Distemper is a highly contagious and serious disease caused by the canine distemper virus (CDV). It affects the respiratory, gastrointestinal, and nervous systems of dogs and can lead to pneumonia, vomiting, diarrhea, seizures, and even death. Vaccination is the best way to protect dogs against distemper. Most vets recommend puppies receive a series of 3 distemper vaccinations, with the first shot given as early as 6-8 weeks of age. But do adult dogs really need to get a distemper shot every year or three years for the rest of their lives? Let’s take a closer look.
What is canine distemper?
Canine distemper is caused by a virus in the family Paramyxoviridae, the same family that includes human measles. It is an enveloped RNA virus that is very fragile when outside of the body. Distemper spreads through airborne exposure (through sneezing and coughing) and contact with body secretions.
The distemper virus attacks the respiratory, gastrointestinal, and nervous systems. The first signs are usually a watery discharge from the eyes and nose as well as fever, lethargy, loss of appetite, and coughing. As it progresses, distemper causes vomiting, diarrhea, dehydration, and labored breathing. The virus may then start attacking the nervous system, leading to seizures, paralysis, and twitching. Distemper is often fatal. Puppies and dogs with weak immune systems are especially vulnerable.
How effective are distemper vaccines?
Fortunately, we have very effective vaccines to protect dogs against distemper. The canine distemper vaccine is considered a core vaccine by veterinarians, meaning it’s one of the “must-have” shots all dogs should get.
Distemper vaccination begins when puppies are 6-8 weeks old. Puppies receive a series of 3 distemper vaccine shots, given 3-4 weeks apart. These initial shots are followed by a booster shot at 15-16 weeks old. The goal is to provide complete protection by 16 weeks of age, before the natural immunity the puppy got from its mother starts to fade.
Some key points about distemper vaccine effectiveness:
- The distemper vaccine provides robust and lasting protection in most dogs.
- Immunity from distemper shots can last at least 5 years in adult dogs, and often for much longer (7-15 years).
- The distemper vaccine protects over 90% of vaccinated dogs from disease.
- Dogs with weak immune systems may not develop as robust immunity and need more frequent vaccination.
With such excellent protection from the puppy vaccine series and boosters, do adult dogs really need distemper shots every 1-3 years?
Why do vets recommend “boosters” every 3 years?
Many vets continue to recommend that adult dogs receive distemper shots, or “boosters,” a minimum of every 3 years. Here are some reasons why:
- Ensure immunity does not wane – While distemper immunity can last over 7 years, some dogs may see their antibody levels start to decrease around year 3. Boosters ensure protection is maintained.
- Protect those at higher risk – More frequent boosters (every 1-2 years) may be advised for very young puppies, senior dogs, unvaccinated adult dogs with an unknown history, and immunocompromised dogs.
- Guard against new virus strains – As with human flu, new strains of canine distemper can evolve. Boosters aim to protect against novel strains.
- Reinforce brand protocol – Some vaccine brands still recommend annual or triennial boosters per their product labeling.
However, recent research indicates that core vaccines like distemper may not need to be administered as often in most adult dogs.
What does the research say?
An increasing number of studies suggest adult dogs may not need such frequent distemper boosters:
- Challenge studies show distemper immunity lasts at least 5 years, and up to 15 years or more.
- Measurement of antibody levels indicates protection extends well beyond 3 years.
- There’s no evidence that vaccinated dogs with antibody levels above a threshold are any better protected against distemper than those with higher antibody levels.
- Adult dogs likely do not need boosters more often than every 5-7 years.
- Risk of adverse effects may outweigh benefit with overly frequent vaccination.
One 2021 study looked at distemper antibody levels in 235 adult dogs who were last vaccinated against distemper 3-13 years prior. 95% of dogs had antibody levels well above the threshold considered protective against distemper. This indicates triennial vaccination is excessive in previously vaccinated adult dogs.
Are 3-year distemper boosters still recommended?
Based on long-lasting immunity data, the American Animal Hospital Association (AAHA) Canine Vaccination Guidelines now recommend distemper boosters just every 3 years in most adult dogs.
However, the World Small Animal Veterinary Association (WSAVA) guidelines state that triennial vaccination against core diseases like distemper may not be necessary in all adult dogs. They note that annual and triennial vaccines are often default recommendations in many practices but “not based on rigorous scientific assessment of benefit and risk.”
The WSAVA guidelines say vets should conduct “thoughtful, evidence-based assessment of vaccine needs,” especially when it comes to boosters for core vaccines like distemper.
So while 3-year intervals are still commonly recommended, research indicates that more individualized approaches to distemper boosters may be warranted in adult dogs, especially beyond 7 years of age. Triennial boosters should not be given by default.
Are there risks to over-vaccinating dogs?
Some vets are concerned that administering distemper and other core vaccines too often may increase the risk of adverse reactions. Potential risks of over-vaccination against core diseases include:
- Increased likelihood of adverse events like lethargy, fever, gastrointestinal signs, hives, and anaphylaxis.
- Increased risk for autoimmune diseases that are immune-mediated in nature.
- Possible increased risk of vaccine-associated sarcomas in cats when vaccines are overused (less evidence for dogs, but still a potential concern).
While serious adverse events are still very rare overall with core vaccines like distemper, veterinary governing bodies note that the “potential for adverse events is likely to increase with unnecessary vaccination.”
