BackgroundPimobendan is effective in treatment of dogs with congestive heart failure (CHF) secondary to myxomatous mitral valve disease (MMVD). Its effect on dogs before the onset of CHF is unknown.Hypothesis/ObjectivesAdministration of pimobendan (0.4–0.6 mg/kg/d in divided doses) to dogs with increased heart size secondary to preclinical MMVD, not receiving other cardiovascular medications, will delay the onset of signs of CHF, cardiac‐related death, or euthanasia.Animals360 client‐owned dogs with MMVD with left atrial‐to‐aortic ratio ≥1.6, normalized left ventricular internal diameter in diastole ≥1.7, and vertebral heart sum >10.5.MethodsProspective, randomized, placebo‐controlled, blinded, multicenter clinical trial. Primary outcome variable was time to a composite of the onset of CHF, cardiac‐related death, or euthanasia.ResultsMedian time to primary endpoint was 1228 days (95% CI: 856–NA) in the pimobendan group and 766 days (95% CI: 667–875) in the placebo group (P = .0038). Hazard ratio for the pimobendan group was 0.64 (95% CI: 0.47–0.87) compared with the placebo group. The benefit persisted after adjustment for other variables. Adverse events were not different between treatment groups. Dogs in the pimobendan group lived longer (median survival time was 1059 days (95% CI: 952–NA) in the pimobendan group and 902 days (95% CI: 747–1061) in the placebo group) (P = .012).Conclusions and Clinical ImportanceAdministration of pimobendan to dogs with MMVD and echocardiographic and radiographic evidence of cardiomegaly results in prolongation of preclinical period and is safe and well tolerated. Prolongation of preclinical period by approximately 15 months represents substantial clinical benefit.

Angiostrongylosis was diagnosed in 23 dogs presenting to the Queen Mother Hospital for Animals between June 1999 and August 2002. The animals' clinical records were reviewed retrospectively and certain risk factors were compared with a control population of 3407 dogs. Twenty-two of the 23 dogs were from south-east England and dogs from Surrey (n=8) were significantly overrepresented. There were also significantly more Cavalier King Charles spaniels (n=5) and Staffordshire bull terriers (n=5) among the affected dogs than in the control group. The median age of affected dogs was 10 months (range five to 90 months). The most common presenting signs were cough (65 per cent), dyspnoea (43 per cent), haemorrhagic diathesis (35 per cent) and collapse (26 per cent). Four dogs were thrombocytopenic and eight had significant prolongations in prothrombin time and/or activated partial thromboplastin time. Thoracic radiographs were abnormal in 18 of 19 dogs. A variety of changes were observed, the most typical being a patchy alveolar-interstitial pattern affecting the dorsocaudal lung fields. Angiostrongylus vasorum larvae were found in seven of 10 bronchoalveolar lavage specimens and 19 of 19 faecal samples. Three dogs died shortly after admission to the hospital. The remainder were successfully treated with fenbendazole at a dose of 50 mg/kg for five to 21 days. A vasorum should now be considered endemic to south-east England.

Background: Myxomatous mitral valve disease (MMVD) continues to be an important cause of morbidity and mortality in geriatric dogs despite conventional therapy.Hypothesis: Pimobendan in addition to conventional therapy will extend time to sudden cardiac death, euthanasia for cardiac reasons, or treatment failure when compared with conventional therapy plus benazepril in dogs with congestive heart failure (CHF) attributable to MMVD.Animals: Two hundred and sixty client-owned dogs in CHF caused by MMVD were recruited from 28 centers in Europe, Canada, and Australia.Methods: A prospective single-blinded study with dogs randomized to PO receive pimobendan (0.4-0.6 mg/kg/d) or benazepril hydrochloride (0.25-1.0 mg/kg/d). The primary endpoint was a composite of cardiac death, euthanized for heart failure, or treatment failure.Results: Eight dogs were excluded from analysis. One hundred and twenty-four dogs were randomized to pimobendan and 128 to benazepril. One hundred and ninety dogs reached the primary endpoint; the median time was 188 days (267 days for pimobendan, 140 days for benazepril hazard ratio 5 0.688, 95% confidence limits [CL] 5 0.516-0.916, P 5 .0099). The benefit of pimobendan persisted after adjusting for all baseline variables. A longer time to reach the endpoint was also associated with being a Cavalier King Charles Spaniel, requiring a lower furosemide dose, and having a higher creatinine concentration. Increases in several indicators of cardiac enlargement (left atrial to aortic root ratio, vertebral heart scale, and percentage increase in left ventricular internal diameter in systole) were associated with a shorter time to endpoint, as was a worse tolerance for exercise.Conclusions and Clinical Importance: Pimobendan plus conventional therapy prolongs time to sudden death, euthanasia for cardiac reasons, or treatment failure in dogs with CHF caused by MMVD compared with benazepril plus conventional therapy.

