Biomedical subjects

K L Morgan

Publications and source records attributed to K L Morgan.

At least 55 records · Page 3Linked to original sources

PubMed2000

A study of feline upper respiratory tract disease with reference to prevalence and risk factors for infection with feline calicivirus and feline herpesvirus.

A cross-sectional survey of a convenience sample of cats was carried out to determine the prevalence of and risk factors for respiratory tract disease, feline calicivirus (FCV) infection and feline herpesvirus (FHV) infection. Seven hundred and forty cats were studied; samples for isolation of FCV and FHV were obtained from 622 (84%). Data on individual cat and household variables were obtained by questionnaire for each cat and analysed using univariable and logistic regression analysis. Thirty-eight percent (282/740) of cats surveyed had respiratory tract disease. Eighteen of 24 predictor variables were found to be significantly (P<0.05) associated with the presence of respiratory tract disease in a cat on univariable analysis. Following logistic regression, several factors retained significance including isolation of FCV and FHV, younger cats (4-11 months of age) and multiple cat households. A negative association was found with breeding catteries and other types of household in comparison with rescue catteries. Overall, feline calicivirus was isolated from 162/622 (26%) of cats sampled; 33% of the cats with respiratory tract disease were FCV positive compared to 21% of healthy cats. Variables significantly associated with FCV isolation on logistic regression were the presence of respiratory tract disease and contact with dogs with and without respiratory tract disease. Feline herpesvirus was isolated from 30/622 (5%) of all cats sampled; 11% of cats with respiratory tract disease were FHV positive compared to 1% of healthy cats. Variables significantly associated with FHV isolation on univariable analysis included age, gender, and the presence of respiratory tract disease. Vaccination showed a negative association. Logistic regression analysis of the data for FHV was limited by the sample size and the low prevalence of FHV.

Age Factors↗

PubMed2000

Risk factors associated with clinical mastitis in low somatic cell count British dairy herds.

A cross-sectional survey of dairy farms with low bulk milk somatic cell counts was carried out to assess the level of clinical mastitis and to quantify risk factors associated with the incidence rate of clinical mastitis. Questionnaires were sent to 3009 milk operations with an annual mean bulk milk somatic cell count of less than 100,000 cells/ml during 1997. A response rate was 61%. The mean incidence of clinical mastitis reported was 22.8 cases per 100 cows/yr. Negative binomial regression models were used to assess statistically significant risk factors associated with the incidence of clinical mastitis. The incidence increased when farmers reported that they had straw yard housing for milking cows (compared with cubicle housing), mucked out the calving area less frequently than once per month, kept cows standing in a yard after milking, always practiced postmilking teat disinfection, had greater than 50% replacement rate, had some cows that leaked milk on entry to the parlor, had some cows that leaked milk at other times, and foremilked before cluster attachment. The incidence of clinical mastitis was lower on farms when the gathering yard used before milking was scraped at least twice a day, cows were offered feed after both milkings, rubber gloves were not worn during milking, teat liners were changed after 6000 milkings, and the average dry period was less than 40 d. The study has identified areas of the environment in which efforts to improve hygiene should be focused.

Animals↗

PubMed1999

Orf (contagious pustular dermatitis) in farmworkers: prevalence and risk factors in three areas of England.

Orf is a zoonotic skin disease which is commonly self-diagnosed by those who tend sheep and goats. This paper reports the prevalence, incidence and risk factors associated with the infection in a cohort of farmworkers from three areas of England, derived from the results of self-reporting and serology. Twenty-three per cent of those employed or living on a sheep farm reported ever having had orf, and the antibody serological profiles indicated a prevalence of 4 per cent and an annual incidence of 2.8 per cen. The main risk factors associated with the infection were contact with sheep, the size of the sheep flock, and contact with dogs.

Animal Husbandry↗

PubMed1999

Sheep scab outbreaks in Great Britain between 1973 and 1992: spatial and temporal patterns.

