Chagas disease is spread by Triatominae bugs (kissing bugs) and can damage a dog's heart and central nervous system. Most dogs are asymptomatic, but those who develop symptoms will do so in phases. Most commonly, dogs contract Chagas disease after ingesting the feces of an infected bug or animal. A vet will diagnose and treat a dog based on the stage of its illness, and the prognosis is good for asymptomatic dogs. Still, there is a high risk of death for dogs that have reached the chronic stage of Chagas disease.
What Is Chagas Disease?
Chagas disease is a blood-borne disease by the protozoal parasite called Trypanosoma cruzi. It is spread between dogs by insects often called "kissing bugs." The disease is primarily found in Latin American countries but has been migrating north into the United States in recent years. Chagas disease can cause damage to the heart and central nervous system and can sometimes be fatal.
T. cruzi is spread by Triatominae bugs. In addition to kissing bugs, insects belonging to this subfamily are called kissing beetles, conenose bugs, assassin bugs, and vampire bugs.They often live in areas where a blood meal can be found easily. This includes kennels and bedding materials in barns.
Symptoms of Chagas Disease in Dogs
Most dogs with Chagas disease don't exhibit symptoms, but they are nonspecific, appear in phases, and sometimes resemble heart disease symptoms when they do.
The clinical signs of Chagas disease are variable and non-specific. Most infected dogs demonstrate subtle signs, such as lethargy, decreased appetite, and weight loss. You may notice symptoms like fainting, exercise intolerance, vomiting, and diarrhea in more severe cases. If your dog becomes infected by T. cruzi, there are three stages of infection with unique sets of clinical signs.
- Acute Phase: The first phase occurs within a few weeks of infection. In some cases, there may be no symptoms during the acute phase of the disease, but if your dog does exhibit symptoms during this phase, they may include lymph node enlargement, spleen enlargement, pale gums, a decreased appetite, and diarrhea. Some infected dogs may die suddenly during this phase of infection, but most will enter the latent phase.
- Latent Phase: The latent phase is typically asymptomatic and lasts one to four months. An infected dog may die suddenly during this phase, but most will enter the chronic phase.
- Chronic Phase: The final phase of infection will see T. cruzi organisms continue to replicate and migrate to internal organs, mainly targeting your dog's heart and brain tissue. This results in clinical signs including coughing, exercise intolerance, shortness of breath, heart arrhythmia, and even sudden death.
Causes of Chagas Disease
Dogs usually contract Chagas disease after ingesting infected feces, but there are additional means of contraction.
- Infected feces: Most commonly, Chagas disease is contracted when a dog ingests the feces of infected insects or infected feces enters an open wound. The feces may be accidentally ingested through a dog pawing at its eyes or mouth after contact with the feces. Insects often defecate near open wounds and enter a dog's bloodstream when the dog licks its wound.
- Bug bites: The bite of some bugs, such as the Mexican kissing beetle, can transmit T. cruzi and cause Chagas disease. The insect will infect the dog as it feeds on its blood, usually while the dog is sleeping.
- Eating infected insects: When a dog eats an infected insect and digests its blood and feces, it can contract Chagas disease.
- Blood transfusions: Although uncommon, a dog can develop Chagas disease after unknowingly receiving a blood transfusion containing infected blood.
Diagnosing Chagas Disease in Dogs
During the acute phase, T. cruzi may be found in your dog's blood or lymph nodes but typically present in such low numbers that your vet won't be able to make an accurate diagnosis. A vet can administer an antibody test, but they often result in false positives. However, in the chronic phase, Chagas disease can be diagnosed by its clinical symptoms. Your vet will ask questions about your dog's medical history and the environments it has been exposed to in recent weeks.
Most dogs that develop Chagas disease never develop symptoms, so treatment isn't always necessary. Unfortunately, for symptomatic dogs, there is no curative treatment. Once your dog reaches the chronic phase, you may palliatively manage its symptoms with heart medications and anti-inflammatories.
Prognosis for Dogs With Chagas Disease
The prognosis for dogs with Chagas disease varies based on the stage of the illness. The earlier the Chagas disease is diagnosed and addressed, the higher the chance of survival. Dogs that reach the chronic phase of Chagas disease will likely die due to heart disease, and sick dogs younger than one year old will usually die as well. Asymptomatic dogs can live their lives without any effect of the disease.
How to Prevent Chagas Disease
To prevent Chagas disease, keep your dog indoors at night, where it can sleep in clean bedding. It is essential to keep your dog from eating T. cruzi carriers, including bugs, skunks, raccoons, and opossums. If you live in an area with a high population of kissing bugs, you may also use pesticides in your yard to help control the population. Ensure that wood piles are inaccessible to your dog while outside to minimize your dog's exposure to bugs. Administering anti-kissing bug medication to your dog, such as Bravecto, Nexgard, and Trifexis can provide protection.
If you live in an area where Chagas disease is prevalent, speak to your veterinarian for more information on how to best protect your dog.
Can Humans Get It?
Although Chagas disease isn't zoonotic, it is an infection that people can get from Triatominae bugs. If your dog becomes infected with Chagas disease, it indicates the presence of T. cruzi in your environment and that you may be at risk for infection.
How do I know if my dog has Chagas disease?
Most dogs with Chagas disease are asymptomatic. If your dog has Chagas disease, you likely won't be able to tell until it is late stage, at which point, visit a vet for a definitive diagnosis.
Can my dog give me Chagas disease?
Your dog cannot pass along Chagas disease, but you can get infected by a kissing bug if it bites you. Like dogs, most humans are asymptomatic.
Will Chagas disease kill my dog?
If your dog has Chagas disease but is asymptomatic, it won't be impacted. But, If your dog is late-stage and exhibiting symptoms, fatal heart disease may develop. Visit your vet for a prognosis.
Chagas Disease in Dogs. Veterinary Medicine & Biomedical Sciences TAMU.