Objectives: To evaluate the characteristics and survival of a recent population of cats with hypertrophic cardiomyopathy. Methods: Records at the Royal Veterinary College Queen Mother Hospital for Animals were searched for cats diagnosed with hypertrophic cardiomyopathy between 1997 and 2005. Referring veterinarians and owners were contacted to determine survival times. Results: Cats with hypertrophic cardiomyopathy were evaluated for population characteristics (n=127) and survival times (n=109). Overall median survival from date of hypertrophic cardiomyopathy diagnosis at the Queen Mother Hospital for Animals was 1276 days. Cats with hypertrophic cardiomyopathy were younger (P=0·009), and more likely to be male (P<0·001) compared to a hospital control group (n=1473), and Ragdolls were over‐represented (P<0·05). Characteristics associated with increased survival in univariate analysis included younger age (P=0·007), asymptomatic status (P<0·001), normal left atrial size (P<0·001) and presence of systolic anterior motion of the mitral valve (P=0·003). Systolic anterior motion was associated with asymptomatic status, and did not influence survival in asymptomatic cats or those in congestive heart failure. Age, left atrial size and breed were significantly associated with survival time in a multivariate analysis. Clinical Significance: Cats with hypertrophic cardiomyopathy and left atrial enlargement have a poorer prognosis. The positive influence of systolic anterior motion on survival is likely to be linked to its association with asymptomatic status.

Background: Left atrial (LA) enlargement, congestive heart failure (CHF), and aortic thromboembolism (ATE) are associated with decreased survival in cats with hypertrophic cardiomyopathy (HCM), but the prognostic value of echocardiographic variables has not been well characterized.Hypothesis/Objectives: We hypothesized that LA echocardiographic variables and assessment of left ventricular (LV) diastolic and systolic function would have prognostic value in cats with HCM.Animals: Two hundred eighty-two cats diagnosed with HCM.Methods: Clinical and echocardiographic records of affected cats seen at the Royal Veterinary College from 2004 to 2009 were retrospectively analyzed. Only cats with echocardiographic confirmation of LV diastolic wall thickness ≥6 mm were included. Outcomes were obtained from clinical records or referring veterinarians and owners.Results: Deaths occurred in 164 cats, of which 107 were believed to have been cardiac deaths. Univariable predictors of an increased risk of cardiac death included older age, absence of a murmur, presence of a gallop sound or arrhythmia, presentation with either CHF or ATE, extreme LV hypertrophy (≥9.0 mm), LV fractional shortening (FS%) ≤30%, regional wall hypokinesis, increased left atrial size, decreased left atrial function, spontaneous echo-contrast/thrombus or both, absence of left ventricular outflow tract obstruction, and a restrictive diastolic filling pattern. Cox's proportional hazard analysis identified LA dysfunction, low LV systolic function, and extreme LV hypertrophy as independent predictors of decreased cardiac survival time.Conclusions and Clinical Importance: Echocardiographic measurement of LA function, extreme LV hypertrophy, and LV systolic function provides important prognostic information in cats with HCM.