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Does Ivermectin Kill Worms in Dogs ?

Ivermectin for Dogs

At one point, dog owners may be wondering if the drug ivermectin kills worms in dogs. Ivermectin is a drug that has the potential to kill several types of parasites, but in dogs the drug is most often prescribed as a monthly pill to give to dogs in order to kill heartworm larvae which are transmitted through mosquito bites. There are several products containing ivermectin on the market, but most are meant to kill worms in large farm animals such as cattle, horses and swine. Following is some information on whether ivermectin kills worms in dogs.

Does Ivermectin Kill Tapeworms?

Tapeworms in dog feces

Picture of tapeworms in dog feces

If your dog has tapeworms, most likely you have seen signs of them. Tapeworms cause dogs to itch under the tail and affected dogs may be seen scooting to relieve the itching. If the dog's tail area is inspected or the area where the dog sleeps, you may stumble upon small "worms" that crawl for a little whpraziquantelile and then dry up becoming similar to grains of rice. And, as seen in the picture, they may be also seen in fresh dogs feces.

Something worth mentioning: these rice-like things are actually not worms but simply tapeworm segments (the technical term is proglottis), which are little mobile sacs containing male and female reproductive organs that release eggs.

So if those little mobile segments are not the actual tapeworms, where is the tapeworm and what do tapeworms look like? The truth is, the tapeworm lives in your dog's intestine, where it attaches itself so to gain nourishment from the host (your dog). You will rarely if ever get to see the actual whole tapeworm, unless it dies and is excreted in the dog's feces, although in most cases it's digested.

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You may therefore be wondering if ivermectin containing products such as your dog's Heartgard pill can kill tapeworms. You may also wonder if ivermectin labeled for cattle may kill tapeworms. The answer is no.

Tapeworms require a specific type of medication to eradicate and that medication is a drug called praziquantel, explains veterinarian Dr. Dan.  You can get praziquantel by your vet as a stand-alone product, or you can ask for Iverheart Max, a monthly heartworm pill containing ivermectin, pyrantel pamoate and praziquantel to kill heartworm larvae along with tapeworms and other worms.

Did you know? Tapeworms are often caused by a dog who happens to ingest an infected flea. This is why in the case of tapeworm infestations, it's important that the flea population is kept under control using products that kill the fleas on the dog and the eggs in the environment.

Picture of roundworms in dog feces.

Picture of roundworms in dog feces.

Does Ivermectin Kill Roudworms?

While tapeworms are often seen by the naked eye, roundworms can be a bit more tricky to detect. Whether or not you see these worms in your dog's feces depends on what stage of growth the worms are in. Adult roundworms in the dog's feces appear like long-spaghetti (as seen in the picture), and they can occasionally also be vomited, but as mentioned, they are not always visible. Roudworms eggs instead require a microscope to detect, and only your vet can detect these from a fecal sample test known as a "fecal flotation test."

If your dog has roundworms or you think your dog may have them, you may therefore be wondering if ivermectin can kill roundworms. The answer is yes and no.

Yes, ivermectin in products like Ivomec can kill roundworms in cattle and swine, but this product is very difficult to accurately use in dogs because the dose needed for dogs is very, very tiny. "For example, it is impossible to dose the Ivomec accurately for heartworm prevention" explains veterinarian Dr. Rebecca. Even a single drop of ivermectin can easily be an overdose in a small dog, further warns out Dr. Rebecca. No to mention the risks with dogs breeds with the MDR1 gene such as collies Aussies and several other breeds.

Also, worth considering is liability. Companies that manufacture products that are labeled for use in certain species (like ivermectin for cattle, horses and swine) will bear no responsibility if their product is misused causing the loss of an animal of a different species other than what it was labeled for.

So, yes ivermectin can kill roundworms in large animals like cattle, but in dogs, ivermectin does not typically kill any intestinal parasites, unless you give it at a high dose to kill roundworms, explains veterinarian Dr. Lee. These ivermectin dosages are dosages higher than those approved by the FDA for heartworm prevention, according to The Pill Book Guide to Medication for Your Dog and Cat. This is where things, as mentioned, get risky. It's therefore best to play it safe and only use products purposely made for dogs and at safe dosages.

