FrançaisWhat a positive test means
Antibody tests show that the immune system has met the organism. Antibodies to Lyme proteins such as C6 indicate natural exposure, because these proteins are not in the vaccines [1]. But most Borrelia-positive dogs show no signs of illness [1], and a positive Ehrlichia or Anaplasma result can reflect a past infection, with antibodies persisting for months or years [2].
The ACVIM panel does not routinely recommend treating Lyme-positive dogs that have no signs and no protein in the urine; it recommends checking the urine for protein instead [1].
The three infections at a glance
| Infection | Typical signs | Typical blood and urine findings |
|---|---|---|
| Lyme disease (Borrelia) | Sudden lameness with swollen joints, fever, lethargy; responds to antibiotics within days [1]. | Rarely, protein loss through the kidneys (Lyme nephritis): proteinuria is found in fewer than 2% of positive dogs [1]. |
| Anaplasmosis (Anaplasma) | Fever, lethargy, lameness; most infected dogs probably stay healthy [2]. | Low platelets, mild anaemia, low lymphocytes, high globulins, low albumin, high ALP [3, 4]. |
| Ehrlichiosis (Ehrlichia canis) | Fever, pale gums, nosebleeds, bruising; can become chronic [2]. | Low platelets, low white cells, anaemia; later high globulins and protein in the urine [2, 3]. |
Low platelets: the key clue
The most common finding in ehrlichiosis and anaplasmosis is a low platelet count, which should alert vets to these infections [2]. In anaplasmosis, platelets usually return to normal about a week after treatment starts [2]. See low platelets in dogs.
In ehrlichiosis, very low white cell or red cell counts carry a poorer outlook; a pancytopenia (all cell lines low) in the chronic phase is a bad sign [2, 3].
How to read the platelet line in a tick-exposed dog
Here is an example from a dog with fever and a positive Anaplasma test.
- Abbreviation PLT or platelets.
- Result 48 × 10³/µL in this illustrative line: markedly low.
- Unit 10³/µL, 10⁹/L or G/L: the same number in all three.
- Laboratory interval The dog interval of the Merck Veterinary Manual.
- Flag L: below the interval. With fever and a positive test, it supports active infection; a smear first excludes platelet clumps [2].
Confirming an active infection
- PCR detects the organism’s DNA in blood and supports an active infection; Sainz et al. recommend it to back up a positive antibody test [2].
- Paired antibody tests 2 to 4 weeks apart: a fourfold rise suggests a current infection. Early in the disease, dogs can still test negative [2, 3].
- Blood smear: Anaplasma can be seen inside neutrophils in up to 60% of clinical cases, Ehrlichia much less often [2].
- Urine protein (UPC) for Lyme-positive dogs, at least 2 to 3 times a year in North America [1]. See protein in urine.
Related articles
En français : les maladies transmises par les tiques chez le chien.
Questions to ask your veterinarian
- Which infection is my dog positive for, and does it mean exposure or disease?
- Are the platelets, red and white cells normal?
- Should we check the urine for protein?
- Is a PCR or a repeat antibody test needed?
- Which tick prevention do you recommend for my dog’s lifestyle?
Get your dog’s blood count and tests explained together.
AI DiagAnimals reads the platelets, red and white cells, proteins and urine together with your laboratory’s intervals, and prepares the questions for your vet. The service opens soon: leave your email to be told first.
Frequently asked questions
Can a dog recover from anaplasmosis?
Yes. In a study of 18 dogs with confirmed anaplasmosis, all recovered with antibiotic treatment [4].
How long will a dog test positive for Anaplasma?
Antibodies can persist for months to years after infection, so a positive test does not always mean active disease [2].
Is Anaplasma worse than Lyme?
They differ: most Lyme-positive dogs never get sick, and most Anaplasma infections are acute and respond well to treatment. Signs and blood work matter more than the test alone [1, 2].
Can humans catch anaplasmosis from dogs?
Not directly from the dog: people are infected by tick bites. A positive dog shows that ticks in the area carry the infection [3].
Should a healthy dog with a positive Lyme test be treated?
Most panel members of the ACVIM consensus do not routinely treat Lyme-positive dogs without signs or proteinuria; they monitor the urine instead [1].
Sources
- Littman MP et al. ACVIM consensus update on Lyme borreliosis in dogs and cats. J Vet Intern Med. 2018;32(3):887-903. doi.org/10.1111/jvim.15085
- 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
- ESCCAP. Guideline 05: Control of vector-borne diseases in dogs and cats, 5th edition, 2024. esccap.org/guidelines/gl5
- Kohn B et al. Clinical features of canine granulocytic anaplasmosis in 18 naturally infected dogs. J Vet Intern Med. 2008;22(6):1289-1295. doi.org/10.1111/j.1939-1676.2008.0180.x
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.