Jl Hodgson

A case‐control study of respiratory disease in Thoroughbred racehorses in Sydney, Australia

In order to investigate the role of infectious agents in the aetiology of lower respiratory tract disease in Thoroughbred racehorses, a matched case-control study was conducted. Cases were identified by the presence of coughing, and were compared to a control population matched on time of sample collection and location within the same training establishment. Tracheal wash samples were collected from 100 cases and 148 controls. Case horses were more likely than controls to have endoscopic and cytological evidence of airway inflammation. There was no significant association between serological evidence of infection by commonly implicated respiratory viruses and coughing. Similarly, mycoplasma were rarely isolated and were not associated with disease. In contrast, there was a strong association between isolation of greater than a total of 10(3) colony-forming units/ml of tracheal wash and coughing. Individual bacterial species associated with disease included Streptococcus zooepidemicus, Streptococcus pneumoniae, Streptococcus suis, Streptococcus sanguis, Pasteurella spp and Bordetella bronchiseptica. This study provides evidence of the role of bacterial infection in the aetiology of lower respiratory tract inflammation in racehorses. However, in 58% of cases, few or no bacteria were isolated. Hence, at the time of identification of disease, there was no evidence of viral, bacterial or mycoplasmal infection in the majority of coughing horses. The aetiology of the signs observed in these horses requires further investigation.

Sensitivity to gentamicin of Escherichia coli isolated from foals: comparison of two laboratory methods

The laparoscopic technique described can be highly efficient for collecting pronuclear-stage goat embryos. The overall recovery rate of 77 per cent obtained in the two sessions is comparable with or higher than that reported by authors who used laparotomy as distinct from laparoscopy procedures (Selgrath and others 1990). The lower incidence of postoperative adhesions after laparoscopy, also observed by McKelvey and Robinson (1986), justifies the use of this technique. It should be mentioned that skill in laparoscopy takes time to acquire but the time needed for flushings and embryo recovery rates were improved with practice. To obtain pronuclear-stage embryos from Saanen goats treated with FSH and prostaglandin the optimal time for flushing the oviducts was 75 to 78 hours after the injection of prostaglandin. This correlates closely with the results of Selgrath and others (1990) who found 72 to 79 hours after the removal of progestagen implants to be optimal for the collection of one-cell embryos. Further research is required to find the optimal superovulation regimen for Saanen goats, and thereby to increase the efficiency of gene-transfer programmes. For example, at the time of flushing a large number of unovulated follicles was found at the surface of the ovary. It is probable that a superovulation protocol including the administration of gonadotrophin-releasing hormone could increase the ovulation rate.