[ your horse health questions answered ]
Ask The Vet
By Alfredo Sanchez-Londoño, MV, MS, DACVIM (LAIM)
SHAWn HAMILTOn/CLIxPHOTO.COM
Not all horses are good candidates for joint injections, so be sure to speak with your vet.
I’m currently preparing for show season, and have tried using joint supplements for my older show horse, but they just don’t seem to be working. I’ve heard about hock injections, but am unsure of whether I should use them or not. Can you tell me if this is effective? What makes a horse a good candidate? What are the risks of hock injections, if any, and are there any other options?
As horses age it is not uncommon for them to develop osteoarthritis in multiple joints that can interfere with their activity levels and their ability to compete or continue with their routine exercise regimen. The most important thing to do is to have your veterinarian perform a complete lameness evaluation of the horse including flexion tests to determine the joints that could be involved and the severity of the lameness the horse may have. It will also be of value to perform radiographs of the affected joints to help determine the potential changes that can be occurring with the bones and the joint space. It is very common for people to discuss
joint problems in the old horse, but it can also occur in younger horses. People will often use a variety of joint supplements, just like you have attempted, and may not have had a very positive result or may only see a mild improvement. These joint supplements are also known as nutraceuticals, and will consist of many different ingredients that are supposed to help with joint health. In general these products will only provide symptomatic relief that is not enough for the demands being placed on the horse, such as jumping, showing, or whichever discipline he does. Another way to try to help reduce lameness related problems in horses is by the use of non-steroidal anti-inflammatory drugs (NSAIDs). The most common one is phenylbutazone, but excessive or chronic use of these medications can have side effects such as gastric ulceration or kidney problems in some horses. Another concern with the use of NSAIDs is that they may be prohibited from use in competitions, so it will be important to know the rules for each discipline and event that you may be taking your horse to. Depending on what your veterinarian finds, it will be important to discuss the possibility of performing joint injections. Not all horses will be candidates for performing intra-articular injections, as one with severe changes will probably not respond adequately or as expected, compared to a horse that does not have significant radiographic changes. Medications that can be used intra-articularly include corticosteroids and hyaluronan. Corticosteroids are potent anti-inflammatories that will help decrease the clinical signs of lameness due to osteoarthritis. The other medication commonly used is hyaluronan or sodium hyaluronate, which is normally found as a component of articular cartilage and will provide the joint with adequate lubrication and prevent the bone on bone contact that continues to progress to severe
osteoarthritis. Hyaluronan helps in reducing the clinical signs and symptoms of lameness by decreasing inflammatory factors, and will also support adequate joint health by stimulating production of hyaluronan within the joint. Hyaloronate can be used either intravenously in cases in which multiple joints are affected or intra-articular when used in combination with corticosteroids to inject into particular joints such as the hock. When the hock is injected, the hyaluronan will be released into two separate joints—the distal tarsal joint and the tarso-metatarsal joint, which are the two lower joints in the hock. To perform a hock joint injection, the horse usually has to be sedated and a nose twitch is sometimes applied, as no movement can happen when the needle is being inserted into the joint as it could potentially break and cause major damage in the joint space, and would need to be removed surgically in the majority of cases. The area where the needles are going to be placed will need to be cleaned completely to decrease the chances of contamination and infection of the joint, as this can be one of the most common complications when performing joint injections. After hock injections it is usually recommended to rest the horse for a few days because this will in theory allow for better penetration of the medication into the tissues and will decrease the inflammation present in the joint. It is very important to discuss with your veterinarian a plan of action for each horse, as not all the therapies will apply to all the horses and may require a different frequency of administration, depending on the severity of changes and the activity level of the horse. If using NSAIDs, make sure to monitor him very closely for changes in appetite, behavior and consistency of the fecal material, because as previously mentioned they can have significant gastrointestinal disorders that can result in these clinical signs. Radiographs of the hock joint will be helpful to determine the extent of the damage present and will serve as a guide to determine the prognosis of the horse.
About the Author Alfredo Sanchez-Londoño, MV, MS is an assistant professor and clinician at the Cummings School of Veterinary Medicine at Tufts University, and, specifically, the Tufts Ambulatory Service in Woodstock, Conn. He obtained his MV (Medico Veterinario) degree from Universidad de La Salle in Bogota, Colombia in 1997. In 2000, he completed the requirements of the Educational Committee for Foreign Veterinary Graduates (ECFVG) at Purdue University, then completed an internship and a Large Animal Internal Medicine residency/Master of Science degree program at Purdue University in 2005. He joined the Tufts Ambulatory Service in July of 2005. His main interest is Equine Medicine covering all aspects, from newborns to the growing geriatric equine population. He has performed research on respiratory diseases in horses, focusing on exercise-induced pulmonary hemorrhage (EIPH), inflammatory airway disease (IAD) and recurrent airway obstruction (RAO).
32
horse me n’ s Y a nkee Ped l ar
MAY 2012