Joint injections are a fact of life for many performance horses. Although we have come a long way with nutraceuticals and physical therapy options, annual hock, stifle or coffin joint injections still make up a major component of some joint health programs. Sometimes, geriatric horses even need carpal or “knee” injections to help them get around. No matter which joint is being injected, there is always a risk of infection, albeit a low one.
Joint injections are serious business- the vet must stick needles directly into the joint space to inject cortisone (a long acting anti-inflammatory) and an antibiotic to help reduce the chances of infection. In some cases, owners may also opt to add in hyaluronic acid to further reduce inflammation. Some folks prefer to use Interleukin 1 Receptor Antagonist Protein (IRAP) to aid in joint function. IRAP also reduces inflammation, but through a completely different pathway than cortisone or hyaluronic acid.
Many horse owners live on pins and needles for a few days following joint injections because of their fear of joint infection. Although the veterinarian takes methodical steps to sterilize the skin surface prior to joint injection, there is always a slight chance that a joint can become infected as a result of a needle being introduced into a joint. Virtually all veterinarians have received the frantic call because an owner sees a new bump in the joint and immediately thinks, INFECTION!
Here are a few facts that may help nervous horse owners decide if they have a problem post-injection:
1. A horse with an infected joint will usually not show signs of it until 7 to 10 days post-injection in cases in which cortisone is used. This is because the cortisone suppresses the inflammation that the body would naturally use to respond to the foreign pathogen (usually Staph bacteria.) Most people are super nervous in the 2 to 3 days following the injection- but rarely would you see signs of a joint infection before 5 days- with 7 to 10 being the most common.
2. IRAP is a different story- joint infections have shown up in as little as 24 hours post injection.
3. The signs of joint infection are dramatic. The joint will be swollen and hot and usually painful to the touch. The horse is often 5 out of 5 (toe-touching) lame and reluctant to move even when haltered and asked to lead. Usually, the swelling is confined to just the joint- it is apparent that it is the only thing swollen.
4. Often the horse will not feel well and have a slight fever in the 101 to 102 F range.
When joint infections are suspected, you should call your veterinarian right away. Although 99.99 times out of 100 you probably aren’t dealing with a joint injection, time is of the essence for the unlucky few who are. Joints can be salvaged and horses can recover from joint infections, but it takes swift, aggressive and timely intervention.