Understanding Ehrlichiosis in Dogs
Ehrlichiosis is a serious tick-borne disease that affects dogs worldwide, most commonly spread by the brown dog tick (Rhipicephalus sanguineus). The primary culprit is the rickettsial bacterium Ehrlichia canis, though other species like E. chaffeensis, E. ewingii, and E. muris eauclairensis can also infect dogs. Since its first recognition in Algeria in 1935 and prominence during the Vietnam War, ehrlichiosis has become a well-known threat in tropical, subtropical, and temperate regions—including the southeastern and southwestern United States, Australia, and parts of Europe.
How Dogs Get Infected
The journey starts when a dog is bitten by an infected tick. Transmission can happen within just a few hours of attachment, but the longer a tick feeds, the higher the risk. The brown dog tick primarily spreads E. canis, while other ticks like the lone star and black-legged ticks transmit different Ehrlichia species. Importantly, dogs don't pass ehrlichiosis directly to each other; however, infection can occur through blood transfusions from an infected animal.
Phases of Ehrlichiosis
The disease unfolds in three distinct phases:
- Acute Phase: Usually begins 1–3 weeks after exposure. Symptoms include fever, lethargy, loss of appetite (anorexia), weight loss, enlarged lymph nodes, respiratory distress, joint pain or lameness, spontaneous bleeding (like nosebleeds), vomiting, diarrhea, cough, and sometimes neurological signs such as unsteadiness. This stage typically lasts two to four weeks. Blood tests may show low platelets (thrombocytopenia) and mild anemia.
- Subclinical Phase: Dogs carry the organism without obvious symptoms—sometimes for months or years. Lab findings might reveal low platelets or elevated blood globulin levels. Some dogs clear the infection on their own; others progress to chronic disease.
- Chronic Phase: Here things get more severe: persistent fever, dramatic weight loss, pale gums (from anemia), bleeding disorders, neurological dysfunction (stumbling or confusion), eye problems (inflammation or bleeding), increased urination/thirst, swollen limbs, and even bone marrow failure. Chronic ehrlichiosis can be fatal and makes dogs vulnerable to secondary infections.
Certain breeds—German Shepherds, Doberman Pinschers, Belgian Malinois, Siberian Huskies—seem more prone to severe illness.
Diagnosis: How Vets Find It
Diagnosis involves piecing together clinical signs with known tick exposure and blood test results:
- Antibody testing (serology): Shows exposure but may be negative early on.
- PCR testing: Detects Ehrlichia DNA—most reliable during early infection.
- Bood smears: Rarely show Ehrlichia inside immune cells.
- Add-on tests: Complete blood counts (CBC), chemistry panels for organ function, urinalysis for kidney health.
Treatment Options
The mainstay of treatment is antibiotics—most often doxycycline or minocycline—for at least four weeks. Alternatives include chloramphenicol or imidocarb dipropionate; some cases may require minocycline or rifampicin. Severe illness might need blood transfusions and supportive care. If caught early (especially during the acute phase), prognosis is excellent; chronic or untreated cases have a much more guarded outlook.
Prevention: Keeping Dogs Safe from Ticks
Your best weapon against ehrlichiosis is proactive tick control:
- Tick preventatives: Use vet-recommended topical solutions, oral medications, or collars year-round if you live in an endemic area.
- Daily checks: After outdoor adventures—especially in tall grass or wooded areas—inspect your dog for ticks and remove them promptly using fine-tipped tweezers (grasping close to the skin and pulling straight out).
- Avoid high-risk areas: Steer clear of places known for heavy tick infestations when possible.
- No vaccine exists: So prevention relies entirely on environmental management and routine care.
Zoonotic Risk: Can People Get Ehrlichiosis from Dogs?
You can't catch ehrlichiosis directly from your dog—but infected dogs signal that disease-carrying ticks are around your home environment. Some Ehrlichia species do infect humans after a tick bite (causing fever, muscle aches, headache), but not through contact with pets themselves. Keeping pets protected helps reduce risk for everyone in the household.
Disease Emergencies & When to See a Vet Fast
If your dog suddenly bleeds (nosebleeds or blood in urine), collapses from weakness, spikes a high fever, seems confused or disoriented, breathes rapidly, shows pale gums or has seizures/swelling—get veterinary help immediately. Early intervention saves lives since symptoms can escalate quickly from mild to life-threatening complications.
Lifelong Management & Monitoring
If you live where ehrlichiosis is common—or have a breed at higher risk—regular testing helps catch silent infections before they turn severe. Good tick control habits plus prompt attention to any suspicious symptoms give your dog the best chance at staying healthy despite this challenging disease.