In January 1973, the mange mite Psoroptes ovis was found in a sheep flock in Lancashire, UK after a 20 year period of eradication. Over the next 20 years, a total of 1480 flock outbreaks were reported, until June 1992 when the control of sheep scab was deregulated. The spatial and temporal patterns of the number of outbreaks in each month over this period were analysed using time series methods, a geographical information system (GIS) and second order approaches to the exploration of space-time interaction (K-function analysis). The monthly time series displays clear evidence of seasonal cyclicity, with most outbreaks being reported in the winter months. After removal of the summer compulsory dip in 1988 however, there is evidence of a change in the seasonal pattern, with more cases being reported in the autumn months. There is also evidence of a contribution from a sinusoidal wave with a period of 8 years, which roughly corresponds to the major changes in the national control policy. The spatial pattern also appears to expand and contract on a roughly 4 year cycle, again reflecting the oscillating periods of success and failure. Examination of the spatial and temporal pattern revealed strong evidence of space-time clustering (p < 0.001) and a major contribution to the pattern from very local (< 12 km) spread within 5 months of an arbitrary outbreak.

Animals↗

PubMed1999

Within-flock transmission of sheep scab in naive sheep housed with single infested sheep.

The within flock transmission of sheep scab was studied in two trials, which lasted 14 and 12 weeks, respectively. A total of 40 non-infested, scab-naive sheep were divided into six groups of between 6 and 20 individuals. Each group was subsequently housed with a single infested index case, carrying scab lesions of different ages. The groups of sheep in both trials were video recorded continuously and all the sheep were individually examined on a weekly basis. The occurrence of transmission was measured in two ways: first, by the detection of early scab lesions during clinical examination and, second, by an increase in the rubbing of individual sheep as noted from the analysis of the video recordings. These two methods complemented each other in predicting the week on which transmission occurred. Overall, transmission was detected in 34 of the 40 scab-naive sheep. Transmission was shown to occur at about the time when the population of adult mites in lesions on index cases reached their peak numbers. The highest number of mites at this time, however, differed markedly between index sheep. There was no obvious relationship between the incidence of transmission and the time index sheep spent rubbing each day or other index sheep variables, including the age of the lesion or the time since the introduction to the scab free sheep.

Animals↗

PubMed1999

Prevalence and risk factors for feline Bordetella bronchiseptica infection.

A cross-sectional survey of a convenience-sample of 740 cats was undertaken to obtain an estimate of the prevalence of Bordetella bronchiseptica infection, and to identify risk factors that might predispose them to the infection. Data on individual cats and household variables, including disease status and animal contacts were obtained by questionnaire. B bronchiseptica was isolated from 82 (11 per cent) of the cats sampled. The prevalence of B bronchiseptica varied with the type of household sampled, being 19.5 per cent in rescue catteries, 9 per cent in breeding catteries, 13.5 per cent in research colonies, and 0 per cent in household pets. On the basis of a univariable analysis, 19 of 29 predictor variables were found to be significantly associated with the isolation of B bronchiseptica, including an association with cats in rescue catteries, and with cats from premises with larger numbers of animals. Separate analysis of the rescue cattery subpopulation showed a highly significant association on multivariable analysis with current respiratory disease, suggesting that different risk factors may operate in this type of environment. In the whole sample there was also strong association with cats from households containing a dog with recent respiratory tract disease. The clinical signs observed in the B bronchiseptica-positive cats included sneezing, ocular and nasal discharges and coughing, although only the association with sneezing was statistically significant. There was no significant association between the isolation of B bronchiseptica and the isolation of respiratory viruses, suggesting that in some circumstances B bronchiseptica may be able to cause disease independently.

Analysis of Variance↗

PubMed1999

Prevalence of antibodies to Coxiella burnetii (Q fever) in bulk tank milk in England and Wales.

In the United Kingdom, the infection of people with Coxiella burnetii, the causative agent of Q fever, is of significant public health importance and is associated with contact with dairy cattle. An ELISA was developed for the detection of IgG antibodies against C burnetii in bulk tank milk, and in a survey of randomly selected samples from dairy herds in England and Wales, 21 per cent showed serological evidence of C burnetii infection.

