Heartworm in Dogs: Prevention & Treatment

Heartworm disease is a serious condition in dogs and can cause significant damage to your pet's internal organs. Here, our Laguna Beach vets discuss the treatment and prevention of heartworm in dogs.

Heartworm Disease in Dogs

Your dog can contract heartworm when they are bitten by an infected mosquito and a parasitic worm called Dirofilaria immitis is passed into their bloodstream. Heartworm isn't contagious, and can't be transmitted from one infected dog to another pet, it can only be spread by mosquitoes that carry the parasite.

Don't make the mistake of believing that your dog's risk of heartworm is low; there have been reports of heartworm in all 50 states and it is particularly common between New Jersey and the Gulf of Mexico, even along the Mississippi River and its major tributaries.

If your pup has been bitten by an infected mosquito, the worms will grow into adults, mate, and produce offspring while residing in your companion's heart, lungs, and blood vessels.

Treating Heartworm in Dogs

In situations where preventative measures don't work in preventing infection, there are treatment options available for your dog, however, all have potential side effects that can be serious and can cause health complications, however, fatalities are rare.

Since heartworm is undetectable until at least 5 months after infection, many dogs already have advanced Heartworm Disease by the time they are diagnosed and require fast and intense treatment. In rare situations, the damage to the dog's internal organs can be so severe that by the time the condition is found, it's better to treat the damage and keep the pooch comfortable rather than take the additional risks associated with attempting to kill the heartworms. Dogs in this advanced condition have a life expectancy of only a few weeks or months. 

If you see your dog displaying any of the signs of heartworm disease contact your vet immediately. Some of the symptoms of heartworm include fatigue, getting tired easily after only mild exercise, a persistent cough, a large belly, reduced appetite, and weight loss. There are some rare and very severe situations where dogs can get Caval Syndrome where your pup could suddenly collapse and potentially die.

Thankfully, a new medication has been developed for killing adult heartworms while having fewer dangerous side effects. Melarsomine is an injectable drug that kills adult heartworms and is administered through multiple injections. Typically your dog will be given a 30-day rest period after their first injection, after which they will receive two more injections 24 hours apart. Antibiotics will also be prescribed to combat any infectious bacteria the heartworms may be carrying. With this new medication, 95% of dogs with heartworms are now able to be successfully treated.

Your dog will also receive treatment to kill juvenile heartworms (microfilaria) either before or after their Melarsomine treatment. Your dog may need to spend the night in the hospital for observation on the day this treatment is administered.

Possible Side Effects of Heartworm Treatment

Heartworm treatment can cause serious complications for your pet's health and can be potentially toxic to the dog’s body. Many dogs experience soreness and swelling at the site of their injections. The most severe side effects are related to a large number of worms suddenly dying. You must contact your vet immediately if your dog is panting excessively, has difficulty breathing, is suddenly lethargic or collapses, begins to reject their food, begins to vomit, or develops diarrhea.

A Dog's Recovery From Heartworm Treatment

Your dog must be allowed to rest following its injection. Heartworm treatment in dogs kills adult heartworms within a few days, but further complications can occur while their corpses are decomposing. It can take several months for the heartworms to be reabsorbed into the patient's bloodstream.

Most post-treatment complications arise from these fragments of decomposing heartworms, so to minimize this risk your dog must not be allowed to exercise and should be kept as quiet as possible for the first month following treatment.

For seven to eight weeks following injection, cough will be noticeable. If this cough persists beyond this or is especially severe, as well as if your dog is demonstrating shortness of breath or fever, contact your veterinarian right away.

Heartworm Prevention for Dogs

Our vets at Canyon Animal Hospital can't stress enough the importance of heartworm prevention because it is far superior to the treatment involved. We recommend contacting your vet as soon as you can to establish a parasite prevention plan for your dog if you have not already. 

Usually, heartworm prevention is administered through a monthly medication that is prescribed by your vet. 

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets, or search and rescue advice for pets.

Is your dog due for their parasite prevention measures? Contact our Laguna Beach vets to book an appointment.