YES!!  While the incidence is low, we do have heartworm in Arizona.  There were 641 reported cases of Heartworm in Arizona in the last four years.  More and more of these cases are in dogs with no travel history to areas with more pronounced Heartworm problems.

Heartworm, or Dirofilaria immitis, is a nematode which infects dogs.  The Heartworm life cycle begins when an infected mosquito bites the dog and transmits infective larvae into the dog's blood stream.  The larvae migrate to the heart and mature into adult worms.  The adult Heartworm usually takes up residence in the pulmonary artery and release microfilaria into the blood.  Mosquitos then ingest these microfilaria with a blood meal from the dog.  The microfilaria mature into infective larvae within the mosquito and are now ready to infect another dog.

Since the desert supports so few mosquitos, Heartworm has never been a problem in Arizona.  With the increase in man made bodies of water and with the increasing numbers of dogs traveling to and from areas with Heartworm problems, we are seeing an increase in the numbers of Heartworm positive dogs in Arizona.

Heartworm causes severe health problems in dogs and untreated will lead to congestive heart failure and death.  Treatment for adult Heartworm is expensive, time consuming and dangerous to the patient.  The alternative, Heartworm preventative treatment, is inexpensive, given once per month and has the alternative benefit of treating and controlling Hookworm and Ascarid infection.  Prior to Heartworm preventative treatment, your dog must have a blood test performed to ensure that it is not already infected with Heartworms.  Once heartworm preventative treatment has begun, it is necessary to test your dog for heartworms once every two years, especially if monthly doses have been missed or if your pet has gained weight.  Retesting prevents occult infections.

We recommend testing and treating all dogs that travel with their owners.  In addition, the need for Heartworm preventative in Arizona is increasing.  We believe that the statement "Better safe than sorry" may hold true for our dogs here in Tucson.  If you have questions concerning your dog's risk or your current Heartworm preventative, feel free to ask your veterinarian.