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Ehrlichia in dogs: phases, blood work and test results

Ehrlichiosis is a tick-borne infection of white blood cells. It can cause a sudden illness, hide for months or years without signs, and then return as a severe chronic disease. The blood count and the protein lines often tell which phase a dog is in.

Written by the AI DiagAnimals editorial teamReviewed by the AI DiagAnimals TeamUpdated Our editorial policy

The essentials

Ehrlichia canis is carried by the brown dog tick. After 1 to 3 weeks of incubation, the disease can go through an acute, a subclinical and a chronic phase. Low platelets are the most common finding. High globulins build up over time and can even mimic a bone marrow cancer. A positive antibody test shows exposure; PCR shows an active infection. Antibodies can stay positive for months or years after treatment. The chronic form with all blood cells low has a poor outlook, and German Shepherds are hit harder.

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What ehrlichiosis is

Ehrlichia canis is a bacterium that lives inside white blood cells. It is spread by the brown dog tick, Rhipicephalus sanguineus, which can start passing it on within 3 hours of attaching and can live indoors and in kennels [1]. This article goes deeper on ehrlichiosis; for the overview of Lyme, Anaplasma and Ehrlichia, see tick-borne diseases in dogs.

In the United States, Ehrlichia ewingii, spread by the lone star tick, is the most common Ehrlichia found by antibody tests: about 5.1% of dogs in the South and Central regions, against 0.8% for E. canis. It infects other white cells (granulocytes) and usually causes a milder illness, often with fever, low platelets and joint pain [10]. The Ehrlichia spot on in-clinic tests such as the 4Dx Plus reacts to E. canis, E. chaffeensis or E. ewingii exposure, without telling them apart [10].

Incubation and the three phases

The phases are clear in experimental infections, but hard to tell apart in real dogs [1, 3].
PhaseHow longWhat the dog showsWhat the blood work shows
Incubation1 to 3 weeks [1]; 8 to 20 days in the ESCCAP guideline [2]Nothing yetAntibodies usually not before day 12 to 14, so tests can be negative [1].
Acute2 to 4 weeks [1]Fever, lethargy, poor appetite, swollen lymph nodes, nosebleeds, small bruises [1, 2]Low platelets, low white cells, mild non-regenerative anemia [2].
SubclinicalWeeks to months, sometimes years [1, 2]Looks healthyPlatelets can be mildly low; globulins high [1, 2].
ChronicOnly in some dogs [1, 3]Weight loss, bleeding, eye problems, swelling of the legs, sometimes kidney or nerve signs [2]Low platelets, white and red cells; in the severe form all three low (pancytopenia) from a failing bone marrow [1, 3].

Signs of the acute phase can fade on their own, even without treatment, but some of these dogs stay infected without signs for months or years [1]. A dog imported from an endemic area can fall ill years later: one dog went blind from chronic ehrlichiosis 36 months after arriving in the UK [12].

What the blood count, chemistry and urine show

  • Low platelets (thrombocytopenia): the most common finding, and the one that should make vets think of Ehrlichia [1]. Platelets can also work poorly (thrombocytopathy) [1]. See low platelets in dogs.
  • Anemia: usually mild to moderate and non-regenerative (the bone marrow is not responding) [1]. In 100 Israeli dogs, low platelets, anemia and low lymphocytes were the main blood count changes [5].
  • White cells: neutrophils can be low or high, lymphocytes low, monocytes high [1].
  • Pancytopenia: red cells, white cells and platelets all low, from an empty bone marrow, in 15–20% of clinical cases, mainly in the chronic form [1].
  • High globulins, low albumin: high total protein, high globulins (mainly gamma globulins) and low albumin [1, 6]. See albumin and globulin in dogs.
  • Liver enzymes: ALT and ALP can be mildly raised [1].
  • Urine: protein in the urine (proteinuria) and, in some dogs, raised kidney values [1, 2].

