Ask Your Veterinarian Presented By Kentucky Performance Products: Dr. Larry Bramlage On Bisphosphonates In Young Horses – Where Are We Now?

Veterinarians at Rood and Riddle Equine Hospital answer your questions about sales and healthcare of Thoroughbred auction yearlings, weanlings, 2-year-olds and breeding stock.

Question: You first raised the alarm about the potential drawbacks of bisphosphonate use in young racehorses several years ago now. Where are we with these drugs now?

Dr. Larry Bramlage, Rood and Riddle Equine Hospital: In 2016, we began talking to our clients about a phenomenon that we were seeing more and more frequently in young racehorses. The problem was being seen in all common bone injuries that we encounter in the racehorse from dorsal cortical stress fractures to condylar fractures to the very common subchondral bone inflammation/bruising of the distal cannon bones. In some horses, orthopedic injuries were not healing or healing very slowly compared to what we expected. Clinical experience, retrospective studies of success rates, and published papers has given us pretty solid evidence of what to expect as the healing time with the treatment of the commonly encountered racehorse conditions. But suddenly some horses were taking three or four times the time expected to heal and a few never fully healed. The number of these slow healing injuries continued to grow during 2015.

As we began assessing the histories of horses where the aberrant healing was occurring, many had a history of bisphosphonate use as yearlings to improve the radiographs for sale or as a racehorse during a bout of lameness. So, we began discussing the findings and informing veterinarians, trainers, and owners of the possible detrimental side effect of bisphosphonate use. Veterinarians in many locations were making the same observations of disturbed healing and possible increased injury rates in young training horses of several breeds.

Bisphosphonates were approved in 2014. In 2015 we began to see storms of slow healing fractures and slow healing distal cannon bone subchondral bone inflammation/bruising. That led to the suspicion that bisphosphonates may be the reason.

Bone healing is a two-phase process. The bone bridges the fracture gap with new, poorly-organized bone that can be formed very quickly. Then it remodels the stabilized fracture back to the bone's pre-fracture architecture. Once the fracture gap is filled, the bone damaged by the fracture and the newly-deposited bone are removed and replaced with the appropriate trabecular or cortical bone, depending on the structure involved. This process involves two cell types — osteoclasts which remove bone and osteoblasts which make bone. As the osteoclasts remove the weak bone, the osteoblasts follow immediately behind to reconstruct the normal bone. The anatomy varies depending on which bone is injured and where it is injured, but bone is one of the few tissues capable of perfectly replacing itself when injured.

Bisphosphonates kill osteoclasts. It bonds to the surface of bone and when the osteoclasts try to remove the bone that needs to be replaced, they die after ingesting the bisphosphonate. This arrests the remodeling process and stalls bone healing by stopping the remodeling phase of healing. This is true for macro injuries such as fractures and for micro injuries which result from routine training. The injured bone can make new bone but it can't be remodeled without osteoclasts to clear the way for the osteoblasts.

Osphos, one of two bisphosphonates FDA-approved for use in horses four years old and up

So what good are bisphosphonates and why were they developed? Bisphosphonates were developed to arrest the hormone-driven bone remodeling which is common in post-menopausal women who get too little exercise. The hormonal driven remodeling removes an inappropriately large amount of bone and weakens the skeleton, especially the vertebrae, which when weakened can result in the “dowager's hump” spinal deformity. The bisphosphonates were given to prevent the removal of the bone by killing the osteoclasts.

But bisphosphonates also have another effect. They cause non-specific pain relief, analgesia, in bone. This led to their use to manage pain in bone tumors in people, especially in cancer of the spine. The mechanism is still unclear, but the analgesia is significant and non-specific so if you give it systemically it will help manage the pain no matter where the tumor is located. This analgesia led to the use of bisphosphonates to manage lameness in horses. The proposed mechanism is that it stops excessive bone remodeling in sites of lameness by arresting bone removal. Whether blocking bone re-absorption or a primary analgesia is the mechanism of action is still debated. The blocking of bone re-absorption led to use to try and increase the density in the skeleton by stopping bone loss to the remodeling process. So, bisphosphonates gained popularity to try to increase the density of bone in bone remodeling sites such as sesamoids and navicular bones. And, they became popular as the perfect lameness treatment; it is effective if the lameness originates in the bone, and you don't even have to know the site of origin.

