Heartworm (Dirofilaria immitis)in dogs is prevalent across Australia and can be a serious and potentially fatal condition. A dog affected by Heartworm will have an infestation of long thin worms (up to 30cm in length) lodged in the heart and vessels that feed on surrounding blood. Immature stages of heartworm are spread by mosquitoes when they bite dogs. Prevention is possible through a monthly or annual preparation. Puppies should be started on prevention from 12 weeks of age – talk with your vet for the best prevention treatment for your puppy.
Heartworm is a parasitic worm that can infect your pet through a mosquito bite. An infected mosquito injects a larval stage of the worm under your dog’s skin. These larvae mature in the dog’s organs for approximately six months, traveling through the body to the heart and blood vessels of the lungs. These adult worms breed to produce microfilaria in the bloodstream which are then drawn up by a mosquito when it feeds on the dog, continuing the cycle once again.
Mosquitoes are hard to keep out of both the yard and house, so even your indoor-only dogs are at risk.
The prevalence of heartworm in Australia remains poorly understood. What we know is wherever there are mosquitoes, there is potential for heartworm. There are ongoing studies to help experts find out more about heartworm infection in pets, which will assist in the treatment and prevention of the disease. With the information currently available, it has been concluded that prevention is the best form of heartworm control.
Initially, it’s tough to tell that anything is wrong with your pet at all. Heartworm is a slow onset disease, so months or even years may pass before the signs become obvious. When symptoms do appear, your canine companion could have a large heartworm burden. Worms interfere with the movement of the heart valves, creating turbulence in the blood flow, and causing the blood vessels that lead to the lungs to become “blocked” with worms. This puts the heart under immense strain, where it can become enlarged and exhausted.
Early signs could be shortness of breath, loss of stamina, or a nagging, dry cough. As the disease progresses, breathing becomes more difficult, and in severe cases the abdomen may swell with fluid. Your dog could become lethargic and lose weight and their appetite. These symptoms are often subtle and hard to detect, so prevention is the best option. Treatment for heartworm disease is not without potential risk, may be difficult, and if left untreated, it is nearly always fatal.
Have your pet tested at the vet. A simple blood test can reveal whether your pet is infected. Unfortunately, diagnosis is more difficult in cats, so prevention in all cases is always the best option. Keeping your pet up to date with regular heartworm medication, paired with regular vet check-ups is the best way to ensure their health is optimised.
Yes. However, prevention is far better than treatment. Since diagnosing heartworm can be challenging, especially in cats, your pet’s illness may be quite advanced and challenging to treat. Allergic reactions to heartworm treatments have been identified, and some of the treatments can have serious side-effects, so staying on the safe side and keeping your pet up to date with their heartworm prevention is strongly recommended.
There are many heartworm preventatives available. If your dog has not had heartworm medication for more than six months, a blood test is necessary before you can commence preventative treatment, just to make sure they don’t already have heartworm. Prevention should begin at six to eight weeks of age. Medications come in either tablet form or as top-spot application, and many brands help protect your pet against intestinal worms and other parasites like fleas as well. The most convenient and effective heartworm prevention is a yearly injection administered by your veterinarian. This can be given from 12 weeks of age, then boosted at 6 months.
