Multi-centrefield trial to evaluate the effectiveness of clodronic acid for navicular syndrome

Reasons for performing study:

Clodronic acid (CA) is a bisphosphonate which inhibits bone resorption through inhibition of formation/dissolution of hydroxyapatite crystals and by direct cellular effects on osteoclasts. The study was conducted to assess the short- and long-term effectiveness of CA for the control of lameness associated with navicular syndrome.

Objectives:

To demonstrate the effectiveness of CA in navicular syndrome. Study design: Randomised, multi-centre, doublemasked, placebo controlled field trial in client-owned horses.

Methods:

Horses with unilateral or bilateral forelimb lameness (AAEP lameness scale grade ≥2); positive anaesthesia of the distal palmar digital nerve(s); radiographic evidence of navicular syndrome and the absence of other causes of lameness were eligible for enrolment. Horses were randomised to treatment groups in a 3:1 ratio of CA to saline control. Treatment was administered once via intramuscular injection at 1.2 mg/kg bwt (maximum 765 mg CA or 15 ml saline). Efficacy was assessed by comparing lameness grades before and after treatment.

Results:

146 horses of various breeds were enrolled at 6 sites in Germany and US. At 8 weeks, horses in the CA group had a significantly higher success rate than horses in the control group (least squares mean 74.72% vs. 3.30%; P = 0.0028). Efficacy was sustained through 180 days in 66% of horses. Adverse events were few and considered to be mild and transient.

Conclusions:

Clodronic acid was safe and effective in navicular syndrome.