posted 07-29-2003 02:26 AM         

If you have recently taken your dog to the veterinarian your vet may have recommended putting your dog on heartworm medication. In the last couple of years heartworm medication has become the rage. Some pharmaceutical companies have even combined flea medication with heartworm medication so that now your dog only has to take one pill. What is heartworm and why is it important to guard your dog against this disease?

Heartworm is a parasite that prefers to attack the heart. It is responsible for thousands of deaths each year. Most deaths occur from the destruction these worms due to not only the heart, but also the lungs liver and kidneys. In some cases the worm may attack the heart so profusely that circulation of the blood is compromised resulting in the he sudden death of a dog. A dog can go years without showing symptoms of the disease. This disease is preventable.

Heartworm is transmitted through the vector of a mosquito. When a mosquito feeds on your dog, the dog could be infected with heartworm. Now the mosquito becomes a carrier of the disease and when it lands on its next victim it transmits the disease. Wherever mosquitoes are found you can find the occurrence of heartworm. Some regions, of course, have a greater prevalence. All dogs can get the disease, it is not limited to dogs that spend the majority of the time outside. Of course the incidence is higher among working dogs, such as the Labrador Retriever. The incidence of the disease seems to be higher among dogs ranging in age from 4 to 7 years and is more prevalent in male dogs.

The length of the dog’s coat does not increase or decrease the chance of your dog contracting this disease. Dogs are the only victims; it can affect cats and foxes. In rare cases it has been known to affect humans.

The symptoms of this disease include coughing and breathing difficulties. Heartworms cause the thickening of the blood vessels causing an increase in blood pressure and thus a heavier workload for the heart. Congestive heart failure is a common side effect since the heart affected with heartworm compensates. Eventually the heartworms become so great that they can actually block the flow of blood from other parts of the body. Dogs affected may collapse, unable to breathe. Usually when it gets to this stage the disease is too far advanced to attempt treatment.

The diagnosis of the disease is performed by a blood test or X-ray. Before your dog can be put on preventive medication, a blood test must be performed to ensure that your dog does not already have the disease. If your dog has the disease and it is treated with preventive medication it can actually do more damage or even cause death.

The treatment of heartworm infection depends upon the stage in which the dog is in. The drug which many veterinarians use to treat the disease is an arsenic compound known as thiacetarsamide. Usually this drug is given intravenously. In the early stages this drug can kill the adult worms in the heart and lungs. The bad side to the drug is that it can be highly toxic, causing damage to the liver and kidneys. Before this treatment can occur a veterinarian will request a full work up on the dog, including the blood test and x-ray, to ensure that this is the problem. After the treatment has begun the dog will receive more injections of antibiotics and vitamins. If all goes well the dog will be sent home to recover at home for the next four to six weeks. Special medication is administered to eliminate any circulating heartworm larvae. After treatment a veterinarian might request another series of tests to ensure that the heartworm is entirely gone.

Preventative heartworm medication is widely available. It is expensive and most owners do not want to fork the expense for this optional medication. It should be given daily or monthly depending on the particular medication, but most definitely should be given during mosquito season. The veterinarian will have a recommendation on how often the heartworm medication should be given depending on the drug itself and the region you live in. Ivermectin is a popular heartworm preventative that is usually administered once a month. It is important to always have your dog tested for heartworm before starting them on any preventive. If a dog has circulating heartworm larvae in its blood, the heartworm preventative can cause a severe allergic reaction. If you only give your dog the heartworm preventive during a particular season, the dog must be tested before administering it.

Most people don’t think much of this disease but it is more common than most people know. A dog can harbor symptoms for several years and then have sudden death. Discuss the alternatives with your veterinarian but it is always more plausible to err on the side of caution.