What’s it like to have a dog with heartworms?

When we found out that our lab, Jack, had heartworms, it was pretty scary news. Heartworms are fatal when not treated, and can cause truly horrifying health problems. Even the cure can be deadly, which is why so many vets advocate preventative medication, like Heartguard.

Canine heartworms, like many dog parasites, come from mosquitoes. They can’t be passed on to other dogs, so even if you have one dog with heartworms, the other will be safe if he’s on preventative medication. Vets can only detect heartworms through a specific blood test, so even if you have your dog on HeartGuard, it’s still a good idea to get him tested once a year or so. That’s because preventative medication only kills larvae, and not adult worms. It takes the larvae 6 months to become adults, so a dog can test negative ,even if he has baby worms in his system.

Before treatment begins, dogs are usually given a drug to help them kill off the parasites that help heartworms breed. Because the parasites have a symbiotic relationship with the worms, killing them off can prevent more adult worms from clogging the heart and lungs of your pet.

Dog heartworms are usually treated with a medication called Immiticide, which is arsenic based, and is injected into the lumbar region of the dog’s spine. It will make them sore for a few days, but they will soon recover from the pain. The hard part comes after the injection. When you inject dogs with Immiticide, it kills the adult worms by dissolving them into the bloodstream. If a dog is too active during recovery, he may cause some of the adult worms to break off into his bloodstream and cause a blood clot. If dogs are not kept in kennels or dog pens during treatment, acute death can occur.

After the first shot and a month of bed rest, your pet will go back to the vet for two more rounds of shots. One on one day, and the next the following. These will kill the last of the adult worms, and your dog will need to rest for another month with minimal activity.

After the final shot, the vet will give some medication to kill the microfillae, or the baby worms in your dog’s system. Once these babies are dead, your dog will need to remain on preventative medication for the rest of his life to prevent a re-occurrence of the worms. You should still have your dig tested once yearly to make sure that the medication has removed all traces of worms from your dog’s heart and lungs.