Side Effects of Heartworm Medicine for Dogs

Heartworm medication for dogs is used as a preventative for this debilitating disease, which is completely preventable with medication but still infects more than 250,000 dogs annually. Since heartworm medication is considered to be relatively safe by most veterinarians, if you live in an area with high incidence of heartworm, the risks of side effects from medications don't outweigh the risks associated with contracting the disease.

Types of Medication

Adulticide, melarsomine and thiacetarsamide are medications, often given in a series of injections, that treat heartworm once it is contracted. Though these have side effects, they are often necessary once the disease has been contracted since there is no other cure.

There are many types of preventative heartworm medication such as Ivermectin, Revolution, Interceptor, Heartgard and Iverhart Max. These usually come in pill form but may come in spot-on treatments and prevent a variety of worms and possibly even fleas and ticks, depending on the brand. The pills contain lose doses of insecticide to kill the worms before they have a chance to develop.

Side Effects of Canine Heartworm Meds

Side effects for the treatment injections, particularly melarsomine and thiacetarsamide, can be nasty, including diarrhea, vomiting, loss of appetite and jaundice. Dogs are routinely hospitalized for heartworm treatment, so they can be treated for the side effects as well.

Preventative pills also have many side effects, which have many pet owners searching for natural worm preventatives. Because these pills contain insecticides, they may become toxic to your pet over time. Your dog's kidneys and liver have to work overtime to remove the toxins from the body, which may cause long-term damage. This also weakens the immune system so dogs are more susceptible to disease shortly after taking the pill, which is often given on a monthly basis.

Additional side effects of the preventative pills include vomiting, diarrhea, weakness and seizures. These medications should never be given to a dog who is prone to seizures without consulting a veterinarian.

Dogs who are prone to medicine sensitivities may also have severe allergic reactions or behavioral symptoms such as increased irritability and aggression in the days immediately following the dosage. If your dog is sensitive to medication, consult your veterinarian before administering. Certain breeds such as shelties and dobermans seem to show increased sensitivity.

Always follow recommended dosage closely. Symptoms of overdose include loss of coordination, dilated pupils and trouble breathing.

Because heartworm symptoms may not appear until the disease has already advanced, preventative medicine is best way to keep your dog safe. As with any medication, there are side effects and health problems related to long-term use. However, heartworm can end in a painful death, and many owners opt to use preventative medications regardless.