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The booster reminder arrives, and a reasonable question follows: does my dog need every vaccine again? Usually, the appointment brings together different schedules. PDSA describes annual leptospirosis boosters alongside less frequent boosters for distemper, parvovirus and infectious hepatitis after the initial vaccination programme1.
The useful question is which protection is due for this dog, with this history, now. Ask the practice to explain the names on the vaccination record. You should be able to leave understanding both today's decision and the next planned review.
Different diseases need different schedules
The World Small Animal Veterinary Association (WSAVA)'s 2024 guidance supports lifelong vaccination without unnecessary doses. Modern modified live vaccines against distemper, adenovirus and parvovirus can protect for years; after an effective initial programme, adult revaccination is generally no more frequent than every three years2.
Leptospirosis vaccines work differently and need annual revaccination. WSAVA considers them core where the disease occurs, relevant bacterial groups are known and suitable vaccines are available. Its global guidance supports local veterinary decisions2.
PDSA recommends protection against all four of these diseases for UK dogs. Other needs depend on circumstances: for example, kennel cough vaccination may be relevant to mixing with dogs or boarding. Tell the practice about day care, walkers and travel plans before the appointment, including activities you are about to start1.
“Booster” is convenient shorthand, but it can hide those distinctions. If a reminder sounds different from what you remember, bring the card or ask the practice to read back the record. A clear explanation is more useful than comparing the colour of somebody else's vaccine sticker.
Why leptospirosis belongs in the UK discussion
Leptospirosis is a bacterial disease that can cause severe liver and kidney damage. Dogs can encounter infection through urine-contaminated water or soil, or infected animals' urine. Farms, rodents and swimming can increase exposure, but PDSA emphasises that any dog can catch it3.
UK Health Security Agency guidance describes rodents, cattle and pigs among the reservoirs and explains that animals can carry infection without appearing ill. Urine-contaminated water is an important transmission route, with flooding and heavy rainfall relevant to exposure. It is a disease shared across animal and human health4.
That does not mean every puddle causes disease or every dog faces an identical risk. It means “we live in town” is only the beginning of a useful history. Explain where your dog actually walks and swims, what wildlife visits the garden and whether their routine changes during holidays.
The same UKHSA guidance notes that leptospirosis forms part of the UK's core dog vaccination programme. Its discussion of human exposure also explains why urine precautions matter when an animal is infected. If your dog is diagnosed or suspected to be infected, ask the veterinary team for household instructions4.
Rarely diagnosed does not mean unnecessary protection
A UK study estimated only 0.8 leptospirosis diagnoses per 100,000 dogs under primary veterinary care in 2016. The authors explicitly suggest that true cases may be missed. That is a historical rate of recorded diagnosis, rather than a current measurement of every infection circulating among UK dogs5.
The study also compared laboratory-confirmed cases with veterinary-record controls to examine risk factors. It cannot tell an owner that a particular dog has no risk, and the low recorded rate should not be turned into an argument for abandoning prevention. These conclusions come from the published abstract5.
A separate VetCompass study, published in 2022, found that 49% of 905,543 dogs had a leptospirosis vaccine recorded during 2016. Older dogs had substantially lower odds of a recorded vaccination than puppies. This was a large study of practice records, not a survey of what every UK owner does today6.
The authors discuss differences in recording, regional representation and the limits of examining one year. Vaccination outside participating practices may not be captured. Its practical value is to highlight the possibility of protection being overlooked as dogs grow older, rather than label half the current dog population unprotected6.
If your dog has changed practices or joined your family as an adult, gathering the previous record is a useful first job. Put gaps on the list of questions without guessing what a missing entry means. The team can distinguish an absent record from a known missed vaccination.
What about L2, L4 and safety concerns?
L2 and L4 vaccines contain components from two or four Leptospira strains respectively. The Veterinary Medicines Directorate's March 2026 update reaffirms that their benefits outweigh their risks, while recommending a plan tailored to local disease exposure and the individual animal's circumstances7.
Using its December 2025 analysis, VMD reports adverse-event incidences of 0.016% for L2 products combined and 0.040% for L4 products combined, both classed as rare. These are reporting figures based on estimated animals treated. An event reported after a vaccine is not necessarily caused by it7.
Reports include situations involving other products, use outside the product instructions and other explanations for the event. These figures should not be read as a controlled comparison proving which product is safer for your dog. Discuss the benefit of additional coverage alongside previous reactions and the product information7.
If something concerning happens after vaccination, contact your vet for care and discuss reporting it. GOV.UK allows suspected reactions to be reported even when you are unsure the medicine was responsible. Reports help VMD monitor whether medicines remain safe and effective; you do not need to establish causation first8.
Keep a factual account: the vaccination date, what you observed, when it began and any other treatments your dog received. Bring that account to the next planning conversation. It makes room for a concern to be investigated without having to settle the cause in a social-media discussion.
Can a titre test replace the reminder?
Blood antibody testing can help inform some decisions about distemper, adenovirus and parvovirus protection. It is not an equivalent way to decide whether leptospirosis protection can be skipped: WSAVA cautions that Leptospira antibody results are much less reliable predictors of protection2.
PDSA similarly distinguishes titre testing for those viral diseases from the annual leptospirosis booster. Testing needs a veterinary interpretation and a plan for what happens next. Ask what question the test would answer for your dog, what its limitations are and how the result would change the recommendation1.
If a booster has been missed, contact the practice with the dates rather than choosing a restart schedule yourself. WSAVA recommends restarting some lapsed leptospirosis courses as a precaution; the appropriate plan depends on the history and vaccine. General guidance should not become a substitute prescription2.
Leave with an understandable plan
- Which diseases were covered today, and what is due next?
- Does my dog's routine change the recommendation?
- Do previous reactions or current medicines affect the decision?
- Would testing answer a useful question in this case?
- Who should I contact if I notice a problem afterwards8?
The reminder can then mean something concrete: an agreed chance to review health, discuss changes and keep the right protection in place. Save the plan with the record, share it with anyone who arranges appointments, and let the next reminder start from that clear explanation.
Sources and further reading8 sources
The small numbers in the article link to the source behind each fact. Sources open on their own websites.
- Dog Vaccines
- 2024 guidelines for the vaccination of dogs and cats … (WSAVA)
- Leptospirosis in dogs
- Leptospirosis
- Incidence and demographic risk factors for leptospirosis in dogs in the UK
- Leptospirosis vaccination in dogs attending UK primary care practices: vaccine uptake and factors associated with administration
- VMD reaffirms safety of Leptospira vaccines in dogs
- Report a problem with an animal medicine or animal exposed to human medicine