September 11, 2013

There are certain misconceptions we hear about over and over again from our fantastic and devoted clients. (E.g., “No, garlic does not prevent fleas – if it did, we’d all be using it” and “No, cats do not urinate on the carpet because they are spiteful!”) Heartworm disease is one of these topics, evoking a good amount of confusion and misunderstanding on the part of pet owners. While this disease can be serious, and sometimes fatal, the good news is that there are safe, virtually 100% effective preventative medications available. Here are some of the most frequently misunderstood aspects of heartworm disease in our pet dogs and cats:

1.) “My dog doesn’t come in contact with other dogs, so he doesn’t need heartworm prevention.” This is probably the most common misconception about heartworm disease. Heartworms are transmitted via the bite of an infected mosquito, not from contact with any other animals. Mosquitoes do become infected by biting animals with circulating heartworm microfilaria (juvenile heartworms) so, in areas where there are lots of heartworm positive dogs, there is more risk to your dog. But there is not direct transmission of this parasite from dog to dog, cat to dog, horse to dog or from any other animal.

2.) “My dog is mainly indoors, so he’s not at risk for heartworm disease.” Does your dog go outside to use the bathroom several times a day? My guess is that the answer is “yes”, in which case your dog can easily be bitten by a mosquito during those potty breaks and potentially contract heartworm. Also, mosquitoes are commonly found indoors, which puts Fido (and Fluffy the cat) at risk for heartworm disease, regardless of how little time they spend outdoors. (We just had a massive ‘skeeter in our bedroom last night, from which I cowered under the covers while I made my husband evacuate the beast.)

3.) “I’ve had dogs all my life and I never used heartworm prevention before. My dogs never got sick.” Well, you’ve been lucky! A few significant changes have occurred in our area which make heartworm disease a more significant threat for Fido today than it was 20 years ago. First, we have unpredictable, and sometimes unseasonally warm weather in the winter months; this allows the mosquito population to persist through a longer portion of the year than ever before. Second, there has been a large influx of heartworm-positive dogs brought from the southern United States to the northeast by well-meaning rescue groups.These southern rescue dogs can act as a reservoir for heartworm infection, causing transmission to our local mosquito population, and, potentially to your dog.

4.) “Heartworm disease is treatable, isn’t it? I’d rather treat it than give my dog an expensive pill once a month.” Yes, heartworm disease is treatable. The treatment, a drug known as Immiticide, is very expensive (much more so than the cost of a monthly preventative) and involves a series of injections a month apart. The injections are incredibly painful, since they have to be given deep in muscle tissue. Finally, the treatment for heartworm disease can, in rare cases, actually result in the death of the dog being treated; this can happen as a result of a large number of heartworms dying off simultaneously and creating a clot in the lungs known as a pulmonary thromboembolism. This is absolutely a situation where it is much better to prevent than treat!

5.) “You’ve convinced me to use heartworm prevention for my dog. What about my cat? My cat is indoors only.” Cats can contract heartworm disease through the bite of an infected mosquito, but our feline friends seem more naturally resistant to this disease. That being said, the essential difference between heartworm disease in cats and dogs (and there are many differences) is that there is no FDA-approved treatment for cats with heartworm disease. If Fluffy contracts heartworm, we have no medication to treat it. Again, it is much better to prevent the disease altogether since we have no treatment options for our feline friends.

6.) “My cat won’t take pills. How can I give her heartworm prevention?” Our preferred heartworm preventative for cats is a monthly topical product known as Revolution, which also prevents fleas, some ticks and intestinal parasites. It’s a wonderful catch-all preventative for cats. (We don’t use this product routinely for dogs, unfortunately, since the tick control with Revolution is lacking. Since ticks are the major parasite in southeastern Pennsylvania, we need separate flea/tick and heartworm products for dogs; our preferred canine heartworm preventative, Sentinel, is a monthly chewable flavored tablet.)

There are a variety of heartworm preventative products available for dogs and cats, in pill or topical form. All heartworm preventatives also treat and prevent intestinal parasites such as roundworms, hookworms and whipworms. This is an important benefit, especially for dogs who eat fecal matter from wildlife or for cats who hunt. Depending on your pet’s lifestyle, we can choose the best product for Fluffy or Fido. Just as a reminder: many heartworm preventatives don’t provide adequate (if any) external parasite prevention, so please don’t forget that dogs should also be on a flea/tick preventative year-round!