Heartworm Disease and Prevention

Heartworm Disease

Heartworm (Dirofilaria immitis) is a white, round worm up to14 inches long that, in adulthood, lives in the heart and pulmonary arteries of an infected dog or cat. Dogs and cats acquire this infection through mosquito bites. Mosquitoes readily pick up larval (baby) heartworms from infected animals and carry them to new animals.

Some geographic areas have severe heartworm problems while other areas have none. South East Michigan is an area that has heartworm disease, and so we recommend a monthly heartworm preventative, and annual testing for heartworm disease.

Signs of heartworm disease include – coughing, exercise intolerance, fainting, lethargy, difficulty breathing, and nose bleeds. Heartworm disease is treatable; however, treatment can be expensive and dangerous for your dog. For this reason we stress prevention of this disease.

Testing: We do not need to test your puppy today if (s)he is under 6 months of age. The test that we use detects the adult worms in the heart and lungs, it takes 5-7 months for a heartworm to mature to this stage. We will do your puppy’s first heartworm test before anesthesia if (s)he will be spayed/neutered. If they are not going to be spayed/neutered, we will do this test on their first birthday.

We need only a few drops of blood for this test and we will have the results that day. We will draw this blood from your dog’s leg vein (cephalic vein) most dogs do not mind this at all.

Year Round vs Seasonal Heartworm Prevention

Brinker Veterinary Hospital used to recommend seasonal heartworm prevention, with the medication given only May through December. We now recommend that you give your dog preventative year round. The reason for this change is our changing weather in South East Michigan; warmer weather means that our mosquitoes are here longer. We still recommend annual testing for heartworm disease even if your pet is taking preventative year round. This is the safest protocol for your dog and the one recommended by the American Heartworm Society.

Heartworm Prevention

Prevention: There are several different types of heartworm preventatives. For the most part we recommend Heartgard Plus. We will start your puppy on monthly prevention immediately and (s)he will get one per month every month for life. All of these preventatives are dosed by weight, so when your puppy is still growing, we will need to check their weight on our monthly rechecks.

  • Heartgard Plus – This is the mainstay of heartworm prevention at Brinker Veterinary Hospital. It contains ivermectin and pyrantel. This comes in a pill or in a beef flavored chewy treat. The pill form does not contain pyrantel. It should be given orally once every month.
  • Ivermectin – medication for the prevention of heartworm disease in dogs. Ivermectin kills microfilaria (the baby heartworms in your dogs blood vessels after being bitten by an infected mosquito)
  • Pyrantel – medication for the treatment of certain intestinal parasites, Roundworms & Hookworms.
  • Interceptor – Contains Milbemycin, we use this heartworm prevention in some breeds of dogs that may be sensitive to Ivermectin and in some cats. Interceptor is a beef flavored tablet that is given orally once per month.
  • Milbemycin oxime – medication for the prevention of heartworm disease. It also treats roundworms, some hookworms, and whipworms
  • Revolution – A topical medication, Selamectin, it is used to prevent heartworm disease, and to treat fleas and kill some species of ticks in dogs and cats. Use topically once per month.
  • Sentinel – Contains Milbemycin and Lufenuron. A flavored pill given orally once per month for the prevention of heartworm disease, treatment of roundworms, some hookworms, whipworms, and helps in the control of flea infestations when given with fatty meal.

Important to note that all animals in the house must all be on Sentinel every month for the flea control to work. Not appropriate for animals with seasonal or flea allergies.

Heartworm Preventative from Internet Pharmacies

Internet pharmacies are becoming more prevalent and some people find them a very convenient way of getting their animals’ medications. Our main goal is to keep your pet safe and healthy, so we have several concerns about this trend.

  • If you buy Heartgard Plus from a veterinarian it is guaranteed. That means that if your dog tests positive while it is getting the preventative year round the company will pay to treat your dog. This guarantee does not stand if your use an internet pharmacy.
  • We need to see your dog every year for a heartworm check, you may purchase your heartworm preventative at that time, there is no extra trip needed.
  • We are very cost competitive at Brinker Veterinary Hospital, the savings are not what the commercials would have you believe.
  • We know that the medications that we sell you come directly from the reputable companies that we work with. We do not have this assurance from internet pharmacies. The handling of many drugs is vital to their effectiveness; our shipments come with hot/cold indicators and are shipped under very specific conditions. Many companies will not directly sell their products to certain online pharmacies. These pharmacies then obtain the drugs through sellers other than the original company. They may come from out of the country or be otherwise illegally shipped.

We are always happy to write you a prescription for medications that your dog needs. You may have these filled at the pharmacy of your choice. However, we reserve the right to not send any prescriptions by fax.

What We Offer

Brinker Veterinary Hospital offers a wide range of veterinary services for pets in the following areas:

• Pet wellness and vaccinations
• Animal medical services
• Pet surgery incl spay and neuter
• Pet dental cleanings and treatment
• And many more


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Location Hours
Monday9:00am – 6:00pm
Tuesday9:00am – 8:00pm
Wednesday9:00am – 6:00pm
Thursday9:00am – 8:00pm
Friday9:00am – 6:00pm
Saturday9:00am – 2:00pm
SundayClosed

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