Heartworm disease is a serious and potentially fatal condition caused by the parasitic worm Dirofilaria immitis. These worms live in the heart, lungs, and blood vessels of infected animals and can cause severe damage to these organs over time.

Heartworms are transmitted through the bites of infected mosquitoes. When a mosquito bites an infected animal, it picks up microfilariae (baby heartworms) from the bloodstream. These microfilariae then develop into infective larvae inside the mosquito over a period of several days. When the infected mosquito bites another animal, it injects these larvae into the new host, where they migrate to the heart and lungs and mature into adult worms.

In the early stages, heartworm disease may not cause any visible symptoms. As the disease progresses, however, dogs may develop a persistent cough, fatigue, weight loss, and difficulty breathing. In severe cases, heart failure and death may occur. You can have your dog tested for heartworm by your vet. It is recommended to have your dog tested for heartworm prior to using any treatment.

The best way to prevent heartworm disease in dogs is to administer a monthly heartworm preventive medication. These medications work by killing the immature heartworms (microfilariae) that your dog may have been exposed to in the previous month, before they can develop into adult worms. They also prevent new infections from taking hold. There are several types of heartworm preventives available, including tablets, chewable tablets, topical treatments, and yearly injections.

Puppies should be started on heartworm prevention at 6–8 weeks of age and continue on a monthly schedule throughout their lifetime. Adult dogs who have not been on heartworm prevention should be tested for heartworms before starting medication, as giving preventives to a dog that is already infected can be dangerous.

Most heartworm preventives are given on a monthly basis, although there are some long-acting preventives such as an injection from your vet that is given annually.

Yes, heartworm preventives are generally safe and effective when used as directed. In rare cases some dogs may experience mild side effects such as vomiting, diarrhoea, or lethargy, but these symptoms are usually temporary and resolve on their own.

If your dog misses a dose of heartworm prevention, it is important to give the missed dose as soon as possible and resume the regular dosing schedule. If your dog has missed several doses, it may be necessary to have a heartworm test performed before restarting medication.

No, heartworms cannot be transmitted directly from dogs to humans. However, mosquitoes that have bitten an infected dog can transmit heartworms to humans and other animals.

There is no one best heartworm tablet for dogs, treating at a regular schedule is the most important part of keeping your pet save from heartworms. Effective brands of dog heartworm tablets include Comfortis Plus, Heartgard Plus, Interceptor Spectrum, Sentinel Spectrum, Milbemax, NexGard Spectra, Nuheart and Valuheart.

From our experience, dog heartworm tablets are more effective than topical treatments in preventing heartworm. The reason for this is when your dog consumes the tablet, they will get the full treatment. When using a topical heartworm treatment, some of the liquid may not enter your dog's system due to outside factors such as incorrectly dosing or your pet rubbing it off.