HEARTWORMS

Heartworms are internal parasites that primarily affect dogs but are reported to occur in cats, ferrets and even humans with increasing frequency.  Microscopic, immature heartworms (microfilaria) are transmitted during the bite of an infected mosquito.  After being injected into your pet during the mosquito bite, the immature heartworms migrate to the heart, grow to maturity and reproduce by giving birth to larvae.  When another mosquito bites your pet,  it ingests these larvae and after a period of time can transmit infective larvae to other pets they feed on.

The immature heartworms become adults 6-8 months after being injected into your pet by an infected mosquito.  These adult heartworms interfere with the normal flow of blood through the heart causing decreased cardiac output.  This can eventually result in a persistent cough, liver, kidney and heart failure. 

Heartworms infestation can be effectively prevented by the administration of a preventative medication.  The preventative is available in either tablet or chewable form and is to be given once a month during and for one month after the mosquito season.  In the Council Bluffs/Omaha area, the preventative should be given from April through December.  These heartworm preventative medications are almost 100% effective and act by killing the juvenile worms injected during the mosquitoes’ bite, thus preventing them from developing into adult heartworms.  Heartworm preventatives are inexpensive, costing only a few dollars a month.  By comparison, you can buy 10 years’ worth of heartworm preventative for the cost of one treatment for adult heartworms.   

Although heartworms primarily infest dogs,20- 30% of cats have been found to be infested with heartworms.  There is no good test for heartworms in cats at the present time but we think it is important to give your cat heartworm preventative (made especially for cats) from April through December.  

A positive or negative diagnosis of heartworm disease is made by examining a blood sample taken from your pet.  The blood sample is first examined microscopically for the presence of immature heartworms.  Twenty percent of dogs infected with heartworms do not have these microfilaria in their bloodstream; therefore, the blood sample is also checked using a serum antigen test.  These yearly tests are usually done in the Spring but can be performed any time of the year.

If your pet is infested with heartworms, your veterinarian will perform blood tests and x-rays to evaluate the severity of the infestation before determining the proper course of treatment.  If these tests and x-rays indicate there are light to moderate symptoms of heartworm disease, a series of injections are given over a three day period of hospitalization.  If the treatment progresses with no unfavorable reactions, your dog will be sent home after 3-4 days with additional medications. It's exercise should be severely limited for the next 8 weeks because the dead adult worms in the heart are dying and floating into the pulmonary blood vessels where the body will dissolve them.   Too much excitement or exercise during this period can lead to collapse and death.  Another medication is given one month after the initial treatment to eliminate any immature heartworms.  

If you have any questions or concerns about heartworms, call the Council Bluffs Veterinary clinic at 323-2147.   We are open 8-6 Monday through Friday, 8-3 on Saturdays.