Understanding Ehrlichiosis in Dogs
Ehrlichiosis is a serious tick-borne illness that affects dogs worldwide. The primary culprit is the bacterium Ehrlichia canis, but other species like E. ewingii, E. chaffeensis, and E. muris eauclairensis can also infect dogs—and occasionally humans. This disease is most commonly spread by the bite of an infected brown dog tick (Rhipicephalus sanguineus), though other ticks such as the lone star, black-legged, and American dog ticks may also transmit it depending on where you live.
How Dogs Get Infected
When a tick feeds on an infected animal (like a dog or fox) and later bites another dog, it transfers the bacteria through its saliva. Transmission can happen quickly—sometimes within just three to six hours after a tick latches on. Rarely, blood transfusions from infected dogs can also spread ehrlichiosis.
Where Is Ehrlichiosis Most Common?
This disease thrives in tropical and sub-tropical regions but shows up around the globe. In North America, it's well established in the southeastern and southwestern United States, and it's even emerging in places like northern Australia. Dogs living or traveling in areas with lots of ticks face higher risks—especially if they're not protected by effective tick control measures.
The Three Phases of Disease
- Acute Phase: This phase usually starts one to three weeks after exposure and lasts two to four weeks. Dogs may have fever, lethargy, loss of appetite, enlarged lymph nodes, weight loss, nasal or eye discharge, lameness, or abnormal bleeding (like nosebleeds or bruising). Swollen limbs or neurological signs (such as loss of balance) sometimes appear. Blood tests often reveal low platelet counts (thrombocytopenia) and mild anemia.
- Subclinical Phase: Here, the bacteria linger without obvious symptoms. Dogs might seem perfectly healthy but could show low platelets or mild lab changes. This phase can drag on for months or years; some dogs clear the infection themselves while others become long-term carriers or progress to chronic illness.
- Chronic Phase: Symptoms here are usually more severe: significant weight loss, weakness, pale gums, severe anemia, eye problems, bleeding disorders, neurological issues, kidney failure, and increased vulnerability to other infections. Some dogs develop pancytopenia (low counts of all blood cells) due to bone marrow suppression—this form can be fatal without treatment.
Diagnosing Ehrlichiosis
Your veterinarian will look at clinical signs alongside your dog's history of tick exposure and results from laboratory tests. Bloodwork often shows anemia and low platelets; sometimes white blood cell counts are off too. Diagnosis is confirmed with antibody tests (serology)—though these may miss early cases—and PCR testing for Ehrlichia DNA. Occasionally the bacteria are visible on a blood smear.
Treatment Options
Treating ehrlichiosis typically involves four weeks of antibiotics—most often doxycycline or minocycline. Other options include chloramphenicol or imidocarb dipropionate if needed. Severely affected dogs may require corticosteroids or even blood transfusions for serious anemia. The prognosis is excellent when treatment starts early during the acute phase; chronic cases with bone marrow involvement may not respond as well.
If a dog appears healthy but tests positive during the subclinical phase, treatment isn't always necessary—overusing antibiotics can promote resistance—so it's best to follow your vet's advice closely.
No Vaccine: Prevention Is Key
No vaccine exists for canine ehrlichiosis yet. That means prevention relies entirely on keeping ticks off your dog:
- Use veterinary-approved tick collars.
- Apply topical treatments or oral preventatives regularly.
- Manage your yard to reduce tick habitats.
Avoid taking pets into known tick-infested areas when possible—and check your dog daily after outdoor adventures for attached ticks. Early removal matters since it lowers transmission risk significantly.
Ehrlichiosis Isn't Directly Contagious
The disease doesn't jump directly from dog to dog—or from dogs to humans—but infected pets can bring disease-carrying ticks into your home environment. Human cases stem from different Ehrlichia species transmitted by ticks—not through direct contact with sick dogs.
Certain Dogs Are More Vulnerable
- Some breeds (like German Shepherds and Siberian Huskies) are more prone to severe forms of ehrlichiosis.
- Any dog exposed to infected ticks can get sick regardless of breed or age.
If you live in an area where ticks are common—or travel there—it pays to screen your pet regularly for tick-borne diseases so you catch problems early.
The Importance of Prompt Care
If your dog shows signs such as fever, lethargy, unexplained bruising or bleeding after possible tick exposure, don't wait: seek veterinary care right away. Following prescribed medication regimens fully—and maintaining ongoing tick prevention—gives your pet the best chance at recovery while helping prevent further spread among animals (and people) nearby.