Animals↗

PubMed1998

Case control study of diarrhoea and faecal soiling in two- to six-month-old lambs.

A case control study was nested within a longitudinal study of faecal soiling on eight commercial farms in the south west of England. Eighty-two incident cases of faecal soiling in lambs between two and six months of age were individually matched with a single unaffected control lamb. A range of variables was examined including sex, neonatal history, trace element concentrations in blood, wool characteristics and faecal bacteriology and parasitology. Odds ratios and their 95 per cent confidence limits were estimated by using Mantel Haenszel methods and conditional logistic regression. Faecal soiling was significantly associated with longer fleeces, lower crimp frequencies, male lambs and multiple births. Significant relationships were also found between faecal soiling and neonatal diarrhoea, blood selenium concentration and the presence of Clostridium perfringens type A in the faeces.

Animal Husbandry↗

PubMed1998

Prevalence, incidence and geographical distribution of Johne's disease in cattle in England and the Welsh borders.

The prevalence, incidence and geographical distribution of clinical Johne's disease in dairy cattle in England and the border regions of Wales were determined by a postal survey of 3772 dairy farmers. The study area was divided into three regions; south, central and north. The response rate was 78.3 per cent. The proportion of farms that reported 'ever' having the disease was 17.4 per cent. For the 10 years between 1985 and 1994 it was 4.9 per cent, and only 1.5 and 1.3 per cent in 1993 and 1994 respectively. The highest prevalence figures were always in the south. The incidence rate of clinical disease was 3.0/10,000 cow-years in both years in all herds and 16.7 and 22.8/1000 cow-years in infected herds in 1993 and 1994 respectively. An estimate of the criterion validity of diagnosis by farmers was obtained by comparing the reporting of the clinical signs with positive veterinary or veterinary investigation centre diagnoses. The proportion of farmers reporting one or other of the correct clinical signs was 95.3 per cent, and 70.6 per cent reported both correct signs (diarrhoea and weight loss).

Animals↗

PubMed1998

A multi-level model of data with repeated measures of the effect of lamb diarrhoea on weight.

Over a 1-year period, data were collected from three flocks of sheep. A total of 213 lambs were examined routinely from birth to 32 kg (2178 examinations in total). Diarrhoea was seen in lambs of all ages but did not appear to make them systemically ill. The effect of diarrhoea on lamb weight was investigated using MLn, a multi-level modeling program. The data were set at three hierarchical levels: level one, the repeated examinations on each lamb; level two, the lamb; and level three, the litter. Age, the quadratic of age, litter size, sex and farm of origin, all had significant effect on the weight of the lambs. There was also significant random variation in examinations within lambs, between individual lambs and between litters of lambs. There was a reduction in absolute weight of lambs for each week until four weeks after an episode of diarrhoea.

Animals↗

PubMed1998

South American camelids in the United Kingdom: reproductive failure, pregnancy diagnosis and neonatal care.

The results of a postal questionnaire survey conducted between December 1992 and March 1993 indicated that a third of mated female South American camelids in the United Kingdom failed to produce offspring. This failure did not include abortions or stillbirths, which accounted for up to 4 per cent and up to 3 per cent of further reproductive losses respectively. The most common method of pregnancy diagnosis was observation (40 to 70 per cent). Plasma progesterone estimations and ultrasonography were used by a small proportion of respondents. A combination of methods was seldom used. Between 25 and 46 per cent of camelid owners housed their animals at parturition and 50 to 82 per cent routinely dipped the navel of the newborn calf. Neonatal mortality was an important cause of loss.

Animal Husbandry↗

PubMed1998

South American camelids in the United Kingdom: population statistics, mortality rates and causes of death.

