The use of impedance aggregometry to evaluate platelet function after the administration of DDAVP in healthy dogs treated with aspirin or clopidogrel.

OBJECTIVE: To evaluate the effect of 1-Desamino-8-d-arginine vasopressin (DDAVP; desmopressin acetate) on platelet aggregation in healthy dogs receiving aspirin or clopidogrel. ANIMALS: 7 healthy staff-owned dogs. PROCEDURES: In this randomized double-blinded crossover study, impedance aggregometry was performed on samples of lithium-heparinized whole blood samples from dogs before (T0) treatment with aspirin (1 mg/kg, PO, q 24 h for 4 days; ASP group) or clopidogrel (1 mg/kg, PO, q 24 h for 4 days; CLP group) and then before (T1) and after (T2) treatment with DDAVP (0.3 µg/kg, IV, once). There was a 14-day washout period before the crossover component. Aggregometry was performed with 4 different assays, each of which involved a different agonist reagent to stimulate platelet function: ADP, thrombin receptor activating peptide-6, arachidonic acid, or collagen type 1. RESULTS: Median results for platelet aggregometry with agonist reagents ADP, arachidonic acid, or thrombin receptor activating peptide-6 significantly decreased between T0 and T1 for the CLP group; however, no meaningful difference in platelet aggregation was detected in the ASP group. Results for platelet aggregometry did not differ substantially between T1 and T2 regardless of treatment group or assay. CONCLUSIONS AND CLINICAL RELEVANCE: Findings suggested that administration of DDAVP may have no effect on platelet aggregation (measured with platelet aggregometry) in healthy dogs treated with clopidogrel. Because no inhibition of platelet aggregation was detected for dogs in the ASP group, no conclusion could be made regarding the effects of DDAVP administered to dogs treated with aspirin.

Treatment of Congestive Heart Failure with Intravenous Nitroglycerin in Three Dogs with Degenerative Valvular Disease.

We described the use of IV nitroglycerin as adjunctive therapy in three canine patients with left congestive heart failure secondary to degenerative mitral valve disease. All three dogs were admitted for signs of respiratory distress and all were determined to be in left congestive heart failure by history, exam findings, thoracic radiographs, and echocardiography. In addition to standard therapy for left congestive heart failure, IV nitroglycerin was administered as a constant rate infusion at a dose of 1-6 mcg/kg/min. No adverse events attributable to the drug were noted. This is the first reported use of IV nitroglycerin in clinical veterinary patients. Further studies are warranted to investigate the safety, efficacy, and optimal dosing of IV nitroglycerin infusions in dogs with left congestive heart failure.

Evaluation of PaO2 /FiO2 and SaO2 /FiO2 ratios in postoperative dogs recovering on room air or nasal oxygen insufflation.

OBJECTIVE: To evaluate partial pressure of oxygen in arterial blood/fractional percentage of inspired oxygen (PaO2 /FiO2 ) and SaO2 /FiO2 ratios (where SaO2 is percentage of oxyhemoglobin saturation in arterial blood), and the correlation between PaO2 /FiO2 and SaO2 /FiO2 , in healthy dogs recovering postoperatively on room air versus nasal oxygen insufflation. DESIGN: Retrospective study. SETTING: University veterinary teaching hospital. ANIMALS: Nineteen dogs. MEASUREMENTS AND MAIN RESULTS: Medical records were retrospectively evaluated for data from a previous prospective study of dogs undergoing ovariohysterectomy, subsequently randomized to receive 100 mL/kg/min of nasal oxygen insufflation (estimated 37% FiO2 , n = 9) or room air (estimated 21% FiO2 , n = 10) for 2 hours postoperatively. Baseline information was obtained 1 hour intraoperatively, followed by three postoperative time points (10, 60, and 120 min). Data recorded for each time point included FiO2 , PaO2 , SaO2 , PaO2 /FiO2 , SaO2 /FiO2 , partial pressure of carbon dioxide in arterial blood (PaCO2 ), rectal temperature, and arterial blood pH. The PaO2 /FiO2 in dogs recovering on supplemental oxygen was significantly higher compared to dogs recovering on room air (516 ± 28 vs. 359 ± 10, P < 0.0001), whereas the SaO2 /FiO2 ratio in dogs recovering on supplemental oxygen was significantly lower compared to dogs recovering on room air (268 ± 0.5 versus 448 ± 1.4, P < 0.0001). The PaO2 /FiO2 and SaO2 /FiO2 ratios demonstrated excellent correlation for both groups at each postoperative time point. In dogs breathing room air, PaO2 /FiO2 and SaO2 /FiO2 correlation coefficients were 0.90, 0.95, and 0.93 (P < 0.001). In dogs receiving supplemental oxygen, PaO2 /FiO2 and SaO2 /FiO2 correlation coefficients were 0.94, 0.93, and 0.90 (P < 0.001). CONCLUSIONS: In this population of postoperative dogs breathing either room air or with nasal oxygen insufflation, PaO2 /FiO2 and SaO2 /FiO2 had excellent correlation. Further evaluation into the correlation between SaO2 /FiO2 or pulse oximeter oxygen saturation (SpO2 )/FiO2 with PaO2 /FiO2 in both healthy dogs, and dogs with pulmonary dysfunction is warranted.