Heartworm is a parasitic worm spread by mosquitoes. It occurs through most of Southern and Eastern Europe, North America, South America, the Middle East, South East Asia, Australia, Korea and Japan, generally in the warmer months of the year. Mosquitoes transmit the worm larvae while feeding, which migrate through the blood stream, travelling to the heart and arteries of the lungs. They grow to about 20-30cm over the course of about 7-8months, and can live for years. They cause serious symptoms in infected dogs and cats, typically respiratory disease, heart failure and death. They can infect humans too.

Symptoms

• Symptoms develop gradually over about 7-8 months in dogs, usually starting with an ongoing cough. This progresses to breathing difficulty, weakness, weight loss and eventually heart failure.
• Dogs can develop clots or sudden heart failure as worms move into the heart, this can be fatal.
• In cats, symptoms often take a long time to develop, but others show a sudden onset of breathing difficulty, coughing, heart failure and sudden death. Cats can develop an inflammatory response a few months after infection that looks like asthma.
• There is another form of Dirofilariasis that leads to skin nodules, as the worms migrate and live in tissue under the skin.

Prevention

• There are highly effective preventative drugs available for cats and dogs. Many dogs on effective lungworm prevention will be protected against Heartworm when travelling. I can advise you as part of your travel consultation.
• Whilst treatment is possible, it is dangerous and can be life threatening. Dying worms can lead to vessel obstruction and heart blockage. Prevention is ideal, and should be started before travel, with at least one treatment after returning to the U.K.