How do you explain vaccine benefits and safety to owners who are worried?
Sykes: Tell stories. Explain that the vaccines have changed and they appear to be as safe as the distemper, hepatitis, and parvo vaccines. Share that most of the dogs we see with leptospirosis are unvaccinated or improperly vaccinated. Point out that leptospirosis can be fatal and that treatment costs can run into the thousands of dollars and the dog might not survive. If an owner declines vaccination document that decision in the medical record.
When should a GP test for leptospirosis?
Sykes: Test dogs with consistent clinical signs, especially when there is evidence of acute kidney injury after 24 to 48 hours of illness. Early on leptospirosis can be a nonspecific febrile illness. We often see evidence of acute kidney injury after the first day or two. While leptospirosis can also cause liver disease those findings usually occur alongside kidney injury. Also consider vaccination history. Dogs that are properly vaccinated are much less likely to have leptospirosis and prior vaccination can interfere with antibody-based testing.
If you have a suspected case in clinic what is your workflow?
Sykes: We do handling precautions rather than full isolation. For the first 48 hours of antibiotic therapy the risk of transmission is highest. During that period wear water impermeable gowns, gloves, and facial protection and handle urine and excreta carefully. Take a dog outside to urinate on a gurney or similar to avoid contamination of hospital surfaces. Inside the clinic if urine is spilled use any effective disinfectant according to label instructions. We do not need to use extreme chemicals or bleach routinely. Pregnant staff should not handle suspect cases. After the first 48 hours of appropriate antibiotics the risk of transmission becomes extremely low and handling precautions can be lifted while still using good judgement.
Practical lepto takeaways
- Vaccinate all dogs annually for leptospirosis when following the current consensus guidance.
- Test dogs with compatible signs and evidence of acute kidney injury, especially after 24 to 48 hours of illness.
- Use handling precautions for the first 48 hours of antibiotic therapy. Wear impermeable gowns, gloves, and face protection when handling urine or excreta. Pregnant staff should avoid direct handling.
- Use PCR on blood and urine early when available. Interpret point of care antibody tests in context of timing and vaccination status. Consider repeating antibody testing in one week for seroconversion.
How have diagnostics changed and how should clinicians use point of care tests?
Sykes: We now have point of care antibody assays in the US such as the IDEXX SNAP Lepto and the Zoetis Witness Lepto rapid test. The IDEXX test detects IgG and IgM antibodies. The Witness test detects IgM only. Both are antibody tests so in the first week of illness they can be negative because antibody response takes time. If you get a negative point of care result do not rule out leptospirosis. Retest in a week and you may see seroconversion. Also, antibody tests can be positive from past vaccination or subclinical exposure. In surveys of healthy dogs, 10% or more can be antibody positive. An IgM based test like Witness is less likely to be positive from past exposure and in a sick dog with compatible clinical signs and acute kidney injury a positive IgM rapid test is strongly supportive of leptospirosis.
What about PCR and MAT testing?
Sykes: We have increased use of PCR on blood and urine. In our Los Angeles outbreak work many dogs were PCR positive in blood or urine and combining both sample types detected nearly all cases. The microscopic agglutination test or MAT remains the serologic gold standard, but it is labor intensive and often performed retrospectively by reference labs. MAT requires acute and convalescent samples and interpretation can be delayed by batching. Use PCR early in illness on blood and urine and interpret antibody tests with vaccination and timing in mind.
Do you have a soapbox or a final strong opinion on this topic?
Sykes: I have advocated for vaccinating every dog because leptospirosis causes very severe disease in dogs and we see cases that require dialysis. Treatment costs can run into the tens of thousands of dollars. I remain determined to prevent this disease with vaccination.
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