But there is a price to be paid. Killing the osteoclasts prevented the normal bone remodeling necessary to maintain a developing skeleton (e.g., the young training racehorse). This retards adaptation to training, potentially increasing the susceptibility to injury, and it nearly arrests the remodeling process that is the second phase of bone healing in a fracture or in trauma to the bone.

The difficulty is if a horse is given bisphosphonates it binds to the interior surfaces of bone and can persist two years or more. So many horsemen weren't even aware, when a horse arrived for training, that there was a history of bisphosphonate use.

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To their credit, most horsemen and veterinarians quickly understood the risks of bisphosphonate use and the use rapidly declined over the next two years in young training horses. The drug still has a place in certain conditions in older horses, but it does not in the young training athlete. It can be dangerous to the horse's career and their resistance to injury. It is approved by the FDA for horses with navicular disease who are four years old or older.

So, where are we now? Sales companies and racing jurisdictions have stepped in and outlawed the use of bisphosphonates in most venues. Currently we still see an occasional horse with a fracture that shows disturbed healing but there is nowhere near the incidence of the problem that was occurring in 2015 and 2016. Veterinarians, owners, farm managers and trainers appear to have mitigated the use of bisphosphonates and should be credited with their response to protect the health and welfare of the horses. Sales companies and regulatory agencies have done their part and the current situation appears to be generally free from bisphosphonate use in the young growing and training horses. A horse that we suspect is showing signs of bisphosphonate treatment in the past still presents occasionally, but not regularly any longer. I suspect bisphosphonates are still intermittently used when a horse does not respond to common treatments.

To all of our credit, this has been a positive response to an initially unknown complication of treatment that was detrimental to the racehorse. For all of the things we wring our hands about that we have trouble changing, this is one we could, and did, circumvent for our good and for the good of our athletes.

Dr. Larry Bramlage of Rood & Riddle

Larry Bramlage is a 1975 graduate of the Kansas State University College of Veterinary Medicine (DVM) and received a Master of Science degree from Ohio State (MS) in 1978. He holds a Diploma of the American College of Veterinary Surgery (Diplomate ACVS). 

Bramlage is an internationally recognized equine orthopedic surgeon, and is a senior surgeon at Rood and Riddle Equine Hospital in Lexington, Kentucky. He is a past President of the American Association of Equine Practitioners, and of the American College of Veterinary Surgeons.

In recognition of his dedication and contribution to Thoroughbred racing, Bramlage was awarded the 1994 Jockey Club Gold Medal for contributions to Thoroughbred Racing in the United States. He is also a past chairman of the Research Advisory Committee of the Grayson-Jockey Club Research Foundation and serves on the Board of Directors for that organization. His additional honors include the 1997 Tierlink Hochmoor Prize for his work regarding the internal fixation of fractures, the 1998 distinguished alumnus award from The Ohio State University, Alumni Fellow Award from Kansas State University, a British Equine Veterinary Association's Special Award of Merit, and the American College of Veterinary Surgeons Legends award for the development of the fetlock arthrodesis procedure for horses in 2009, and the Thoroughbred Club Testimonial Award in 2014. He has received the American Association of Equine Practitioners Distinguished Service Award twice. He was elected to membership in the Jockey Club in 2002 and to Distinguished Lifetime Membership in the American Association of Equine Practitioners in 2010.

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Ask Your Veterinarian Presented By Kentucky Performance Products: Hay In Nets Vs. Hay On The Ground

Veterinarians at Rood and Riddle Equine Hospital answer your questions about sales and healthcare of Thoroughbred auction yearlings, weanlings, 2-year-olds and breeding stock. Email us at info@paulickreport.com if you have a question for a veterinarian.

Question: Hay nets or hay on the ground – which is better for the horse's respiratory tract?

Dr. Kate Christie, Rood and Riddle Equine Hospital: The hay net can be a useful tool in equine management. It can limit hay wasting, slow down horses who eat large volumes of hay quickly, and be a great way to make a smaller volume of hay last longer when trying to achieve weight loss. Ensuring horses have consistent access to forage may also have some benefit in managing and preventing gastric ulceration. So, should all horses use a hay net? The answer, as always, is that it depends on the situation and the individual horse.

Despite their advantages, hay nets are not appropriate in all cases. Studies have shown increased airborne particulate exposure in horses fed from hay nets as compared to those fed hay on the ground, making them less suitable for horses with inflammatory airway conditions unless the hay is steamed prior to feeding. Hay nets may also force the horse to eat in unnatural positions, adding stress and strain to the back and neck. The raised hay net also prevents the horse from eating in a natural grazing position, which may present a problem for those horses who are unable to properly protect their airway, such as those horses who have undergone surgery for laryngeal hemiplegia or roarers.

