Spring is in swing by now and even though March can be a tumultuous month when it comes to weather, the animals all seem to know that warmer weather, sunshine, and longer days are just around the corner.

Horse owners seem to know this too, since the coming of spring means the coming of "spring shots," and the equine vet’s appointment book explodes with rendezvous after rendezvous of horse and syringe. There are some days, especially after looking at a whole barn full of horses, that I feel like I’m vaccinating the entire equine population, one horse at a time.

With this partnership that seems to marry horse vaccines with the season (it seems mostly dictated by the schedule of the horse show season, which gets a major start in the spring), there are some differences between how horses are vaccinated and how pets such as cats and dogs are vaccinated. Let’s take a look at the horse world.

As with cats and dogs, there are some core vaccines that all horses, regardless of geographic location, are strongly encouraged to receive. Dictated primary by the AAEP (American Association of Equine Practitioners), these core vaccines are: tetanus, Eastern/Western equine encephalitis, West Nile Virus, and rabies.

Other equine vaccines are categorized as "risk-based," meaning your vet will decide to administer them depending on geographic locale, herd status, and even an individual’s travel status. This group of vaccines is comprised of the following: anthrax, botulism, rhinopneumonitis ("rhino"), EVA (equine viral arteritis), influenza, Potomac Horse Fever, rotavirus, and strangles.

Personally, I give rhino, flu, PHF, and strangles vaccines on a frequent basis here in Maryland. I give botulism infrequently, and have never administered vaccines against anthrax, EVA, or rotavirus.

Where do you give a horse a vaccine? One great difference between horses and cats and dogs is that all equine vaccines are given intramuscular (IM). There are a few horse vaccines that are intranasal, similar to the kennel cough (bordatella) vaccine given to dogs. Also, horses get a much bigger needle — we’re talking 1.5 inches long. The reason for this is that you want to deliver the vaccine deep into the muscle tissue. If you get it too shallow, there is a greater chance of infection.

The most common and safest areas to give IM equine vaccines are the side of the neck, the pectorals (the chest, right between the front legs), and the gluteals (back end). The two key points for consideration when choosing a vaccination site are the safety of the person giving the vaccine, and proper drainage if the vaccine were to cause an abscess.

Surprisingly, many horses don’t seem to mind at all when you stick them with a 1.5 inch needle. I favor the neck as the location to give vaccines, but sometimes I’ll give them in the pecs if the horse has a tendency to get sore. Also, if a horse has become sour toward getting shots in the neck, sometimes getting them in the pecs is different enough that they either don’t mind, don’t realize what’s going on, or just happen to be thinking about something else at the second you are jabbing them. I hardly ever give vaccines in the gluteals. Just seems too close to those hind legs, if you ask me. But hey, some people do favor that site.

Other farm animals, such as cattle, sheep, and goats, are different still. Many cattle get vaccines referred to as a "5 way" or "9 way," which is just a cool way of saying a vaccine protects against five or nine different diseases, all in one. Many of these vaccines are against respiratory pathogens that make up the dreaded bovine respiratory disease, or BRD. A complex of viral and bacterial antigens, BRD can spread like wild fire through a herd.

Other cattle vaccines include tetanus and other nasty Clostridial diseases, such as a gnarly disease called black leg. The AABP (American Association of Bovine Practitioners) does not produce a vaccine guideline like AAEP. The reason is that the large variation in the ways cattle are raised (pasture-based, feed lot, etc.) makes one set of guidelines that fit every scenario impossible. This is the same reason why there are no guidelines for pigs either.

Sheep and goats are mostly on their own. There are very few USDA approved vaccines for these species, so we vets sometimes struggle to make vaccine recommendations. Primarily, I recommend vaccinating your small ruminants and camelids (llamas and alpacas) against tetanus and a few other Clostridial diseases, and rabies, and that’s about it.

And pigs? Don’t even get me started on pigs. Those bacon-makers are so smart, they’re likely to trip you, steal the syringe, and vaccinate YOU. But Dr. Anna’s Reasons Why Pigs Will Take Over the World is a blog for another day. Stay tuned!

Dr. Anna O’Brien

Image: Kondrashov MIkhail Evgenevich / via Shutterstock.com