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Abstract

Objective—To determine whether 3 variations of the 1,9-dimethylmethylene blue (DMMB) assay yield comparable results when measuring sulfated glycosaminoglycan (sGAG) concentrations in equine synovial fluid (SF).

Sample Population—25 samples of SF collected from affected joints of 13 horses and 13 samples of SF collected from nonaffected (control) joints of 4 horses.

Procedure—Sulfated glycosaminoglycan concentrations were measured by the direct spectrophotometric (ie, Farndale), microplate, and indirect DMMB assays in samples of SF collected from normal and affected joints and in samples digested with nucleases, papain, and hyaluronidase.

Results—All 3 assays reacted similarly to standard solutions of sGAGs and digestion of SF samples with nucleases, papain, and hyaluronidase. Nucleic acids were not important interfering substances, and papain and hyaluronidase could not be used interchangeably to digest SF. All 3 assays proved to have satisfactory precision (SD < 10%), but each DMMB assay resulted in significantly different measures of sGAG in equine SF.

Conclusions and Clinical Relevance—Samples of SF should be digested with papain or hyaluronidase prior to measurement via DMMB assay. Researchers currently are unable to compare clinical information when variations of the DMMB assay are used, because each DMMB assay yields substantially different sGAG concentrations in SF. Of the 3 assays examined here, we recommend use of the direct spectrophotometric DMMB assay. (Am J Vet Res 2003;64:900–906)

Full access
in American Journal of Veterinary Research

Objective

To investigate causes of seizure disorders in cats.

Design

Case series.

Animals

30 cats referred to the Ontario Veterinary College for recurrent seizures.

Procedures

Signalment and seizure pattern were evaluated. Diagnostic procedures included physical, neurologic, and fundic examinations; CBC; serum biochemical analyses, including determination of pre- and postprandial bile acid concentrations; urinalysis; serologic assays for FeL V and feline immunodeficiency virus, feline infectious peritonitis, and Toxoplasma gondii; magnetic resonance imaging of the brain; CSF analysis; and neuropathologic examination of euthanatlzed cats and of surgical biopsy specimens.

Results

All cats were found to have structural brain diseases; nonsuppurative meningoencephalitis of unknown cause was found in 14 cats, feline ischemic encephalopathy in 6, meningioma in 2, polycythemia vera with secondary brain lesions in 2, posttraumatic epilepsy in 1, and cerebral abscess in 1. A definitive diagnosis could not be reached in 4 cats.

Clinical Implications

The most common cause of seizures in cats is structural brain disease. Structural brain lesions often can be detected on the basis of seizure pattern and results of neurologic examination. Cerebrospinal fluid analysis and brain imaging are essential to determine the cause of these lesions. Causes of seizures found in the cats of this study differ from those reported to be the most common. Nonsuppurative meningoencephalitis of unknown origin appears to be a frequent cause of neurologic disorders in cats, including seizure disorders. Feline ischemic encephalopathy appears to exist in a milder form than the classic disease and may be a common cause of seizures in cats. (J Am Vel Med Assoc 1997;210:65–71)

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

We tested the hypothesis that lymphocytes from swine with susceptibility to malignant hyperthermia (mh) had calcium extrusion activity higher than unaffected swine. Cytoplasmic concentration of ionized calcium was determined by use of dual emission spectrofluorometry and measurement of the ratio of free to calcium-bound form of the fluorescent calcium dye indo-1. Net calcium accumulation and unidirectional calcium extrusion rate were dependent on intracellular calcium concentration. Calcium extrusion from calcium-loaded lymphocytes was monitored while calcium influx was inhibited by suspending the cells in calcium-free medium with a calcium chelator. Net calcium accumulation of untreated lymphocytes was monitored in calcium-replete medium. A novel method of calculation of ionized calcium was used. This method confirmed our previous findings of lower ionized calcium concentration (86 ± 40 and 370 ± 216 nmol/L; P < 0.01) and slower rates of calcium accumulation 39 ± 16 and 127 ± 52 nmol/L/min) in untreated lymphocytes from mh-susceptible swine compared with controls. These changes were attributable to calcium extrusion activity two- to three-fold higher in lymphocytes of mh-susceptible swine (154 ± 36 and 408 ± 47 nmol/L/min at 175 nmol/L; 972 ± 111 and 1,690 ± 505 nmol/L/min at 425 nmol/L). These data were compatible with our model of higher calcium extrusion activity being a compensatory adaptation of mh-susceptible swine lymphocytes to their hypersensitivity to stimuli that increase cytoplasmic calcium concentration.

