Clearance of bacteria in turkeys with Bordetella avium-induced tracheitis

Quantitative clearance of aerosolized Escherichia coli from the trachea, lung, and air sacs was measured in turkeys infected with Bordetella avium. Clearance of E. coli in turkeys with B. avium-induced tracheitis was minimally affected early in infection. Sixteen to 23 days after infection with B. avium, sporadic, mild depressions in clearance of E. coli were observed in the tracheas, which had large areas of deciliated tracheal epithelium or replacement of normal epithelium by immature hyperplastic epithelium or metaplastic squamous epithelium. Clearance of E. coli from the lung and air sacs was minimally affected in turkeys infected with B. avium.     

Some observations on the semen of bulls persistently infected with bovine virus diarrhoea virus

As a result of screening procedures employed for animals entering the AI service, two bulls were identified as being persistently infected with bovine virus diarrhoea virus by isolation of the virus from blood. Semen was collected on two occasions from these bulls; its quality as measured by density and motility was poor. Gross abnormalities of the sperm head, termed 'collapsed' heads, were seen in 28 to 45 per cent of sperm from one bull and in 1 per cent of sperm from the other. The collapsed heads were small and the whole head or its anterior part had the appearance of a dried pea. Electron microscopy showed the defect to consist of convoluted nuclear material with membrane-bound vacuoles and invaginations containing membranous debris and lamellar structures. In the 'high incidence' bull there was a corresponding increase in enlarged sperm heads. The 'low incidence' bull had sperm with heads of similar mean size to sperm from control bulls but with an increased variance. The semen was diluted in a lactose diluent, frozen and stored in liquid nitrogen. The distribution of viral antigen was determined and virus was isolated from several fractions of the semen, both before and after processing and cryopreservation. In one animal raw semen failed to yield virus but virus was recovered after processing, suggesting that raw semen may not be suitable for the efficient detection of the virus.     

Surgical management of intussusception in the horse

During a 14 year period, 27 of 310 horses undergoing laparotomy because of abdominal pain were found to have an intussusception involving the small intestine (16 cases) or caecum (11 cases). The clinical signs, operative findings and techniques adopted to overcome the obstruction are described. An evaluation of possible predisposing factors provided further evidence of the important role of the tapeworm Anoplocephala perfoliata in initiating intussusception involving the ileum and caecum.     

Technique for physiological examination of canine skeletal muscle in vivo

A technique is described for studying the physiological function of canine skeletal muscle in vivo. The contractile properties of the tarsal flexor muscles were examined in three beagle dogs under general anaesthesia. The force responses to electrical stimulation of the common peroneal nerve were measured at various frequencies to determine the frequency:force relationship for this muscle group. Fatigue characteristics were also examined during intermittent stimulated activity delivered in a set pattern of frequencies. The results provide quantitative characterisation of muscle function which is repeatable. The technique described could be applied to other animals and is a potentially powerful tool for evaluating the effects of drugs on muscle performance.     

Detection of colonies of Anaplasma marginale in salivary glands of three Dermacentor spp infected as nymphs or adults

Salivary glands from males of 3 Dermacentor species (D andersoni, D variabilis and D occidentalis) that were infected with either the Virginia or Idaho isolate of Anaplasma marginale as nymphs or adults were examined for colonies of A marginale by use of light and electron microscopy. Prior to dissection of salivary glands, exposed ticks were held at 25 C for 15 to 18 days, followed by a 3-day incubation at 37 C. Ticks of 2 species transmitted A marginale to calves; the third tick species was confirmed infected by demonstration of typical colonies in tick gut cells, but transmission was not attempted; Colonies of A marginale were seen with light microscopy in salivary glands of all 3 species of ticks; they were located in acinar cells that contained simple granules. Colonies varied morphologically from small, compact ones to larger structures that contained distinct organisms and often were adjacent to the host cell nucleus. Electron microscopy confirmed that the colonies were rickettsial organisms. Morphologic features of A marginale varied and included reticulated forms, forms with electron-dense centers, and small particles; these various forms were similar to those described previously in midgut epithelial cells of ticks. We believe that the organism seen within tick salivary glands may replicate in the glands before its transmission to the vertebrate host.