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The cutting edge of medicine: an update from recent conferences (Proceedings)

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Nov 01, 2009

27th Annual ACVIM Forum, Montreal

Hypertension in Hyperthyroid Cats

The exact incidence of hypertension in hyperthyroid cats is unknown to date. Certainly some cats with hyperthyroidism do appear to develop clinically significant hypertension. This study from the UK looked at 324 cats presented to a first opinion practice (21 were excluded since they were being treated for hypertension). Hypertension was considered a BP greater than 170 mmHg (using Doppler) if repeatable or if appropriate ocular signs were present. Of the 303 cats tested 12.9% were diagnosed with hypertension. Interestingly over 22% became hypertensive after their hyperthyroidism was treated (between 3 and 9 months after starting therapy). Renal status was not associated with the risk of hypertension. This study does suggest that blood pressure should be checked when hyperthyroidism is diagnosed and routinely during treatment.

26th Annual ACVIM Forum, San Antonio

Pimobendan and Therapy of Pulmonary Hypertension

Pimobendan has shown some benefit in treating pulmonary hypertension (PHT) in humans. PHT is a difficult disease to treat and prognosis is usually poor in dogs. The use of sildenafil has been investigated for the treatment of PHT and may be of benefit. This study involved 10 dogs diagnosed with PHT. These dogs showed clinical signs such as cough, right sided heart failure or syncope. The patients were followed for 91 days with echocardiography and quality of life scores. The patients were given either pimobendan or a placebo for 14 days after which they were switched to the other treatment. After this all dogs received pimobendan for 8 weeks. Pimobendan significantly decreased echo parameters of PHT in the short term. Quality of life also improved. Unfortunately only the effect on echo parameters was maintained at 90 days, quality of life was not changed. This may be from the small number of dogs or more likely that PHT is a progressive disease with poor prognosis. Certainly pimobendan is a viable option for treating PHT in dogs though the prognosis still remains poor though a short-term positive effect can be expected.

25th Annual ACVIM Forum, Seattle

Pimobendan and Treatment of Heart Failure

Pimobendan is a new drug that is highly effective for treating heart failure. The drug is both a positive inotrope as well as a vasodilator. Older positive inotropes that were used in humans showed a significant increase in mortality associated with ventricular arrhythmias and sudden death. This perception has also been associated with pimobendan, though mortality data in humans is at best equivocal and in some studies actually showed improved survival.

Researchers from the University of Guelph Ontario Veterinary College are investigating the efficacy of pimobendan vs. benazapril for the treatment of heart failure in dogs with chronic mitral valve disease. Of 47 dogs enrolled in the study, 23 dogs had Holter monitors before and 1 to 5 months after initiation of therapy. Of these 23 dogs, 13 received pimobendan (0.25 mg/kg BID) and 10 benazapril (0.25 to 0.5 mg/kg BID) together with diuretics. VPCs varied from 0 to 1788 in 24 hours with an average of 0.2/hour. There was no difference between groups at baseline or after initiation of therapy. This study shows that most dogs with chronic mitral valve disease have a low incidence of ventricular arrhythmias, though this is highly variable between individuals. The use of pimobendan did not exacerbate this.