Heartworm Disease Prevention

IN THE UNITED STATES

Heartworm disease is a parasitic disease caused by the blood-borne parasite Dirofilaria immitis. Although the infection is more common in dogs, cats can also become infected.

The threat of heartworm disease exists even in animals that spend all of their time indoors – in one study, 25% of infected cats were reported to be indoor cats. In recent years, heartworm disease has continued to spread throughout the country, and disease transmission has now been documented in every mainland state except Alaska, as well as in the islands of Puerto Rico, Guam, Hawaii and the US Virgin Islands. Relocation of infected dogs appears to be the most important factor in the spread of this disease.

In 2010, the American Heartworm Society (AHS) released updated canine and feline heartworm guidelines, based on clinical experience and recent research findings. The guidelines are available as pdf documents at www.HeartwormSociety.org.

These guidelines are considered to be the official veterinary perspective for the epidemiology, diagnosis and treatment of the disease.

The key recommendations as they relate to consumers include a recommendation for annual testing for heartworm disease throughout the United States, and for year round adminstration of heartworm preventive mediations in an effort to prevent heartworm disease and control other zoonotic diseases (diseases that can infect humans) such as roundworms. They recommend that heartworm preventives should be started no later than 8 weeks of age.

In addition to these recommendations, the report discusses current treatment protocols and recent reports of possible resistance issues with prevention products.

Finally, the report discusses reasons for the increase in prevalence of heartworm disease in the dog that has been seen recently, including environmental changes due to both urban sprawl and climate change.

Similar recommendations for heartworm disease prevention in cats can also be found on the AHS website. The AHS recommends year-round prevention for cats living in areas where heartworm is seen in their canine counterparts.

Heartworm disease is a significant and life-threatening disease that is readily prevented through the use of preventive medications. With the wide array of effective prescription products that are now available, we, as your veterinary health care team, can tailor a personalized prevention program that will best suit your pet and protect you and your family from the threat of this and other parasitic diseases.

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IN CANADA

Dramatic Increase in Heartworm Disease in Canada

A new survey conducted by Dr. Owen Slocombe at the Ontario Veterinary College, and released in early May shows a 59% increase on a national basis in the number of dogs with heartworm disease when compared to the last survey, which was conducted in 2002. The survey was based on responses from 1300 veterinary clinics. A total of 564 dogs were diagnosed with heartworm disease in the newly released study, compared with 354 in the previous study; the increase was greatest in Ontario, where 431 dogs were diagnosed with the disease, compared to 268 in 2002. Roughly 80% of the dogs with heartworm hadn’t received preventive treatments such as the monthly heartworm preventative.

Heartworm disease is a parasitic disease caused by the blood-borne parasite Dirofilaria immitis. Although the infection is more common in dogs, cats can also become infected. The threat of heartworm disease exists even in animals that spend all of their time indoors – in one study, 25% of infected cats were reported to be indoor cats. In 2009, the Canadian Parasitology Expert Panel published the “Canadian Guidelines for the Treatment of Parasites in Dogs and Cats”, which includes guidelines for prevention and treatment of heartworm disease in dogs and cats. These guidelines are similar to those from the American Heartworm Society (AHS), and are considered to be the official veterinary perspective for the epidemiology, diagnosis and treatment of the disease. This document can be found at: http://www.wormsandgermsblog.com/uploads/file/CPEP%20guidelines%20ENGLISH.pdf.

One key recommendation of the guidelines as they relate to consumers is annual testing for heartworm disease in areas where heartworm disease is found in Canada. In areas with a lower prevalence of disease, testing less frequently may be justified under certain circumstances. In all cases, the recommendation is that testing be conducted in the spring, ideally seven months after the last possible exposure date from the previous year (usually considered to be early October in Canada). The recently released survey shows that the primary infection areas in Canada include the southern halves of Ontario, Manitoba and Quebec, but the disease is also considered to be endemic in the Tracadie area of New Brunswick and the southern Okanagan Valley in British Columbia.

At a minimum, the panel recommends that animals at risk of this disease should receive preventive medications during the ‘at risk’ season (mosquito season), typically late spring, summer and fall. Treatment should continue until after the transmission period has ended. In most parts of Canada, this means that treatment should be continued until early November. Puppies should be started on heartworm preventive medications no later than 8 weeks of age. Most heartworm preventive products also contain medications that control other zoonotic diseases (diseases that can infect humans), such as roundworms. For animals that spend considerable time outdoors in parts of the country that experience mild winters, or pets that travel to the southern US or the Caribbean during winter months, or pets in coastal areas of Western Canada, year-round administration may be appropriate.

Heartworm disease is less common in cats than in dogs, but cats appear to be more susceptible to severe illness if they are infected. The AHS recommends year round preventive treatment for cats that live in areas where heartworm disease is seen in their canine counterparts, including cats that are indoor only. In Canada, cats that are at risk of heartworm disease should receive preventive medication during the ‘at risk’ season, as recommended for dogs.

Heartworm disease is a significant and life-threatening disease that is readily prevented through the use of preventive medications. With the wide array of effective prescription products that are now available, we, as your veterinary health care team, can tailor a personalized prevention program that will best suit your pet and protect you and your family from the threat of this and other parasitic diseases.

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Caution: These news items, written by Lifelearn Inc., are licensed to this practice for the personal use of our clients. Any copying, printing or further distribution is prohibited without the express written permission of Lifelearn Inc. Please note that the news information presented here is NOT a substitute for a proper consultation and/or clinical examination of your pet by our clinic veterinarian.