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Biomedical subjects

M L Doherty

Publications and source records attributed to M L Doherty.

At least 19 recordsLinked to original sources
PubMed2006

A herd health approach to dairy cow nutrition and production diseases of the transition cow.

This paper presents a practical, on-farm approach for the monitoring and prevention of production disease in dairy cattle. This integrated approach, should be used in an interdisciplinary way by farmers, veterinarians, nutrition advisors and other relevant professionals for the improvement of animal health and welfare and producer profitability. The key areas that form the basis for this approach are body condition score management, negative energy balance, hypocalcaemia, rumen health and trace element status. Monitoring criteria are described for each of these key areas, which when considered collectively, will facilitate the assessment of dairy cow health with regard to clinical and subclinical disease. The criteria, which are informed by published scientific literature, are based on farm management and environmental factors, clinical data, milk production records, dietary analysis, and assessment of blood and liver concentrations of various metabolites or trace elements. The aim is to review the efficacy of production disease control measures currently in place, and if necessary to modify them or formulate new ones.

Animal Nutritional Physiological Phenomena↗
PubMed2006

A study of dry cow therapy and effects on SCC in 10 Irish dairy herds.

Somatic cell count (SCC) data for 480 cows in 10 Irish dairy herds from January 2001 until June 2002 were analysed. Herds were selected on the basis of a recent or ongoing history of clinical or subclinical mastitis. An individual cow SCC of 200 000 cells per ml was used as the threshold for elevation of SCC. The duration of elevated SCC prior to drying-off and the magnitude of the elevation in SCC were found to have an impact on the response to dry cow therapy (DCT). A trend also emerged indicating that increasing parity had a negative influence on the response to DCT.

Animals↗
PubMed2005

New transtracheal bronchoalveolar lavage technique for the diagnosis of respiratory disease in sheep.

A new transtracheal bronchoalveolar lavage technique for the diagnosis of respiratory disease in sheep under field conditions was tested in 76 sheep. The sheep were divided into three groups, normal sheep, sheep with clinical signs of respiratory disease and housed sheep, on the basis of their respiratory disease history and husbandry conditions. The detection of Mannheimia haemolytica and Mycoplasma ovipneumoniae or parainfluenza virus type 3 and bovine respiratory syncytial virus antigen in the lavage samples was closely correlated with clinical disease. The sheep with clinical respiratory disease had a higher mean percentage of neutrophils in the lavage fluid than the sheep in the other two groups.

Animal Husbandry↗
PubMed2005

Milk amyloid A: correlation with cellular indices of mammary inflammation in cows with normal and raised serum amyloid A.

This study compared concentrations of amyloid A in bovine milk with the cell-based indicators of intramammary inflammation, somatic cell count and California Mastitis Test. Mammary quarter data pertaining to 180 cows were categorised according to concentrations of serum amyloid A in the cow of origin. Ranked correlation, ranked regression and receiver operator characteristics all demonstrated acceptable agreement between milk amyloid A concentrations and cell-based indices. There were some indications of reduction in this agreement, in cows with raised concentrations of serum amyloid A. However, there were also indications that serum amyloid A did not significantly influence milk amyloid A. The results of the current study indicate that milk amyloid A exhibits good correlation with established cell-based indicators of intramammary inflammation.

Animals↗
PubMed2000

Congenital arthrogryposis: an inherited limb deformity in pedigree Suffolk lambs.

Thirty of 52 pedigree Suffolk lambs (58 per cent) were born with arthrogryposis characterised by bilateral flexion rigidity of the metacarpophalangeal and carpal joints. The recent introduction of a breeding ram was identified as the only significant risk factor in the flock, and embryo transfer was used to test the hypothesis that the arthrogryposis was an inherited disorder associated with the introduction of this ram. Two adult ewes that had previously produced lambs with arthrogryposis by the ram and four of its affected daughters were available as donors, and 20 crossbred ewes were used as recipients. Ten Suffolk-crossed ewes that had no known familial relationship with the ram were also mated by the ram as controls and they produced 10 normal lambs. Following embryo transfer, 19 lambs were born, of which seven were stillborn; arthrogryposis was evident in 10 of the 12 live lambs. Analysis of the data suggested that in the population under study, arthrogryposis was inherited as an autosomal recessive condition.

Animals↗
PubMed1999

T cell subset involvement in immune responses to Fasciola hepatica infection in cattle.

The lymphocyte response to F. hepatica during a primary infection in cattle was analysed to define the role of T cell subsets in the immune response. Blood lymphocytes were isolated from eight cattle infected with F. hepatica via trickle infection over a ten-day period and from two non-infected controls. CD4+, CD8+ and gamma delta + T cells were depleted from whole lymphocyte populations by magnetic bead depletion. Lymphocytes from infected animals demonstrated a transient, but marked elevation in responsiveness to F. hepatica antigen between weeks 3 and 8 post-infection. Responses were attenuated by depletion of CD4+ and CD8+ T cells during this period. Depletion of gamma delta + T cells attenuated antigen responses at one time point only, and at an earlier stage post-infection than when alpha beta + T cells were depleted. Responses to antigen correlated positively with both hepatic fluke burden and with the degree of hepatic damage. This suggests that the cellular immune response was not protective. Antigen responses in gamma delta + T cell-depleted populations were also associated with post-mortem fluke burden and with hepatic damage. This suggests that gamma delta + T cells are involved in down regulating alpha beta + lymphocytes which may have a role in a non-protective or immunopathological immune responses.

