How to Prevent Heartworm in Dogs

4 min read

Updated - Jun 21st, 2022

Heartworm disease in dogs is a serious condition with severe symptoms. Just like fleas, tapeworms, hookworms, roundworms, or ringworms, it’s caused by a parasite.

Most commonly, heartworm is spread by mosquitoes. When a mosquito bites an infected dog, following an incubation stage, it spreads the parasites to the dogs it bites next. The mother worms spread their larvae, called microfilariae, into a dog’s bloodstream. Once the larvae are inside a dog, they can grow, mature, and breed inside their body. Adult worms cause serious health problems for your dog.

Fortunately, heartworm prevention for dogs is possible. But it’s a process that requires you to take precautions, get your dog tested regularly, and consult your veterinarian to make sure your furry friend stays in tip-top shape.

Signs and risks of heartworm disease

Dogs are more vulnerable to heartworm than other animals that can contract the disease, like cats and ferrets. That’s why recognizing the signs and symptoms of heartworm disease, and knowing the best heartworm treatment and heartworm medication, is critical for dog owners.

Your dog might not show symptoms immediately, but if the disease worsens, you’ll see the symptoms, including difficulty breathing, fatigue, decreased appetite, weight loss, and syncope – that is, passing out. If you witness any of these symptoms, you should consult your vet about the possibility of heartworm disease.

More severe symptoms include dark urine and pale gums, both of which can be symptoms of potentially-fatal caval syndrome, which can cause lung damage and heart failure. It’s no exaggeration to call it a medical emergency, and it needs to be treated as such. If you notice these, you should talk to your veterinarian immediately to get your dog the treatment they need. 

Heartworm disease is not contagious in the sense that dogs can’t spread it directly to each other. But when dogs live in close proximity, it’s not hard to imagine the disease spreading through successive mosquito bites. That doesn’t mean you need to quarantine your pups from each other – it just means that detection and prevention are even more important.

Detecting and preventing heartworm disease

If you live in a climate where mosquitoes are common, your dog may be at a higher risk of heartworms. This means that in hot, humid regions, you might want to be especially wary. But as anyone who’s ended up covered in bug bites after a day in the sun can tell you, mosquitoes can strike anywhere. That’s why it’s important, no matter where you live, to be aware of the risks of heartworm disease and be prepared to manage them.

You should get a heartworm test for your dog at least once a year, even if they’re on medication. If you have a new puppy, most vets start heartworm testing at seven months. Annual wellness exams are also essential, not just for heartworm but for all diseases that affect canines, particularly parasites. Vets recommend an annual blood test for heartworm and tick diseases and a yearly stool test for intestinal worms. The goal is to detect infections early so that treatment is more effective.

Don’t wait until your dog starts to look or act ill to take action: prevention is protection. Treatment for heartworm is often arduous and has more serious side effects than preventive medication. Puppies can start heartworm prevention without needing a blood test up to seven months; after seven months, your dog will need to be tested before starting preventive treatment.

The American Heartworm Society recommends year-round preventative treatment for dogs. Their slogan is “Think 12” – in other words, twelve months of prevention, and testing every twelve months.

Some of the most common include ivermectin (commonly sold as Iverhart or as Tri-Heart Plus), selamectin, moxidectin, and milbemycin oxime. Some of these medications are multipurpose: selamectin is also used to treat ear mites. It should go without saying, however, that humans should definitely not take these medications, whatever their symptoms.

All of these medications have to be prescribed by a vet, since they may have serious side effects for certain breeds. Ivermectin, for instance, poses risks to collies and some other related breeds.

You may feel tempted to look into “natural” prevention options. But any natural prevention options, helpful as they might be, should be undertaken in conjunction with, not in place of, medication and veterinary treatment. Vets agree that regularly applied medication – in chewable, topical, or injectable forms – is the best preventive treatment.

You only want to do what’s best for your dog, and that’s understandable. But being able to weigh the risks and benefits is crucial – and the benefits of preventive medication far outweigh the risks. Trust the veterinary science and give your dog the treatment they need.

We know that heartworm is a serious concern for pet owners. That’s why Pumpkin’s optional non-insurance wellness package, Preventive Essentials, fully refunds a yearly heartworm test for dogs six months and older. And when the unexpected happens, Pumpkin Pet Insurance plans can help you pay for the best veterinary care possible by covering 90% of eligible vet bills.

George Menz

George is a copywriter who has lived alongside cats his entire life.
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