View Full Version : An update on heartworm prevention

05-10-2004, 10:57 AM
At the request of a couple people here's the low down on heartworm prevention products. Let me know if you have any questions.

1) ProHeart and ProHeart 6 (drug name is moxidectin)- ProHeart is a monthly tablet available in a 6-tablet package, and ProHeart 6 is an injection that is given once every 6 months. This is the newest product on the market and works well. The injectable product represents an especially interesting development in the prevention of heartworm infevtion. No longer is it necessary to remember a monthly tablet or chewable; instead, a twice a year shot is given. Veterinarians love this because it forces the client to come in to the clinic at least twice a year. It is also popular among dog owners. I use it for my dog - not because it is “better” but because I don’t have to remember the monthly pill. ProHeart 6 also controls hookworms in addition to heartworm (the oral ProHeart is for heartworm only). Dogs must be six months of age or older for a ProHeart 6 injection, but can be only 8 weeks of age or older for the ProHeart pills.


2) Heartgard or Heartgard Plus (drug name is ivermectin) - The development of Ivermectin in 1987 represented a huge breakthrough in heartworm prevention. Preventive medication for the first time could be given once a month instead of daily. These medications utilize an extremely low dose of ivermectin which is adequate to kill any immature heartworm larvae which are inhabiting the dogs blood at the time the medication is given. This drug cannot kill adult heartworms but the larvae take quite a while to mature into an adult worm once inside the dog. In other words, when a mosquito bites your dog it may still get heartworm infection - however all larvae will get killed every 30 days and no adults will ever form. .

Heartgard is not strong enough to kill any other intestinal parasites by itself but the product Heartgard Plus is ivermectin combined with another durg (pyrantel pamoate) that kills hookworms and roundworms. These once a month pills are considered very safe, however Collies and Shelties have been reported in some cases to have adverse reactions.

3) Interceptor and Sentinel (drug name is milbemycin)- This product is also given monthly and works similarly to ivermectin. It kills the heartworm larve present in the blood of your dog every 30 days. There are a few differences however between this drug and Heartgard worth noting -

a. If milbemycin is inadvertantly given to a dog with active heartworm disease, the dog may experience a serious shock syndrome if an especially high number of microfilariae are circulating - this does not occur with Heartgard.
b. If you forget to give the medication for awhile (2-3 months), this product is not as good as Heartgard in killing older larve (young adult) worms. Heartgard will kill 3-5 month old larve whereas this product will only kill about 2 month old larvae.

In addition to heartworms, Interceptor controls roundworms, hookworms, and whipworms without the addition of a second parasiticide. It is also available combined with Lufenuron for the control of fleas (Sentinel - see the flea column on this forum). There are no breed-related sensitivities for Interceptor and all animals tolerate it well.

4) Revolution (drug name is selamectin)- this is a topical once a month drug for dogs that kills heartworms, fleas, and ear mites. This is not a pill like the other products but is a topical solution that is applied to the dog every 30 days. The product works well for heartworms and fairly well. for fleas. This product is very safe and can be used in any dog over 6 weeks of age.

5) Filaribits and Filbaribits Plus (diethylcarbamazine)- This is the classic drug used to prevent heartworm infection. Many of the old timers will know about this “once a day” pill. It must be given daily to prevent heartworm infection because it can’t kill larvae in the blood (must kill them before they get there). Aside from the relative inconvenience of giving daily medication, the other problem with this product is that potentially life-threatening reactions can occur if it is inadvertently given to a heartworm infected dog.

Filaribits does not have activity against other common parasites but is available with oxybendazole added (Filaribits Plus) to control hookworms, whipworms, and roundworms. Although I don’t recommend this product it is still used by some people.

All of the above drugs are safe to use in pregnant or nursing bitches. My favorite is the ProHeart 6 injection because I am lazy. The other products work too - the ProHeart or Heartgard tablets would be my personal preference unless you have a Collie and then I would go with Interceptor.

05-10-2004, 11:52 AM
Excellent information Geof !!! :pl: :TT: :pl:

Woods and Water
05-10-2004, 02:21 PM
That is some good reading,I personally use the heartgard.I like the fact with the pro heart 6 you only need to remember twice a year...I will be looking into that for sure at my next visit.

10-03-2004, 06:57 PM
Thanks for the update on "Pro-heart"...:TT:

02-03-2012, 10:16 AM
Good info. I use Interceptor because it was recommend by my vet.

02-04-2012, 06:49 PM
The original post - a good post it was - is nearly eight years old. Is the information still current?

My dog and I live in western South Dakota. I've recently switched vets. Because my dog and I don't travel outside of western SD, except during hunting season (and then we're only going so far as eastern SD) when the likelihood of encountering mosquitos is greatly reduced, my new vet doesn't see the need - and doesn't recommend - using medication to prevent heartworm. Seems the rate of infection in this part of the country is pretty low. Has anyone else in a similar situation and/or climate been told or heard anything like this?

Given we're now in the middle of winter when she doesn't receive the Heartgard medication anyway, I have a couple of months to decide whether or not to have her on the Heartgard program this spring and summer. I'll likely seek a second (professional) opinion, but I'm curious if anybody has an informed opinion about this.

Pig Pen
10-07-2013, 05:16 AM
I've used IVOMEC for the past 25 years on all my dogs...it's used for cattle and swine...1ML per 100lbs once a month in his food...can be purchased on-line