Heartworms are serious and potentially fatal parasites that primarily infect the hearts of dogs, cats and ferrets. However, infection is 100-percent preventable. Larvae is carried by mosquitoes and transmitted to healthy animals when they are bitten. It takes a little over six months for the larvae to mature into adult worms. In dogs, heartworms may live up to seven years. For both dogs and cats, clinical signs of heartworms may not be recognized in the early stages. Recently infected dogs may exhibit no signs of infection, although they will eventually show symptoms like a mild persistent cough, reluctance to move or exercise, fatigue after moderate exercise, and reduced appetite and weight loss.

Infection in apparently healthy animals is usually detected with blood tests for "antigen" or microfilariae, although neither test is consistently positive until about seven months after infection. All dogs over 6 months old can be tested for heartworm and put on preventives by a veterinarian. Younger puppies don't need to be tested before being put on preventives.

There are no accurate statistics on heartworm infection in Beijing, but it's still a risk, especially with so many pets coming from heartworm-endemic areas. Neglected dogs and certain wildlife, such as coyotes, wolves and foxes, can be carriers. Mosquitoes blown great distances by the wind and the transportation of infected pets all contribute to the spread of heartworm disease to areas previously considered heartworm-free. Increasing numbers of dogs that were born and raised in Beijing are testing positive for heartworm.

The best way for easy, safe prevention of heartworm infection is to first test your pet for heartworm disease and then to administer a year-round heartworm preventive as directed by your veterinarian. Heartworm prevention is safe, easy and inexpensive and can be started with puppies as early as 2 months old. While treatment for heartworm disease in older dogs is possible, it is a complicated and expensive process, taking weeks for infected animals to recover. Prevention is always the best medicine.

Needadvice from METRO's pet expert? E-mail your questions to metrobeijing@chinadaily.com.cn. Please give as many details about your situation as possible. Answers supplied by the International Center for Veterinary Services in Chaoyang district, 8456-1939, ICVSASIA.com.

(China Daily 04/19/2011)