Heartworm in Dogs: Transmission, Symptoms, Treatment and Prevention
Easy to prevent but difficult to cure, heartworms can cause serious problems in dogs. If left untreated, these long, string-like parasites can cause a number of complications and even death. Discover how heartworm in dogs is diagnosed, treated and prevented.
How Do Dogs Get Heartworm?
Dogs get heartworms from mosquitoes. When a mosquito bites and feeds on a heartworm-positive dog, it becomes infected with microfilariae (heartworm offspring), which develop into larvae. When that mosquito bites another dog, it can pass on the infective larvae. These larvae will grow and develop over several months inside a dog, eventually becoming adult heartworms that live in the lungs and heart.
Heartworm disease is difficult to treat. Therefore, it’s smart to recognize the signs and symptoms, as well as how to treat and prevent heartworms in dogs.
What Are the Symptoms of Heartworms in Dogs?
Symptoms can vary depending on the number of heartworms present, and often symptoms don’t show up at all until the disease has progressed. Dogs with a low number of worms may show fewer symptoms, like tiring easily during exercise, but a higher number of heartworms can lead to symptoms such as:
- Fainting spells
- Erratic heartbeat
- Difficulty breathing
As time passes, cardiopulmonary disease, heart failure and kidney disease are also possible.
Some of these symptoms can also be indicators of other health conditions. If you observe these symptoms in your pet, consult your vet for a diagnosis.
How Is Heartworm Disease Diagnosed?
Vets can diagnose heartworm disease by testing the dog’s blood and looking for heartworm microfilariae circulating in the bloodstream and the presence of adult worms. Chest X-rays can also help determine the extent of heart and lung damage.
Heartworm disease is a progressive illness, and the earlier it’s detected and treated, the better chance dogs have of surviving and limiting permanent damage to their lungs and heart. If your dog tests positive, treatment is expensive and can be risky. However, treatment will be necessary to save your dog’s life.
How Are Heartworms Treated?
While there is heartworm medication for dogs, it is difficult to treat — largely because killing the worms can cause additional problems, such as the dead worms becoming lodged in the dog’s circulation system.
Heartworm treatment involves giving a drug to kill the adult heartworms. Dogs need restricted exercise and supportive therapy for potentially several months to avoid complications. For instance, if a dog is very active during the treatment process, dead or dying worms can break apart and become stuck in the lungs, creating a clot.
Additionally, a different drug is administered to target microfilariae circulating in the bloodstream. Again, this stage is not without complications, as these dying microfilariae can lead to allergic reactions.
A range of additional therapies may be needed depending on the symptoms the dog is showing, and sometimes the vet will prescribe additional treatment such as pain medication and antibiotics.
Following the treatment, your dog should be retested to make sure all the worms and their larvae are dead. Your vet will set up a timeframe to retest your dog; retesting generally occurs around six months to a year from when treatment first started.
How to Help Prevent Heartworm
When it comes to heartworms, prevention should be top of mind. Use a heartworm preventive product that will kill the larval stages of the parasite before they can become adult worms.
The American Heartworm Society (AHS) recommends that all dogs are treated with heartworm prevention and that puppies are started on prevention as early as possible — no later than 8 weeks of age. The AHS also recommends all dogs and puppies, even those currently on heartworm prevention, are tested for infection once a year. For additional protection, owners can use a product to repel mosquitoes.
Talk to your vet about the steps you should to take to make sure your dog is protected from heartworms.