A survey of the health of South American camelids in the United Kingdom was carried out between December 1992 and June 1993; 123 members of the British Camelid Owners and Breeders Association and 19 non-members were sent questionnaires and usable responses were received from 84 (59 per cent). In total 689 camelids were included, and in 1992, 66 per cent were Ilama, 21 per cent alpaca and 13 per cent guanaco. Their ages ranged from less than six months to over 10 years, with animals aged two to five years constituting the largest proportion. The mortality rates between 1990 and 1992 were 2.7 to 3.3 per cent for Ilama, 3.5 to 6.9 per cent for alpaca and 0 to 11.4 per cent for guanaco. The highest mortality was in animals less than six months and more than 10 years old; 4 to 11 per cent of Ilama deaths and 17 to 33 per cent of alpaca deaths were in animals aged less than six months and a high proportion of these occurred during the first week of life. In the cases for which a cause was reported, accidents and injury accounted for 20 per cent of Ilama deaths, and perinatal deaths accounted for 22 per cent of alpaca deaths. A third of the deaths were reported as being of unknown cause, and a veterinary diagnosis was reported in less than half of the cases. These data suggest that attention to the environment and housing conditions of Ilama, the neonatal care of alpaca and improvements in diagnosis are priorities for reducing the mortality and improving the health of South American camelids in the UK.

Animals↗

PubMed1997

Lameness and foot lesions in adult British dairy goats.

In the first population-based study of lameness and foot lesions in adult goats in the UK, a random sample of 307 adult goats from four large commercial dairy farms was examined. The overall proportion of lame goats was 9.1 per cent (2.6 to 24.4 per cent). The abnormalities detected were horn separation (29.6 per cent), white line lesions (13.0 per cent) slippering (10.1 per cent), abscess of the sole (4.2 per cent), foreign body, and granulomatous lesions (1.0 per cent). Between 83.1 and 95.5 per cent of the goats had overgrown horn on at least one foot. The number of feet of individual goats with horn separation followed a Poisson distribution suggesting that it was associated with environmental rather than genetic or nutritional factors. Horn separation, abscess of the sole and footrot were significantly associated with lameness, but white line lesions, slippering and granulomatous lesions were not. There were differences between the farms in the prevalence of lameness and foot lesions. Routine foot trimming was associated with a lower prevalence of lameness.

Animal Husbandry↗

PubMed1997

Preliminary study of the effect of iron dextran on a non-regenerative anaemia of housed lambs.

A study of the effects of iron dextran supplementation on anaemia in indoor lambs was carried out on one commercial flock of 525 lambs from January to June 1993. The lambs were randomly allocated into two groups, one of which was given a parenteral injection of 300 mg iron dextran and the other was left untreated. Blood was collected from 22 12-day-old lambs and 106 24-day-old lambs, in each case half treated and half untreated. The supplemented lambs had significantly improved haematological values than the unsupplemented lambs. There were also significant differences in the total serum iron concentration, the unsaturated iron binding capacity and the percentage serum saturation with iron between the treated and untreated lambs. At 12 days, the untreated lambs had a total serum iron below the accepted normal range for sheep whereas the treated lambs had values within the normal range. At weaning, lambs injected with iron dextran were significantly heavier (1.0 kg) than those not injected. The daily liveweight gain to slaughter was greater and the proportion of deaths was lower in the treated lambs but these differences were not statistically significant.

Anemia↗

PubMed1997

Relationships between the presence of Johne's disease and farm and management factors in dairy cattle in England.

The data collected by a postal questionnaire sent to 3772 randomly selected dairy farmers in England and the border regions in Wales were used to estimate the relationships between the presence of clinical Johne's disease and farm and management factors associated with that disease. Two binary outcomes (case reported in 1993, case reported in 1994) and 27 predictor variables were considered. Only two variables were consistently and significantly associated with clinical disease in multivariable analysis. Farms on which Channel Island breeds were predominant were associated with an increased risk of reporting disease (odds ratios (ORs) ranged from 10.9 to 12.9). The presence of farmed deer on the farm also increased the risk of reporting disease (ORs ranged from 15.2 to 209.3). There were other significant but inconsistent associations involving the source of replacements, age of first-offering hay, type of concentrate feed to calves, and calving in individual pens when the cows were at grass. Since Johne's disease is predominantly subclinical, these contributing factors may play important roles in switching subclinical infection to overt disease.

