Is it unsafe to give a dog the leptospirosis vaccine and how likely are severe reactions?

Hi Christina,

To quickly answer your question, you need to have a vaccination program that suits your dog’s lifestyle, your philosophy about vaccines and one that matches your dog’s risk of being exposed to the diseases we commonly vaccinate for. There are pros and cons to vaccination and reactions are possible but we often see more reactions to the rabies vaccine than the newer leptospirosis vaccine. Your veterinarian may have had a unique experience with a leptospirosis vaccination that established a rule in their mind that they will stop giving it forever. If so, they need to adapt their guidelines on vaccination to each client and start considering it in cases where the risk of contraction of the disease is high enough to warrant the extremely low risk of a reaction. Your veterinarian could also consider administering something to reduce the risk of a reaction such as an antihistamine prior to administering the vaccine. They need to be open to the discussion and if they aren’t, you’ll have to seek a second opinion.

Aside from that, I’ll give you this information about leptospirosis in general. I think it will help.

Leptospirosis is a bacterial infection that initially causes inflammation of the vessels causing inflammation. They can multiply quickly once in the bloodstream and spread to the kidneys, liver, eyes, spleen, genitals and central nervous system. Symptoms start with fever, muscle tenderness, vomiting, diarrhea, dehydration, inappetence, and lethargy. It can progress to muscle stiffness, coughing, gastrointestinal bleeding, nasal inflammation, rapid breathing, and difficulty breathing. Abdominal pain due to kidney swelling and jaundice when the liver is affected can occur as well.

What is the risk of getting the disease it protects against?

The risk of getting the disease will be different for every pet. It depends on geographic location, seasonality, exposure to wildlife and interaction with the environment. Leptospirosis is carried by racoons, rats, other dogs, and less so mice, cows, horses, and pigs. So your risk will increase if you walk your dog in an area that is visited by these animals. The most common source is racoons for inner-city dogs. They can contract it through infected urine, infected tissue and bite wounds. The most common source would be standing water, such as ponds and puddles, in your neighbourhood that other infected animals have urinated in. Late summer and early fall is a more common time to contract the disease because of the increased rainfall at this time of year. So thinking in these terms, you can reduce your dog’s risk of exposure by eliminating standing water, keeping them on a tight leash and discouraging drinking from outdoor water sources, reducing wildlife exposure to your property, avoiding swimming in lakes and streams where wildlife visit, discourage eating of dead tissue outside and reducing exposure to dogs they could fight with.

How effective is the vaccine?

There are more than 16 species of leptospirosis. There is a vaccine available in North America for the prevention of 4 of the species. There is not total cross-protection of the vaccine from these 4 species to the others so it is still entirely possible to contract the disease despite vaccination. The vaccine has been known to provide less than total protection against the disease. Vaccinated dogs have also shown to have less shedding of the bacteria reducing the presence of leptospirosis in the dog’s immediate environment.

How often does it have to be given?

The vaccine is commonly given once a year. Studies show that protection can last from 8 months to a year. When the vaccine is first given, a booster vaccine is often given one month later to improve the success of initial immunity before moving to the annual schedule. Some veterinarians may recommend a third vaccine initially.

What are the possible side effects? How long and how severe are they?

Reactions can occur with vaccination but it is no more likely than other core vaccines that are given. A rabies vaccine is more likely to cause a reaction in any dog than a vaccine for leptospirosis. The possible side effects of any vaccine could be fever, lethargy, and inappetence. These symptoms are not concerning since the purpose of the vaccine is to interact and challenge the immune system. People receiving a vaccine will often experience these symptoms. A concerning vaccine reaction can occur in some individuals that are sensitive to it and they could be facial swelling, urticaria or skin swellings, vomiting and itchiness. The timing of when these symptoms occur can be immediate or take a few days to develop since a patient could have an anaphylactic reaction or longer ‘cell-mediated’ reaction. An anaphylactic reaction can occur within seconds and create immediate skin reactions, difficulty breathing and can potentially be fatal. 15 years of giving vaccines and I have yet to experience such an event but every vaccine has its possible negative effects. These symptoms can be reduced or mitigated with treatment by your veterinarian with the use of antihistamines and steroids.

What is the probability of getting the side effects?

This is a question every veterinarian would like answered. There is no way to predict what type of dog could be sensitive to a vaccine. Some believe that small, white-coated breeds have more of a risk of reacting. Some breeds are known to be more reactive than others and you can discuss this with your veterinarian. If your dog is known to be allergic or has had previous reactions, you could discuss the concept of ‘splitting’ vaccines and also pre-treating with anti-histamines. These strategies work to reduce the chance of a vaccine reaction. It is well accepted that vaccination in both people and pets are more beneficial than they are harmful but it is hotly debated in the general public. I wouldn’t staunchly recommend vaccination without a conversation first about the risk of exposure to the disease the vaccine is supposed to protect against.

In the end, your veterinarian is supposed to educate you in an unbiased way and allow you to make the decision. I encourage you to watch our videos “Which Vaccines Should I Give My Dog or Cat?”, “Everything You Need to Know About Vaccine Reactions”and “How Often Vaccines Need Boosters & The Benefits of Titer Testing for Dogs & Cats” to educate yourself in preparation for a good conversation with your veterinarian.

Good luck and thanks for your question.

Dr. Greenway