When might more frequent distemper shots be advised?
While most healthy adult dogs may not require re-vaccination more often than every 5-7 years, some dogs are at higher risk and may benefit from more frequent distemper boosters. Situations where your vet may advise distemper vaccines every 1-3 years include:
- Very young puppies – Puppy shots are started at 6-8 weeks, with boosters every 3-4 weeks until 16-20 weeks due to greater susceptibility to infection.
- Senior dogs – Immunity may wane faster in older dogs (8-10+ years old).
- Sickly dogs – Dogs with chronic illness may have weaker immune protection.
- Immunocompromised dogs – Dogs undergoing chemotherapy, with autoimmune disease, etc. are at greater risk.
- Uncertain history – Stray adult dogs with no known vaccine history should receive at least one distemper booster.
Annual distemper boosters may also be advised for dogs living in higher-risk situations, like shelters and boarding facilities, where exposure risk is increased. Geographic location with higher distemper rates may also be a factor.
What do the experts recommend?
With the accumulating research that immunity against core diseases persists for many years beyond traditional booster intervals, experts generally agree that adult dogs likely do not require distemper vaccination more often than every 5-7 years.
The American Veterinary Medical Association’s (AVMA) Canine Vaccination Task Force summarized current expert guidance in its 2022 Report on Canine and Feline Vaccination:
“We should aim to vaccinate every dog, but vaccines should not be given any more frequently than necessary. Core vaccines should not need to be administered annually to most adult dogs… Available data supports vaccination intervals of 3 years or longer in adult dogs for core vaccines like distemper.”
Key points from expert groups like WSAVA, AAHA, and AVMA:
- Puppies need a series of shots for core vaccines like distemper from 6-16 weeks of age.
- After the puppy series, a distemper booster at one year is advised.
- Further boosters are generally not required more often than every 3 years in healthy adult dogs; 5-7 year intervals are often sufficient.
- Dogs at higher risk may benefit from more frequent vaccination.
- Antibody testing can help determine if an individual dog requires an earlier distemper booster.
- Core vaccines should not be administered annually to most adult dogs without a specific medical need.
Should titer tests guide distemper booster frequency?
Instead of routine vaccination at set intervals, some vets recommend using antibody titer tests to guide distemper booster decisions in adult dogs. This is the practice of testing blood antibody levels against core diseases like distemper to verify immunity.
Titer-based vaccination may be warranted in individual adult dogs, especially at mid-life and beyond. Titers can provide objective evidence of a dog’s protective status. If a dog has a high distemper antibody titer, it may not need a booster vaccine that year.
Potential benefits of titer testing include:
- Avoids unnecessary vaccination in dogs with existing immunity.
- May reduce risk of adverse vaccine reactions.
- Prevents needlessly frequent vaccination that provides little added benefit.
- Can identify dogs that do require more frequent vaccination.
- May be advised in dogs with past serious vaccine reactions.
However, there are some limitations with titer testing as well:
- No definitive correlation between titer strength and degree of immune protection.
- Titers only provide a “snapshot” in time and may quickly change.
- Unknown when/if immunity may eventually wane with very high titers.
- Testing has added cost versus standard vaccine schedule.
Overall, titer testing has advantages but also complexities. Your vet can advise if it may be appropriate for your individual dog. But for many low-risk dogs, following general expert guidelines for 5-7 year distemper vaccination intervals without titer testing is still reasonable.
What’s most important for distemper protection?
Vaccination is vitally important to protect dogs against deadly diseases like distemper. However, research shows that most adult dogs maintain robust, long-lasting immunity to core vaccines like distemper when given at the standard intervals as puppies.
The critical foundation is ensuring puppies receive their complete series of distemper shots on schedule. After this:
- For most healthy adult dogs, further distemper vaccination is generally not required more often than every 5-7 years.
- High-risk dogs may benefit from more frequent vaccination (every 3 years or as advised by your vet).
- Work with your vet to determine the optimal distemper booster schedule for your individual dog based on age, health status, and lifestyle. Avoid “one size fits all” approaches.
- If you have concerns about over-vaccination, discuss antibody testing with your vet.
While we all want the very best protection for our canine companions, the evidence indicates that most adult dogs do not require distemper boosters nearly as often as traditionally advised. Following expert guidelines and your vet’s tailored recommendations for your dog are the keys to balancing superb protection with minimal risk.
Summary table of distemper vaccination guidelines
| Age | Initial Puppy Shots | First Booster | Adult Boosters |
|---|---|---|---|
| 6-8 weeks | Distemper shot #1 | ||
| 10-12 weeks | Distemper shot #2 (3-4 weeks after #1) | ||
| 14-16 weeks | Distemper shot #3 (3-4 weeks after #2) | ||
| 15-16 weeks | Distemper booster | ||
| 1 year old | Distemper booster | ||
| Adult (next 5-7+ years) | Distemper booster every 5-7 years or as advised by vet |
Conclusion
In summary, most healthy adult dogs likely do not require distemper boosters more often than every 5-7 years after their initial puppy series, according to expert guidelines and recent evidence. However, a veterinarian’s advice is essential, as dogs at higher risk may benefit from more frequent vaccination. Titer testing can also help determine if an individual dog requires an earlier booster. While we want maximum protection, avoiding over-vaccination helps reduce risks and expense. Work with your vet to find the optimal distemper vaccination schedule for your faithful companion.