High globulins and the myeloma look-alike

Globulins include the antibodies. In a study of 42 infected dogs, globulins and gamma globulins were higher and albumin lower than in healthy dogs. The rise was polyclonal (many antibody types) in all dogs but one, which had a monoclonal spike [6]. Dogs with pancytopenia had lower globulins than the others, a sign of a weaker immune response [6].

A sharp single spike on protein electrophoresis usually means a plasma cell cancer such as multiple myeloma, but Ehrlichia canis is one of the infections that can produce a similar pattern, so it should be ruled out first [7, 12]. When tested more closely with immunofixation, true single-clone proteins were rare in dogs with tick-borne infections: 2 of 112 [13]. Leishmaniasis is another infection that raises globulins.

An annotated line from a lab report · Illustrative example
AbbreviationResultUnitLaboratory intervalFlag
GLOB Globulin6.1g/dL2.7–4.4H
  1. Abbreviation GLOB: globulin, usually calculated as total protein minus albumin.
  2. Result 6.1 g/dL in this illustrative line: clearly high.
  3. Unit g/dL in the US; g/L elsewhere (g/dL × 10) [7].
  4. Laboratory interval An illustrative dog interval; each laboratory sets its own.
  5. Flag H: above the interval. In a tick-exposed dog with low platelets, vets think of chronic ehrlichiosis; protein electrophoresis shows whether the rise is broad or a single spike [6, 7].

Tests: serology, PCR and smears

  • Antibody tests (IFA in the laboratory, ELISA or in-clinic rapid tests such as the 4Dx): a positive result shows exposure. A single positive can be an old infection, and Ehrlichia and Anaplasma antibodies can cross-react [1, 2].
  • Early negative results: antibodies appear 1 to 4 weeks after infection, so a dog in the acute phase can test negative [2].
  • Paired tests 2 to 4 weeks apart: a fourfold rise in titer suggests an ongoing infection [1].
  • PCR finds the bacterium’s DNA and supports an active infection; a negative PCR does not fully rule it out [1, 2]. A definitive diagnosis of infection needs molecular tests [4].
  • Blood smear: Ehrlichia canis clusters (morulae) are seen in only about 4–6% of clinical cases; buffy coat and lymph node smears do better [1].
  • Bone marrow sample: with the blood count, it helps diagnose the severe chronic form [1].

After treatment of an acute case, the blood count and protein electrophoresis usually return to normal within 10–15 days. Lasting high globulins, anemia or low platelets suggest the infection is not cleared or another disease is present [1].

Outlook and German Shepherds

Dogs treated in the acute phase usually do well [1, 3]. An unpredictable share of dogs left in the subclinical phase go on to the chronic severe form, with a failing bone marrow and high mortality [3]. In 56 dogs, pancytopenia raised the odds of death about 23-fold and low neutrophils about 8-fold [9]. In 49 dogs followed for a year, 32 survived and 17 died; severe anemia, severe leukopenia, pancytopenia, bleeding and being a German Shepherd predicted a poorer outcome [5].

German Shepherds were over-represented among sick dogs [5], and German Shepherds and Siberian Huskies tend to have more severe disease [1]. See the German Shepherd breed page. Infection does not give lasting immunity, so a dog can be infected again [1].

Related articles

Tick-borne diseases in dogs

Lyme, Anaplasma and Ehrlichia at a glance.

Read the article

Other tick-borne infections: anaplasmosis in dogs and Lyme disease in dogs.

En français : l’ehrlichiose du chien.

Questions to ask your veterinarian

  1. Is this a past exposure or an active infection: do we need a PCR or a repeat titer?
  2. Are the platelets, red cells and white cells low, and is it all three?
  3. Are the globulins high, and should we run a protein electrophoresis?
  4. Is there protein in the urine?
  5. When should we repeat the blood count, and what titer do you expect after treatment?
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Frequently asked questions

What is the incubation period for Ehrlichia?

About 1 to 3 weeks after the tick bite [1]; the ESCCAP guideline gives 8 to 20 days [2]. Antibodies usually appear only after 12 to 14 days, so early tests can be negative [1].

