Age-related alterations to immune parameters in Labrador retriever dogs

In order to assess age-related changes in the immune status of Labrador retriever dogs, leukocyte phenotypes, lymphocyte proliferative capacity, and serum antibody levels were measured in four cohorts of dogs, ranging from 2 to 10 years of age. Absolute numbers of white blood cells, lymphocytes, monocytes, granulocytes, and CD3+, CD4+, CD8+ and CD21+ lymphocytes significantly decreased with increasing age. Relative percentages of lymphocytes and CD4 cells were significantly decreased, and relative percentages of granulocytes and CD8 cells significantly increased, with age. The CD4:CD8 ratio showed a significant age-related decrease. Proliferative responses of T-cells to mitogens in whole-blood cultures either increased (Concanavalin A) or remained the same (phytohemagglutinin) with age when data was normalised to allow for differences in responding cell number. Similarly, normalised data of proliferative response to anti-CD3 stimulation together with phorbol 12-myristate 13-acetate showed an age-related increase. Serum levels of total IgA significantly increased with age whereas total IgG levels remained unchanged. These observations illustrate a significant change to a number of immune parameters with age. However, further work is required to determine whether the differences reported here are sufficient to cause overt or functional immune senescence in Labrador retriever dogs.     

Activin A: from sometime reproductive factor to genuine cytokine

The growth factor, activin A, was initially characterized as a putative reproductive hormone but is now known to have many other divergent roles. One of these is during inflammation. Following intravenous injection of bacterial lipopolysaccharide (LPS) into sheep, activin A is released extremely rapidly into the circulation. The release of activin A appears to be independent of fever, prostaglandins or other key proinflammatory cytokines such as TNF-alpha or IL-1beta. While the precise roles and function of this factor in inflammation are yet to be elucidated, the activin response occurs in other mammalian species besides the sheep and elevated activin has been documented for a number of clinical inflammatory conditions. Activin A therefore seems to be part of the regulatory component of the innate immune response.     

Relative sensitivity of polymerase chain reaction assays used for detection of feline herpesvirus type 1 DNA in clinical samples and commercial vaccines

OBJECTIVE: To determine relative detection rates and detection limits for 6 published polymerase chain reaction (PCR) assays used for detection of feline herpesvirus type 1 (FHV-1) DNA. SAMPLE POPULATION: 5 vaccines licensed for use in preventing FHV-1-associated disease; 15 conjunctival biopsy specimens collected from cats with keratitis, conjunctivitis, or both; and a plaque-purified field isolate of FHV-1 cultured in vitro. PROCEDURE: Vaccines and clinical samples were assessed for FHV-1 DNA by use of all 6 assays. Detection rates were calculated by assuming that any sample in which FHV-1 DNA was detected was a true-positive result. Detection limits were estimated by use of serial dilutions of DNA extracted from cultured FHV-1 and 1 clinical sample. RESULTS: Testing by use of all 6 assays resulted in detection of FHV-1 DNA in all 5 vaccines. Testing by use of all 6 assays yielded concordant results for 9 of 15 conjunctival biopsy specimens (8 with negative results and 1 with a positive result). Calculated detection rates for clinical samples ranged from 29% to 86%. Assay sensitivity was ranked similarly by use of detection rate or detection limit. CONCLUSIONS AND CLINICAL RELEVANCE: Testing by use of all assays was equally likely to detect vaccine virus. Therefore, a positive PCR result in a cat may reflect vaccine virus rather than wild-type virus. Test sensitivity as assessed by detection limits and detection rates varied greatly. Because FHV-1 can be shed in clinically normal animals, high detection rate will not necessarily correlate with high diagnostic sensitivity.     

High doses of highly pathogenic avian influenza virus in chicken meat are required to infect ferrets

High pathogenicity avian influenza viruses (HPAIV) have caused fatal infections in mammals through consumption of infected bird carcasses or meat, but scarce information exists on the dose of virus required and the diversity of HPAIV subtypes involved. Ferrets were exposed to different HPAIV (H5 and H7 subtypes) through consumption of infected chicken meat. The dose of virus needed to infect ferrets through consumption was much higher than via respiratory exposure and varied with the virus strain. In addition, H5N1 HPAIV produced higher titers in the meat of infected chickens and more easily infected ferrets than the H7N3 or H7N7 HPAIV.     

Endotoxin activity in whole blood measured by neutrophil chemiluminescence is applicable to canine whole blood

The dog is widely used as a translational experimental model studying the host response and new treatments for human endotoxemia. The present study evaluated the applicability of a novel patient-near neutrophil chemiluminescence assay for the measurement of endotoxin activity in human blood when applied to canine blood samples. The assay was observed to be analytically sensitive and specific to endotoxin when tested in vitro, spiked with purified Escherichia coli lipopolysaccharide and live E. coli. The diagnostic sensitivity was sustained during Gram-positive contamination. Finally, it also demonstrated diagnostic potential when able to discriminate dogs with spontaneously occurring endotoxemia from both healthy dogs and diseased dogs without endotoxemia. The rapid patient-near assessment of endotoxin activity in canine blood should facilitate future studies on endotoxemia in both spontaneous disease and in experimental settings.     

Streptococcus zooepidemicus Myocardial Abscessation in a 1-Month-Old Thoroughbred Foal

A 1-month-old male Thoroughbred foal was presented at necropsy. A focal purulent lesion was observed in the right ventricular free wall of the myocardium. To the authors' knowledge, this is the first report of Streptococcus zooepidemicus myocardial abscessation in an equine.     

Review of diagnostic laboratory submissions of adult cattle 'found dead' in England and Wales in 2004

A total of 253 submissions from adult cattle 'found dead' in England and Wales were referred to the Veterinary Laboratories Agency in 2004. Carcases accounted for 54 per cent of the submissions and were of more diagnostic value than other types of sample. Whether the animals were beef or dairy, their distance from the laboratory and the number of deaths in the incident affected the likelihood of samples being submitted. The probability of reaching a diagnosis was influenced by the type of sample, the level of testing and the interval from sampling to receipt in the laboratory. Systemic disease was the most frequent cause of death in both dairy and beef cattle with hypomagnesaemia being the most frequent diagnosis (52 per cent) in beef cattle. In dairy cattle, 34 per cent of the diagnoses were for sporadic events, including haemorrhage and torsions of the digestive and reproductive tracts.