Mad about the Rabies Vaccine?
By Molly Cavanaugh, December 2025
Rabies has captured the attention of people for thousands of years, with the first written reference to rabies in 2300 BC as part of the Mosaic Esmuna Code of Babylon (1). The classic American novel, Their Eyes Were Watching God, by Zora Neale Hurston in 1937, concludes with a scene where a woman must kill her husband who is infected with rabies and has gone mad (2). Steven King’s 1981 book, Cujo, focuses on a rabid dog who terrorizes a family through his aggressive behavior caused by rabies (3). While rabies is well known for its terrible symptoms and nearly 100% death rate, more and more people in the US are hesitant to vaccinate their pets (4).
Rabies is spread by the saliva of an infected animal entering the body through a wound or the eyes/mouth (5). Typically, people are infected by a bite from an animal but in extremely rare cases, one occurring this year, rabies can be spread when an infected person donates their organs to a healthy person (6). Rabies symptoms start with a headache and anxiety and progress into pain, extreme behavioral changes such as a deathly fear of water, and finally death (5). Roughly 60,000 people die world-wide from rabies spread by dogs (7). Many dogs in Asia and Africa are unvaccinated and carry the risk of being infected with rabies with 95% of rabies cases occurring in those areas (8). Additionally, there are 4,000 cases of rabies tracked in the US each year, spread mostly by wild animals such as bats, foxes, and skunks causing 100,000 people to receive post-exposure prophylaxis due to exposure to rabies (9). Through aggressive vaccination requirements, the US has seen a drastic reduction in rabies spread by dogs (10). Despite this progress, a 2023 study found that 53% of dog owners in the US thought that the rabies vaccine for dogs was either unsafe, ineffective, or unnecessary (15). That statistic is concerning as rabies continues to be an ongoing problem in the US.
Rabies has a long incubation period, ranging from a week to a full year for symptoms to appear (11). This can be a huge issue as animals can be infected before vaccination. In May 2025, a dog in Chicago entered a rescue clinic. The dog was then vaccinated for rabies and adopted out in July. In December 2025, the dog started displaying concerning, aggressive behavior. After it bit its owner, the dog was returned to the shelter and euthanized. After testing, it became evident that the dog had contracted rabies, likely before the clinic ever had a chance to vaccinate (12). This incident marked the first infected dog in the state of Illinois since 1994 (13). Ninety dogs from the same doggy daycare as the infected dog have been isolated and given a rabies vaccine booster due to potential exposure but as all were vaccinated, they are all expected to survive (14). This example highlights how far rabies prevention has come for dogs, and how vulnerable the country is if we chose to stop vaccinating. If the bitten owner had not received treatment, he would have died.
Safety:
The rabies vaccine is safe for pets. The highest estimate of adverse reactions is 38.2/10,000 dogs vaccinated and 51.6/10,000 cats vaccinated (16, 17). These side effects are usually mild, ranging from vomiting to allergic reactions. Death from rabies vaccines only occurs in the rarest of cases: 0.104/10,000 dogs vaccinated and 0.161/10,000 cats vaccinated (18). Due to mandatory vaccinations in most US states, 90 million dogs and cats are vaccinated against rabies in the US each year (19). While the possibility of side effects from the rabies vaccine can be scary for pet owners, the alternative – the possibility of catching rabies – is a far worse option. The CDC recommends that all unvaccinated animals who have been exposed to rabies should be immediately euthanized (20). Unfortunately, this means that by trying to save a pet from vaccine side effects, pet owners are ensuring that the pets will die if they are exposed.
Effectiveness of the vaccine:
The rabies vaccine is nearly 100% effective against rabies, saving pets and humans from certain death ((5). If a person, or vaccinated animal, is bitten by a rabid animal, not all hope is lost. If a human receives postexposure prophylaxis within days after the bite, the treatment is nearly 100% effective at preventing rabies (21). The postexposure prophylaxis treatment includes the immediate injection of human rabies immune globulin (antibodies against the virus until the vaccine takes effect) and 4 separate vaccine shots over days (22). Only 35-45 people have been well documented as surviving rabies after symptoms have started. Many of these patients survived using a technique called the Milwaukee Protocol (23, 24). The Milwaukee protocol, invented in 2004, includes a medically induced coma, ketamine, and anti-viral treatment (25). Unfortunately, this protocol has been largely shown to be ineffective for most people. Postexposure prophylaxis before symptoms is the only treatment shown to consistently save lives (26). Pets that are vaccinated also stand a strong chance of survival. While pets do not receive postexposure prophylaxis, if they are vaccinated, they already have the antibodies to start fighting the infection. Vaccinated pets that have been exposed to rabies receive 2 booster shots and will be isolated for 45 days to ensure that they do not develop rabies (27).
Are the vaccines necessary?
Some pet owners wonder why they need to vaccinate their animals if they plan on keeping the pet inside. Rabies is spread in the US mostly by wild skunks, foxes, and bats. However, bats have a nasty habit of finding their way into homes, meaning your indoor pets can never truly be safe from rabies (28, 29). And even if no wild animals find their way inside, indoor pets also have a habit of getting outside. Bat bites are so small that they are often not noticed, meaning that you would only know that your animal was exposed to rabies once they start showing symptoms. Except in the reported 35-45 cases, once a person or animal starts showing rabies symptoms, they will die, usually within 7-14 days (30). Once rabies symptoms start, animals will exhibit behavior changes that often include aggressive behavior, which is when most bites from infected animals occur (31). Pets who go outside, especially in the woods, are at a significantly higher risk for rabies (32). Pet owners can further protect their pets by carefully watching animals who are outside and making sure they do not interact with wildlife. Unfortunately, diligently watching your animal is not a substitute for vaccination. Wild animals behave unpredictably, especially those with rabies, and you cannot protect your pet fully without the rabies vaccine.
Rabies is a terrifying virus that causes a painful, horrible death. Thankfully, we can prevent rabies through vigilance and vaccinations. Pet owners have a responsibility to protect their pets and the best, and easiest, way to do that is through vaccinations. Together, we can eliminate rabies spread by pets (33).