CEREBELLAR HYPOPLASIA OF GENETIC ORIGIN IN CALVES

Within 2 years, following the introduction of 2 Shorthorn bulls from the same stud into an Australian Illawarra Shorthorn (AIS) herd, 16 calves were born with cerebellar hypoplasia. All affected calves were the progeny of one bull mated to the daughters of the other. All other progeny of these bulls, most of which were from AIS dams, were normal. Affected calves exhibited severe ataxia, consistent head movement and abduction of the forelimbs. Microscopic changes in the cerebellum included sparsity of cells of the granular layer, loss of Purkinje cells and narrowing of the molecular layer. Observations on the frequencies of normal and abnormal calves are consistent with the hypothesis that the condition is caused by an autosomal recessive gene for which affected calves were homozygous and which was introduced into the herd in heterozygous condition by both of the Shorthorn bulls. Evidence is given for an unusually high frequency of the gene in the stud of origin of the Shorthorn bulls and a procedure for reducing its frequency is outlined. The possibility of a viral or toxic aetiology is discussed but is considered to be an unlikely explanation for the condition in this herd.     

Dietary aureomycin and the response of the fowl to stressors.

1. Conventional or gnotobiotic chicks, when injected from 1 d to 3 weeks of age with adrenocorticotrophic hormone (120IU/kg, three times weekly), showed a depressed growth rate, adrenal hypertrophy and depletion of cholesterol form the adrenal glands. 2. Feeding a diet supplemented with aureomycin (10 mg/kg) did not have any consistent ameliorating effect on the response of the stressed bird as judged by the above parameters. 3. It was found that treating germfree chicks with five daily injections of sterile milk on days 3 to 7 did not depress growth rate at any time, nor could differences in adrenal size or cholesterol stores be detected at the end of the 21-d experimental period. The responses were not modified by feeding an aureomycin-supplemented diet.     

PREOPERATIVE CLINICAL EVALUATION OF THE SURGICAL PATIENT WITH POTENTIAL OR APPARENT INFECTION

Because of the type of patient treated, and the nature of the injury, the veterinarian is often called upon to treat surgical infections. These infections may be primary, or can be sequelae or trauma or elective surgery. Each clinician has his own protocol and priorities in evaluation of the patient with a surgical infection. A careful history and physical examination, together with clinical and microbiological laboratory testing procedures will help identify the pathogenic organism and indicate the severity of the infection in the animal patient. With this preliminary evaluation, the clinician and surgeon may attack the problem appropriately, and with a greater assurance of success.     

Vascular responses in the equine digit.

The digital circulation was isolated in 12 ponies under pentobarbital anesthesia. Blood flow was either controlled by a pump or measured under natural perfusion. The responses to rapid changes and stoppages of blood flow indicated no evidence of autoregulation or reactive hyperemia. Local administration of acetylcholine, histamine, and prostaglandins E1 and E2 decreased prevenous resistance, whereas epinephrine and serotonin caused prevenous constriction. Large doses of epinephrine and serotonin decreased venous caliber. The effects of prostaglandins A1 and F2alpha were variable. The equine digital vasculature responds to changes in flow and to vasoactive agents like the canine forelimb skin vasculature.     

SNAKEBITE IN THE HORSE

Four cases of snakebite in horses are presented. Diagnosis was made on clinical signs in all, plus fang punctures in 2 cases. Tiger snake antivenene was used in the treatment of 2 patients and these recovered rapidly. Of the 2 in which antivenene was not used, 1 severely affected horse died. The clinical signs which were observed were those of progressive general paralysis and were entirely referable to the neurotoxic component of the venom.     

MYELOID NEOPLASIA IN A DOG

A 4-year-old Scotch Collie bitch was presented for examination because of hyperthermia and anaemia. Haematological examination and bone marrow biopsy led to a diagnosis of myeloid neoplasia. At autopsy there was slight enlargement of the liver, spleen and some lymph nodes. Microscopic examination revealed extensive infiltration of these tissues by neoplastic myeloid cells.     

Persistence of velogenic viscerotropic Newcastle disease virus in litter.

Litter in a room which had housed chickens and turkeys actively infected with velogenic viscerotropic Newcastle disease was no longer infectious for susceptible chickens placed there 10 to 14 days later.     

THE INFLUENCE OF AGE ON THE SUSCEPTIBILITY OF BULLS TO CAMPYLOBACTER FETUS SUBSP VENEREALIS

Observations were carried out on 22 Hereford bulls to determine the age at which they bacame carriers of C. fetus. During preliminary investigations, 5 bulbs were repeatedly exposed to the organism by artificial or natural means from the age of 18 months. All animals became longterm carriers on reaching an age of between 40 and 70 months. Prior to this, a temporary carrier state lasting from 4 to 29 days was produced in 4 bulls. In a subsequent experiment, 17 bulls of 3 different age groups were artificially exposed to C. fetus on 5 occasions over a 2-year period. Thirteen bulls became long-term carriers, including 9 (53%) when less than 4 years old. A transient carrier state occurred in 4 bulls, 2 of which subsequently became long-term carriers. It usually lasted 1-2 weeks, although in 1 animal the organism persisted for 11 weeks. These results are discussed in relation to the findings of other workers and it is concluded that the use of young bulls to limit the spread of C. fetus in infected herds is of dubious value.