HEARTWORM DISEASE
Heartworm Disease - For CSRNE
by Angela Conrad
What is Heartworm Disease:
The Heartworm (Dirofilaria immitis) is a major pest for dogs in America. Once
considered a parasite of southern climates, the heartworm has spread to all
50 states. According to the Heartworm Society, the highest infection rates occur
in dogs within 150 miles of the Atlantic and Gulf Coasts and along the Mississippi
River and its territories. Other areas with a large mosquito population also
have a high rate of infestation.
The Heartworm parasite goes through several life stages before emerging as
adult worms. In heartworms, a mosquito serves as the intermediate host for the
larval stage of the worm, also known as the microfilariae. The mosquito ingests
the larva when it bites and infected dog and deposits the larva to an uninfected
dog when it bites the dog. The microfilariae burrow into the dog and then undergo
several changes to reach adult form. The adult worm then travels to the right
side of the heart through a vein and awaits the opportunity to reproduce. Adult
heartworms can grow between 8 to 12 inches in length and can remain in the dog’s
heart for several years.
Dogs can have some microfilariae in their blood and worms in their lungs without
manifesting the disease. Once the number of worms exceed a certain number based
on the size and activity level of the dog, the adult worms will move the the
heart and symptoms will begin to appear.
What are the symptoms:
- a cough that can advance as the disease advances
- the liver and lungs slowly decrease in functioning
- dog tires easily
- dog is weak and listless
- loses weight
- respiratory distress
- exercise intolerance
- abnormal lung sounds
- hepatomegaly (enlargement of the liver)
- syncopr
(temporary loss of consciousness due to poor blood flow)
- ascites (fluid accumulation in the abdominal cavity)
- abnormal heart sounds
How can dog owners prevent Heartworm:
Heartworm prevention is simple! Every year, in the early spring, dog owners
need to take their dog(s) to a veterinarian for a simple blood test to determine
whether the parasite is present. In addition, all dogs should receive a regular
dosing of a heartworm preventative. Some veterinarians recommend preventative
medication be given all year, while all veterinarians agree that dogs should
be put on a heartworm preventative from the months of April to November. There
are multiple preventative medications; some are oral, others topical or an injection.
Only a veterinarian can issue these preventatives to dog owners.
What can the dog owner do:
Keep your dog(s) healthy! Have a heartworm test performed on your pet every
spring. Keep your pet on a heartworm preventative during the months of April
through November, and if you choose, all year long. Watch you pet's health and
if you suspect any problems make an appointment with a veterinarian.
Works Consulted:
1. University of Pennsylvania School of Veterinary Medicine
2. The American Heartworm Society:
www.heartwormsociety.org
