What is heartworm disease?
Heartworm disease is a serious and potentially fatal condition caused by parasitic worms that live in the arteries of the lungs and heart in a number of species like dogs, cats and other mammals. Heartworms are nematodes or roundworms and fall under the filarid specie. Dogs and cats of any age or breed are susceptible to infection. The disease is carried by mosquitoes that are infected with the microfilariae (baby worm stage) while taking blood from an infected animal. Within the mosquito, the microfilariae mature and develop into larvae (adolescent worm stage). When the mosquito then bites another animal, the larvae are deposited into the skin and actively migrate into their new host. They work their way through muscles under the skin and then into the blood going to the arteries of the lung. It can take up to six months for the infective larvae to mature into adult worms that produce offspring. Adult heartworms can live for five to seven years in a dog.
In a dog host, the larvae progress in their development to an adult worm and live in the pulmonary vessels where they continue the life cycle and cause extensive injury to the heart and lungs. Baby worms can be detected in the bloodstream about six to seven months after the infective larvae enter the
dog. The male and female heartworms become fully grown about one year after infection. The onset and severity of the disease in a dog is mainly reflected by the number of adult heartworms present, the age of infection and the activity level of the animal. Dogs with higher worm counts are generally found to have more severe heart and lung disease. The common early pathological changes that are caused by heartworms include inflammation in and around the pulmonary arteries. Later changes include an enlargement of the heart and congestive heart failure due to weakening of the heart muscles. A very active dog can develop a very severe condition with a fewer number of worms as compared to an inactive one.
Where is heartworm found?
Canine heartworm infection is widely prevalent in the United States. All dogs should be considered at risk, placed on prevention programs and frequently examined by a veterinarian. Heartworm disease may cause a combination of medical concerns in a dog including lung and heart dysfunction as well as liver and kidney complications. The disease can have an acute onset but begins with barely detectable signs as a result of a chronic infection. Dogs with low worm counts that are not exercised strenuously may never have obvious signs of heartworm disease. However, in most dogs, the heart and lungs constitute the major organs affected by the disease with a range of clinical signs.
| Early infection stage | No abnormal signs observed |
| Mild disease | Cough |
| Moderate disease | Cough, exercise intolerance, abnormal lung sounds,excessive shedding or hair loss, weight loss, lethargy |
| Severe disease | Cough, exercise intolerance, breathing difficulties, excessive shedding or hair loss, weight loss, lethargy, abnormal lung sounds, liver enlargement, syncope (temporary loss of consciousness from poor blood flow to the brain), ascites (fluid accumulation in the abdominal cavity) , abnormal heart sounds and death |
Prevention
Prevention is a much safer and economical option with monthly dose medications ranging from $7-$15 depending on the type and brand of medication. Often, online pet pharmacies offer bulk orders at cheaper costs. A variety of preventatives are available including daily and monthly tablets and chewables, monthly topicals and a six month injectable product. These products are extremely effective when administered properly and on a timely schedule, heartworm infection can be prevented. The American Heartworm Society is now recommending year-round preventative treatments even in seasonal areas to ensure compliance with a proper scheduled dosage of the medication. In addition, most monthly heartworm medications also protect against intestinal parasites. Periodic retesting for heartworm ensures the success of the preventative program.
Diagnosis
Diagnosis depends on an accurate history, the recognition of the varied clinical signs and the use of several diagnostic procedures. A commonly used diagnostic is the “SNAP test” performed by your veterinarian. It requires a blood draw and results of a quick heartworm screen can be processed in as little as 15 minutes that allows you to know what stage of infection your animal is at to provide the correct treatment. Talk to your veterinarian about this test at your next vet screen.

Treatment
The infected dog needs to be clinically evaluated for heart, lung, liver and kidney function to evaluate the risk of treatment. The costs for these procedures can run the gamut from simple blood testing to angiography and ultrasound tests that can be a huge financial dent. Most infected dogs can be successfully treated. Treatments can sometimes run several months during which your pet needs to be exercise-restricted owing to their condition. The goal of a treatment program is to kill all adult worms with an adulticide and all the microfilariae with a microfilaricide. Heartworm infected dogs with no signs or mild signs have the highest success rate with treatment. Patients with more severe infections can be successfully treated but their risks of complications and mortality are also greater. Talk to your veterinarian about the options for your pet if they require treatment. The procedure and medications for treatment are very different from preventatives and cannot be interchanged. Preventatives do not target the adult worms already present that need to die out naturally. This process can take up to 2 years and involves the slow death of the old worms that can cause an embolism as their decaying pieces break off into the bloodstream. Yes, its a gross and dangerous process and requires the specific treatment of the adult worms to ensure the safest recovery for your pet.
Heartworm disease is widely recognized as a major health problem affecting pets. As a responsible pet owner, getting all the information on the prevention and treatment of this disease ensures that you are equipped to provide the best possible care for your furry friend. Here’s wishing you a lifetime of good health together!



The process of positive reinforcement is not a foreign concept. As kids, we remember that acing a test or doing really well on homework assignments would usually mean a reward (ice cream or getting to extend curfew by a little longer!). These rewards made us want to do the actions again because they feel good! That is positive reinforcement. Dogs are similar in that aspect. They want praise and affection for a job well done and of course,…….fooooood! Positive reinforcement training allows you to use praise and rewards (treats) to encourage a behavior in your dog. This is a very important tool in shaping good behavior or changing any negative behavior in your furry friend.