Vaccine reactions in pets are rare but they can occur. Usually they are mild and short lived, very similar to most human vaccine reactions. The benefits of disease protection from the commonly used vaccines greatly outweighs the risks. The most common vaccine reactions include either soreness or swelling at the injection site, stomach upset, lethargy, lack of appetite or swelling/itchiness around the head and face. It is important to know that some animals will be tired or quieter than usual after being vaccinated and this is considered normal. However if this lasts more than 24hrs it is best to contact a veterinarian. Most vaccine reactions occur soon after vaccination, within 20mins to 24hrs. If you have any concerns with your pet after vaccination it is best to speak to your vet right away to decide if the reaction should be monitored or if your pet should be seen right away. Treatment varies depending on the situation but typically will consist of an injection of antihistamines. Sometimes pain medication or anti-nausea medication is prescribed if the case indicates. It is important for us to know about any possible vaccine reactions your pet may have experienced even if they resolved without treatment. We may decide to alter your pet’s vaccination schedule or start pretreating them with antihistamine before vaccination. This way they can still have the benefits of vaccination with less risk of adverse side effect.