Animal Feed↗

PubMed1997

The relationship between abnormalities detected in live lambs on farms and those detected at post mortem meat inspection.

A prospective longitudinal study of diseases of lambs born in December and January and housed through to slaughter was carried out on three flocks (A, B and C) between 1989 and 1991. In the first year of the investigation (1989-90) three cohorts of approximately 80 lambs were examined in detail on a regular (weekly or fortnightly) basis. This involved over 2000 examinations and at least one clinical abnormality was observed in each lamb. In the second year (1990-1) the farmers were asked to present sick lambs for treatment on the farm. Farmers from flocks A and B participated in this part of the study; a total of 97/1295 lambs that were slaughtered received at least one treatment. The carcases and visceral organs of lambs from each flock were observed after slaughter. There was no association between the abnormalities observed during routine examination of the cohort lambs (year 1) and those observed at post mortem meat inspection. However, in year 2, in lambs from flock A, there was a significant association between lambs treated for arthritis or pneumonia on the farm and the presence of arthritic or pleuritic lesions, respectively, post mortem. In both years of the study lambs which were older when slaughtered were significantly more likely to have pleuritic, pneumonic or arthritic lesions at meat inspection. It was concluded that routine examination of groups of lambs is an inefficient and possibly ineffective method to identify lambs with lesions at slaughter. However, lambs which have been treated for disease, and the older lambs in a flock, had an increased prevalence of lesions post mortem and hence more detailed inspection of these animals would increase the efficiency of meat inspection.

Animals↗

PubMed1997

Perceptions of intelligence in leaderless groups: the dynamic effects of shyness and acquaintance.

Perceptions of intelligence were investigated in 2 longitudinal studies of leaderless discussion groups (LDGs). In Study 1 (N = 87), students completed trait-shyness questionnaires and met 7 times in groups of 4-5. After Meetings 2 and 7, participants rated all group members on state shyness and intelligence. Trait-shy participants were initially judged to be less intelligent on both self- and peer ratings. At Time 2, however, trait-shy participants were no longer derogated by peers. Study 2 (N = 103) replicated the same pattern of shy derogation while demonstrating no actual relation between IQ and trait shyness. Again, trait-shy derogation disappeared by Time 2, but state-shy derogation continued. The state shy were now the low-IQ participants, who had begun to talk less. Thus, the bias against quiet individuals, originally inappropriate, gradually became a valid cue for low intelligence. Results were traced to overlapping cues for intelligence and shyness in LDGs.

Female↗

PubMed1996

Mating patterns and reproductive wastage in commercial lowland ewes in west Somerset.

The reproductive performance of 5488 ewes in 34 commercially managed, lowland flocks in west Somerset was assessed by means of a questionnaire survey and flock inspections. The introduction of vasectomised rams before the breeding season (teasing) markedly affected the proportions of ewes mated in the first 16 days after the introduction of fertile rams. In teased flocks, 84.7 per cent (range 37.8 to 100 per cent) of the ewes were mated in the first 16 days, compared with 43.8 per cent (range 2.9 to 100 per cent) in unteased flocks (P < 0.0001). Conception rates to first service and the overall percentage of ewes that conceived were similar in the teased and unteased flocks (89.3 per cent vs 92.6 per cent and 99.2 per cent vs 99.4 per cent, respectively). The overall mean (1.59) and range (1.31 to 2.04) litter size, mean (146 per cent) and range (123 to 196 per cent) lambing percentage and mean (94.6 per cent) and range (88.7 to 100 per cent) proportion of live lambs were similar in the teased and unteased flocks. The causes of reproductive failure were anoestrus (0.3 per cent), failure to conceive after multiple matings (0.3 per cent), visible abortion (2.4 per cent) and barren, that is, failing to lamb (3.4 per cent). The total reproductive loss rate was therefore 6.4 per cent of all ewes. Further non-reproductive losses occurred as a result of culling (0.3 per cent) and death during pregnancy (1.5 per cent).

Animals↗