Ask Dr. Richards: 01/03

Question: I live in Alaska, the land of dogs, where my cat was diagnosed with heartworm disease. Most veterinarians in town give me the same answer: No cure. Is this true? Now I have learned that cats can be put on a medicine that prevents the disease. I wish Id known about it sooner.

Answer: Unless they live with a dog, many cat people are unaware of the danger of heartworm disease in their specie-of-choice. Awareness is high in dog people for good reason: Dogs living in areas where this mosquito-borne disease is present are usually tested for it annually and placed on preventative medication either seasonally or all year round. But ignorance is not bliss. Even though cats are innately more resistant to infection than are dogs, the disease they experience can be just as devastating. (see CatWatch, April 2002, for more information about feline heartworm disease)

Sometimes Theres No Warning
Adult heartworms live about half as long in cats as in dogs (typically about 5-7 years in dogs, and 2-3 years in cats). Thankfully, many cats – perhaps the majority – never show serious outward signs of disease, and just go on their merry way. When the heartworm parasites do cause problems, the signs often mimic those common to a plethora of other feline disorders, like intermittent vomiting, coughing, breathing difficulty, or simply the aint doin right signs of lethargy, and loss of appetite and weight. One of the saddest consequences is sudden death with absolutely no warning. The first case of feline heartworm disease I ever saw came to me as an emergency at 2 AM. This beautiful fluffy cat seemed to be the picture of health until he developed severe breathing difficulty just a few hours before I saw him. His breathing progressively deteriorated over the next several hours, and he succumbed in spite of our best efforts to save him. Ive come to believe this is a fairly rare turn of events, but a tragic one nonetheless.

What About a Cure?
It depends on how you define the word cure. If your question is whether there are ways to help your cat get through the disease, the answer is yes. Supportive therapy carries the day for most of those in need of a little help (for example, corticosteroids, cardiovascular drugs, antibacterial medication, and others based upon the cats needs). Remember, the worms dont live forever, and once theyre gone, normalcy eventually returns.

If your question is whether there is a way to kill the worms living in the blood vessels of the heart and lungs rather than letting them die on their own, the answer is yes, but treatment is controversial. When the worms die, they often induce a life threatening reaction in the lungs. Granted, when the worms die naturally they can do the same thing – thats what killed the first cat I saw with heartworm disease. Proponents of worm-killing treatment posit that its better to know when the reaction will occur (predictably shortly after the medicine is given) so measures can be taken to assure the best outcome for the kitty. Even so, worm-killing treatment should be reserved for cats that are stable but still sick in spite of supportive care.

An Ounce Of Prevention…
Heartworm prevention is the way to go. Preventative medicines are available for cats, and theyre virtually 100 percent effective in preventing infection. In my opinion, heartworm preventive medication is under-prescribed in cats. I believe that if your cat lives in an area where the disease is present in dogs, then he should be receiving preventive medication – even if he lives exclusively indoors. Outdoor and indoor cats are at equal risk of infection.


Question: How many kittens can there be in one litter? The most I’ve seen are five.

Answer: In one of the largest surveys done to date, 5,073 litters yielded a total of 19,813 kittens who lived long enough to be weaned, an average of 3.9 kittens per litter. The largest litter contained 10 kittens. Most veterinarians estimate the average number of kittens born in a litter is around four or five. That’s about the ideal litter size, at least from the mother’s standpoint. Unassisted, few queens can nurse many more than five and successfully raise them all until weaning age.