Ventricular rhythm disturbances are a common pathology in human and veterinary medicine. In humans, the algorithmic approach is used to differentiate wide QRS complex tachycardia. The most commonly used are the aVR and Brugada algorithms as well as the ventricular tachycardia (VT) score developed by Jastrzębski and coworkers. In veterinary medicine, no such algorithms are available and the only parameter used to describe VT abnormalities is the duration of the QRS complexes. The aim of this analysis was determining whether human medicine algorithms for VT are applicable in veterinary medicine to differentiate wide QRS complex tachycardia in dogs. A retrospective analysis was performed on 11 dogs of both sexes and various breeds and age diagnosed with VT. The diagnosis was based on ambulatory ECG, further established based on the reaction to lidocaine or adenosine or an invasive electrophysiological study. Of the 11 tracings passed through the aVR algorithm, 10 met the VT criteria. The most common criterion was the Vi/Vt ratio (8 out of 11 tracings). Based on the VT score, seven out of eight dogs had a high probability of VT. Retrospective analysis of ECGs by aVR and VT score indicates that the applied algorithms may be useful in differentiating wide QRS complex tachycardia as a quick, easy, and non-invasive alternative to cardiac electrophysiology.

OBJECTIVE To determine the locomotor response to the administration of fentanyl in horses with and without the G57C polymorphism of the μ-opioid receptor. ANIMALS 20 horses of various breeds and ages (10 horses heterozygous for the G57C polymorphism and 10 age-, breed-, and sex-matched horses that did not have the G57C polymorphism). PROCEDURES The number of steps each horse took was counted over consecutive 2-minute periods for 20 minutes to determine a baseline value. The horse then received a bolus of fentanyl (20 μg/kg, IV), and the number of steps was again counted during consecutive 2-minute periods for 60 minutes. The mean baseline value was subtracted from each 2-minute period after fentanyl administration; step counts with negative values were assigned a value of 0. Data were analyzed by use of a repeated-measures ANOVA. RESULTS Data for 19 of 20 horses (10 horses with the G57C polymorphism and 9 control horses without the G57C polymorphism) were included in the analysis. Horses with the G57C polymorphism had a significant increase in locomotor activity, compared with results for horses without the polymorphism. There was a significant group-by-time interaction. CONCLUSIONS AND CLINICAL RELEVANCE Horses heterozygous for the G57C polymorphism of the μ-opioid receptor had an increased locomotor response to fentanyl administration, compared with the response for horses without this polymorphism. The clinical impact of this finding should be investigated.

The objective of this study was to evaluate a novel accelerometer-based sensor system, the Walkabout Portable Gait Monitor (WPGM), for use in kinetic gait analysis of dogs. The accelerometer was compared to the common reference standard of force platform analysis. Fifteen client-owned, orthopedically sound dogs of various breeds underwent simultaneous force platform and accelerometer gait trials to measure peak vertical forces (PVFs). The agreement between PVF for the accelerometer and force platform was measured using concordance correlation coefficient (CCC) and was found, overall, to be moderate [CCC = 0.51; 95% confidence interval (CI): 0.46 to 0.56]. The agreement between PVF for the accelerometer and force platform for the forelimbs was positive and substantial (CCC = 0.79; 95% CI: 0.74 to 0.84) and for the hind limbs was positive and low (CCC = 0.34; 95% CI: 0.29 to 0.38). As measured by the accelerometer, PVF was systematically higher than as measured by the force platform (forelimbs 55.3 N, hind limbs 144.3 N). It was also found that, when positioned over the lumbar spine, the WPGM cannot measure PVF of the individual forelimbs and hind limbs, which limits its use as a clinical tool to measure kinetic variables in dogs.

