We are now able to treat heart disease with more success than in the past. We used to rely on digoxin, but its side effects
and lack of efficacy in cats made treatment of heart failure disappointing. The mainstay of my treatment protocol for congestive
heart failure in cats is benazepril (2.5 mg/cat once a day for cats weighing up to 5 kg; cats weighing 5 kg or more are given
5 mg/cat once a day). Not only is it more effective than digoxin in correcting heart failure, but it has been shown to cause
thinning of the left ventricular wall in cats with early hypertrophic cardiomyopathy.4 It recently became available as a
generic product, so its cost is reasonable. Spironolactone, an older drug previously used as a diuretic, is making a resurgence
because it helps treat heart failure when used in subdiuretic doses (6.25 mg b.i.d.). Atenolol, a betablocker, is indicated
when premature ventricular contractions or tachycardia is present. It should be given at 6.25 mg b.i.d. Furosemide (1.1 to
2.2 mg/kg b.i.d.) and topical nitroglycerin round out the list of cardiac drugs I typically use.
Diagnosing and treating heartworm disease
Once thought to be a rare anomaly, feline heartworm infection is diagnosed with increasing frequency in most parts of the
United States. Heartworm disease is an important cause of heart disease in cats. However, diagnosis and treatment are plagued
with problems. Because the worm burden is so low in most affected cats, serum antigen tests often yield false negative results.
Serum antibody tests lack the specificity to be reliable. Therefore, the typical diagnostic workup for feline heartworm disease
includes serum antigen and antibody tests, thoracic radiographs, and echocardiograms.
Treatment is based on supportive care of the cat, usually with corticosteroids, until the adult worms die. The only approved
drug for treating adult heartworms in dogs, melarsomine, is toxic in cats. Therefore, the best way to deal with feline heartworm
disease is prevention. A chewable preventive product is available, but cats' finicky appetites often lead to noncompliance.
Applying selamectin (Revolution—Pfizer Animal Health) monthly is a very practical way to prevent heartworm infection and
control most external and internal parasites.
Figure 4. Echocardiogram of the cat in Figure 3 showing greatly thickened left ventricular walls associated with hypertrophic
cardiomyopathy. Because the wall thickening is principally directed inward, severe disease was present even though the cat
had a normal cardiac silhouette on radiography. Radiographs lack the sensitivity of echocar-diography in diagnosing this disease.
Advances in ultrasonography
Ultrasonography is a skill that many practitioners think is beyond their reach. Fewer than 10% of primary-care, small-animal
hospitals own an ultrasound machine. However, like other skills practitioners possess, it can be mastered with determination.
The major ultrasound companies offer hands on, off-site training courses to help practitioners become proficient with this
technology. Several hours of personal instruction are needed to develop skills and build confidence. Most practitioners become
quite proficient in routine scanning procedures after a few courses, as long as they practice with their own machines.
Most ultrasound units allow images to be saved. Images can then be e-mailed to veterinary consultants for interpretation.
Using the specialists' feedback, practitioners can review the images on the ultrasound machine's hard drive to improve their
interpretation abilities. Most practitioners who use telemedicine services do so regularly at first and then decrease their
use as they become more proficient.
Feline medicine has never been more rewarding. Once mistakenly considered "small dogs,"cats have become a major part of the
pet population and smallanimal practice. Improved healthcare, an indoor lifestyle, and more dedicated owners allow many cats
to live 20 years or longer.They are the sole focus of my practice, but they also comprise a large portion of most small-animal
practices.With increased understanding of feline diseases and new diagnostic and therapeutic products,we're able to give new
meaning to the saying, "cats have nine lives."
1. Brown S.A.: Evaluation of chronic renal disease: A staged approach. Comp. Cont. Ed. 21(8):752-763; 1999.
2. DiBartola, S.P.; Rutgers, H.C.: Diseases of the kidneys. The Cat: Diseases and Clinical Management, 2nd Ed. (R.G. Sherding, ed.) Churchill Livingstone, London, England, 1994;pp 1711-1767.