Life gets busy. A move, a new baby, a hectic work season, or simply losing track of a reminder card can all lead to a missed vaccine appointment. If you have realized your dog or cat is overdue for their shots, you are not alone, and in most cases it is easy to get back on track.
At Arlington Animal Clinic, we regularly help pet owners from Arlington, Somerville, Medford, Cambridge, and Belmont catch up on missed pet vaccinations. Here is what you need to know about overdue vaccines, what happens if a booster is late, and how we build a catch-up plan.
Why Booster Timing Matters
Vaccines work by training the immune system to recognize a disease. Over time, that protection fades, which is why pets need boosters at regular intervals. When a booster is missed, your pet’s protection may drop below the level needed to prevent infection.
How much a late booster matters depends on three things:
- Which vaccine was missed, since some offer longer protection than others
- How late it is, whether a few weeks or several years
- Your pet’s age and history, especially whether they completed their initial puppy or kitten series
What Happens If Your Pet Misses a Vaccine?
If Your Puppy or Kitten Missed a Booster in Their Series
Young pets receive a series of vaccines every three to four weeks until around 16 weeks of age. If there is a long gap in that series, your veterinarian may need to restart part of it to make sure your puppy or kitten develops full immunity. Until the series is complete, young pets should avoid dog parks, pet stores, and other high-traffic areas. You can review the basics in our guides to your puppy’s first vet visit and kitten vaccines.
If Your Adult Pet Is a Little Late
For adult pets that completed their initial series, being a few weeks or even a few months late usually just means getting the booster as soon as possible. In many cases, no restart is needed.
If It Has Been Several Years
If your pet’s vaccine history is unknown or it has been a long time, your veterinarian may recommend a booster followed by a second dose a few weeks later. In some situations, blood tests called titers can help assess existing immunity for certain diseases.
Rabies Vaccines Are a Special Case
Massachusetts law requires dogs, cats, and ferrets to be vaccinated against rabies. A lapsed rabies vaccine is about more than health. If an unvaccinated or overdue pet bites someone, or is exposed to a wild animal like a raccoon, skunk, fox, or bat, the required quarantine or observation period can be much stricter. Dog licensing in Arlington and surrounding towns also requires proof of current rabies vaccination.
If your pet’s rabies vaccine has lapsed, please make it a priority.
Common Vaccines Pets Fall Behind On
For Dogs
- Leptospirosis, which is given yearly and is important for dogs that drink from puddles or visit places like Menotomy Rocks Park or the Mystic Lakes
- Lyme disease, since ticks are active across Massachusetts for much of the year
- Bordetella for kennel cough, often required by groomers, daycares, and boarding facilities
- Canine influenza, for social dogs
For Cats
- FVRCP boosters, which protect against common respiratory viruses and panleukopenia
- Feline leukemia (FeLV), recommended for cats that go outdoors or live with other cats
- Rabies, which indoor cats still need
How We Create a Catch-Up Plan
When an overdue pet comes in, we start with a full exam to make sure they are healthy enough to be vaccinated. From there, we:
- Review any past records you have, including records from other clinics or shelters
- Prioritize required and core vaccines
- Space out vaccines when appropriate, especially for small pets or those with past reactions
- Schedule any needed second doses before you leave
- Set up reminders so you stay on track
Tips to Keep Vaccines on Schedule
- Pair vaccines with your pet’s yearly wellness exam
- Add reminders to your phone calendar when you leave each appointment
- Keep a digital copy of vaccine records for travel, boarding, and grooming
- Let us know if you have moved or changed your contact information
Planning a trip? Some destinations require proof of current vaccines, so check our health certificate service well before you travel.
Common Questions About Overdue Pet Vaccines
Does my pet need to restart vaccines if they are late?
Usually not for adult pets that completed their initial series. Puppies, kittens, and pets with long or unknown gaps may need an extra dose.
Can my pet get several vaccines at once to catch up?
Many pets can safely receive more than one vaccine at a visit. For smaller pets or those with a history of reactions, we may spread them out.
Is it safe to vaccinate a pet that has been overdue for years?
Yes, as long as they are healthy at the time of the exam. Getting them protected is far safer than leaving them unvaccinated.
What if I do not have my pet’s records?
Call your previous clinic or shelter first. If records cannot be found, we will build a safe plan based on your pet’s age and lifestyle.
When to Schedule a Visit with a Veterinarian
If your dog or cat is overdue for vaccines, the best time to catch up is now. Arlington Animal Clinic at 191 Broadway has been caring for pets in Arlington and nearby communities for more than 45 years. Call 781-646-0758 to book a wellness visit, and we will help you get your pet’s protection back on schedule.


