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InFocus

A round-up of recent international literature on laboratory work and diagnostics

Comparing two methods for cross-matching blood for canine transfusions

Leo Guzman and others, Eastern Iowa Veterinary Specialty Center, Cedar Rapids

Blood transfusions have become the standard treatment for life-threatening anaemia in companion animal practice and are carried out with increasing frequency. However, transfusion carries a risk of triggering serious adverse reactions unless the donated blood is tested for serological compatibility with that of the recipient.

The authors investigated the accuracy of a novel gel tube technology when compared with the standard laboratory method for cross-matching blood. The two technologies were tested in 10 healthy dogs, 11 anaemic animals and 24 sick dogs that had received previous transfusions and may have therefore developed allo-antibodies to mismatched blood.

The time needed for testing the blood sample using the gel tube was 15 minutes, or one-third of that required for the laboratory test. But micro-agglutination and low-grade haemolysis reactions were difficult to identify with the simpler test alone and so the laboratory test should remain the gold standard.

Veterinary Emergency and Critical Care 26 (2): 262-268.

Ultrasound and laboratory examination of canine gallbladder contents

Audrey Cook and others, Texas A&M University, College Station

Substantial differences have been seen on ultrasound examination of the canine gallbladder, involving hyperechoic and nonechogenic luminal contents. The authors assess the significance of these differences in relation to the biochemistry of biliary sludge samples.

The amount of echogenic material appears to increase with age and dogs with spontaneous hyperadrenocorticism or hypothyroidism were also more likely to have dense echogenic material in the gallbladder. But there was no correlation between the sludge content and biochemical parameters, such as serum cholesterol or bilirubin concentrations or alkaline phosphatase and gamma-glutamyl transferase activities.

Journal of the American Animal Hospital Association 52 (3): 125-131.

Urinalysis in chinchillas (Chinchilla lanigera)

Grayson Doss and others, University of Wisconsin, Madison

Urine analysis can be useful in diagnosing a wide range of urinary tract and systemic disorders. Reference ranges for healthy individuals have been reported for some exotic rodent species but there are no published data on the chinchilla.

The authors examined urine samples from 41 clinically normal animals and report their preliminary findings. They note that measuring urine specific gravity by refractometry before centrifugation provides acceptable results and recommend that protein concentrations should be determined by quantitative protein analysis rather than dipstick tests.

Journal of the American Veterinary Medical Association 248 (8): 901-907.

Assessment of a multiplex, bead-based assay for detecting feline cytokines

Rachel Halpin and others, University of Missouri, Columbia

Enzyme-linked immunosorbent assays are the established method for detecting cytokines and other immunoproteins but such tests can be expensive, laborious and require large sample volumes. Multiplex immunoassays have now been developed which allow simultaneous testing of several target molecules.

The authors assessed a feline-specific, bead-based system designed to detect 19 different cytokines, growth factors, etc. However, in this study they report that the poor percentages of analytes recovered and the adverse effects of the sample protein matrix did limit the usefulness of this technology.

American Journal of Veterinary Research 77 (5): 495-504.

Serum amyloid A and haptoglobin as prognostic indicators in equine colic

Trina Westerman and others, Oregon State University, Corvalis

Acute phase proteins are used in human medicine as diagnostic and prognostic indicators for cardiovascular diseases, cancer and sepsis. Analytes such as brinogen are also widely used in veterinary laboratories. The authors investigate the relationship between levels of the acute-phase proteins serum amyloid A and haptoglobin and outcomes in 42 horses with colic.

Their findings show that horses with colic that had an abnormally increased serum amyloid A concentration were more likely to require surgical intervention, develop thrombophlebitis or have to be euthanased.

Journal of the American Veterinary Medical Association 248 (8): 935-940.

Evaluation of a point-of-care assay for cardiac troponin I in dogs

Adam Porter and others, New England Veterinary Center, Windsor, Connecticut

Troponins are a group of cardiac biomarkers that have been used in human medicine in predicting mortality in intensive care and cardiac patients.

The authors studied the potential value of a point-of-assay ELISA-based test for cardiac troponin I in 129 dogs presenting as emergency cases. Among these, 88 had normal, 29 had elevated and 12 had high troponin I levels. Dogs with elevated troponin I were eight-times more likely to die than those with normal levels and those with a high level were at 17 times greater risk.

