Recently, the American Animal Hospital Association (AAHA) designated leptospirosis vaccination to be a “core” vaccination in dogs. That means it’s recommended for all dogs. I’ve had a lot of veterinarians asking questions about this, since traditionally leptospirosis vaccination has been positioned as “optional” based on an individual dog’s risk of exposure.

I’ve considered this vaccine to be a core for dogs in much of North America for years. Lepto is a very nasty (and sometimes fatal) disease with a safe and effective vaccine, so a large percentage of the dog population would benefit from vaccination. I’ve been adamant I want all dogs around here (in southern Ontario) vaccinated.

But is it necessary for all dogs everywhere? That’s a tougher question, because the risk of exposure to lepto varies regionally:

• In some areas, it’s a major issue.
• In some areas, it’s uncommon but there’s an ever-present low risk of exposure.
• In some area, it’s largely (or completely) non-existent.

As is unfortunately still typical with many veterinary guidelines (we’re working on improving that ), they didn’t describe any clear evidence basis, evidence synthesis and formal guideline development process that lead to this change. Making lepto a core vaccine for dogs is consistent with the recently updated ACVIM consensus statement on leptospirosis in dogs, but even that statement similarly lacks formal evidence synthesis and clear differentiation of what’s based on hard evidence and what’s based on expert opinion.

Overall, this is a well-meaning change that works for dogs in most areas and could be very useful to help drive better vaccine coverage in higher risk areas. But we still have to acknowledge that variability in risk and the fact that lepto is rare in some areas, where the cost-benefit for vaccination may not add up the same way.

Here are my take home messages on lepto vaccination for dogs:

• Dogs in areas where lepto is endemic: Core vaccine for all dogs.
• Dogs that might travel to areas where lepto is endemic: Core vaccine for all dogs.
• Dogs in areas where there is enough information to confidently say lepto is rare (to non-existent): Non-core vaccine, but consider vaccinating based on the individual dog.
• If there’s any doubt about the risk of exposure, vaccinate.

We don’t want to leave at-risk dogs unprotected, but at the same time, I’m wary of suggesting to veterinarians and dog owners that everyone needs to follow this change. Veterinarians have concerns about liability if they don’t recommend vaccination, even in areas where they’ve never seen a dog with lepto in decades. We should use guidelines to guide us, not tie our hands. Well-developed guidelines are important and useful, but they will never cover every situation, and are not meant to be blindly followed 100% of the time (and I write that as someone who is extensively involved in guideline development).

People in areas where the lepto risk is truly low shouldn’t feel bound to vaccinate their dogs. It’s something to consider and discuss, but not mandate.