Veterinary Wellness Blog

We let pets into our hearts, don’t let heartworms into theirs!

May 2, 2013

Heartworm disease is a common illness here in Minnesota.  It is carried by mosquitoes, and spread when an infected mosquito bites your pet.  As the worms mature, they can block the blood vessels of the heart and lungs, causing both circulatory and respiratory disease such as difficulty breathing, exercise intolerance, asthma like symptoms, blood clots, anemia, heart murmurs, irregular heart beats, high blood pressure, and thickening of heart muscles (hypertrophy).  Infection can also cause protein loss through the kidneys, which over time can damage the kidneys.  Lastly, it can be fatal.

Treatment of heartworm disease involves a series of shots which are derived from arsenic.  There is a lot of follow up and cost involved-multiple chest x-rays, medications to help prevent reactions to the arsenic and dying worms and anaphylactic shock, hospitalization, and follow up testing.  Pets must be kept confined to a cage just large enough for the dog to stand, turn around, and lie down in for a couple of weeks.  This to help prevent the pet from having a blood clot or piece of dying worm getting stuck in a blood vessel in the lungs, called a pulmonary thromboembolism or PTE.  PTE can cause difficulty breathing and even death.  Cats and ferrets cannot tolerate the arsenic compound used to treat heartworms, and there is not a medical treatment available to these pets.  In severe cases, open heart surgery has been used, but often these pets make poor anesthesia patients.  Because of all of the terrible side effects to a very risky treatment, prevention is much easier and safer for the pet.

Yearly testing for heartworm disease is recommended by us at Heritage Animal Hospital, as well as Companion Animal Parasite Council, and the American Heartworm Society.  There are several reasons for testing yearly.  No preventative is 100%, and let’s face it, most of us are not 100% on getting it on time every month.  The sooner a diagnosis is made, the less evidence of disease changes are present in the body, and the more successful treatment can be.  Also, the preventative, if given to a heartworm positive animal, has a slim but real chance of causing the same side effect of a PTE that treatment does.

We also recommend yearly heartworm preventative for all pets as opposed to seasonal for a number of reasons:

• Mosquitoes may survive indoors longer than the traditional 6 months of treatment
• Many pets travel with their owners during the winter months and may go to an area where heartworm disease is a threat year round
• Many of the heartworm preventatives also cover intestinal parasites such as hookworm, whipworm, and roundworm, as well as some having flea and/or tick control
• Approximately one third of cats diagnosed as heartworm positive are indoor only pets!

Heartworm disease is a preventable illness that can be quite serious and possibly fatal.  Talk with us today about our recommendations for your pet and heartworm preventative!