Heartworm is an important issue in both dogs and cats. However, a lot of confusion exists for pet owners about the different terms that relate to heartworms and heartworm disease.
The Facts About Heartworms in Dogs and Cats
Heartworms are parasites that are carried by mosquitoes. When an infected mosquito bites your dog or cat, microfilaria (the larval form of the heartworm) is injected into your pet's skin. Over time, the microfilaria mature through several different stages of their life cycle and migrate to your pet's heart.
In dogs, it is the adult heartworm living in the heart and pulmonary arteries that carry the blood to the lungs that causes the signs of heartworm disease. The adult heartworms cause damage to the heart and arteries and the symptoms of heartworm disease are directly related to this damage. Symptoms in dogs with heartworm disease involve both the heart and the lungs.
In cats, usually the lungs are involved moreso than the heart and their symptoms differ from those seen in dogs.
Heartworm Infection Versus Heartworm Disease
Heartworm infection differs from heartworm disease. Heartworm infection implies that your dog or cat has been bitten by an infected mosquito and has become infected also. Pets with heartworm infection may not be sick and may not be showing any signs of heartworm disease.
In contrast, dogs and cats with heartworm disease are sick. They are showing symptoms resulting from the damage done by the heartworms.
- In dogs, these symptoms may be coughing, exercise intolerance, bloody nasal discharges (bloody noses) or other signs of heart failure.
- In cats, the symptoms are more likely to be wheezing and difficulty breathing. The symptoms of heartworm disease in cats very closely resemble those of feline asthma and the two diseases can be hard to differentiate from one another.
Heartworm Prevention and Heartworm Preventative Medications Versus Heartworm Treatment
Fortunately, it is easy to prevent heartworm infection in both dogs and cats. Heartworm preventative medications can be given to keep your dog or cat from getting heartworms.
- The most common type of heartworm preventative medication is the monthly medications. These may be an oral medication (a pill that is given every month) or a topical medication (a liquid that is applied to the skin every month.) Examples of oral heartworm preventative medications include Heartgard Plus®, Interceptor® and others. Examples of topical heartworm preventative medications include Advantage Multi®, Revolution® and others.
- The other form of heartworm preventative medication sometimes used in dogs is an injection known as Proheart 6® which is administered every six months.
Heartworm prevention differs from heartworm treatment in that heartworm treatment infers treatment of a dog that is either infected with heartworms or suffering from heartworm disease. Heartworm treatment, though it may include monthly heartworm preventative medications that contain the ingredient ivermectin, requires much more aggressive treatment to kill the adult heartworms. Monthly heartworm preventation medications do not kill the adults, only the larval form of the heartworm.
Unfortunately, for cats, there is no effective heartworm treatment that will kill the adult heartworms. Treatment is symptomatic, using medications designed to control the symptoms of heartworm disease. Preventative medications are readily available for cats however, as they are for dogs.
By understanding the different terminologies applied to heartworms, pet owners may better understand the specifics of their own dog or cat's treatment protocol. The majority of pets will be free of heartworm infection and should therefore be on some type of prevention program. For those dogs and cats that are infected with heartworms, treatment may be necessary and the treatment protocol may vary depending on whether the pet is asymptomatic (free of symptoms) or is suffering from actual heartworm disease.
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