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Special consideration should also be given to horses with ophthalmologic issues, as very high hay nets may increase the risk of corneal ulceration and contamination. This may be a larger problem during shipping when hay nets are often hung high and windy conditions may lead to hay and particulate matter getting in the eyes.

As with any piece of equipment, care should be taken to ensure that the hay net is safe to use. Hay nets should be avoided in stalls with mares and foals, as foals are particularly adept at getting their feet stuck places they do not belong. Small hole hay nets may be safer, but care should always to be taken to make sure they stay full as an empty hay net can cause more harm than good. Special consideration should also be given to horses with shoes – it is not unheard of for a horse to catch a shoe in a hay net and become stuck.

Overall, the decision to use or not use a hay net is an individual choice. Hay wasting, weight loss, and concerns for gastric ulceration may be good reasons to choose to use a hay net. Horses with abnormal throats, ophthalmologic disease, or those accident-prone friends of ours who are always getting stuck places may be a little bit safer grazing from the ground. With so many options available, there is a solution for every horse. As always, if you have questions or concerns about using a hay net, ask your veterinarian.

Dr. Kate Christie

Dr. Kate Christie grew up in Halifax, Nova Scotia, where she developed her love of horses, actively competing in the show hunter world and watching Standardbred racing with her grandfather. She received her undergraduate degree in life sciences as well as a master's degree in pharmacology and toxicology from Queen's University in Kingston, Ontario, where she continued her riding career and further developed a passion for veterinary medicine. Kate graduated from the North Carolina State College of Veterinary Medicine in 2014 and went on to complete a year-long rotating hospital internship at Rood and Riddle Equine Hospital (2014-15) prior to entering a Large Animal Internal Medicine Residency at the University of Georgia. She became boarded in large animal internal medicine in 2018 at the completion of her residency program. Kate remained at the University of Georgia as a clinical associate professor for one year and is excited to be returning to Lexington to join the Rood and Riddle internal medicine team. Her professional interests include gastrointestinal disease, infectious and non-infectious respiratory disease, and equine pharmacology. Outside of work, Kate enjoys spending as much time as possible with her retired show jumper, Skye. When not in the saddle, she enjoys trail running, hiking, and traveling with her husband.

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Ask Your Veterinarian Presented By Kentucky Performance Products: How To Pick Up On Signs Of Discomfort From A Stoic Horse

Veterinarians at Rood and Riddle Equine Hospital answer your questions about sales and healthcare of Thoroughbred auction yearlings, weanlings, 2-year-olds and breeding stock.

Question: Some horses can be really “stoic” when they're experiencing pain or illness. How can an owner pick up on subtle signs of pain in a stoic horse?

Dr. Jordan Kiviniemi-Moore, Rood and Riddle Equine Hospital: Stoicism has an evolutionary advantage for horses, as it helps them avoid being singled out by predators. As such, horses may conceal substantial levels of pain and carry on without dramatic symptoms, making it easy to miss subtle signs that reflect underlying discomfort. It is also important to recognize that certain common signs such as stiff movement or a squinty eye are in fact a reflection of pain, even if the horse is bright, eating, and otherwise behaving normally.

Knowing what is “normal” for a particular horse will help owners pick up on small cues that may indicate an issue. Horse owners may notice subtle changes in behavior such as decreased enthusiasm for feed, slower or reluctant movement, or uncharacteristic separation from the rest of the herd or group of horses. The horse may become “girthy” or fussy when being bridled, or very reactive under saddle. Such behavior alterations can also occur in the absence of physical discomfort, but ruling out underlying pain and physical causes should be among the first steps in investigating behavior changes or training issues.

Additional signs of generalized underlying pain include lethargy, low head carriage or abnormal posture, shifting weight, and bruxism or teeth grinding. The “horse grimace scale” was developed by researchers who correlated pain levels with changes in equine facial expressions such as squinting, stiffly backward ears, and strained mouth and nostrils. This is particularly helpful to assess discomfort following medical procedures or for horses suffering from ongoing issues such as chronic lameness.

Learn more about the horse grimace scale here.

