Pet Health Guide - Heartworm
Heartworm Prevention
Heartworm infection is a clinical disease caused by the parasitic worm Dirofilaria immitis. Heartworm larvae are transmitted by mosquitoes to dogs and cats when then are deposited on the skin of the animal and enter the subcutaneous tissue through the bite wound.
Approximately 6-7 months after entering into the tissues, the immature heartworm (referred to as microfilaria) enter into the bloodstream. These microfilaria then continue to grown in the circulatory system eventually being carried to the heart. Once in the heart, the microfilaria mature into adult worms in the pulmonary arteries and right heart ventricle.
Female heartworms can reach 10 inches in length when mature. Once in the heart, the mature female heartworm begins to produce and release small microfilaria back into the bloodstream to re-infect the dog or cat.
Clinical Signs
The duration and severity of infection, as well as the dog’s or cat’s reaction to the parasite, determines the severity of clinical signs. Only your veterinarian can test for an infection. However, if you suspect or see clinical signs, contact your veterinarian.
Dogs - Clinical signs include coughing, exercise intolerance, swelling, fever and weight loss.
Cats - Clinical signs include anorexia, lethargy, coughing, respiratory distress and vomiting.
Heartworm Medications
All heartworm medications work by destroying the pre-circulatory microfilaria living in subcutaneous tissues thereby preventing their release into the circulatory system. However, these medications also destroy any adult heartworms lodged in the heart or microfilaria released and circulating in the blood stream. When this happens, rapid shock, debilitation, coma, and possible death can occur.
If you forget to administer a monthly heartworm preventative and restart the medication without having your animal tested, you run the risk of seriously injuring your pet because the adult heartworms may already be established or the immature microfilarial stage may have already entered into the circulatory system. That’s why preventative medications are strictly controlled in the United States and require a prescription in order to be purchased.
Heartworm prevention must be practiced every month and your pet should be screened periodically by your veterinarian, especially in climates were mosquitoes are prevalent throughout the entire year. Similarly, if you have missed or forgotten to dispense the monthly preventative, a blood test to check for the presence of any infective heartworm stage should be part of a preventative health care plan for your pet.
Oral Heartworm Preventatives (Dogs)
- Heartgard Plus Chewable
- Interceptor
- Iverhart Max
- Iverhart Plus
- Sentinel
Topical Heartworm Preventatives (Dogs)
- Advantage Multi
- Revolution
Oral Heartworm Preventatives (Cats)
- Heartgard Chewable
- Interceptor
Topical Heartworm Preventatives (Cats)
- Advantage Multi
- Revolution