HEARTWORM DISEASE During the warm weather months in Colorado when mosquitos are active, we turn our attention toward the risk of heartworm infection in dogs.  This potentially fatal disease spreads through the bite of an infected mosquito and has been found to exist in all fifty states.   Heartworm disease is easy to prevent, but can be difficult and sometimes dangerous to treat, especially in its more advanced stages.   As a part of our commitment to preventing heartworm disease, we encourage you to have your dog tested and are currently offering a 20% discount on the heartworm test.  The test involves a simple blood draw and analysis, and is an important first step in preventing heartworm disease.   Heartworm tests can be performed on a walk-in basis and results are usually available within 24 hours.   If your dog's test results are negative for heartworm infection, your dog can safely be placed on a heartworm prevention program.   Please note that as with all medications, we require a physical exam within the past year with one of our veterinarians in order to dispense a heartworm preventive medication.

Why Test? The heartworm test is important because it determines if it is safe to give a heartworm preventive. Giving preventive medication to an already infected dog can cause worms and larvae already present in the blood vessels and heart to die quickly and in large numbers, overwhelming the dog's ability to metabolize the waste and safely excrete it.  Instead, the rapid die-out of worms at any stage of development could cause blood vessel blockages, toxicity, and shock, resulting in the dog to suffer and die. Safely treating heartworm disease requires administering small doses of medication at certain intervals over a long period of time, allowing the dog's body to break down and excrete the dead worm waste gradually.  Treatment can take several weeks to months and requires close monitoring.  During the course of treatment, dogs often endure considerable discomfort and, in some cases, especially in the advanced stages of the disease, some dogs will not survive.  In 2007, our veterinarians successfully treated two dogs with heartworm disease that had been placed with us by the Denver Dumb Friends League after hurricane Katrina.  Both dogs were hospitalized and monitored closely while being treated, which lasted over two months.  Fortunately, both dogs recovered and were eventually able to be placed in homes.

How Do Dogs Become Infected? Heartworm infection is caused by the parasite dirofilaria immitis and is transmitted to dogs by female mosquitos.   The transmission cycle begins when a female mosquito feeds on an infected dog and takes in 'stage 1' larvae of the parasite, called microfilaria.  Once inside the mosquito, the larvae mature to 'stage 2' and 'stage 3' larvae, which takes about one to two weeks, providing the outside temperature stays at around 60o during that time.   It is at 'stage 3', that the larvae can be transmitted by the infected mosquito to a healthy dog during a bite.  Once deposited into the dog's tissues, the larvae migrate into the bloodstream, which can take about three months, during which time they will continue to mature to juvenile 'stage 4' worms.  By five to six months, the larvae will have become young adult worms and have reached the heart and pulmonary artery.  It is there that they will mature into adult 'stage 5' worms and remain for the duration of their life span, which can last three to five years.   Adult heart worms look like strands of cooked spaghetti and because most infected dogs will have multiple worms, they will inflame and clog the arteries over time, greatly diminishing the ability of the heart to function.  Unfortunately, the infected dog will become weak and toxic, and eventually die.

What Are The Symptoms?  The first signs of heartworm disease may not show for several months after infection occurs, but usually begins with a soft cough that increases during walks or play activity.  As the disease progresses, the cough will worsen and the dog will become increasingly listless and weak, and tire easily.  The infected dog will begin to lose weight and its overall appearance will deteriorate.  Breathing will become more difficult, resulting in respiratory distress during the simplest activity, and the dog may also begin to cough up blood.  The progression of heartworm disease will result in a dramatic loss in quality of life, as the dog will no longer be able to perform normal activities or take walks and play.     In the end stages of the disease, as the heart and vessels become engulfed with worms, congestive heart failure ensues, and death will follow -- but not without considerable pain and suffering.

How Can It Be Prevented? Heartworm prevention is as easy as feeding your dog a tastey chewable once a month.  We carry two types of chewable preventives, Heartgard and Interceptor, and your veterinarian will help you decide which one is best suited for your dog's needs.   The added benefit of our heartworm medications is that they also kill other parasitic worms, including roundworms, hookworms, and whipworms.  Because roundworms and hookworms can be transmitted to humans, posing serious health risks to both children and adults, our veterinarians recommend placing your dog on a year-round prevention program. If you have additional questions, just call us at 303-708-8050, and we will be happy to discuss them with you.  We will also be happy to discuss the prevention of other parasites, including ticks, fleas, and lice.