Babesiosis in Dogs: Symptoms and Treatment

Babesiosis in dogs is an infection caused by Babesia, a protozoal parasite that attacks red blood cells. Infection most commonly spreads through tick bites but can also occur through exposure to infected dog blood.

Babesiosis can range from mild illness to severe disease and may cause anemia, fever, pale gums, dark urine, jaundice, and other symptoms.

What Is Babesiosis in Dogs?

Babesiosis in dogs is caused by infection with Babesia, a protozoal parasite that attacks red blood cells. It is found across the world in domestic dogs and cats.

In North America, most cases of babesiosis in dogs occur in the Southern U.S. The disease is considered uncommon in healthy, spleen-intact adult dogs but is considered an emerging infection in dogs.

Veterinarians often diagnose babesiosis incidentally after pet parents bring their dogs in for sudden illness.

Because babesiosis is a tick-borne infection, infected dogs may also have other tick-borne infections, such as ehrlichiosis, Rocky Mountain spotted fever, and Lyme disease. These infections may interact with each other, making the condition more severe.

How Does Babesiosis Spread in Dogs?

The most common mode of transmission of Babesia in dogs is a tick bite. Infection can also spread through exposure to infected dog blood. Dogs with babesiosis, even those without clinical signs, can spread infection to other dogs, most commonly in kennels.

The Ornate dog tick, Brown dog tick, and American dog tick, among other tick species, have been implicated in transmitting Babesia to dogs. The tick must bite, attach, and feed on a blood meal from the dog for two to three days.

The incubation period, or time from a tick bite to when symptoms start, averages about two weeks, but symptoms may remain mild. Some cases are not diagnosed for months or even years.

Types of Babesia in Dogs

Several disease-causing species of Babesia have been identified as causing infection in dogs, including:

• Babesia canis (subspecies vogeli, canis, rossi*)*
• Babesia gibsoni
• Babesia vulpes
• Babesia conradae

Babesia organisms are usually classified as large or small.

• Babesia canis is a large blood parasite that infects dogs and is distributed worldwide.
• Babesia gibsoni is a genetically distinct small blood parasite with worldwide distribution and is considered an emerging disease in the U.S. It mostly affects Pit Bull Terriers and is the most common Babesia in North America.

Babesia gibsoni is believed to spread directly through infected blood from dog fights and bites or blood transfusions. It may also spread into a puppy's bloodstream from an infected mother dog (transplacental transmission).

Dogs at Increased Risk for Babesiosis

Specific breeds, such as Greyhounds and members of the Terrier group, have an increased risk of infection. Babesiosis is considered a serious threat to racing Greyhounds and Pit Bull Terriers.

Young dogs tend to be most severely infected.

What Are the Symptoms of Babesiosis in Dogs?

Symptoms of babesiosis in dogs can range from mild illness to severe disease and may include lethargy, lack of appetite, pale gums, fever, dark-colored urine, jaundice, weight loss, and neurologic signs.

Common signs of babesiosis in dogs include:

• Lack of energy, lethargy, or depression
• Lack of appetite
• Pale gums and other mucous membranes
• Fever
• Enlarged lymph nodes or spleen
• Abnormally dark-colored urine, usually dark red or orange
• Yellow or orange skin (jaundice)
• Enlarged or swollen abdomen
• Weight loss
• Discolored stool
• Neurologic signs, including:
  • Imbalance and/or a wobbly gait
  • Seizures
  • Neck pain

Signs of infection can vary from a mild illness that passes quickly to severe disease that rapidly results in death.

How To Check Your Dog for Ticks

Ticks are typically found near a dog's neck, head, and ears and in the creases under the legs.

Ticks are generally tiny and feel like a hard bump on your dog's skin. They are typically dark brown or black. Depending on their life stage, ticks have six legs as larvae or eight legs as nymphs and adults.

If a tick has been on your dog for a while, it may be engorged from feeding on your dog's blood and appear light brown or gray.

Dogs can still get ticks even if they are up to date on monthly flea and tick preventatives. Check your dog often if you live in an area where ticks are prevalent and after spending time in wooded areas or parks with other dogs.

What Causes Babesiosis in Dogs?

Babesiosis in dogs occurs when blood-borne parasites such as Babesia enter the bloodstream, most commonly after a tick bite. The parasite replicates in red blood cells, which can lead to anemia and jaundice.

Tick Transmission

Once a tick bites a dog, blood-borne parasites such as Babesia enter the bloodstream. A tick must feed for two to three days to infect a dog with Babesia.

The parasite replicates in red blood cells, resulting in anemia.

The infected red blood cells are broken down, and hemoglobin is released into the body. This can lead to jaundice (yellow discoloration of the skin and whites of the eyes) and anemia when the body cannot produce enough new red blood cells to replace those being destroyed.

Dogs that spend a lot of time outdoors, especially in wooded areas, are at an increased risk for tick bites and contracting this parasite.