Does Ehrlichia ever go away in dogs?

Often the signs do, and most dogs treated in the acute phase recover. But some dogs stay infected without signs for months or years, and fully clearing the bacterium is not always possible or provable [1, 3]. When a dog no longer makes antibodies, the infection is considered cleared [1].

How long will a dog test positive for Ehrlichia?

Antibodies can last for months. In most dogs they fall over 6 to 9 months after treatment and are sometimes gone at 12 months, but some dogs stay positive for years, especially those that started with very high titers [1, 8].

Can Ehrlichia in dogs cause seizures?

Yes, but uncommonly. When the infection reaches the brain and its membranes (meningitis), it can cause seizures, a wobbly walk or neck pain [2]. Ehrlichia has been found in the spinal fluid of a dog with seizures [11].

Can a dog get ehrlichiosis again?

Yes. Infection does not leave lasting immunity, so a dog can be reinfected by new tick bites; tick protection remains the main prevention [1, 2].

Sources

  1. Sainz Á et al. Guideline for veterinary practitioners on canine ehrlichiosis and anaplasmosis in Europe. Parasit Vectors. 2015;8:75. doi.org/10.1186/s13071-015-0649-0
  2. ESCCAP. Guideline 05: Control of vector-borne diseases in dogs and cats, 5th edition, 2024. esccap.org/guidelines/gl5
  3. Mylonakis ME, Harrus S, Breitschwerdt EB. An update on the treatment of canine monocytic ehrlichiosis (Ehrlichia canis). Vet J. 2019;246:45-53. doi.org/10.1016/j.tvjl.2019.01.015
  4. Harrus S, Waner T. Diagnosis of canine monocytotropic ehrlichiosis (Ehrlichia canis): an overview. Vet J. 2011;187(3):292-296. doi.org/10.1016/j.tvjl.2010.02.001
  5. Harrus S et al. Canine monocytic ehrlichiosis: a retrospective study of 100 cases, and an epidemiological investigation of prognostic indicators for the disease. Vet Rec. 1997;141(14):360-363. doi.org/10.1136/vr.141.14.360
  6. Harrus S et al. Serum protein alterations in canine ehrlichiosis. Vet Parasitol. 1996;66(3-4):241-249. doi.org/10.1016/s0304-4017(96)01013-8
  7. eClinPath, Cornell University College of Veterinary Medicine. Globulins. eclinpath.com/chemistry/proteins/globulins
  8. Bartsch RC, Greene RT. Post-therapy antibody titers in dogs with ehrlichiosis: follow-up study on 68 patients treated primarily with tetracycline and/or doxycycline. J Vet Intern Med. 1996;10(4):271-274. doi.org/10.1111/j.1939-1676.1996.tb02061.x
  9. Mylonakis ME et al. Serum acute phase proteins as clinical phase indicators and outcome predictors in naturally occurring canine monocytic ehrlichiosis. J Vet Intern Med. 2011;25(4):811-817. doi.org/10.1111/j.1939-1676.2011.0728.x
  10. Qurollo BA et al. Clinicopathological findings in 41 dogs (2008-2018) naturally infected with Ehrlichia ewingii. J Vet Intern Med. 2019;33(2):618-629. doi.org/10.1111/jvim.15354
  11. Meinkoth JH et al. Ehrlichiosis in a dog with seizures and nonregenerative anemia. J Am Vet Med Assoc. 1989;195(12):1754-1755. pubmed.ncbi.nlm.nih.gov/2599963
  12. Gould DJ et al. Canine monocytic ehrlichiosis presenting as acute blindness 36 months after importation into the UK. J Small Anim Pract. 2000;41(6):263-265. doi.org/10.1111/j.1748-5827.2000.tb03937.x
  13. Jornet-Rius O et al. Evaluation of serum protein electrophoresis and immunofixation in dogs seropositive for various vector-borne pathogens. Vet Clin Pathol. 2024;53(4):420-430. doi.org/10.1111/vcp.13399

Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.

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