There is still debate within the veterinary community as to what constitutes a definitive diagnosis of canine Borreliosis. This is because of the subjectivity of criteria used in defining the naturally occurring disease. Diagnosis should be based on history, clinical signs, elimination of other diagnoses, laboratory data, epidemiologic considerations, and response to antibiotic therapy.

Clinical laboratory findings are non-specific for canine Borreliosis. Abnormalities present on blood and urine tests may include:

An inflammatory leucogram (elevations in white blood cells)
Renal azotaemia (kidney failure)
Hypoalbuminaemia (decreased levels of albumin in the blood)
Proteinuria (protein present in the urine)
An inflammatory urine sediment (evidence of kidney inflammation)
Joint fluid changes include an increase in cell counts that consist primarily of a neutrophilic response.