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Norwich Bulletin - 2/20/2005

The Heartworm Controversy

Heartworm is a preventable, but highly serious and potentially fatal disease, caused by parasites that primarily affects our canine friends, and also our feline pals. The organ that is most affected, is, of course, the heart, but the lungs are also majorly affected by heartworms in dogs.

An adult heartworm can be 14 inches long and lives in the right side of the heart, which connects the heart to the lungs. This can lead to heart failure and can also damage other organs, such as the liver and kidneys. A dog may have hundreds of heartworms causing havoc in its system. Cats usually have smaller and fewer heartworms but they also very rarely develop microfilaremia, which is the infected larvae that matures into adult heartworms.

Heartworms are transmitted by a mosquito and then the adult female heartworm release microfilariae into the bloodstream of infected animals. When a mosquito bites an infected animal and goes to the next animal, he affectively passes the infected larvae from one to another. In cats, the microfilariae are usually short lived and the cats naturally rid themselves of the heartworm infections spontaneously. In this manner, the larvae never matures into adult heartworms. However, dogs are not that lucky.

Heartworms exist as a threat to our dogs in every state. All dogs, regardless of age, pedigree or living environment are susceptible to this parasite. Indoor and outdoor cats are affected because mosquitoes are everywhere.

If your dog is recently or lightly infected with heartworm, changes are you will see no signs of the disease. It is not until it gets dangerous that you start noticing a heavy cough, a loss of appetite, difficulty breathing or lethargy. As the disease progresses, the symptoms get worse.

Your dog should be going to the vet for a yearly health checkup and one of the tests performed is a blood test to check for heartworm. Once it is found that your dog is free of heartworm, you can prevent it by administration of a daily, monthly or injectable (good for six months) medication. And this is where the controversy comes in.

The daily and monthly oral medication has an almost 100% guarantee that your pet will not get heartworm. Of course, the medication is only as good as the administrator and you need to remember to give your dog the medication for it to be effective. Fort Dodge came up with ProHeart 6, an injectable medication that lasts for six months.

There has been a lot of activity on the internet reporting dogs suddenly dying within a week of having this shot. While there are no concrete answers, there are lots of questions and some of those questions are being asked by the US Food and Drug Administration Center for Veterinary Medicine. They have asked Fort Dodge to voluntarily cease production of ProHeart 6, as well as do a recall. There are safety issues that need to be resolved.

Fort Dodge has complied, but make it very clear in their compliance that they do not agree with the FDA conclusions. They maintain that the drug is safe and there are only 3.2 unfiltered reports of allergic reactions and illness for every 10,000 doses given. I suppose those are great odds, unless you are in that 3.2 category and lose your dog.

An independent advisory panel is being formed to study the information gathered and hopefully, resolve some of the issues that are out there on this shot. You can get more information by going to the Fort Dodge Web Site as they have put up a letter to their customers.

While heartworm is a relative simple disease to prevent with the oral tabs, for some reason many dogs are not protected by their owners. If the disease is detected early on, it can be treated but it is a long process (and expensive). The heartworms are killed with a drug called an adulticide, which is given through carefully administered injections.

Following the treatment, complete rest is needed and the dog needs to avoid excitement or exercise for a week after each treatment. A gradual return to normal life can happen. But it is so much easier on the dog and your bankbook if you just use the preventative in the first place!

Cats are a whole other ball game. There are currently no approved drugs in the United States for treating heartworm in cats. So while cats are more resistant to heartworms than dogs and may be able to rid themselves of the infection spontaneously, if they can't, chances are it's a death sentence.

I have never known a cat to have heartworm but many dogs that are in pounds and shelters have tested positive for the parasite. Please make it a point to protect mans best friend from this intrusive and potentially lethal parasite.

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