DOGS · Condition guide
Heartworm disease in dogs: what real veterinary cases show
Heartworm disease in dogs is caused by a parasitic worm called Dirofilaria immitis, which is transmitted through mosquito bites. The worms live in the heart, lungs, and associated blood vessels, causing severe lung disease, heart failure, and damage to other organs. It is a common condition in areas with high mosquito populations.
Owners typically notice symptoms such as a persistent cough, reluctance to exercise, fatigue after moderate activity, decreased appetite, and weight loss. Early detection is crucial as it can prevent the progression to more severe disease, which can be life-threatening.
What vets typically check for
- Perform a blood test to detect heartworm proteins (antigens).
- Conduct a microfilariae test to identify immature heartworms in the bloodstream.
- Use chest radiographs to assess the condition of the heart and lungs.
- Perform an echocardiogram to evaluate heart function and detect adult worms.
- Initiate treatment with a series of injections to kill adult heartworms, followed by a course of antibiotics and anti-inflammatory medications.
Not a replacement for veterinary care. Use this to walk into the conversation prepared, not to self-diagnose.
Real cases from the veterinary literature
Peer-reviewed reports our semantic search surfaces for Canine heartworm disease (dirofilariasis). Click into any case for the full abstract — or run a personalised search with your pet's exact details.
- Canine heartworm disease in Porto Velho: first record, distribution map and occurrence of positive mosquitoes
Revista Brasileira de Parasitologia Veterinária · BR
A study found that 12.8% of dogs in Porto Velho, Brazil, tested positive for heartworm disease, which can cause serious health issues. Blood samples from 727 dogs were analyzed, and the most effective tests were immunochromatography and PCR, which detected the disease better than traditional methods. Most of the infected dogs were born in the area, indicating local transmission
- Effects of Oral Macrocyclic Lactone Heartworm Preventatives on Retinal Function and Chromatic Pupillary Light Reflex in Healthy Companion Dogs.
Veterinary ophthalmology · 2026 · United States
A study looked at whether oral heartworm preventatives affected the eyesight of healthy dogs. Researchers tested the retinal function and pupil response in 85 dogs before and after giving them the medication. They found no significant changes in how well the dogs' eyes responded to light or their overall retinal function after taking the heartworm preventatives. This suggests t
- Serological and molecular detection of Dirofilaria immitis in pet dogs of Lahore, Pakistan.
Annals of parasitology · 2026
A group of pet dogs in Lahore, Pakistan, was tested for heartworm disease caused by a parasite called Dirofilaria immitis. The researchers used various methods, including blood tests and imaging, to detect the infection. They found that about 10% of the dogs had heartworms, and some diagnostic techniques were more effective than others. This study highlights the importance of e
- American Association of Veterinary Parasitologists Hookworm Task Force review on best practices for diagnosis and treatment of multidrug-resistant hookworms.
Journal of the American Veterinary Medical Association · 2026
A dog with hookworms may show signs like anemia, weight loss, or bloody diarrhea. Recently, many cases of drug-resistant hookworms have been reported in dogs across the U.S. and Canada, meaning common treatments may not work as effectively. This issue started in Greyhound breeding farms but is now affecting dogs of all breeds and sizes. Veterinarians are now focusing on better
- Hypercalcemia as the primary finding in the first autochthonous(French heartworm) case in a dog from mainland Canada.
The Canadian veterinary journal = La revue veterinaire canadienne · 2026
An 8-month-old male Labrador retriever from New Brunswick was brought to the vet because he had high calcium levels, was drinking and urinating a lot, and was leaking urine. X-rays showed some unusual patterns in his lungs, but he didn't have any breathing problems. Tests revealed he had a rare heartworm infection, which is the first confirmed case in a dog in mainland Canada.
- Relative accuracy of point-of-care tests to rule-in heartworm infection in clinically suspected dogs using Bayesian latent class modelling.
Preventive veterinary medicine · 2026 · Australia
A group of dogs in Western Fiji showing signs of heartworm infection were tested using different diagnostic methods to see which was most effective. The modified Knott's test and several antigen tests, including the Anigen Rapid and SNAP tests, were evaluated for their ability to confirm heartworm infection. Results showed that the Anigen Rapid and SNAP tests provided the stron
Frequently asked questions
- How did my dog get heartworms?
- Heartworms are transmitted to dogs through the bite of an infected mosquito. The larvae enter the dog's bloodstream and mature into adult worms over several months.
- Can heartworm disease be prevented?
- Yes, heartworm disease is preventable with regular use of heartworm preventive medications, which are available in various forms such as tablets, topical treatments, and injections.
- What are the risks of not treating heartworm?
- Without treatment, heartworm disease can lead to severe lung disease, heart failure, and damage to other organs. It can be fatal if left untreated.