Preventing Heartworm Disease

Heartworm disease is a silent killer of dogs and cats.

It’s a slow, insidious disease that gradually incapacitates pets. By the time you notice the telltale signs of the disease, the damage that has been caused is serious. This is one disease that can be totally prevented and now, a new form of heartworm prevention is available to make your job even easier.

Heartworms are transmitted to dogs and cats by mosquitoes. After injection by a mosquito, adult worms eventually start to grow inside a pet’s heart and lungs, causing very serious damage. Being so large, they are a major barrier to the free passage of blood from the heart to the lungs. The infection slowly progresses. The heart dilates and becomes weak and in the lungs, the worms cause scarring and pneumonia.

In a dog, the disease initially causes a cough which progressively becomes worse. The dog becomes inactive and lethargic due to the weakening of its heart. It will not be able to tolerate exercise without coughing. In severe cases, fluid leaks out of the blood vessels and accumulates in the lungs and the lower part of the abdomen. This fluid gives the dog’s abdomen a ‘pear-shaped’ appearance, resembling the shape of a balloon filled with water

Sometimes, the animal will suddenly collapse. This occurs with no warning. It is associated with deep, laboured breathing, extreme weakness and a blue appearance to the tongue, and very pale gums.

In cats, heartworm disease is well recognised as a problem. Serious disease can be caused with just one worm, whereas in dogs, one or two worms are usually well tolerated. Tragically, the most common sign of the disease in cats is sudden death, but if your cat is breathless or develops a cough, you should also be concerned.

Preventing Heartworm Disease

Thankfully, preventing heartworm disease is easy and all dogs and cats should be on some form of preventive medication.

There are several choices. A daily heartworm preventive has been available for dogs for many years and was the first form of prevention used. This is an effective method, but daily preventive medications are falling in popularity.

Monthly heartworm medications are very popular. There are several brands available, such as Proheart, Revolution, Heartgard, Sentinel and Interceptor and Advocate. Many monthly preparations are available in a chewable treat form which makes them easy to administer, while Revolution and Advocate are available as a ‘spot on the back of the neck’ preparation. In addition, many of the monthly preparations also help to control intestinal worms.

The most recent advance in heartworm prevention is the yearly Once-A-Year Heartworm Prevention injection.

This product represents an exciting breakthrough for modern science because of the unique way it works. The active ingredient, moxidectin, is enclosed in minute beads called microspheres. After injection, the microspheres slowly release moxidectin which then diffuses into fatty tissues. From there, the moxidectin kills the immature forms of the heartworm menace for a full twelve months.

The ideal time for your dog to receive the injection is at the time of its annual vaccination.

The  Once-A-Year Heartworm Prevention injection can be given to pups as early as three months of age. Due to the pup’s rapid growth it needs to be repeated at six months of age.

If your dog is currently on a monthly or daily heartworm preventive, it can be easily switched onto this new injection.

While it is not suitable for cats, the Once-A-Year Heartworm Prevention will be attractive for those dog owners that have difficulty remembering to give their dog its monthly or daily heartworm preventive.

It is very important that you know with certainty that your dog is free from heartworm disease before starting on any heartworm preventive medication, including Once-A-Year Heartworm Prevention. Therefore, unless your veterinarian knows that your dog is free from heartworm disease, he or she may advise that your dog is tested for heartworm infection before the medication is sold to you.

For more advice on heartworm prevention, contact your veterinarian.

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Dr Cam Day

Dr Cam Day

Vet Behavioralist

Dr Cam Day is a Veterinarian consulting full-time in pet behaviour in South-East Queensland, Australia.