Subtle signs of pain often correlate with the underlying issue and affected body system. In my practice I most commonly see horses dealing with musculoskeletal and hoof pain, gastrointestinal pain, and ocular pain. Dental pain is also quite common and can be difficult to recognize. Musculoskeletal pain often manifests as an altered gait (i.e., stiffness or limping), failure to keep up with the group of horses, and lying down excessively. Horses suffering from ocular pain may squint one or both eyes or have increased redness or discharge. Of course, the more severe manifestation of gastrointestinal pain is overt colic signs such rolling, pawing, sweating, and flank-watching, but more subtle signs include decreased appetite, lethargy, and grinding teeth. Horses suffering from dental pain may become fussy with the bit, drop feed, act reluctant to accept treats, or seem to chew predominately on one side of their mouth.

Horses have evolved to eat, watch for predators, run when needed, and keep up with their social group, and most will attempt to maintain and preserve these activities even in the face of discomfort. If you notice uncharacteristic behaviors or changes with your horse your veterinarian can help you assess comfort level and also examine for underlying painful conditions. Together you can construct a plan to evaluate problems and optimize performance and quality of life for your horse.

Dr. Jordan Kiviniemi-Moore

Dr. Kiviniemi-Moore grew up in Lexington, Ky., pleasure riding and dreaming of becoming a veterinarian. Living in central Kentucky presented Dr. Kiviniemi-Moore with wonderful opportunities from local veterinarians who fostered her desire to become one herself.

In 2010 she graduated from Transylvania University with a BA in Biology and earned her DVM from Auburn University College of Veterinary Medicine in 2014. She completed a rotating equine internship which included internal medicine, surgery, and ambulatory rotations at the University Of Missouri College Of Veterinary Medicine in 2015. Her areas of interest include theriogenology and primary care.

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Ask Your Veterinarian Presented By Kentucky Performance Products: Laminitis Vs. Navicular Syndrome

Veterinarians at Rood and Riddle Equine Hospital answer your questions about sales and healthcare of Thoroughbred auction yearlings, weanlings, 2-year-olds and breeding stock. Email us at info@paulickreport.com if you have a question for a veterinarian.

Question: What are some of the differences in treatment and prognosis for laminitis vs. navicular syndrome?

Dr. Craig Lesser, Rood and Riddle Equine Hospital: Having the diagnosis of laminitis or navicular syndrome can be terrifying. The diagnosis of either disease has traditionally been considered to be career-ending. However, in recent years with advances in medicine and farriery, many of these horses can return to their previous careers.

The diseases are, in many ways, polar opposites. Most laminitis cases involve inflammation of the dorsal lamina and pain in the toe, whereas navicular syndrome exhibits pain in the back half of the foot.

There are a variety of medical treatments to help reduce inflammation and slow the progression of the disease. However, mechanical stabilization in the form of therapeutic farriery is essential for a positive outcome. The basics of therapeutic farriery are to transfer loads away from structures that hurt to structures that can handle the extra load.

In regards to laminitis, this means protecting and unweighting the toe and recruiting the frog and bar into load sharing, in addition to decreasing the tension on the deep digital flexor tendon (DDFT), which is pulling against the inflamed lamina, causing the rotation. Early intervention is critical. When the condition is treated aggressively before there are any radiographic changes, we will hopefully prevent rotation and get us back to performance faster. However, once there is rotation, it takes a full year for a new healthy hoof to grow out completely. While shoeing these horses, it is essential to have your veterinarian and farrier work together and be willing to change the plan depending on the horses' response to therapy. There are many different shoeing options with varying application techniques, making treatment very much an art, and what has worked for one horse may not work for the next.

Horses with navicular syndrome can have many of the same concepts apply. Reducing concussion through the back half of the foot, where they are painful, can be achieved with various applications, including pads, heel plates, or floating of certain aspects of the foot. Reduction in the tension of the DDFT as it runs over the navicular bone is often vital, as the tendon uses the bone as a fulcrum for leverage. This can be achieved with stagnant wedges or mechanical wedges with something like a rocker shoe. However, no matter what is placed on the foot as an apparatus, if the trim isn't correct, they will not function properly, which is why sometimes radiographs can be helpful in guiding this therapy.

Dr. Craig Lesser

Suppose your horse is diagnosed with either of these. In that case, it is important to be aggressive not only with medical therapies but also with mechanical therapies to ensure your athlete makes it back into performance or even so that they have a long and healthy life.

Dr. Craig Lesser, CF graduated from Colorado State University College of Veterinary Medicine in 2015.  Following the completion of an internship at Anoka Equine, he moved to Lexington to complete a podiatry fellowship at RREH and has continued with us as an associate. As an extension of podiatry Dr. Lesser has an interest in lameness and imaging. 

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