Dogs that need protection against both Lyme disease and Leptospirosis have always required two separate injections. On June 15, 2026, Elanco received United States Department of Agriculture (USDA) approval for TruCan Ultra Lyme-L4, the first 1/2 mL combination Leptospirosis/Lyme vaccine for dogs, closing that gap with a single shot.
The approval marks a meaningful step for practices looking to simplify preventive care protocols and for pet owners who have been hesitant to add another injection to their dog's annual visit.
Why This Combination Matters
Leptospirosis and Lyme disease are both increasingly relevant threats. Leptospirosis is a bacterial infection spread through water and soil contaminated by infected animals. It is also zoonotic, meaning it can pass from dogs to people. In 2024, the American Animal Hospital Association updated its Canine Vaccination Guidelines to designate Leptospirosis as a core vaccine for all dogs, regardless of lifestyle or geography.
George Moore, DVM, PhD, Professor Emeritus of Epidemiology at Purdue University College of Veterinary Medicine, framed the stakes:
Lyme disease, carried by ticks, is also expanding its geographic reach. The Companion Animal Parasite Council's 2026 annual parasite forecast points to continued spread of tick populations across the U.S., putting more dogs at risk each year. Both diseases require annual boosters, unlike the three-year core distemper-adenovirus-parvovirus combination, making a single injection covering both a natural fit.
Why Do So Many Dogs Fall Behind on These Vaccines?
Despite clear veterinary guidance, protection rates fall short. A 2020 study found that only 63.4% of dogs current on core vaccines had received a Leptospirosis vaccine in the preceding 14 months. Lyme numbers were lower still: in the 11 states identified by the Centers for Disease Control and Prevention (CDC) as high-risk for Lyme disease, only 47.9% of dogs current on core vaccines were also current on Lyme vaccine.
Vaccine hesitancy in pet owners compounds the problem. A 2023 study found that 52% of dog owners exhibited some degree of canine vaccine hesitancy, a trend researchers link in part to spillover from debates around human vaccination.
Jill Pattee, DVM, Medical Strategy Lead for Infectious Diseases at Elanco, sees the new combination vaccine as a direct response to that resistance.
Research in human pediatric medicine, across studies published in 2007, 2009, and 2017, has consistently found that combination vaccines improve overall vaccination compliance.
Why Fewer Injections Means Less Stress for Dogs
The practical benefits extend beyond compliance. Fear Free veterinary care has made reducing injection counts a recognized priority. Every additional needle stick increases the stress of a visit, for dogs and owners alike. A single injection that covers two annual vaccines fits naturally into that philosophy.
A dog whose owner dreads the multi-needle visit is a dog whose boosters are more likely to lapse. Cutting the injection count makes the appointment itself less of an obstacle.
How At-Home Visits Close the Compliance Gap
Even with a simplified vaccine, annual veterinary visits still require scheduling, transportation, and managing a dog who may not love the waiting room. Those logistics add up, and the friction shows up directly in the compliance numbers. As covered in Taking Vet Care Home, delivering routine and preventive services outside the clinic is one of the more direct ways practices have found to close the vaccine-compliance gap.
For practices looking to close that gap, at-home vet tech visits offer a practical path. When a practice partners with Homelove, a Fear-Free Certified Caregiver can administer vet-approved vaccines, including annual boosters like the new Lyme and Leptospirosis combination, at the client's home. The practice retains the clinical relationship and directs the care.
Closing that compliance gap doesn't hinge on the vaccine alone. It also depends on making the appointment itself easier to keep, whether through simplified protocols, more flexible scheduling, or a visit that happens somewhere the dog already feels comfortable. Practices that treat all three as connected levers, rather than waiting on the newest vaccine to do the work by itself, are the ones most likely to move that 47.9% Lyme compliance number in the right direction.