs than Farmer B.     

Pest and disease control on intensive apple trees by overhead mobile spraying

In 3 year field experiments on pest and disease control by mobile overhead spraying of intensive Cox's Orange Pippin apple trees, overhead booms applying 1125 litres/ha and overhead mist-blowing equipment applying 562 litres/ha, each spraying two complete rows from one alley in half the normal time, were compared with conventional automatic mast spraying at 2250 litres/ha and with conventional mist-blowing at 562 litres/ha. The overhead boom application of demeton-S-methyl (0.0036% a.i.) with azinphos-methyl (0.0165% a.i.) or of fenitrothion (0.031% a.i.) at the green cluster stage gave control of the applegrass aphid, Rhopalosiphum insertum, virtually equal to that obtained by conventional application of the same insecticides. Similarly, the overhead mist applications of conventional quantities of insecticides gave equal control, but not when applying one-quarter of the normal amount of insecticides. The conventional methods generally gave better control of apple sucker, Psylla mali. In 1971, when the incidence of apple scab, Venturia inaequalis, was only moderate, the overhead boom method gave equal control to conventional spraying with both dodine/captan (0.03% a.i. and 0.094% a.i.) and benomyl (0.025% a.i.) programmes: in 1972 and 1973, when the scab incidence was heavier, the overhead boom spraying was again equal to the conventional method with the benomyl programme but was less effective with the dodine/captan programme. The overhead mist applications gave control only when the scab incidence was light. Repeated applications of dinocap emulsion (0.025% a.i.), included in the fungicide programme in 1971, gave as good control of the active stages of fruit tree red spider mite, Panonychus ulmi, when applied by the overhead methods as by conventional spraying, but application of the benomyl programme gave poor control. Mobile overhead spraying of small intensive apple trees is a promising method but needs further development before becoming fully acceptable.     

Mortality in early born, housed lambs in south-west England

During a 2 year study of diseases in lambs in three early lambing (housed) flocks a total of 428 of 4413 (9.7%) lambs died. All these lambs were examined at post mortem by one investigator who used a routine procedure. Results were stored on a database (dBase III Plus) and analysed using Epiinfo. The peak rate of death occured in lambs less than 1 week old. Over 50% of deaths took place in this period. A small proportion of lambs (approximately 10 out of 1000) died during the prenatal period. Fatalities included chlamydial and mycotic abortions, but in the majority of cases there was no specific abortive agent, lambs were either freshly dead or mummified. Partum deaths (23.3–45.1 per 1000) were categorised into those due to the lambing process, lambs born dead and congenital defects. The most frequent abnormality observed was subcapsular liver rupture (9.3–20.9 per 1000) with up to 60% of affected lambs also having signs of malpresentation (subcutaneous oedema of the neck). Early postpartum deaths (12.9–31.5 per 1000) were primarily associated with starvation.