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.
