Saturday, April 3, 2010

Heartworm Treatments (Dirofilaria immitis)

Heartworm prevention and treatment is big business and a cash cow for veterinarians and pharmaceutical companies.

If you have read, heard or been told that you cannot give a preventative (such as Heartgard®), to an already infected dog, remember this: The American Heartworm Society (AHS), recommends giving Heartgard® (Ivermectin) monthly for the first several months as TREATMENT for a heartworm infected dog. This sterilizes the female worms which reduces them in size. This results in far less lung damage when the worm dies and deposits in the lungs. Then, the Heartworm Society wants you to take the dog back to your vet so he/she can treat the animal but the Society reluctantly admits that 12 more months of monthly Heartguard would probably CURE the infected canine. This would obviously be a huge savings to the pet owner and MUCH safer treatment for the pet compared to the standard veterinary approach (arsenic injections). Although most vets will disagree!! To review the AHS veterinary guidelines click here.


What if you can't afford the bloated veterinary cost of expensive name brand heartworm medications? You still have options! For many years kennel owners and dog breeders have used at home treatment programs that cost as little as .30 cents a month per dog! This gives people who want to protect their dogs but can't due to their present budget, the advantage to do so.

The good news is that heartworms can be prevented for less than one cent per day for a 20 pound dog (Beagle size). Yes, I said less than one cent per day (30 cents monthly). Many breeders and kennel owners along with myself have used the prevention described in this article since the early 1980's, with no heartworm infestation. However, I want to remind everyone that I am not prescribing, but rather, sharing information with you as to what I use and do. You can use your own judgment whether you want to follow in my footsteps. This article is presented only as a documentation of how I prevent heartworms in my dogs at a fraction of the cost that a Veterinarian will charge for the Merck Heartgard ™ (Ivermectin), chewable tablets. Also, the law restricts Heartgard to use by or on the order of a licensed Veterinarian; therefore, if you use the prescription tablets you will be paying $15 - $45 for a box of 6 tablets (six month supply) plus the cost of office visits.

I use the same chemical that is in the expensive (prescription only) pills at a fraction of the cost. The prevention that I use is given once every 30 days (monthly) the same as the pills.

Also, if you are giving your dog a year-round preventative in areas of the country with a harsh winter climate it would be a waste of money. If it’s too cold for mosquitoes, there can be no danger of your dog catching heartworm. You should be able to safely discontinue the preventative dosing during the freezing months.

If you suspect a dog may already have heartworms, before putting a dog on the following prevention it should be checked by a Vet to be sure it has no heartworms. The cost of this exam is generally between $5 - $15. It is a lot cheaper to have the exam to make sure your dog is not already infected, than it is to have a Vet save an infected dog during the advanced stages of heartworm infestation. This prevention (describe below) is only good to prevent an infection from ever occurring, once a dog is already infected then it must be seen by a veterinarian.

The exam consists of a vet drawing a small amount of blood, putting a smear of it on a slide and looking at it through a microscope. The microfilariae look like tiny wiggler fishing worms. This prevention is not to be given to collies or part collies. What I use is Ivermectin. It is a 1% injectible cattle wormer with the trade name of Ivomec ™ . You can purchase it (without a prescription) for $40 - $50 at your Veterinarian Supply Store or through a catalog from a Vaccine Wholesale Supplier. The bottle comes in a 50cc size. I give it orally which means by the mouth. I use 1/10th of 1cc for each 10 pounds of body weight. The syringes I use are 3cc and are marked off in tenths of 1cc.

The way I do it is to draw out 2cc of Ivomec. Then I inject what is needed into an empty syringe (without a needle) with the plunger pulled down on the 1cc mark. I dribble it into the empty one until I have the proper amount. I will have a few ounces of soft drink or orange juice in an open container. I will draw in 1½ - 2cc of the juice to mix with the Ivomec. I put my finger over the end of the syringe and shake up the mixture. The reason for this is to give me more volume to work with and to make it taste better for the dog. I put my hand across the dog's nose with my thumb on one side and my fingers on the other side. Then I put pressure on my thumb and fingers to force open the dog's mouth. I then tip its head up and squirt the contents of the syringe in the roof of its mouth. Finally, I close the mouth and hold it closed until the dog swallows. This is the only correct way to orally administer all types of liquid medications to dogs so that you do not accidentally squirt the liquid into the dog's windpipe and/or lungs.