Free access
in American Journal of Veterinary Research

SUMMARY

Characteristic alterations in the serum and urine biochemical profiles of Doberman Pinschers with congestive heart failure (chf) resulting from idiopathic dilated cardiomyopathy were determined. We compared these alterations with those observed in 2 other models of chf: rate overload induced by rapid ventricular pacing in dogs, and biventricular hypertrophy and dilatation induced in turkey poults by furazolidone toxicosis. Serum and urine biochemical changes in both models of chf in dogs were mild to moderate in degree, and were moderately consistent. They could be attributed to secondary neurohumoral, hepatic, and renal effects of heart failure. The most marked and consistent changes observed were mildly decreased anion gap that developed, in part, because of decreased serum sodium concentration, moderately increased catecholamine concentrations, moderate lactaciduria, hyposthenuria, and mildly increased urea concentrations and liver enzyme activities. In birds with furazolidone cardiomyopathy, we observed mild increases in serum urate concentration, liver and muscle enzyme activities, but moderately increased sodium concentration with decreased chloride concentration. In the pacing and furazolidone models, in which chf was rapidly induced, moderate to marked hypoproteinemia was attributable to decreases in albumin and globulin concentrations. Using the avian model we found that the hypoproteinemia could be largely attributed to blood volume expansion, and to a lesser extent, inanition. Development of hypoalbuminemia during rapid ventricular pacing and furazolidone treatment may contribute to the effects of rate overload or drug toxicity in the pathogenesis of chf, because hypoalbuminemia may contribute to altered hemodynamics and neuroendocrine system activation. Our data indicate that clinical biochemical analysis of serum and urine may be useful for assessing progression of chf.

Free access
in American Journal of Veterinary Research

Objective

To evaluate the accuracy of point-of-care tests for the diagnosis of disseminated intravascular coagulation (DIC) in dogs and assess the correlation and agreement of results between point-of-care and laboratory tests in the evaluation of hemostatic function.

Design

Prospective case series.

Animals

59 critically ill dogs (affected dogs) with clinical signs of diseases known to predispose to DIC and 52 clinically normal dogs.

Procedures

Accuracy of the point-of-care tests (activated clotting time [ACT], estimated platelet count and number of schizocytes from a blood smear, plasma total solids [TS] concentration, and the protamine sulfate test) was evaluated, using receiver operating characteristic curves and likelihood ratios. A strategy, using likelihood ratios to calculate a post-test probability of DIC, was tested with 65% used as a threshold for initiation of treatment. Results of laboratory tests (coagulogram and plasma antithrombin III activity) were used as the standard for comparison in each dog.

Results

ACT and estimated platelet count provided the best accuracy for detection of DIC. The plasma TS concentration, schizocyte number, and protamine sulfate test had poor accuracy. The strategy using post-test probability of DIC identified 12 of 16 affected dogs that had DIC. Estimated platelet count was correlated and had acceptable clinical agreement with automated platelet count (r = 0.70). The plasma TS (r = 0.28) concentration and serum albumin (r = 0.63) concentration were not accurate predictors of plasma antithrombin III activity. The ACT did not correlate with activated partial thromboplastin time (r = 0.28).

Conclusions and Clinical Relevance

Strategic use of likelihood ratios from point-of-care tests can assist clinicians in making treatment decisions for dogs suspected to have DIC when immediate laboratory support is unavailable. (J Am Vet Med Assoc 1999;215:805–810)

Free access
in Journal of the American Veterinary Medical Association

Objective

To describe and evaluate hemostatic function in critically ill dogs with clinical signs of diseases that predispose to disseminated intravascular coagulation (DIC).

Design

Prospective case series.

Animals

59 critically ill dogs (affected dogs) with clinical signs of diseases known to predispose to DIC and 52 clinically normal dogs (control dogs).

Procedure

Activated partial thromboplastin time (aPTT), prothrombin time (PT), thrombin clotting time (TCT), plasma fibrinogen concentration, serum concentration of fibrin and fibrinogen-related antigens (FRA), and plasma antithrombin III (AT III) activity were determined for all dogs. Results from affected dogs were compared with those of control dogs. In some affected dogs, postmortem tissue specimens were examined for evidence of microvascular thrombosis. A diagnosis of DIC was made by fulfilling at least 3 of the following criteria: 1) abnormal aPTT, PT, or TCT value, 2) low plasma fibrinogen concentration, 3) low plasma AT III activity, 4) high serum FRA concentration, or 5) low platelet count. To evaluate the severity of hemostatic dysfunction, 3 arbitrary categories (mild, moderate, and severe) were proposed.

Results

A diagnostic strategy based on moderate hemostatic dysfunction identified DIC in 16 of 59 (27.1%) affected dogs. The AT III activity was < 70% in 15 of 16 dogs with DIC. Microvascular thrombosis was observed in tissue specimens from 7 of 8 affected dogs. Serum FRA and plasma fibrinogen concena did not contribute in establishing a diagnosis of DIC.

Conclusions and Clinical Relevance

A diagnosis of DIC can be made when hemostatic dysfunction is moderate in dogs with clinical signs of diseases associated with DIC. (J Am Vet Med Assoc 1999;215:798–804).

Free access
in Journal of the American Veterinary Medical Association