Animals↗
PubMed1998

Concanavalin A-stimulated proliferation of T cell subset-depleted lymphocyte populations isolated from Fasciola hepatica-infected cattle.

Over 14 weeks, peripheral blood lymphocytes (PBL) were isolated from eight adult cattle which had been orally infected with Fasciola hepatica via trickle infection over a 10-day period. Two age, breed and sex-matched cattle served as controls. CD4+, CD8+ and gammadelta+ T cells were depleted from whole PBL populations by magnetic bead depletion. Lymphocyte proliferation assays demonstrated a transient, but marked elevation in responsiveness to Concanavalin A (Con A) between weeks 2 and 4 post-infection in PBL from infected animals. Proliferative responses to Con A were significantly greater in PBL from infected cattle than uninfected/control cattle over the initial period of the experiment. Con A-stimulated proliferation of PBL isolated from infected cattle followed a similar pattern to PBL responses to F. hepatica antigen. In both whole and subset-depleted lymphocyte populations from infected cattle, proliferative responses to Con A decreased from day 28 post-infection. Depletion of CD4+, CD8+ and gammadelta+ T cell subpopulations significantly augmented responses soon after infection. These findings suggest that the capacity of bovine PBL to proliferate in response to Con A stimulation, was in some way attenuated by F. hepatica infection and proliferative responses due to non-specific activation was suppressed by the coordinated activities of various lymphocyte subsets.

Animals↗
PubMed1998

Use of excretory/secretory antigens in a competition test to follow the kinetics of infection by Fasciola hepatica in cattle.

Eight 16-18-month-old Charolais heifers were experimentally infected with Fasciola hepatica. An antigen competition assay was used to follow the kinetics of the infection and was compared to antibody tires and serum liver enzymes. The antigen competition assay was able to detect the presence of infection as soon as 6 days after the start of the experimental infection which is considerably sooner than other methods. Consequently, this assay would be useful in diagnosing fasciolosis early in the prepatent period. The animals were slaughtered at the end of the experiment, the livers recovered and post-mortem fluke burdens determined. However, only serum liver enzyme levels gave any indication of the intensity of infection in the different animals.

Animals↗
PubMed1998

Local immune responses in colon from cattle infected with Fasciola hepatica.

Colonic mucosae isolated from eight Charolais heifers 14 weeks after oral infection with Fasciola hepatica metacercariae were voltage clamped in Ussing chambers. Antigen challenge provoked a rapid-onset, inward short circuit current in infected but not in control tissue preparations. Chloride secretion accounted for part of the response as the loop diuretic bumetanide attenuated the response to antigen by 89%. The bacterial cell wall component n-formyl-methionyl-leucyl-phenylalanine induced a similar response to antigen and partly desensitised tissues to subsequent antigen challenge, consistent with the involvement of immunocytes in the response to antigen. Infection induced an elevation in the number of tissue eosinophils compared with control colon.

Animals↗
PubMed1998

A study of cattle-to-cattle transmission of Mycobacterium bovis infection.

Twenty steers, positive to the single intradermal comparative tuberculin test (SICTT), were selected from herds with a recent history of Mycobacterium bovis infection. Ten steers, negative to SICTT, were selected from herds with no history of M. bovis infection and served as in-contact animals. The animals were divided into 10 groups, each consisting of two SICTT-positive (reactor) animals and one in-contact animal. Each group was housed in an individual loose-box for a period of 1 year. Five of the groups were fed a restricted diet for part of the experiment. All cattle were slaughtered at the end of the study period and examined at post mortem. Transmission of infection to an in-contact animal occurred in four of the 10 groups. One of the four in-contact animals, which became infected, had a retropharyngeal lymph node tubercle and M. bovis was isolated from lymph nodes without visible lesions from the other three. Two of the infected in-contact animals without visible lesions did not show any detectable cell-mediated immune response. There was no evidence that dietary, restriction had any effect on transmission of disease.

Animal Husbandry↗
PubMed1997

Cervico-thoracic vertebral osteomyelitis in 14 calves.

Fourteen cases of cervico-thoracic (C-T) vertebral osteomyelitis in calves were investigated over a 6 year period. The onset of clinical signs was between 2 and 9 weeks of age. There was no breed or sex predisposition. The clinical history prior to referral extended from 5 days to 8 weeks (mean 20 days). The most common clinical presentation was difficulty in rising with a tendency to knuckle or kneel on the forelimbs which displayed hypotonia and hyporeflexia. In over half the cases pain could be elicited on manipulation of the neck. The lesion in all cases involved one or more of the vertebrae from C6 to T1. The diagnosis was confirmed by radiology and/or at post mortem. Four animals were discharged after treatment, 10 animals were humanely destroyed. Salmonella dublin was isolated from the vertebral lesion in eight of the 10 calves at post mortem.

Animals↗