I do this treatment to each dog once every 30 days. The Ivomec kills all the microfilariae (larva) in the bloodstream so they never have a chance to mature into heartworms. Microfilariae will circulate in the blood for more than 30 days before attaching to the heart, so if you give this prevention on schedule there is "NO POSSIBLE WAY" for your dog to get heartworms. Even if a drug is labeled as safe for pregnant and/or lactating bitches. Personally, I don't recommend you give any kind of medications to a pregnant bitch unless the life of the bitch is in grave danger.

The cost is minimal for each dog. If the 50cc bottle of Ivomec costs you $40.00, this comes to 80 cents per cc. Given 12 months in a row, a 20 lb. dog will take 2½cc per year. That is a cost of $2.00 for a one year prevention! The shelf life for the Ivomec is about 3 years if kept refrigerated. Therefore, this method is feasible to use even if you only have one dog, and it is by far the cheapest and most effective prevention against heartworms. If you have two or more dogs this can save you hundreds of dollars per year.


What if your dog has heartworm disease and you can't afford the expense of conventional veterinary treatment? There are options, there is a very effective and low cost treatment available using a combination of oral Ivermectin (about $40 for a one-year supply) and Doxycycline (an affordable antibiotic). This 'soft-kill' treatment option gradually kills the heartworms over a period of approximately one year, in which time the dog's physical activities must be kept to a minimum. For for young dogs who are hyperactive this treatment approach may even be a safer option compared to conventional protocol which calls for the use of, Melarsomine (Immiticide®), a drug containing arsenic and as you might expect from the ingredient name alone, it can cause problems. Preliminary observations suggest that administration of DOXY + IVM for several months prior to (or without) MEL, will eliminate adult HW with less potential for severe thromboembolism than MEL alone. MEL is the abbreviation for melarsomine, an arsenic-containing compound used to kill immature (4+ month old) and adult heartworms (Dirofilaria immitis) in dogs. More detailed information from the scientific abstract can be found here: Ivermectin and Doxycycline Heartworm Treatment

Please be sure to visit your vet for warranted tests and treatment information to help ensure proper dosing of Ivermectin. Ivermectin can be purchased over the counter at most feed stores or online, but it can be very deadly if given in an improper dose, or to certain breeds of dogs (see collie reference at bottom of page). But it is considered extremely safe when it is given at the correct dose. Doxycycline is a pharmaceutical antibiotic and to obtain it you will need a prescription from your vet.

The dosages used by the Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA are: Treatment with ivermectin (IVM; 6 μg/kg - by mouth, weekly) combined with doxycycline (DOXY; 10 mg/kg/day orally from Weeks 0–6, 10–12, 16–18, 22–26 and 28–34).

If your vet is not familiar with this economical form of treatment, consider printing the scientific abstract from the International Journal for Parasitology Volume 38, Issue 12 and giving it to your vet. If your veterinarian refuses to help you with this approach, try calling another vet in your area who may be more receptive.

Breed Toxicity to Ivermectin: Dr. Katrina Mealey at Washington State University’s College of Veterinary Medicine pinpointed the mechanism and its gene that cause Collies and potentially other breeds to react so erratically when administered ivermectin.

Her medical evidence validated the presence or absence of a single protein, Pglycoprotein (P-gp). When P-gp is present and functional, ivermectin cannot remain in the brain, and a dog can tolerate the heartworm preventive. When P-gp is absent, ivermectin penetrates the brain and stays there, thus setting in motion the circumstances for toxic reaction.

The breeds most affected are closely related herding breeds. Along with the Collie, anecdotal statistics claim Australian Shepherds, Bearded Collies, Border Collies, Old English Sheepdogs, and Shetland Sheepdogs as those breeds at high risk for ivermectin toxicity. Similar suspicious events have added a variety of other breeds to this list from Whippets to Irish Water Spaniels to Bullmastiffs. Many of these breeds were already documented in veterinary journals as either proven or suspected to be hypersensitive to or intolerant of an assortment of medications including particular anesthesia and wormers. Toxicosis appears to be dose-dependent in Collies with a demonstrated sensitivity to ivermectin. Dr. Mealey agrees that ivermectin is safe for Collies at the six mcg per kg heartworm preventive dose, administered once a month. Mealey adds, “Even a large number of sensitive Collies do not show signs of toxicity at that dosage.”

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1 comment:

  1. Thank you so much for all this information! In my research class I was assigned to look up information on heartworms and heartworm treatments. Your post was VERY informative and SO helpful! Thanks so much!