HEARTWORM DISEASE

What is heartworm disease?  Heartworm disease is a serious and potentially fatal disease in dogs and cats.  It is caused by a mosquito-borne parasite, called Dirofilaria Immitis.  Adult heartworms cause disease by invading blood vessels of the heart and lungs, causing mechanical obstruction and inflammation.  The female heartworm can produce millions of offspring, called microfilariae, in the bloodstream of the dog or cat.  These immature heartworms cannot complete their life cycle in the animal; they must develop and mature in the mosquito. 

How are heartworms transmitted? When a mosquito feeds on the blood of a dog or cat infected with heartworms, it ingests the microfilariae, causing these immature heartworms to develop into infective larvae within the mouthparts of the mosquito.  These larvae are then transmitted when the mosquito feeds on another dog or cat.  Heartworm disease is not transmitted directly from animal to animal.                                                                                                                                                   

What symptoms do infected animal’s exhibit? Most dogs infected with heartworms do not show any signs for a long time.  Eventually, as the disease progresses, the animal may exhibit such signs as coughing, weakness, shortness of breath, and exercise intolerance.  The signs depend on the number of adult heartworms present, the location of the worms, and the length of time the worms have been present. Infected cats may be asymptomatic or may exhibit signs of respiratory distress, such as coughing or wheezing.

How is heartworm disease diagnosed and prevented? Heartworm disease is diagnosed with a blood test that detects antibodies to the parasite in cats and antigen produced by the worms in dogs.  We recommend testing all dogs in the spring of the year, and starting Heartgard heartworm prevention on dogs with a negative test May 1^st.  The treatment continues once a month through December 1^st.  We recommend testing cats that go outside, and any cats that show signs of respiratory distress or coughing.

How is heartworm disease treated? Dogs that test positive for heartworm disease are treated with an injectable medication called Immiticide, which kills adult heartworms.  One month later, the immature heartworms are killed with an oral dose of Ivermectin.  During the treatment, owners are advised to keep the dog very quiet, with no strenuous exercise, which could hinder recovery and exacerbate the clinical signs of illness.  We often prescribe an antibiotic as well to treat Wohlbachia, a parasite that often accompanies adult heartworms.  Other medications are prescribed based on the degree of damage to the heart and blood vessels sustained as a result of infection.  Cats are generally treated with a combination of an anti-inflammatory medication, prednisone, and a bronchodilator.

Call us at (952)929-0074 if you have any questions about Heartworm Disease or preventative medications.  We are here to provide your pet with the best quality if life possible.