Cutting the Cost of Heartworm Prevention

The dogtor is in

Heartworms are a serious threat to dogs. The heartworm larvae are carried and transmitted by mosquitoes: mosquitoes are everywhere, even in our home at times. Keeping your dog from being bitten by a mosquito is almost impossible, therefore heartworm prevention is important to keep the heartworm larvae from developing in your dog’s blood stream.

Heartworm prevention medications can be pricey since they need to be given every month, year round. One very popular brand is Heartguard: a chewable treat for your dog. It is reliable and well liked by veterinarians and dogs alike. Pet Armor is the same formula but is less expensive. If that is still too much for your budget, there is another option.

Heartworm preventionThe active ingredient in both brands is Ivermectin. Liquid Ivermectin is available without prescription for use on large livestock at most Co-op stores and places like Tractor Supply Co. While it is not generally recommended to use a livestock medication on dogs – because the formulation for large animals can be different enough to cause harm to your dog – this drug is the same for both applications. The only difference is the dosage.

A Word of Warning

Ivermectin belongs to a class of drugs called macrocyclic lactones, which work by paralyzing the nervous system of susceptible organisms. The drug does not typically affect mammals because the blood-brain barrier prevents the drug from reaching the central nervous system. However some dog breeds possess a genetic mutation, called the MDR–1 gene deletion, which permits Ivermectin to cross the dog’s blood-brain barrier. The genetic trait has been documented in 10 breeds: white German shepherds, Australian shepherds, miniature Australian shepherds, English shepherds, longhaired whippets, McNabs, old English sheepdogs, Shetland sheepdogs, silken windhounds and collies. Not all members of these breeds possess the mutation, so it is wise to have your veterinarian test your dog for the mutation before using Ivermectin. In these breeds and any dog who has suffered a head injury, if Ivermectin is safe to use at all, the dosage must be extremely accurate. Overdosing even a little can cause serious harm.

Signs of Ivermectin toxicity include vomiting, drooling, staggering gait, weakness, dilated pupils, seizures, the inability to stand, blindness and coma. If you observe any of these symptoms, contact your veterinarian immediately. Unfortunately, Ivermectin poisoning is irreversible, so there is little your vet can do to help your pet, besides treat the symptoms and wait for the drug to leave the dog’s system.

Cutting the Cost of Heartworm Prevention

A bottle of liquid Ivermectin, in a generic brand, currently costs around $35.00 at a farm supply store. One bottle will provide heartworm prevention to your entire herd of dogs for years (depending on the number and size of dogs).

Use a hypodermic syringe to draw out .1cc (1/10cc) per ten pounds of your dog (a 50 pound dog needs .5 (½) cc of Ivermectin) and squirt it onto an absorbent treat or food that they like and let them eat it. Do this once a month and your dog is protected against heartworms.

Other Uses

Alabama Angels Dog Rescue says if your dog tests positive for heartworms, and is 5 yrs old or less, give 2 doses a month and after 2 years all the heartworms will be dead. And for Mange, use same amount every 2 days for about 2 weeks and it kills the mange mites.

Because of that blood-brain barrier thing, I’d check with a veterinarian before administering such high doses.


I am not a veterinarian, nor a doctor. I don’t even play one on TV. But in our animal rescue efforts I do work closely with veterinarians and we are involved in the medical treatment of foster dogs placed in our care. We try to keep up with developments in this area, and pass information like this along to you. I have verified these facts and consider them reliable. What you do with them is up to you.

About Doug

Jesus follower, writer, gardener, Sci-Fi fan, Beagle herder, occasional author, mountain man. My dogs think I'm a super-hero.

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