Leptospirosis vaccination recommended to be core for most dogs

In October of 2023, the American College of Veterinary Internal Medicine (ACVIM) issued an updated consensus statement on leptospirosis in dogs, recommending that the leptospirosis vaccine “should be administered annually to all dogs starting at 12 weeks of age, regardless of breed.” The consensus statement goes on to recommend that leptospirosis vaccination should be required for dogs to board or enter a daycare facility as well. 

The multidisciplinary panel appointed by the ACVIM to review the available body of knowledge cited improvements in the understanding of the disease, the widespread access to diagnostic tests and vaccines, and the continued prevalence of the infection in dogs of all sizes and breeds in both urban and rural areas as reasons why a revised consensus was needed.   

The World Small Animal Veterinary Association (WSAVA) issued a more nuanced recommendation in their 2024 Vaccine Guidelines, designating the leptospirosis vaccine as “core for dogs in regions where canine leptospirosis is endemic, implicated serogroups are known, and suitable vaccines … are commercially available.” While this statement still leaves much room for practitioner discretion, it is inclusive of more dogs than would be included with a designation as a noncore vaccine.  

How the thinking around leptospirosis has changed 

“In the 70s, the thought was that the risk [for leptospirosis infection] was mainly for hunting dogs in wet areas,” said John Ellis, DVM, PhD, DACVP, DACVM, professor of microbiology at the University of Saskatchewan and a member of the AAHA Canine Vaccine Guidelines task force. “That has definitely changed over the years.”  

He described how leptospirosis has been found in areas that are dry and high in elevation, such as Laramie, Wyoming, and Phoenix, Arizona—the opposite of the tropical or semi-tropical environment typically associated with increased risk for leptospirosis.  

Some of this apparent geographical spread of leptospirosis may be the result of improved awareness and testing for the disease, but another likely factor is the increased development of land for human use. With the building of more housing communities, more racoons and other reservoir hosts for leptospirosis have begun to inhabit new areas, raising the risk for disease spread.   

The idea that leptospirosis is limited by geography and climate is not the only one that requires revision.  

George Moore, DVM, PhD, professor of epidemiology at Purdue University and another member of the AAHA Canine Vaccine Guidelines task force, commented on the stereotype of larger dogs and dogs who swim or hunt being at increased risk. Now, he says, we are seeing leptospirosis infections in smaller breed dogs without any farm or rural background. Why? Because these dogs were not vaccinated against the disease.  

Rather than it being the breed or lifestyle of the dog, Moore said, “the real risk factor [for leptospirosis infection] is whether or not the dog is vaccinated.” This is why small breed dogs are overrepresented in cases of leptospirosis infections: they are less likely to have gotten the vaccine.  

The leptospirosis vaccine’s bad rap 

There are likely multiple reasons why pet owners and some practitioners have been more hesitant to administer the leptospirosis vaccine routinely to all canine patients, and chief among them has been the concern for a higher risk of vaccine reactions in comparison to other vaccines. But that may not be such a concern any longer. 

Both Ellis and Moore noted that, due to improvements in the manufacturing processes used to produce the vaccines and additional studies quantifying the rates of vaccine reactions, the leptospirosis vaccine does not appear to be associated with an increased risk of vaccine reactions compared to other vaccines.  

Additionally, the belief that leptospirosis was solely a disease affecting large breed hunting dogs in wet, rural areas and dogs that swim in standing water has undoubtedly contributed to a lack urgency in the minds of many practitioners to vaccinate for the disease. When clients request to only administer the “necessary” vaccines, veterinary teams may not push very hard for the leptospirosis vaccine. Due in part to its previous designation as a noncore vaccine, it has not typically been required by boarding facilities, daycares, and other similar facilities either. 

Plus, a general trend of vaccine hesitancy among pet owners is also partly to blame. “More than 50% of dog owners don’t think their dogs should be vaccinated at all,” Ellis said, “even for rabies.”  

The COVID-19 pandemic didn’t help matters, he added. Since the general public doesn’t always have an accurate understanding of how vaccines work, there can be a tendency to lose faith in vaccines when some vaccinated individuals still contract the disease and show clinical signs. This distrust in vaccine efficacy against human diseases often translates over to feelings of skepticism toward vaccines for pets.  

Using the leptospirosis vaccine  

Even though the leptospirosis vaccine is categorized as noncore by the 2022 AAHA Canine Vaccination Guidelines, it still is likely indicated for most dogs in the United States. “Because of the increasing prevalence of leptospirosis, this vaccine may be considered core for areas where the disease is present,” explained Ingrid Taylor, DVM, director of guidelines at AAHA. “According to the Guidelines, dogs should receive leptospirosis vaccinations if they spend any time outdoors (including in rural, urban, and suburban environments), spend time in kennels and/or dog daycares, and/or have potential exposure to wildlife reservoirs.” 

Moore stressed that leptospirosis is endemic in the United States. Since we know the serovars of the disease that are most likely to infect dogs in this country and we have good multivalent vaccines that carry a very low risk of reactions, there is little argument in his mind against routine use of the vaccine. 

Besides, said Moore, “It’s a zoonotic disease.” For the health and safety of both humans and dogs, both he and Ellis recommend the routine administration of the leptospirosis vaccine in all dogs regardless of their size, breed, geographical location, or lifestyle.  

Specifically, Moore recommends giving two doses of the vaccine to puppies starting at 12 weeks of age, which would typically align with the final two puppy vaccine visits. Regarding the practice of routinely “splitting” vaccines or giving the leptospirosis vaccine separately from other vaccines to reduce the risk of a reaction, Moore and Ellis believe that, most of the time, this is not necessary or helpful. One of the main concerns around separating vaccines out into multiple appointments is that the client may not return as directed and the patient will be incompletely vaccinated as a result.  There are exceptions, though, and in patients where there is a history of vaccine reaction, it may make sense to give fewer vaccines at any one time.  

With the continued movement of people and animals throughout the world, the leptospirosis risk for dogs will likely continue to increase. This is bad news, said Ellis. But, he added, the good news is that we have vaccines that are safe and effective when used appropriately.  

Moore concurred. “It’s uncommon to see leptospirosis in a properly vaccinated dog.”  

Further reading: 

WSAVA 2024 Vaccination Guidelines  

ACVIM Leptospirosis Consensus Statement 

AAHA Canine Vaccination Guidelines 

Photo credit: © Brand X Pictures via Getty Images Plus

Disclaimer: The views expressed, and topics discussed, in any NEWStat column or article are intended to inform, educate, or entertain, and do not represent an official position by the American Animal Hospital Association (AAHA) or its Board of Directors.