Signs of Heartworms in Pets

Heartworms are deadly parasites transmitted to dogs and sometimes cats via mosquito bites. During the bite, the heartworm larvae called microfilia transfers into the animal's bloodstream to incubate for several days before moving to the lungs, heart and other vital organs. Heartworm prevention consists of oral, cutaneous or injectable monthly doses of a medication such as selamectin. Heartworms often remain undetected until the advanced stages of infection, which is when symptoms occur.

  1. Coughing

    • Most owners will notice a soft, dry cough as the first system of heartworms. Unfortunately, this means that the parasites have already found their way into the dog's lungs and the lungs have become irritated by multiplying adult heartworms. According to WebMD's Healthy Dogs Guide, the owner may notice abnormal breathing and that the dog becomes winded easily. The dog may experience chest pain.

    Lethargy

    • According to the website Dog Heartworm Guide, a dog suffering from heartworms has a severely weakened internal system. This causes them to become much less active than usual. Often, dogs infected with heartworms sleep more than normal. They lose interest in play, exercise and food.

    Advanced Heartworms

    • Left untreated, heartworms cause the dog's vital organs to shut down. In the advanced stages of heartworm infection, a dog may lose consciousness because of loss of blood to the brain or may display fluid accumulation in the chest and abdomen. The website Heartworm Free says the dog may have diarrhea, vomiting, severe weight loss or blood in its mucus or saliva. Sudden death often occurs.