Strong suspicion of bone changes, ideally confirmed by radiographs, MRI, CT, or scintigraphy, is typically the determining factor for treatment with clodronate.
Case selection with medical imaging
When determining if a horse with lameness issues is a good candidate for treatment with clodronate, the panelists generally agreed that radiographic evidence of bony inflammation (bone remodeling or osteolysis) is the strongest predictor of treatment success. For that reason, MRI radiography could be one of the diagnostic modalities in determining whether or not to proceed with clodronate treatment in horses with navicular syndrome.
However, practitioners should not rely on medical imaging in isolation for case selection; it should always be used in conjunction with a comprehensive clinical exam that may include hoof tests, a palmer digital nerve block, and lameness and pain assessments to determine if concurrent soft tissue injury is involved.
“If you see some radiographic changes, you're probably going to reach for some [clodronate] and give that a go. But there's so many horses out there that also have radiographic changes with a concurrent tendon injury, concurrent collateral ligament, and cartilage damage […] you also have to correlate the degree of lameness. If your horse is lame at a walk, you might want to dig just a little bit deeper, versus the horse is kind of a little bit sore and been that way for a while.”
Case selection without medical imaging
Despite the apparent benefits of including radiography as part of the diagnostic workup for navicular syndrome, cost is a major reason why clients may decline it for the initial workup. Due to the safety profile, positive results, and the economical costs of clodronate, the panelists concur that it is reasonable for the practitioner to make an educated guess to decide whether or not to proceed with clodronate treatment based on clinical indication.
“[Clodronate] has cut down on the number of navicular bursa injections I'm doing […] I don't have a hard time selling that drug to my clients for that use. They're all on board, and the results have been good.”
Medical imaging may not be feasible when clodronate is being considered for the treatment of axial skeletal issues. In addition, especially in older athletes, there are often multiple concurrent conditions that may make it difficult for practitioners to identify the primary issue of concern. In these cases, some panelists have found that clodronate’s analgesic and anti-inflammatory effects can help relieve some secondary and tertiary problems; once those issues have cleared, the practitioner can better assess and address the primary issue.
"Many of the cases that we look at are complicated […] And what's happening in my practice now in some cases, is that they're wanting to clean up this situation or get rid of the mud in the water by giving [clodronate] first […] and what I've found is, in my opinion, some of the secondary or tertiary issues go away."
Practitioners should note that, despite the cost effectiveness and safety of treating with clodronate, success is not guaranteed when treatment is administered without radiographical confirmation or a diagnosis of bone involvement. Panelists agree that clodronate alone will not be an effective treatment for significant soft tissue injury and should not be utilized as a first-line treatment if there is no evidence or suspicion of bone lesions.
“If there's not a bone change [that is] obvious on radiographs, I won't necessarily go to [treatment with clodronate]. We may end up there, but I wouldn't go to it right away.”