Canine Heartworm Disease

 Heartworm disease is a parasitic infection where large worms develop within the heart and major blood vessels of the dog.  The disease is spread by mosquitoes.  Mosquitoes carry the larval stage of the heartworm when it takes a blood meal from a dog that has already been infected with the disease.  When the mosquito feeds on another dog, it deposits the larvae (microfilaria) into the next dog.  Over a period of 3 - 4 months, the larvae will migrate from the site of infection in the skin through the tissues until it finally comes to reside in the heart and major vessels of its new host.  As the worms mature in the dog?s heart, they start producing microfilaria that circulate in the blood stream. The microfilaria then become the new source of infection for the next mosquito, and so the cycle continues.

What will heartworm do to my dog?
In the early stages of disease, often there are no symptoms at all.  Dogs appear healthy and active.  As the disease progresses, they may show exercise intolerance, coughing, weight loss, or just a general look of poor health.  There are some cases of sudden death occurring in dogs with heartworm.  These cases are usually diagnosed by autopsy.

Heartworm can be treated if it is detected early enough, but it is costly and can be hard on the dog.  It involves a series of x-rays and painful intramuscular injections to kill the adult worms.  After the treatments, dogs must have very strictly limited activity for a minimum of four weeks.   

How can I prevent heartworm in my dog?
Every dog must have a blood test once yearly to determine if they are heartworm negative.  The test is simple and performed in the hospital by the technicians, and results are usually available by the next day.  Once your dog is found to be negative, he or she can be started on a heartworm prevention program.

Does my dog need heartworm preventative?
Absolutely!  Any dog that spends any amount of time outside can potentially become infected with heartworm.  And don?t forget about the mosquitoes that sneak inside your home on those pleasant days when you?re in and out all day with the windows open.  It only takes being in the wrong place at the wrong moment.

Heartworm preventative medication is very safe and very effective, and is conveniently available in several once-monthly forms.  Interceptor, Sentinel, and Heartgard are monthly oral medications offered at Palos Animal Hospital.  These medications also help control intestinal parasites such as hookworms, roundworms, and whipworms.  Revolution is a topical monthly product that prevents heartworm, as well as preventing fleas and ear mites.

Remember - your dog must have a blood test performed before beginning any heartworm medication.  A potentially serious reaction could occur if a heartworm positive dog is given heartworm preventative.  Do your best friend a favor - keep them protected against heartworm. They only have you to count on!