Lucy’s Case: Lyme Disease or Leptospirosis?

ArticleDecember 20236 min readSponsored
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Lucy, a 4-year-old spayed female goldendoodle, was presented with a 2-day history of anorexia, vomiting, and lethargy. She lived in Ohio and enjoyed walking with her family in their suburban neighborhood and visiting the dog park.

Records showed that Lucy was up to date on rabies and DA2PP (distemper, adenovirus [type-2], parainfluenza, and parvovirus) vaccination but had not received any other vaccinations. The owner said she regularly received flea and tick prevention, but her records showed it had been 6 months since prevention was purchased.

On physical examination, her temperature was 104.2°F (40.1°C) and BCS was 3/9, with recent weight loss and mild muscle loss over the epaxial muscles. The owner approved initial in-house laboratory testing, including a CBC, serum chemistry profile with electrolytes, and urinalysis. Results showed mild nonregenerative anemia, thrombocytopenia, stress leukogram, azotemia, hypoalbuminemia, and dilute urine (USG, 1.015) with 2+ protein.

Differential Diagnoses

Given her clinical signs, physical examination findings, and initial diagnostics, in conjunction with her lack of vaccination against Lyme disease and leptospirosis, these 2 infectious diseases were high on the differential diagnosis list. Other differentials included chronic kidney disease, pyelonephritis, and Addison’s disease.

Lyme Disease

Lyme disease is caused by the spirochete Borrelia burgdorferi, which is most commonly transmitted through the Ixodes scapularis and Ixodes pacificus ticks in North America.1 Although many infected dogs are asymptomatic, 2 clinical manifestations have been documented: Lyme arthritis and Lyme nephritis.1,2 Patients with Lyme nephritis may be presented with acute or chronic renal failure, hypertension, protein-losing nephropathy, and vasculitis.2 Unfortunately, a definitive diagnosis often cannot be achieved, so diagnosis is based on exclusion of other causes of protein-losing nephropathy in a seropositive dog.1


Leptospirosis is also caused by a spirochete. These organisms are found in soil or water that has been contaminated by the urine of infected animals, including both domestic and wildlife.3 The disease can cause renal failure, hepatic failure, vasculitis, and pulmonary hemorrhage.3 The gold standard for diagnosis is paired titers (via microagglutination testing [MAT]), first performed on acute presentation and repeated in 7 to 14 days3; however, specialized laboratories are often needed to perform this test, leading to delayed results, and MAT results are typically negative during the first week of the disease process. Because titers may be negative early in the course of disease, other tests such as PCR or ELISA can be utilized.3

Additional Diagnostics for Lucy

Urine culture revealed no growth, urine protein:creatinine ratio confirmed proteinuria, and cortisol level was >2.0 µg/dL. A SNAP 4Dx Plus test was positive for B burgdorferi, which is indicative of exposure but does not indicate that the organism is responsible for clinical signs.1 Lucy’s leptospirosis testing was performed with an in-clinic SNAP test and was positive.4 Vaccine interference can occur with leptospirosis SNAP testing, but because Lucy was unvaccinated, that was not a concern. For patients with a positive SNAP test and history of recent vaccination against leptospirosis, additional diagnostics would be recommended. For Lucy, PCR was performed on blood and urine, and initial leptospirosis MAT titers were performed on serology.

Given the initial results of diagnostic testing, both Lyme nephritis and leptospirosis remained on the differential diagnosis list, and appropriate antimicrobial therapy for both diseases was initiated, along with hospitalization for IV fluids and supportive care. Isolation and hygiene protocols were maintained while Lucy was in the hospital to protect against the zoonotic risk for leptospirosis. Lucy’s family was given a guarded prognosis pending response to treatment. Lucy’s family had another dog at home and they inquired about vaccination and what steps they could take to reduce the risk for illness to their pets.

Prevention Strategies for Leptospirosis & Lyme Disease

The risk for both Lyme disease and leptospirosis can be greatly reduced through vaccination. Vaccination against these diseases not only decreases patient risk for morbidity and mortality but also protects human family members from the zoonotic potential of leptospirosis, which is considered endemic in much of North America and has a growing incidence in dogs.5,6 Lyme disease has historically been thought to be restricted to New England, but there is excellent evidence distribution is expanding and growing into areas not historically considered Lyme-endemic.7

With the expanding presence of both diseases throughout the United States, each patient should be carefully evaluated to determine if vaccination is recommended. The 2022 AAHA guidelines recommend that dogs that live in or may travel to emerging or Lyme-endemic territories be vaccinated against Lyme disease.6 The 2023 ACVIM Leptospirosis Consensus Statement advises for all dogs in North America to be vaccinated against leptospirosis beginning at 12 weeks of age, citing concerns for potential zoonosis, the severe and potentially fatal consequences despite treatment, and the fact that exposure can occur regardless of age, geography, or lifestyle.3

Elanco's vaccine portfolio is the only one to offer vaccination against Lyme disease in combination with leptospirosis and other core diseases in a single injection. These combination products mean fewer needle sticks, increased patient comfort, decreased stress, and less risk for vaccine-associated adverse events, which can increase with the number of injections at a single time.8 In one retrospective study, the risk for vaccine-associated adverse events in large dogs (22-99 lb) increased by 11.5% with each additional injection,8 and the risk for small dogs (<22 lb) increased by 27.3% with each additional injection.8

Additional protection from Lyme disease should include tick prevention that prevents attachment and/or kills rapidly.1 Unfortunately, although most veterinarians recommend year-round prevention, only 13% of clients purchase it.9 Based on the analysis of purchasing data from 6 veterinary clinics, dogs only received protection for 6.1 months out of a 12-month period.9 This compliance gap makes vaccination even more important for protection against Lyme disease.


Lucy had a good clinical response to antimicrobial treatment and supportive care, and MAT titers 14 days later showed a 5-fold elevation, raising suspicion for leptospirosis infection. Fortunately, no one else in Lucy’s household developed signs of leptospirosis and Lucy made a full recovery. The owner returned with their dogs to seek vaccination with the TruCan™ Lyme-L4 vaccine, eager to reduce the risk for infectious diseases through the power of safe and effective vaccination.


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