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Heartworm in dogs and cats: symptoms and prevention

The first mosquitoes start to appear with the arrival of spring, and represent a real threat for our four-legged friends. Mosquitoes can carry filariasis, or filarial parasites responsible for a potentially fatal cardiopulmonary disease.

Both the tiger mosquito and Korean mosquito species are most responsible for filariasis, or heartworm. The insect transmits the disease by, first of all, biting an infected animal with microfilariae in its blood, and then a healthy animal.

Heartworm in dogs

The disease follows a chronic-subacute course among dogs. Symptoms appear slowly, and it can take several years after the initial infection before the first indications really appear.  Without careful prevention, this tends to be the real problem.

Initial symptoms are respiratory with coughing, breathing difficulties and inability to exercise. Then, more serious cardiac complications arise as the disease progresses.

Heartworm in cats

Cardiopulmonary filariasis, or heartworm disease,  develops quite differently in cats. Some cats recover quickly and spontaneously. Others often suffer from an acute syndrome vomiting rather than respiratory, or cardiac symptoms.

How to protect dogs and cats from heartworm

The only weapon at our disposal is prevention. This means administering a drug that kills microfilariae while they are still present in the subcutaneous tissue. Prevention is possible during the so-called migratory phase, and there are three types of product currently on the market:

  • tablets, taken once a month.
  • monthly spot-on pipette administration.
  • annual injections, which must be carried out by your vet.

Springtime is the best time to start prevention when the mosquitoes arrive. Bear in mind that products have a retroactive efficacy of about a month, so it is better to avoid delaying  administering tablets, pipettes and injections any longer than mid-April if mosquitoes start to appear mid-March.

Prevention using spot-on pipette administration or tablets can start in the sixth or seventh week for puppies. Depending on the size and breed of the animal, it is better to wait for until at least six months, if not one year, of age for annual injections.

Heartworm can be accurately diagnosed with a clinical diagnostic test or in the laboratory. The test should be repeated annually before the start of the filariasis prevention season, or even several times per year in certain high-risk endemic areas if your vet feels it is necessary.

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