Ehrlichiosis in dogs is a tick-borne bacterial disease that can progress from flu-like symptoms to life-threatening bone marrow suppression. Early treatment with doxycycline is highly effective, but delayed treatment allows the bacteria to establish a chronic phase that is much harder to eliminate.
Last reviewed: June 2026
What Is Ehrlichiosis in Dogs?
Ehrlichiosis is caused by rickettsial bacteria — primarily Ehrlichia canis (transmitted by the brown dog tick, Rhipicephalus sanguineus) and Ehrlichia ewingii (transmitted by the lone star tick). The bacteria infect white blood cells (monocytes or granulocytes), causing immune dysfunction and blood cell destruction. As described in Greene's Infectious Diseases of the Dog and Cat, ehrlichiosis has three phases: acute (1–3 weeks post-infection), subclinical (months to years of apparent normalcy with persistent infection), and chronic (severe bone marrow failure). German Shepherds are notably over-represented in severe/chronic cases, possibly due to a genetic predisposition. AAHA Canine Vaccination Guidelines, 2022 recommend tick control as a key preventive strategy because no vaccine exists for Ehrlichia.
Signs of Ehrlichiosis in Dogs
Acute phase (weeks 1–3 after tick bite):
- Fever (103–106°F)
- Lethargy and loss of appetite
- Enlarged lymph nodes
- Runny nose and eye discharge
- Bruising or petechial hemorrhages (tiny red/purple spots on skin or gums)
- Low platelet count causing bleeding tendency
Chronic phase (months to years later if untreated):
- Severe weight loss and muscle wasting
- Spontaneous bleeding — nosebleeds, blood in urine or stool
- Pale gums from anemia
- Neurological signs (seizures, ataxia, meningitis)
- Eye inflammation (uveitis)
- Kidney failure in some cases
Approximately 60% of dogs with acute ehrlichiosis show thrombocytopenia (low platelets) as a hallmark finding, as documented in the 5-Minute Veterinary Consult (Tilley). The chronic phase, if reached, carries a mortality rate of 20–40% even with treatment.
Diagnosis and Treatment
Diagnosis uses combination serology (4Dx or similar tick panel), PCB (polymerase chain reaction) blood test, and CBC showing characteristic cytopenias. Doxycycline (5–10 mg/kg twice daily for 28 days) is the cornerstone of treatment. Dogs treated in the acute phase typically recover within 24–48 hours of starting antibiotics. Chronic cases require longer courses, supportive care (blood transfusions, IV fluids), and immunosuppressive drugs if bone marrow suppression is severe. Response to treatment should prompt re-testing in 6 months to confirm clearance.
Treatment Costs
Tick panel plus CBC and chemistry: $200–450. Doxycycline course: $50–100. For uncomplicated acute cases, total treatment cost is commonly $300–600. Chronic or severe cases requiring hospitalization, blood transfusions, and supportive care can cost $1,500–5,000+ depending on severity and duration.
When to See a Vet
Call your vet today if:
- Dog has unexplained fever and lethargy following known tick exposure
- You notice bruising or small red spots on gums or skin
- Dog has had a tick attached for more than 24 hours AND becomes unwell
Go to the ER immediately if:
- Spontaneous nosebleed or bleeding from any orifice
- Dog collapses or has a seizure
- Gums are pale white or bluish
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Frequently Asked Questions
How do dogs get ehrlichiosis? Dogs contract ehrlichiosis through the bite of an infected tick — primarily the brown dog tick (R. sanguineus) for E. canis or the lone star tick for E. ewingii. The tick must typically feed for several hours to transmit the bacteria, so prompt tick removal reduces — but does not eliminate — risk.
Can humans get ehrlichiosis from infected dogs? Not directly from dogs. However, the same ticks that infect dogs can bite humans and transmit Ehrlichia (human monocytic ehrlichiosis, HME). Dogs in your household serve as a sentinel warning that infected ticks are present in your environment — protect yourself too.
How long does doxycycline treatment take for ehrlichiosis? A full 28-day course is required. Many dogs improve dramatically within 48–72 hours of starting treatment, but stopping early allows bacteria to persist and can lead to the chronic form. Complete the entire course even if your dog seems fully recovered.
What is the cost of treating ehrlichiosis in dogs? For uncomplicated acute cases, diagnosis plus a 28-day doxycycline course typically costs $300–600 total. Dogs that progress to the chronic phase and require hospitalization, blood transfusions, or immunosuppressive therapy can cost $1,500–5,000 or more to treat.
Can ehrlichiosis be prevented? There is no vaccine for ehrlichiosis. Prevention relies on tick control — year-round use of a veterinarian-recommended tick preventive, thorough tick checks after outdoor activity, and prompt tick removal within 24 hours. Acaricidal products that kill ticks before feeding (isoxazolines, permethrin-based spot-ons for dogs only) offer the best protection.
Still Not Sure if Your Dog Needs a Vet?
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