Jul 9 2010

Protect Your Pet From Heartworm Disease

Protect Your Pet from Heartworm

Protect Your Pet from Heartworm

Heartworm disease – what a terrible sounding disease!  Worms, living in your heart!  As gross as this sounds, some people might think it’s some made up story, to scare little puppies who won’t listen to their mothers.  Alas, the sad fact is that this is indeed a real disease, just as creepy as the name sounds.  A real disease that can affect any and all dogs, regardless of age, breed, color, or living status (i.e. indoors vs. outdoors).  Nevertheless, as horrible as it sounds, this disease is quite preventable.   We have had a lot of rain this year and combined with the heat – makes for a prime breeding ground for mosquitos – which is how heartworms are transmitted to your pet.  Here is some information about heartworm disease in detail to help you as a dog owner (or cat owner) to help prevent you family friend from being possessed by creepy, heart dwelling wormies. 

Let’s start with the basics – what exactly are heartworms

Heartworms are exactly what they sound like – worms (a kind of roundworm, similar to the intestinal parasites) that live in the right side of the heart and the arteries of the lungs.  They can infect dogs and cats, although there are some differences between dog heartworm disease and cat heartworm disease.  The adults live in these areas and produce babies, called microfilaria.  The microfilaria circulate in the bloodstream.  

How does my pet get heartworms?              

Heartworms are transmitted by mosquitos.  When a mosquito bites an animal with microfilaria in their blood, the microfilaria are sucked up into the mosquito.  They then spend some time maturing within the mosquito to the infective form.  The next time that mosquito bites another cat or dog, the infective microfilaria enter the bloodstream through the bite wound.  After this they mature to adults and eventually end up in the right side of the heart and the lung vessels – this maturation process takes about 6 months. 

How do I know if my pet has heartworms?

This can be tricky, as in the early stages of heartworm disease, most pets are asymptomatic (meaning they do not have any clinical signs of the disease).  In dogs, the heartworms will eventually begin to affect the heart function – as they build up in the heart and vessels, the heart must work harder to pump blood.  Eventually, the heart will be unable to keep up, resulting in signs similar to heart failure.  Signs can include coughing, weakness, exercise intolerance, weight loss, and decreased appetite.  

In cats, they will not have as many adult worms (as they are not the natural host) – they typically may only have a few adult worms living in their heart and vessels.  These worms do not so much directly affect heart function as they do in dogs; however, they often result in a sort of allergic reaction to the worms that are present, causing inflammation in the lungs themselves and potentially throughout the rest of the body as well.  Clinical signs in cats can be somewhat non-specific but can include coughing, lethargy, vomiting, weight loss, breathing difficulties, and sudden death.  Heartworm disease in cats can often be misdiagnosed as asthma because of the similarity of clinical signs.

The best way to diagnose heartworm disease is through testing by your veterinarian.

What sort of tests will my vet do? 

Testing for heartworm disease is different for cats and dogs.  There are 2 different types available – antigen testing and antibody testing.  The antigen test looks for proteins in the blood from the female adult heartworm.  The antibody test looks for antibodies in the blood that are produced by the cat or dog against the heartworm.  Antigen testing is the most common test and is very reliable in dogs.  However, for cats, since they do not usually have very many worms (none of which may even be female), this is not always accurate.  If your veterinarian suspects that your cat has heartworm disease, they may need to run both the antigen and antibody test to detect the disease.

If your pet is heartworm positive, x-rays of the chest and ultrasound examination of the heart can help determine the severity of the disease and may help your veterinarian to choose the best treatment for your pet. 

How do you get rid of the heartworms?

  • Dogs: Treatment for heartworm disease is both risky and expensive.  It involves treatment with a drug that is injected into the large muscles of the lower back.  The treatment is usually given over 2 days, but can also be given slower if an animal is severely ill.  After treatment, the animal must remain calm (think couch potato), with short leash walks only for about a month while the adult worms die off.  Any sudden or vigorous exercise can put the animal at risk for clogs of the blood vessels caused by the dead or dying worms.  The injections can also cause severe muscle pain, so sometimes after treatment the animal may need to be put on pain medication for a short time afterwards.   Complications can include breathing problems, allergic reactions to the dying worms, and sudden death. 

Cost for heartworm treatment varies based on the size of the animal but can easily approach $500, if not more.

  • Cats:  Cats are more difficult as there are no products approved to treat heartworm infection in cats.  They also have severe allergic type reactions to the dying worms, which can cause even more health issues.  Cats can sometimes spontaneously clear the infection, but again, the dying worms can cause significant health problems.

How do I keep my pet from getting heartworms?

Preventative products are available for both dogs and cats.  They come in different forms, such as tasty tablets or topical products that are applied to the skin and absorbed.  The preventatives kill the microfilaria before they mature into adults.   Preventative products need to be given monthly, and depending on where you live, they may need to given year round (even in the winter!).  In Missouri it is recommended that you keep your pet on heartworm prevention year round.  Many heartworm preventatives also include deworming products so intestinal parasites are also controlled.  

Dogs should be tested by your veterinarian for heartworms before starting on preventative.   You can purchase your heartworm, flea and tick preventatives from Wayside Waifs.  We carry Interceptor, Frontline and Advantage Multi.  To order, call 816-986-5545. 

Written by Dr. Cynthia Moon
Veterinarian at Wayside Waifs


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