Heartgard Medicine Side Effects

Heartgard medicine, the ivermectin-based, once-monthly heartworm preventative, is a relatively safe drug. It's also used to combat ear mites, sarcoptic mange and demodectic mange. They're used to kill microfilaria, the heartworm larvae that live in your dog's blood when he's suffering from an active infection.

Uses for Ivermectin

Ivermectin, in the form of Heartguard, is most often used for the prevention and treatment of active heartworm infections in dogs. It's also used in a topical medication called Acarexx, which is used to treat ear mite infestation.

Ivermectin has some off-label uses as well. While it's not yet been approved by the FDA, veterinarians have found that ivermectin is effective in the treatment of sarcoptic and demodectic mange.

Side Effects Associated with Ivermectin Use

Even at the higher dosages used to treat mange infestations, ivermectin has been found to be a fairly safe drug. However, as with any drug, Heartgard medicine can have some side effects. Some of the side effects of ivermectin include:

  • Depression
  • Lethargy
  • Diarrhea
  • Vomiting
  • Lack of appetite
  • Seizures
  • Lack of coordination
  • Excessive salivation
  • Dilated pupils

Some of these symptoms are more serious than others. If your dog exhibits dilated pupils or lack of coordination, seek emergency veterinary care right away.

Ivermectin shouldn't be used at the same time as Valium or drugs similar to Valium. Amitraz dips and some topical drugs can also have adverse side effects. Always let your vet know about any medications your dog is using, even over the counter flea remedies, just in case there might be a potential for drug interaction.

Some Dogs Are Sensitive to Ivermectin

Some dogs are genetically predisposed to be sensitive to ivermectin, the active ingredient used in Heartgard medicine. These breeds include:

  • Collies
  • Shetland sheepdogs
  • Old English sheepdogs

Not all members of these breeds possess genetic sensitivity to Heartgard medicine, and dogs of other breeds have been found to possess the mutated gene as well, though this occurs rarely. If your dog belongs to one of these breeds, it's a good idea to have a blood test performed before Heartgard medicine is prescribed. A blood test can determine whether or not your dog was born with genetic sensitivity to Heartgard. If you have one of these dogs and he's already taking Heartgard medicine, don't panic. Most of the time, the doses of ivermectin present in Heartgard, when it's used as a preventative measure, are low enough to be safely used even in genetically sensitive dogs.

Alternative Methods of Heartworm Prevention

If your dog can't take ivermectin based medications like Heartgard, or if you're simply uncomfortable with the long term use of such medications, there are alternative steps you can take to prevent heartworm infection. They are:

  • Feed your dog a healthy diet. Good nutrition is key to his health, and the healthier your dog is, the more likely he'll be able to fight off heartworm infection.
  • Exercise your dog daily.
  • Try to reduce or eliminate stress in your pet's life.
  • Visit a holistic veterinarian, a homeopathic veterinarian or a veterinary herbalist to investigate alternative medicines.
  • Try to keep the area around your home free of mosquitoes. Remove standing water and consider using insecticide.