Heartworm Symptoms in Dogs

Heartworm Symptoms in Dogs

Heartworm infection in dogs, damages their vital organs. Knowing heartworm symptoms can help you save your dog in time.
DogAppy Staff
Did You Know?
Around 250-300 heartworms might be present in the dog, at a time!
Heartworm is a roundworm that belongs to phylum nematoda. Also known as Dirofilaria immitis, it is a thread-like parasite and its vector is mosquito which transmits it from one host to the other. It is called 'heartworm' because the adult worm is found in the right ventricle of the heart where it can live for years. The heartworm infection generally affects dogs but other animals like cats, foxes, wolves, and coyotes can also be infected by it.
Dog Heartworm Symptoms
The symptoms in dogs do not appear until it is in an advanced stage. The asperity of the disease depends upon the number and location of the worm, the duration of infection, and the response of the immune system of the dog. Dog heartworm symptoms include:
  • Cough: The dog experiences mild, dry cough mostly when the parasite infests the lungs. This symptom mostly never raises an alarm and is generally taken by the owners as a seasonal cold and cough.
  • Shortness of breath: Breathing difficulties are often indicative of serious illness. If your dog is having trouble breathing, go to a vet immediately.
  • Vomiting: Vomiting can be due to many reasons like stomach upset, etc. But it could be one of the heartworm symptoms. Vomiting could also occur when the dog is nervous and uneasy.
  • Reduced appetite: If your dog is not eating as much as it used to, try to find a reason. Loss of appetite is a definite indication of a malady.
  • Tiredness: If the dog gets tired easily, shows lack of interest, laziness, or faints after exercise and physical activity, it is an alarming situation. The dog may experience these because the heart is severely infested by the parasite and is not able to pump the blood properly.
  • Nervousness: The dog might be acting in a strange way, not responding properly to your calls, etc. This is due to nervousness and anxiety that the pet feels. Any strange behavior of the pet that continues for more than a day should never be ignored, in any case.
  • Considerable weight loss: If your dog is eating properly and still losing weight, it indicates that there is a serious health concern. It could be a heartworm symptom.
  • Swelling: The dog's body may swell around the ribcage and there may be abdominal swelling as well. These may indicate to an advanced stage of infection and must be looked into, by a vet.
Apart from these, the symptoms may also include jaundice, anemia and presence of blood in phlegm and stool.
Treatment and Prevention
Now it's time for some good news. Heartworm disease can be treated to save your dog if it is diagnosed in time. So, as a dog owner, it is your responsibility to keep your eyes open for these symptoms in your dog. As the parasite is transmitted by mosquitoes, the first and foremost thing to do is to stop their growth. That will save your dog from heartworm infection and also save you from any possible malaria threats. An antigen detection test and blood tests for microfilaria can be done by the vet to confirm the presence of infection in the blood. The availability of a good patient history can lead to better prognosis.
Heartworm treatment for dogs is both complex and dangerous. Since the disease affects the vital organs, the treatment becomes intricate. It includes two steps:
  • Adulticide therapy, that is killing the adult worm by administering heartworm medication for dogs, like thiacetarsamide sodium or melarsomine dihydrochloride (IV or IM).
  • Filaricide therapy, that includes the killing of microfilaria by administering ivermectin and milbemycin drugs. This is carried out 3-6 weeks after the adulticide therapy.
A blood test is performed after 3 weeks of filaricide treatment to ensure that there are no more parasites present. More than 95% of dogs are treated successfully. Heartworms may sometimes have to be surgically removed for critically ill dogs.
Heartworm preventive program is the next step. If your area has a few cases of heartworm in dogs, it is best to consult the vet and start a prevention program before the dog is infected. Several oral and topical preventive heartworm medications for dogs are available nowadays. Diethylcarbamazine is a daily medicine. Ivermectin and Moxidectin require once a month doses. Selamectin is applied topically. Although these preventives are effective, they are not sans risks. According to the American Veterinary Medical Association, 65% and 45% of all the reported incidents of drug reactions and deaths respectively, were due to heartworm preventive medications.
How the Infection Occurs
Let us first understand how this infection occurs. The mosquito sucks the blood of an infected dog and the larva of the heartworm with it. It is then transmitted to another uninfected host animal when the carrier mosquito bites it. The heartworm undergoes changes inside the body of mosquito that prepares it to infest the dog. The parasite then goes through many stages of its life cycle in the host before finally emerging as an adult. The adult heartworm is found in the right side of the heart and some arteries of the lungs.
The heartworm symptoms in dogs mentioned above could be a sign of any serious disease, if not heartworm. Hence, it is necessary to keep an eye out for these to ensure that your dear pet stays healthy and lives longer. Take care!