Vaccinations—Spring Shot Time

Spring is quickly on the approach which means it's also "spring shots" time again. Some horse owners and stable managers buy their vaccines online and administer them themselves, others chose to skip certain vaccines, or all vaccinations all together, all with only the best intentions. Regulations as to who is allowed to administer certain vaccines, and which, might differ depending on what part of the country you are in. Recommended for our region here in Western Massachusetts are rabies, Eastern and Western encephalomyelitis, tetanus and West Nile inocculations. Influenza and rhinopneumoitis (EHV1-4), Potomac horse fever and strangles are recommended based on individual horse's risk. Here is a good site that gives you a lot of information about horse diseases and which ones have been reported in your area (U.S.). https://www.outbreak-alert.com/

Adverse vaccination reactions can take many forms, from mild cases such as a stiff neck to the extreme of anaphylactic shock and death. Understanding how to minimize adverse reactions and having a plan in case of an unwanted reaction can help your horse stay comfortable following vaccination. Nonspecific reactions can result in swelling and soreness. Occasionally, an abscess might form at the site of injection. Always check with your vet!

horse reacts to vaccine

adverse reaction to vaccine

What You Should Know

Vaccine handling is extremely important. Vaccines which aren't handled properly are less likely to be effective and more likely to cause adverse reactions. When you purchase vaccines online they have been shipped at least twice and that increases the risk that they may have gotten too warm (or too cold) during shipping.

Vaccines come with expiration date and lot numbers stamped on the package. From time to time there are manufacturer recalls of certain lots.

Carefully chose the injection site, some sites are better than others. Watch and check for swelling and heat at the injection site, make sure the horse does not go off its feed, isn't listless, and check for fever. The most common reaction to vaccination is swelling and soreness at the injection site for a few days. The horse doesn’t want to put its head down to eat or drink because the neck is sore. Don’t vaccinate horses just before a competition. Do it well ahead of any event or ride, just in case the horse has a fever for a few days.

Fifteen or 20 minutes after vaccination (up to a few hours later) the horse may get hives. Fever and soreness may show up 12 to 24 hours after vaccination. An abscess may not show up for several days to a week later. Anywhere from 1 to 4 weeks later a vaccinated horse may develop purpura hemorrhagica. This is why it’s important to keep monitoring the horse and not just assume that everything is ok after the first day. See Tips to Prevent or Minimize Vaccination Reactions by EquiMed.

Possible Reactions

  • Swelling at the injection site
  • Local tissue swelling
  • Infection
  • Stiffness
  • Hives
  • Muscle swelling
  • Mild fever
  • Off feed
  • Lethargy
  • Anaphylaxis (occurs very quickly, generally first sign of anaphylaxis is difficulty breathing, followed by collapse)

If Your Horse Had A Reaction

  • It is more likely to develop reactions again
  • Bute, Banamine, or antihistamine to prevent, or treat symptoms
  • Cool and warm compresses, topical DMSO gel, and gentle exercise
  • Avoid 3-way/5-way combination vaccines to determine which vaccine is causing problems
  • Switch brands/manufacturer when an adverse reaction occurred
  • Schedule injections separately from other vaccines
  • Spread them out over several days
  • Alternate injection site

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