Heartworm disease is a serious and potentially fatal condition caused by parasitic worms (Dirofilaria immitis) living in the heart, lungs, and associated blood vessels. It causes heart failure, lung disease, and organ damage.
This condition requires veterinary attention.
If your animal shows the Key or Common signs listed, please visit a clinic immediately. This is a life-threatening emergency.
Report Case / Get HelpTransmitted ONLY by mosquitoes. Microfilariae (baby worms) in an infected dog's blood are eaten by a mosquito, mature, and are injected into a new dog.
Class 1: No symptoms. Class 2: Mild cough/fatigue. Class 3: Weight loss, severe cough, heart failure (ascites). Class 4 ("Caval Syndrome"): Worm mass blocks blood flow—fatal without surgery.
Antigen blood test (SNAP) detects adult female worms. Microfilaria test checks for baby worms. X-rays and Echo assess heart damage.
Treatment involves a strict protocol: Doxycycline (to kill symbiotic bacteria), followed by injections of Melarsomine (Immiticide) to kill adult worms. STRICT cage rest is mandatory to prevent dead worms from causing embolisms.
Monthly prevention (oral/topical) or 6/12-month injections are nearly 100% effective and essential year-round.
Good for Class 1-2. Guarded for Class 3. Poor for Caval Syndrome. Lung damage can be permanent.
Medical DisclaimerThis information is for education only and does not replace examination, diagnosis, or treatment by a qualified veterinarian.