Heartworm disease is one of the most dangerous and potentially fatal diseases a dog can contract, and pet owners should be aware of the risks and understand how to prevent, detect, and treat it. As veterinarians, we’d like to share an overview of heartworm disease in dogs, including what it is, how it’s transmitted, how to detect and diagnose it, and how to treat it. If your dog needs a veterinarian in Point Pleasant, [practice:state,] the vets here at Bridge Veterinary Hospital are committed to providing the highest quality and best service to pet owners, and we believe that educating dog owners about heartworm disease is the best way to keep their furry friends healthy.
What is heartworm disease and how can it affect my dog?
Heartworm disease, also known as dirofilariasis, is a severe and potentially fatal disease caused by a blood-borne parasite known as Dirofilaria immitis. The adult heartworms inhabit infected dogs' hearts, pulmonary arteries, and adjacent large blood vessels. They can live for five to seven years, and a single dog may host as many as 300 worms. Female heartworms produce millions of offspring called microfilariae, which mainly reside in the small vessels of the bloodstream.
Heartworm disease can cause lasting damage to the heart, lungs, and arteries affecting the dog’s health and quality of life long after the parasites are gone.
How would my dog catch heartworms?
Heartworm disease is spread via the bite of an infected mosquito. When a mosquito bites a dog, it transmits the infective larvae into the dog’s bloodstream. These larvae then migrate to the heart and adjacent blood vessels, where they mature into adult heartworms, mate, and produce offspring.
Heartworm disease has been reported in all 50 states of the U.S. but is most commonly found along the Atlantic and Gulf coasts from the Gulf of Mexico to New Jersey and along the Mississippi River and its major tributaries.
Can dog heartworms be prevented?
Preventing heartworm disease is the best defense against this serious health risk. Preventive medications are available only by prescription from veterinarians and come in various forms, including monthly chewable pills, topical “spot-on” medications. Some preventives only protect against heartworms, while others protect against other parasites, including heartworms, intestinal worms, fleas, ticks, and mites. Consult their vet to discuss the most suitable option for your canine companion.
Regular veterinary check-ups are also essential in the early detection and prevention of heartworm disease, as vets can detect signs and symptoms of heartworms that the pet owner may miss. Additionally, providing dogs with a diet consisting of whole-food ingredients can enhance their overall health and potentially increase their resistance to parasites.
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What are the signs in my dog that would indicate they may have heartworms?
Mild or low worm burden cases of heartworm disease are asymptomatic, so most veterinarians will screen dogs every year for heartworm antigen, even if they're asymptomatic and have been on heartworm prevention, as we can catch any cases that might pop up.
When an infected dog starts showing symptoms, they typically depend on the stage of the infections, such as:
- In the early stages, you can see lethargy, coughing, and shortness of breath.
- Once your dog has adult worms that live live inside the heart, they can do a lot of damage over time. Again, the dog will be coughing, lethargic, and possibly experience exercise intolerance, so they cannot go as long as they usually would.
- If you have a severe worm burden in the mid to late stages, you can have a dog with congestion in the lungs or the liver, so you could see bulging ribs or abdomen. The dog could also develop a heart murmur because of the worms affecting the function of the heart.
- In more severe, late-stage cases, infected dogs can have edema or swelling of the extremities, and the abdomen will fill up with fluid. Those are much more advanced cases, but they do happen.
How will a veterinarian diagnose if my dog has heartworms?
The only way that we can easily detect heartworms is by doing a blood test. The female heartworm releases an antigen that we can pick up on in the dog's blood. The vast majority of infections are going to be circulating heartworm antigens in the blood. A small blood sample allows us to detect adult worms, and then we know that the dog is infected.
It's vital to understand the life cycle of a heartworm. When the mosquito bites the dog, it takes five to six months for that worm to develop into an adult worm, and the adult heartworm is what we’re able to detect in the blood. If your dog were infected within the last six months, the heartworm test today would not be able to pick up that heartworm. That’s why if they've been off prevention and are an adult dog, we test them now and then again in six months to ensure they're negative.
Why is early detection and diagnosis of heartworms so important?
Early diagnosis and detection are essential because early detection of adult heartworms often can allow us to intervene and treat the heartworms before they do significant damage to the heart and lungs. And if we can do that, we can usually have long-term success with minimal to no long-term complications.
How is heartworm disease diagnosed?
Initially, we conduct an antigen test, which tells us that adult heartworms are giving off a substance that's screened for in the bloodstream. If you want to confirm that diagnosis, you do something called a microfilaria test, which tests for the larva in the blood. And that tells us you do have an adult heartworm infestation that we need to deal with.
How is heartworm disease treated?
Although somewhat manageable in the early stages, the treatment for heartworm disease is certainly no fun for the dog. We typically do three spinal muscle injections—one on the first day, then one a month later, and one a day later. These injections can be painful, do put them on steroids to reduce inflammation. We also have them on strict activity restriction because as these worms die off, they might give little pieces off into the dog's heart and the bloodstream. And we never want those to cause any sort of clots or other issues. So, the dog's pretty restricted for a couple of months and has to come into the clinic to do all these things, which is why we would much rather your dog not get heartworm disease than have to be treated for it.
How soon should I bring in my dog to see a veterinarian for heartworm prevention?
Your dog should come in as soon as possible. If you have a puppy, we recommend bringing it in as quickly as possible after you get it. We recommend starting puppies on heartworm prevention at eight weeks, or, again, as soon as you have them. Any dog over six months should have a heartworm test before starting for heartworm prevention. All veterinarians will highly recommend bringing any rescues, adoptees, or adult dogs that you might get to the clinic as soon as possible, and we would screen for heartworm and then get them on heartworm prevention.
The AVMA is another helpful resource on dog heartworm disease. If you have further questions about this serious yet preventable illness, reach out to your veterinarian. If you live in or near Point Pleasant, NJ, we’d love to get your dog on heartworm prevention to keep them as healthy as possible, so please don’t hesitate to call us at (567) 361-3407 or email us at [email protected].