“Implementing a bisphosphonate treatment protocol has elevated my practice, our client relationships, and, most important, the prognosis for our navicular patients.” Steve Colburn, DVM
From the time I was a junior high schooler, I knew I wanted to be a veterinarian. My interest in horses began in my late teens when I started volunteering in a large animal ambulatory practice. As my familiarity with horses increased, I came to appreciate them for the athletes they are. That’s why navicular has been such a frustrating disease throughout my career.
During my 35 years in practice, there haven’t been a lot of medical options for managing navicular. In the past, a diagnosis of navicular disease in middle-aged performance or sport horses was usually career-ending. Not only would the horses no longer get to do the job they loved, but also the owners would lose the joy of competing with horses they were invested in financially and emotionally.
Even with the bleak outlook, I did my best to manage navicular, typically by implementing a regimen of a vascular-effect drug like Isoxsuprine or aspirin. I’d also prescribe therapeutic shoeing and look for ways to manage footing by recommending the horse try different exercises on different ground. If horses didn’t respond, sometimes I’d inject a corticosteroid in the coffin joint or navicular bursa. If the pain was still uncontrollable, I might perform a neurectomy.
That was then.
Now with the introduction of bisphosphonates—my treatment of choice is Osphos (clodronate injection)—the prognosis for 60 to 70 percent of my navicular patients has improved significantly. Every day in practice I see a diverse population of equine athletes, everything from Saddlebreds to racehorses to English hunter jumpers to Western performance horses. And every day I see a case of navicular in at least one of them.
Protocol for Prescription
I start working up a lameness case the same way I always did: by putting my hands on the horse, asking the owner a lot of questions and getting a good history. Here’s a little more detail about the typical clinical scenario when I prescribe a bisphosphonate for navicular:
- Consider breed and discipline. Genetics and conformation predispose horses to navicular, as does a horse’s discipline. Western performance horses, especially Quarter Horses, experience higher incidents of navicular, but I see the disease in other event horses as well.
- Confirm foot pain. Like I said, I start with the basics of a complete examination and history.
- Block and image. I do a nerve block and most of the time take digital radiographs.
- Recommend advanced imaging. Because dramatic radiographic changes aren’t always present, an MRI or CT can help differentiate any soft tissue injuries that might be in the heel region. Not all clients are economically able to opt for additional imaging. In those cases, I rely on the history and radiographs.
- Diagnose and prescribe. If the horse shows some evidence of mild to moderate changes in the navicular bone and presents with an appropriate history, I prescribe and administer Osphos according to the product label.
- Monitor clinical response. After injecting Osphos, I recommend clients give the horse some light work and watch the response over the next six to eight weeks. If there’s no positive response or if the horse worsens, I look at a change in course.
Before administering treatment on any horse with any product, I discuss the potential benefits and challenges with clients. With Osphos specifically, I share the information below and ask clients to strictly follow the steps:
- Pause NSAID use. Bisphosphonates can affect the kidneys, especially if used with non-steroidal anti-inflammatory drugs (NSAIDs). I advise my clients to stop giving NSAIDs four to five days before we inject Osphos and to keep the horse off NSAIDs for up to two weeks afterward.
- Hand walk the horse for 15 minutes immediately following injection. This helps minimize the sensitivity horses may experience.
- Observe the reaction. We watch the horse to make sure it’s not experiencing any side effects beyond some potential transient stinging. I’ve administered thousands of doses of Osphos, and I’ve never seen a horse develop a serious case of colic or experience any level of renal failure.
- Call me in six months. My practice sends a six-month reminder after an Osphos treatment, and about 70 to 80 percent of clients respond. When we talk, we openly discuss how the horse is doing. This conversation lets me know when clients are pleased with the results, and sometimes we decide to administer a follow-up dose. Once in a while, a client will say the product hasn’t made much difference in the horse. I welcome this discussion too, because it tells me we may need to look further into a soft tissue issue, for example.
I didn’t buy into Osphos immediately after it was launched five years ago. I’m a creature of habit who leans toward pessimism about new products. I don’t want to be the first—or last—to jump on board. I like a product to be on the market for a while so I can monitor the incidence of side effects and negative responses.
I tried Osphos in just a few cases at first, measuring my patients’ results as well as results in the overall market. As my confidence in the safety and efficacy improved, my use of Osphos grew exponentially. I like that it is a trusted, FDA-approved tool backed by science rather than hearsay. Osphos has dramatically improved navicular prognoses in my patients, and I consider it to be one of the most significant advancements in equine sports medicine.
Problem-solving with clients around issues like navicular is what drives me. I thoroughly enjoy working as a team with clients to get their horses performing to potential. Through tending to a horse’s needs year after year, I develop a relationship with the horse and its owners. These personal relationships are important to me. Finally having a tool to treat navicular is a relief for me and my clients, and it makes my relationship with clients even stronger.
SIDEBAR: My Favorite Case
A client came in with a very nice 15-year-old Quarter Horse that had developed foot soreness. I did the typical workup. Even though the radiographs weren’t bad, the history, blocking pattern and hoof tester results pointed to forelimb heel pain. The client immediately asked if it was time to retire the horse. I encouraged him to give Osphos a chance first. He agreed. I administered Osphos to the horse and didn’t hear from the owner for a couple months. Then he called out of the blue and said, “Hey, I just want to thank you. I went roping this weekend and made five thousand dollars on that old horse we gave Osphos to.” Hearing the horse performed well and they could still compete together made me feel so good. The same client now brings me all his horses for evaluation, and his first question is always, “Does this horse need Osphos?”
About the Author
Dr. Steve Colburn is owner and founder of Creekside Veterinary Service, a four-doctor practice in Escondido, California. Colburn graduated from the University of California, Davis, School of Veterinary Medicine in 1984. His wide range of experience in equine practice includes working with racehorses, broodmares and stallions, gaited show horses, Western show horses, rodeo performance horses, dressage and jumping horses, and backyard pleasure horses. Colburn has a special interest in maintaining horses’ peak performance, and his team of associate veterinarians employs their respective expertise in managing orthopedic, dental and reproductive problems. Colburn prides himself on offering the latest technologies in a comprehensive, caring and cost-effective manner. He and the team at Creekside Veterinary Service avidly support equestrian riding and advocacy groups in their local community.
As with all drugs, side effects may occur. In field studies and post-approval experience the most common side effects reported were signs of discomfort, nervousness and colic. Other signs reported were: renal insufficiency/failure, anorexia, lethargy, hypercalcemia, behavioral disorders, hyperkalemia, hyperactivity, recumbency, hyperthermia, injection site reactions, muscle tremor, urticaria, hyperglycemia and fracture. In some cases, death has been reported as an outcome of these adverse events. The safe use of OSPHOS has not been evaluated in horses less than 4 years of age or breeding horses. OSPHOS should not be used in pregnant or lactating mares, or mares intended for breeding. NSAIDs should not be used concurrently with OSPHOS. Concurrent use of NSAIDs with OSPHOS may increase the risk of renal toxicity and acute renal failure. Use of OSPHOS in patients with conditions affecting renal function or mineral or electrolyte homeostasis is not recommended. Refer to the prescribing information for complete details or visit www.dechra-us.com.