A high rate of mortality, expense, and complications of immunosuppressive therapy in dogs underscores the need for optimization of drug dosing. The purpose of this study was to determine, using a flow-cytometric assay, the 50% T-cell inhibitory concentration (IC50) of dexamethasone, cyclosporine, and the active metabolites of azathioprine (6-mercaptopurine) and leflunomide (A77 1726) in canine lymphocytes stimulated with concanavalin A (Con A). Whole blood was collected from 5 privately owned, healthy dogs of various ages, genders, and breeds. Peripheral blood mononuclear cells, obtained by density-gradient separation, were cultured for 72 h with Con A, a fluorochrome-tagged cell proliferation dye, and various concentrations of dexamethasone (0.1, 1, 10, 100, 1000, and 10 000 μM), cyclosporine (0.2, 2, 10, 20, 30, 40, 80, and 200 ng/mL), 6-mercaptopurine (0.5, 2.5, 50, 100, 250, and 500 μM), and A77 1726 (1, 5, 10, 25, 50, and 200 μM). After incubation, the lymphocytes were labeled with propidium iodide and an antibody against canine CD5, a pan T-cell surface marker. Flow cytometry determined the percentage of live, proliferating T-lymphocytes incubated with or without immunosuppressants. The mean (± standard error) IC50 was 3460 ± 1900 μM for dexamethasone, 15.8 ± 2.3 ng/mL for cyclosporine, 1.3 ± 0.4 μM for 6-mercaptopurine, and 55.6 ± 22.0 μM for A77 1722. Inhibition of T-cell proliferation by the 4 immunosuppressants was demonstrated in a concentration-dependent manner, with variability between the dogs. These results represent the initial steps to tailor this assay for individual immunosuppressant protocols for dogs with immune-mediated disease.

Objective: To evaluate the pharmacokinetics and clinical efficacy of budesonide in dogs with inflammatory bowel disease (IBD). Animals: 11 dogs (mean ± SD age, 5.7 ± 3.9 years; various breeds and body weights) with moderate or severe IBD. Procedures: Each dog received a controlled-release formulation of budesonide (3 mg/m2, PO, q 24 h) for 30 days (first day of administration was day 1). The concentration of budesonide and its metabolite (16-α-hydroxyprednisolone) was measured via liquid chromatography–tandem mass spectrometry in plasma and urine samples obtained on days 1 and 8 of treatment. On those days, plasma samples were obtained before the daily budesonide administration and 0.5, 1, 2, 4, and 7 hours after drug administration, whereas urine samples were obtained after collection of the last blood sample. A clinical evaluation was performed on the dogs before onset of drug administration and on days 20 and 30 after start of drug administration. Results: The highest plasma concentration of budesonide and 16-α-hydroxyprednisolone on day 1 was detected at 1 hour and at 2 hours after drug administration, respectively. After standardization on the basis of specific gravity, the ratio between urinary concentrations of budesonide and 16-α-hydroxyprednisolone was 0.006 and 0.012 on days 1 and 8, respectively. The clinical response was adequate in 8 of 11 dogs. Conclusions and Clinical Relevance: Budesonide was rapidly absorbed and metabolized in dogs with IBD. The drug gradually accumulated, and there was an adequate therapeutic response and no adverse effects.

Objective: To compare temporospatial variables (TSVs) and kinetic variables (KVs) for fore-limbs and hind limbs of small and large dogs of various breeds during walking and to determine associations among body weight (BW), TSVs, and KVs in these groups. Animals: 12 adult dogs with no evidence of lameness. Procedures: Dogs (grouped according to BW as small [< 10 kg; n = 6] or large [> 25 kg; 6]) were walked in a straight line at their preferred velocity on a wooden platform with an embedded pressure-sensing walkway. Five valid trials were analyzed for each dog; mean TSVs and KVs were determined for each group. The TSVs and KVs for forelimbs and hind limbs were compared between groups, and correlations among BW, TSVs, and KVs were determined. Results: Small dogs had significantly smaller TSVs and KVs than did large dogs. Temporal variables of small dogs and absolute vertical force variables of small and large dogs increased as BW increased. However, normalized peak vertical force and weight distribution values among the 4 limbs were similar between groups. Conclusions and Clinical Relevance: Substantial similarities and differences were detected in gait characteristics between small and large dogs. Results indicated TSVs and KVs can be used for comparison of the walking gait between dogs or for comparison of variables between limbs in an individual dog. Use of the pressure-sensing walkway is a simple method for acquisition of TSVs and KVs for large and small dogs.

