Ivermectin is used in dogs and cats to treat a variety of different diseases. It is one of the most widely used medications for preventing heartworm infection in dogs (it's also used in cats for the same purpose but to a lesser extent). Some of the most well-known of the brands of heartworm prevention medications that contain ivermectin include Heartgard Plus®, Iverhart Plus®, Iverhart Max® and Tri-Heart®. When used as heartworm prevention medication, ivermectin is typically used at a relatively low dosage range based on the size of the animal.
Ivermectin to Treat Heartworm Infection and Heartworm Disease in Dogs
Ivermectin is also used in the so-called "slow-kill" or "soft-kill" method of heartworm treatment — although this is a bit of a misnomer. Ivermectin does not directly kill adult heartworms, but it does kill the microfilaria (larval form) of the heartworm. By killing the microfilaria, ivermectin prevents additional worms from maturing and occupying the heart and blood vessels. The adult heartworms already present there eventually die with time as the natural course of their life comes to an end.
In most cases, dosages of ivermectin used to treat heartworm infection and heartworm disease in dogs are the same monthly dose as that used for prevention. However, there is a higher risk of complications because of the presence of heartworms with this treatment.
It is also important to remember that this method of heartworm treatment leaves the adult worms in the heart and blood vessels for a long period time, sometimes for a period of years. During that time period, these heartworms continue to damage the heart and lungs.
Though this treatment may be recommended for severely ill and debilitated dogs, it is not the generally recommended method of treating heartworm infection or disease for most dogs. In most cases, the dog should be treated with Immiticide® to kill the adult heartworms, although ivermectin is still used to kill the larva and prevent additional infections.
Ivermectin in Dogs and Cats for Treating Other Parasites
Besides preventing and treating heartworm disease, ivermectin is also used widely to treat other types of parasites. These parasites include:
- Demodex, the mite responsible for causing demodectic mange in both dogs and cats
- Sarcoptes, the mite responsible for causing sarcoptic mange in dogs and in people
- Ear mites (Otodectes cynotis), in dogs and cats
- Lungworms (Capillaria), in dogs and cats
- Oslerus (Filaroides) osleri, another lungworm in dogs
- Eucoleus boehmi, a nasal worm seen in dogs
- Pneumonyssoides caninum, a nasal mite found in dogs
- Aelurostrongylus abstrusus, a lungworm in cats
Ivermectin can be used to treat ear mites in both dogs and cats either systemically as an oral medication or an injection. It is also available as a topical medication in a medication known as Acarexx®. Acarexx® is applied directly inside of the ear canal.
When using ivermectin to treat the many other parasitic infections in dogs and cats, it is used systemically at varying doses, depending on the type of parasite. In most cases, the dosages used for eradication of these parasites is much higher than the dosage used for heartworm prevention.