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An example of a dewormers for dogs that kill roundworms are products containing pyrantel pamoate such as Nemex for dogs or monthly heartworm products like Heartgard Plus containing ivermectin along with pyrantel pamoate which dog owners can easily get from their vet after having the dog heartworm tested.

"Ivermectin at the heartworm preventive dose is not strong enough to kill common intestinal parasites. Because of that, the dewormer pyrantel pamoate was added to cover roundworms in the original Heartgard product." Dr. Wendy C. Brooks, veterinarian

Does Ivermectin Kill Hookworms?

The tissue sample taken from the liver is checked under a microscope.

The tissue sample taken from the liver is checked under a microscope.

Hookworms are also pesky parasites that can be tricky to identify. This is why it is so important to have fecal tests performed routinely by vets. Not to mention the fact that roundworms and hookworms are zoonotic parasites, which means they can be transmitted to humans. A vet can properly diagnose hookworms by looking at a fecal sample under the microscope.

So you may as well be wondering if ivermectin kills hookworms in dogs. As in the case with roundworms, it's best to use a dewormer containing pyrantel pamoate, or once again, a heartworm medication containing pyrantel pamoate to kill hookworms and roundworms such as Heartgard Plus.

"Ivomec, is a cattle preparation, and is not routinely used in dogs for this purpose. If you think that your dog may have intestinal parasites, and specifically hookworms, it would be better to use a dewormer called pyrantel pamoate."~Dr. K. veterinarian

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Does Ivermectin Kill Whipworms?

Along with tapeworms, roundworms and hookworms, whipworms are part of the group of the "big four" intestinal parasites known for affecting dogs. Whipworms are much more smaller than other worms affecting dogs, and their presence is rarely noticed due to the fact that these worms live in the dog's cecum, the area where the dog's small intestine and large intestine meet. The name of this worm derives from the fact that it tends to taper off in shape, giving it its staple whip-like shape.

Whipworms can be identified through a fecal test, but things can be challenging with this type of worm because female whipworms only occasionally lay eggs. This means a dog can have whipworms, but they might not be identified through a fecal test.

Does Ivermectin kill whipworms in dogs? As with roundworms and hookworms, it may at high doses, but its use is risky as mentioned. The only safe way may be under the direction of a vet under close supervision but not many vets may feel comfortable doing this though because of the risks for dog owner miscalculations. If a dog shows signs of potential whipworm infestation, it is therefore best to just deworm him with a product labeled to kill whipworms.

There are not many medicines meant to kill whipworms in dogs. The most popular are fenbendazole (Panacur), and febantel (Drontal Plus).

Recently, some heartworm medications have been designed to kill whipworms as well. These products are Sentinel Spectrum; containing ingredients meant to kill heartworm larvae and intestinal parasites such as hookworms, whipworms, roundworms, and tapeworms, Interceptor; containing ingredients meant to kill heartworm larvae, roundworms, hookworms and whipworms, and Trifexis; made to prevent heartworm disease and capable of killing adult hookworm, roundworm and whipworm. Advantage Multi contains moxidectin which is also capable of killing whipworms in dogs.

If your dog has parasites therefore it's important to consult with your vet for proper diagnosis and treatment. This way you know exactly what worms are affecting your dog (there may be more than one type) and the most appropriate treatment. While ivermectin is freely available in feed stores to treat worms in large animals (Ivomec), its use in dogs is not safe because of the risks for giving a potential toxic dose that may result in illness and even death.

"Heartgard products do not carry a high enough dose of ivermectin to kill whipworms, though at other doses ivermectin could be used with appropriate cautions."~Mar Vista Vet

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  • The Pill Book Guide to Medication for Your Dog and Cat
  • Veterinary Partner: Preventing Heartworm Infection in Dogs (Chemoprophylaxis)
  • Marvista Vet: Whipworms
  • Marvista Vet: Ivermectin

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