Other Ways Babesia Can Spread

There is evidence of direct dog-to-dog transmission of Babesia under certain circumstances, including:

• An infected dog with oral lesions or abrasions bites another dog. This is particularly true for Babesia gibsoni, which primarily affects Pit Bull Terriers.
• An unborn puppy is infected in the uterus of the mother.
• A dog is unintentionally infected through a contaminated blood transfusion from another dog.
• Dogs are housed in kennel settings with poor tick control.

How Is Babesiosis in Dogs Diagnosed?

Veterinarians diagnose babesiosis in dogs using a history, physical examination, and blood and urine testing.

Additional laboratory tests, including Wright's stain, immunofluorescent antibody (IFA), enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR) testing, may be used to confirm the diagnosis.

Initial Testing

Your veterinarian will obtain a full history of symptoms, including when a tick bite might have occurred or whether your dog was involved in a dog fight.

Your veterinarian will also perform a complete physical examination and may run:

• Complete blood count
• Blood biochemical profile
• Urinalysis
• Electrolyte panel

Low blood protein levels, a decreased number of blood platelets, and anemia are often noted.

Babesiosis can be confused with other illnesses that cause fever, anemia, destruction of red blood cells, jaundice, or red urine. One or more laboratory tests may be performed to confirm the diagnosis.

Wright's Stain

Wright's stain is used on a dog's blood sample, which is then examined under a microscope. The stain helps your veterinarian differentiate blood cells and makes a blood infection more apparent by allowing the protozoa to be seen on the blood smear.

Immunofluorescent Antibody (IFA) Test

Immunofluorescent antibody (IFA) tests look for antibodies in blood serum that react with the Babesia organism.

Serum is the part of the blood left behind when all the cells are removed by high-speed spinning of a blood sample. IFA tests are limited because they cannot usually distinguish between different species and subspecies of Babesia.

Enzyme-Linked Immunosorbent Assay (ELISA)

ELISA is another blood test. A positive test result depends on an antibody response by the infected dog, which may take up to 10 days to develop.

Polymerase Chain Reaction (PCR) Test

PCR tests look for the presence of Babesia DNA in a biological sample, usually whole blood in dogs.

The PCR test has the advantage that it can detect all four species of Babesia. It is more sensitive because it does not use a microscope.

How Is Babesiosis in Dogs Treated?

Treatment for babesiosis in dogs depends on the Babesia species identified and the severity of the disease. Treatment may include imidocarb dipropionate, antibiotics, and supportive care for more severely affected dogs.

Medications for Babesiosis

The FDA-approved treatment for babesiosis is imidocarb dipropionate, an antiprotozoal drug commonly used to treat large Babesia species. It is given as an injection by a veterinarian.

In some cases, antibiotics such as azithromycin and/or clindamycin may also be recommended.

Treatment for Severe Babesiosis

More severely affected dogs may require:

• Anti-inflammatory or steroid medications
• Hospitalization
• IV fluids
• Blood transfusions
• Oxygen therapy
• Anti-nausea medications
• Other supportive care

Blood transfusions may be lifesaving in dogs with severe anemia and are commonly performed in dogs.

Recovery and Management of Babesiosis in Dogs

Recovery and management of babesiosis in dogs require veterinary follow-up to monitor treatment success and determine whether the infection persists. The prognosis is guarded and depends on which body systems are affected at the time of diagnosis.

Follow-Up After Treatment

If an imidocarb injection is used, a single dose is usually successful for eliminating Babesia canis (large organism), but two injections given two weeks apart are needed for the smaller Babesia species.

The injection is often painful and can cause muscle tremors, drooling, elevated heart rate, shivering, fever, facial swelling, tearing of the eyes, and restlessness.

Your veterinarian will monitor your dog's progress and schedule regular follow-up appointments to repeat blood work and urine testing.

Two to three consecutive negative PCR tests beginning two months after treatment should be performed to make sure treatment was successful and the infection does not persist.

Prognosis for Dogs With Babesiosis

Most cases of babesiosis are not diagnosed until the disease is fairly progressed. The prognosis for a dog diagnosed with babesiosis is guarded, depending on which body systems are affected at the time of diagnosis.

Persistent Infection and Relapse

Dogs that survive babesiosis often remain subclinically infected and may experience a relapse of the disease in the future.

Persistently infected dogs can serve as a source for further spread of the disease. Dogs that have recovered from babesiosis should never be used as blood donors because recipients may develop the disease.

How To Prevent Babesiosis in Dogs

Preventing babesiosis in dogs focuses on reducing exposure to ticks and controlling transmission through infected dog blood. Using appropriate tick-control products and removing ticks promptly can help reduce your dog's exposure to the parasite.

Use Regular Tick Prevention

Dogs should receive regular tick prevention with a collar, a topical medicine applied to the skin, or a chew or pill taken by mouth.

Products that prevent ticks include parasite preventatives such as Revolution, Bravecto, and NexGard, as well as tick collars such as Preventic and Seresto. Follow your veterinarian's advice when using these products.

Reduce Other Routes of Transmission

Prevention also centers around controlling dog-to-dog transmission through blood, such as from dog bites, mother dogs to puppies, and blood transfusions.

Reduce Ticks Around Your Home

Keep grass and brush trimmed in your yard. In areas where ticks are a considerable problem, you can also treat the yard and kennel area for ticks.