Objective-To use an amplified ELISA technique to document the presence and quantify the concentration of the house dust mite allergen, Der f 1, in skin and coat dust samples collected from dogs. Animals-29 pet dogs of various breeds. Procedure-Dogs were weighed, and body surface area in square meters was determined. Skin and coat dust samples were obtained by vacuuming dogs. Collected dust was analyzed by use of standard and amplified ELISA techniques. Results-By use of the standard ELISA technique, Der f 1 was detected in skin and coat dust samples from 6 of 29 (21%) dogs. Mean concentration of Der f 1 in the 6 samples with positive assay results was 16.16 ng/mL (range, 5.61 to 31.24 ng/mL). Samples with negative assay results were retested for dust mite allergen by use of an amplified ELISA technique; an additional 14 dogs had positive assay results. Mean concentration of allergen was 0.36 ng/mL (range, 0.19 to 2.20 ng/mL). Combining both techniques, 20 of 29 (69%) dogs had positive assay results for Der f 1. Conclusions and Clinical Relevance-Results of our study indicate that house dust mite allergens are present on the skin and in the coat of dogs, and this source of allergen may act as a reservoir for allergen exposure in hypersensitive dogs. Use of an amplified ELISA technique to determine environmental concentrations of house dust mite allergens in homes and on dogs will help to identify the relationship between immunologic findings and environmental exposures in dogs with atopic dermatitis.

Biochemical changes in the small intestine during development of naturally acquired wheat-sensitive enteropathy of Irish Setters were investigated. To distinguish primary biochemical abnormalities from secondary effects of intestinal damage, progeny of affected dogs reared on a normal wheat-containing diet were compared with their own littermates reared on a cereal-free diet and with age-matched clinically normal Irish Setters fed the same wheat-containing diet. Peroral jejunal biopsy specimens were sequentially obtained between weaning and 1 year of age; specific activity and reorientating sucrose density-gradient distribution of organelle marker enzymes were determined. Major primary biochemical abnormalities were not detected in affected progeny. In affected dogs fed wheat, there was a selective, but secondary, loss of the brush border alkaline phosphatase and aminopeptidase N activities. This loss was associated with the development of partial villus atrophy, but represented a specific effect of dietary wheat on the brush border, not merely a nonspecific effect of mucosal damage, because other brush border enzymes, including disaccharidases, were not similarly affected. Increased soluble activities of lysosomal and peroxisomal marker enzymes late in the disease process may represent alterations in these 2 organelles as a secondary consequence of mucosal damage.

Cell proliferation kinetic values were established for the epidermis, hair follicle epithelium, and sebaceous glands of 8 Cocker Spaniels with primary idiopathic seborrhea. Values were established by intradermal pulse labeling injections of tritiated thymidine followed by cutaneous biopsy and autoradiography.The epidermal basal cell-labeling index was 4.96 +/- 0.97%, and the epidermal nucleated cell-labeling index was 3.33 +/- 0.71%. Calculated epidermal cell renewal time for the viable layers of the epidermis was 7.85 +/- 1.80 days. The hair follicle infundibulum basal cell-labeling index was 5.48 +/- 2.01%, and the sebaceous gland basal cell-labeling index was 5.94 +/- 4.15%. When compared with previously reported cell kinetic values for Cocker Spaniels and Beagles with healthy skin, these data indicate accelerated cellular proliferation in all 3 cutaneous structures in seborrheic Cocker Spaniels.

Skeletal muscles from healthy dogs and Labrador Retrievers with hereditary muscular dystrophy were examined morphologically and histochemically and were analyzed biochemically for Na+, K+, Ca2+, Mg2+, Zn2+, Cu2+, Cl-, total muscle water, and total neutral lipid content. Flame atomic absorption spectrophotometer was used for elemental quantitation of hydrochloric acid tissue extracts. Muscle samples from dystrophic dogs contained substantially increased concentrations of Na+, Ca2+, Zn2+, Cu2+, and Cl-, and a considerable reduction in the content of K+ and Mg2+ compared with samples from healthy dogs. Total muscle water and total fat content was higher in muscles from dystrophic dogs. Most muscle samples from dystrophic dogs had a type-2 fiber deficiency and an increase in number of fibers with internalized nuclei.