Babesiosis is a tick-borne disease that can cause serious illness in dogs.
The infection is caused by a single-celled organism (a protozoan) called Babesia. This family of parasites is widely found throughout the world, including some parts of the United States. Disease is acquired when a dog is bitten by a tick infected with Babesia.
Symptoms are most common in youngsters or naïve dogs (not previously exposed) who move into Babesia-endemic regions. Researchers believe not all dogs exposed to Babesia become sick, but a percentage encounter infection and develop immunity.
This theory could certainly account for why clinical disease tends to occur in young dogs. The older dogs were infected in their youth but developed immunity — a bit like being vaccinated.
The incubation period is approximately 10 to 20 days from being infected by the tick, after which point the dog starts showing signs of illness.
Unfortunately, once symptoms develop, the dog may become very ill very quickly. Some dogs die within 24 hours of first signs.
The symptoms are linked to Babesias’s nasty habit of multiplying inside the host’s red blood cells. When the dog’s immune system recognizes that there are invaders in the bloodstream, it sets about protecting the dog to the best of its ability, which means attacking and destroying the body’s own blood cells, causing a serious anemia that makes the dog increasingly weak and lacking in energy and appetite.
The blood thins while more cells are destroyed, and circulation to major organs suffers. The heart races as it attempts to compensate by working harder. The reduced blood flow to organs can cause complications, such as kidney failure, and another complication is fluid accumulation in the belly. Other signs include:
- Pale gums
- Jaundice (yellow-colored gums and whites of the eyes)
- Heavy breathing
The Babesia parasite sets up home in a dog’s red blood cells to reproduce. Not only does this damage the red blood cells but also it triggers the body to recognize that these cells are altered or alien, and the immune system sets about destroying them.
This creates problems because the dog becomes profoundly anemic and has the waste products of red blood cell destruction sloshing around in his circulation. This triggers a series of micro-blood clots that cause organ damage such as kidney failure.
A general blood test will give strong hints that red blood cell damage is taking place.
The veterinarian then must work out if this is caused by a condition called autoimmune hemolytic anemia (which requires steroids to treat it) or Babesia (which needs a different treatment). A blood test looking for serological (the body producing antibodies against Babesia) evidence helps differentiate the two.
A collapsed dog may well need aggressive intravenous fluids or even a blood transfusion to protect his organ function and save his life.
Unfortunately, there is no licensed treatment of babesiosis in the dog, although therapies do exist. The best option is a drug called imidocarb given by intramuscular injection. It has potential side effects such as diarrhea, heavy salivation and depression.
Any dog living in an area where ticks are common should be regularly treated with a tick-killing product.
The good news is that the tick needs to feed for around 3 days before infection is transmitted, so there is plenty of opportunity to remove the ticks, and daily tick checks of your pet should be part of your regular routine.
- “Polysystemic protozoal infections.” Nelson & Couto. Small Animal Internal Medicine. 3rd edition. Publisher: Mosby. 1300–1301.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 2, 2015.