Canadian Veterinary Journal 57 (6): 641-646.

Comparison of an in-feed glucose test with the oral sugar test

Sarah Smith and others, Royal Veterinary College, London

Horses with insulin dysregulation are predisposed to pasture-associated laminitis and early detection of endocrine changes may help to prevent this cause of lameness. The authors compare two field tests for investigating insulin sensitivity in horses: the in feed oral glucose test and the oral sugar test.

Eight ponies and five horses were examined in a randomised crossover study. The two tests showed agreement in identifying insulin dysregulation in 85% of the subjects but the results were not comparable in all cases and further work is required to ascertain which test is more accurate.

Equine Veterinary Journal 48 (2): 224-227.

Serum antibody responses to vaccination in lean and obese older dogs

John Ellis and others, University of Saskatchewan, Saskatoon

Studies conducted in Labrador retrievers indicate that there is a decline in immune function with increasing age. The authors investigated whether similar changes occur in all breeds and, if so, whether it affects the response to vaccination.

They measured serum titres to various components of routine vaccine treatment in older dogs and examined whether these responses were also affected by body condition. Their results suggest that younger dogs had a stronger response to parvovirus antigens than either lean or obese older animals. Responses to other disease pathogens were not significantly different in the various groups.

Canadian Veterinary Journal 57 (5): 532-534.

Response of sheep to modified-live and killed-virus bluetongue vaccines

Kelsie Speiser and others, University of Wyoming, Laramie

BTV-17 is one of 26 recognised serotypes of the bluetongue virus found worldwide. This strain has caused a series of epidemics in sheep and wild ungulates in Wyoming where is no commercial vaccine available locally.

The authors examined the humoral response of sheep to a multicomponent modified live virus vaccine, currently licensed only in California, and an experimental killed-virus vaccine. Tested in 374 sheep, both vaccines induced antibodies against BTV-17 that persisted for at least one year and also provided passive immunity for the lambs of treated ewes.

Journal of the American Veterinary Medical Association 248 (9): 1,043-1,049.

Iron metabolism in thoroughbreds during a standard training programme

Anna Assenza and others, University of Messina, Italy

In both human and equine athletes, exercise has been shown to reduce levels of iron available for its vital physiological roles in oxygen transport, etc.

The authors looked at the effects of a standard training regime in thoroughbreds on their iron profile and other haematological parameters. Blood samples taken at 20-day intervals over a period of 80 days showed statistically significant effects on iron, ferritin, transferrin, total iron-binding capacity, transferrin saturation and unsaturated iron-binding capacity.

Australian Veterinary Journal 94 (3): 60-63.

Hypernatraemia in a cat with toxoplasma-induced panencephalitis

Christine Weingart and others, Free University of Berlin, Germany

Water metabolism disturbances associated with hypernatraemia are rare events, caused by changes in water availability or increased intake of sodium. The authors describe an unusual case of severe hypernatraemia with azotaemia, hyperglobulinaemia and erythrocytosis in a 12-year-old neutered female Carthusian cat that presented with progressive neurological signs of disorientation and anisocora.

Imaging studies revealed a loss of structure in the cerebrum, hypothalamus and pituitary gland. The cat was euthanased and post mortem examination showed subacute granulomatous and necrotising panencephalitis with a Toxoplasma-like protozoan.

Journal of the American Animal Hospital Association 52 (1): 63-67.

Aerobic and anaerobic exercise effects on canine plasma biochemistry

Michael Bell and others, Craigieburn Animal Hospital, Craigieburn, Victoria

Leptin and adiponectin are two hormones excreted by adipose tissue that are involved in a range of metabolic processes. The authors studied the effects of short-term anaerobic exercise in greyhounds and long-term aerobic exercise in sled dogs on plasma levels of these two hormones and irisin, a hormone involved in fat metabolism during exercise.

Endurance racing in the sled dogs caused a decrease in leptin but no change in adiponectin or irisin levels. Short bursts of exercise in greyhounds had no effect on leptin or adiponectin levels but plasma irisin rose significantly 10 minutes after exercise.

Australian Veterinary Journal 94 (5): 154-159.

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