Filaria is believed to be the cause of death for famous faithful dog Hachiko. It used to be one of the major causes of death in dogs, but now it can be prevented almost 100 % by administering preventives.

What is filariasis (also known as “heartworm”)?

Dogs can be infected with filaria when they are bitten by mosquitoes that have bitten another infected dog. Filaria larvae grow in dogs’ skin or muscles for 2 months, then migrate to the heart vessels in 3 to 4 months and cause various symptoms. The mature worm can grow to be about 20 to 30 cm in size and after 6 months of infection, starts giving birth.

How does prevention work?

Preventives kill the larvae before it moves to the heart vessels. It does not prevent the mosquito from biting, but kills any larvae found in the animal within the last one month. Therefore, it is important to give the pill monthly until one month after mosquito season ends.

Timing of administering preventives.

In Tokyo, there are mosquitoes around from April through to November, so you should give your dog filaria preventives from late April or early May, to late November or early December. It’s ok to give it all year round as well.

Why is the antigen test essential?

If your dog was infected the previous year, there is a possibility that many larvae produced by the adult filaria are swimming around in his/her blood vessels. If preventives are administered in this situation, the larvae will die and get stuck in the capillary blood vessel, which can lead to systemic shock. This is why it is important to check there is no infection from the previous year, before administering preventives.

Types of medicine

Chewable type (It’s flavored, so perfect for dogs that love to eat!)

       ★NexGuard SPECTRA (For flea, tick, filaria and gastrointestinal parasite prevention. All in one!)

　　★Ivermec (Filaria and gastrointestinal parasite prevention. You can combine with Simparica to prevent fleas and ticks. 　　　Double the treats for your dog!)

　　★Interceptor chews (Filaria and gastrointestinal parasite prevention. Can be administered to tiny dogs weighing 1 kg. 　　　Combine with flea and tick prevention.)

Tablet type (Available in small size tablets for dogs that don’t enjoy flavored treats.)

　　★Milbemycin A (Filaria and gastrointestinal parasite prevention.)

Topical type (For dogs that can’t handle oral medication. Do not shampoo for 24 hours after.)

　　★Revolution (Combine with FRONTLINE PLUS which is also a topical type preventive, for ticks.)

Injection type

　　★Pro Heart (Valid for one year, so no need to worry about forgetting the monthly meds!)

Filaria in cats?

In cats, most of the larvae cannot grow and die shortly after infection. However, dead larvae can cause considerable damage to the lungs, causing respiratory symptoms. If even a few of the surviving larvae migrate to the cat’s heart, severe symptoms can be expected. Prevention for cats can be done with Revolution plus, a topical filaria/flea/tick preventive.