British Veterinary Journal最新文献

In two studies on overcrowding and foot lesion development, claw healthwas monitored monthly, and behavioural activities such as lying/standing observed every 15 min for 5 consecutive days and nights each month of the housing season. In the first experiment, 35 autumn-calving heifers were housed at a 2:1 heifer to cubicle ratio immediately after calving. In the second study, 40 spring-calving heifers were housed at a 2:1 ratio for 2 months before calving and with one cubicle each after calving. Lying time was reduced to 5 h per 24 h in some of the autumn-calving animals and these animals had significantly worse foot lesion scores and clinical lameness than animals lying for 7 or 10 h per 24 h. The spring-calving animals did not show such a severe reduction in lying time and no significant correlation between haemorrhage score and lying time was detected. It is concluded that reduced lying time acts as an exacerbating factor in the development of claw lesions.

Markers of joint disease are much sought after in human and veterinary rheumatology. This study investigated the relationship between markers of bone and cartilage turnover in sera and synovial fluids in naturally occurring canine joint diseases. Osteocalcin (OC) was measured by radioimmunoassay; enzyme-linked immunosorbent assays were used to measure keratan sulphate, chondroitin sulphate, hyaluronan and antibodies to collagen I and II. Dimethylmethylene blue binding assay was used for the estimation of sulphated glycosaminoglycans. Compared to normal dogs significantly higher serum OC was seen in dogs with osteoarthritis (P<0.005), rheumatoid arthritis (RA) (P<0.01) and rupture/stretching of cranial cruciate ligament (P<0.02). Reduced OC was found in RA synovial fluids but this finding is probably of little value as there was too much overlap with normal joint data. Apart from a weak correlation between synovial fluid OC and keratan sulphate, there were generally no correlations between markers of bone and cartilage turnover probably reflecting the lack of any relationship between bone and cartilage metabolism in most canine arthropathies.

Six susceptible Galana and five trypanotolerant Orma Boran (Bos indicus) cattle were infected experimentally with Trypanosoma vivax KETRI 2501 by cyclical transmission using Glossina morsitans morsitans during early and mid-pregnancy. Four pregnant animals, two of each Boran type were used as controls and remained uninfected throughout the study period. Three out of the six infected susceptible Galana Borans aborted, whilst one had a stillborn calf. None of the trypanotolerant Orma Boran cattle aborted and all carried their pregnancies to term. All control animals produced live calves at term. The mechanisms leading to disruption of reproductive function in susceptible Boran cattle were not clear but could involve a number of factors, including anaemia, weight loss and post-infection decline of plasma progesterone levels. It is concluded that infection with T. vivax disrupts maintenance of pregnancy in susceptible Galana Borans but does not affect maintenance of pregnancy in the Orma Boran, demonstrating their tolerance to infection with T. vivax.

This study characterized the peripheral plasma cortisol profile throughout gestation and examined the effect of stage of gestation and foetal number in Holstein cows after non-surgical embryo transfer. Cows (n=10) were divided into two groups: Group 1=single embryo recipient cows (n=5); and group 2=twin-embryo recipient cows (n=5). Mean plasma cortisol concentrations remained basal (2–4 ng ml⁻¹) in both groups up to 2 days prepartum increased significantly (P<0.05) to peak at parturition day, and then declined rapidly 1 clay post-partum. Twin-bearing cows had significantly (P<0.01) higher mean plasma cortisol concentration on the day of parturition than in the singleton cows. There was no effect of the stage of gestation on cortisol levels in either group (P>0.1), except in the last 48 h prior to parturition. A single cow giving birth prematurely had 100% higher plasma cortisol levels on the day of parturition and 1 day post-partum than cows giving birth at term.

Animal viruses may be transmitted by arthropods in two ways, either biologically or mechanically. Many different species of Diptera are implicated in mechanical transmission, but haematophagous species are the most important. The insects become contaminated with virus during normal feeding behaviour, and virus persists on their mouthparts or body until the next feed. Some viruses are inactivated rapidly on mouthparts, whereas others survive for many days or weeks, prolonging the potential period of transmission. Some viruses produce high titres in the skin of the infected vertebrate host, which facilitates transmission, whereas other viruses are transmitted even during relatively low levels of viraemia. Mechanical transmission by arthropods is important in the epidemiology of many animal diseases, and may be the major mode of horizontal transmission. In other instances vector spread is merely incidental.

A model of pneumonic pasteurellosis has been established in goats usingPasteurella multocida harvested from pneumonic lungs of goats (types A and D), rabbits (type A) and sheep (type D). The resultant infections were acute, subacute or chronic. The gross and histological lesions of the subacute and chronic infections were typical of pneumonic pasteurellosis. P. multocida type D produced significantly (P<0.01) more severe lesions when compared with other isolates. There were strong correlations between the clinical signs and the severity of lesions.