Heartworm Disease

Heartworm disease is a serious and potentially fatal disease caused by a parasite (Dirofilaria immitis), which lives in the circulatory system (primarily in the right side of the heart and the large blood vessels going to the lungs).  Heartworms are spread by the bite of an infected mosquito. 

Symptoms of heartworm disease range from no outward signs to severe respiratory distress.  Dogs will develop exercise intolerance, cough, lethargy, weight loss and general unthriftiness with time.  Cats normally do not show any outward signs of heartworm disease other then acute death.  Pets can have heartworms in their bodies for several years before illness develops.

A diagnosis of heartworm disease is achieved through a simple blood test.  The blood test will look for heartworm antigens and requires female worms to be present in the body.  The blood filter test may be run to look for circulating microfilaria (baby heartworms) in the blood.

Treatment of heartworm disease does not exist for cats.  Our poor kitties can not tolerate the medication to kill the heartworms and will more then likely succumb to the heartworm disease with time.  Dogs with positive heartworm tests will be retested to confirm a correct results.  A confirmed positive result will be followed up with a thorough assessment of the dog prior to treatment.  A complete blood count, chemistry blood screen, thyroid screen, urinalysis, fecal and chest x-rays will acquired to determine the dog's ability to withstand treatment.  Treatment consists of 2-3 injections of melarsomine, an arsenic-derivative that is injected into the back muscles.  Dogs that are treated for heartworm disease must be kept as quiet as possible and observed for severe reactions to the medication or to the dying of the heartworms.  If there are microfilaria present in the blood stream, an ivermectin oral medication may be given after the injectable treatment.

Prevention of heartworm disease is easily achieved with a once-monthly preventative medication.  There are many brands on the market and most also control intestinal parasites.  Cats have heartworm preventatives available to them also.  For cats especially, heartworm prevention is key.  A heartworm test will be performed prior to placing your pet on prevention and will be used as a monitoring device through the years.  Heartworm disease is one of the most common, most potentially deadly and most easily preventable disease in our pets.