It`s a phrase quite often bandied about, but it can be difficult to explain.
Bridle lameness is an asymmetric movement in the horse that simulates lameness either when the horse is ridden, or wearing tack. Bridle lameness can be psychological from the horse – they don`t feel comfortable in their tack, or they lack confidence in either rider or tack, or are remembering a painful experience. Or it can be a result of resistance from the rider`s hands or resistance to the leg and seat aids.
Bridle lameness is different to a true lameness because it is not caused by pain. A true lameness causes an irregularity of gait due to the horse trying to “save” that leg and consequently transferring more weight onto their good limbs. Bridle lameness can happen in the fore or hind legs and can either be seen by a horse rushing through the bridle or raising his head, hollowing his back, and not going forwards.
Sometimes a horse, especially a nervous one, can appear bridle lame under a new rider, until he builds his trust in their hand or body language. Perhaps a change in bridle or tack can cause the bridles lameness, especially if the bit is harsher and the rider`s hands do not compensate by becoming lighter. A horse ridden from the hand instead of the from the leg can develop a swing in his head and neck, causing him to bob up and down and look lame.
Sometimes just warming the horse up, and encouraging them to move forwards on a loose rein can help eliminate any bridle lameness because the horse does not feel restricted and can relax his muscles so that his hind legs come under and he works correctly.
If a horse is presented lame, and bridle lameness is suspected then it is a good idea to strip him of his tack and lunge or trot him up on a hard surface. I read an article about a horse with extreme bridle lameness who still appeared lame when lunged in a bridle, however it became sound when lunged only in a headcollar, which means that there is a psychological factor in this problem.
If a horse shows up lame when ridden by just one person it may be the rider who is causing the lameness, so another rider hopping on can be useful in finding the root cause, and then the original rider can work on the causative factor.
From here, I would strip the tack back to the bare bones – snaffle bridle, cavesson noseband – and perhaps hack the horse for a couple of weeks to get the horse confident, and help them forget about the arena and school work, which could be the triggering factor. During this hacking time it is a good idea to get the usual checks done; saddle, back, dentist, etc.
Then the school work should be introduced at the horse`s pace. Firstly just trotting around a couple of times after a hack. If all is well then next time a light contact can be picked up and work can begin slowly so that the rider, or observer, can pinpoint the moment that causes bridle lameness – is it a particular transition, or one rein more than the other, or on a corner or bend. Then the rider can work on improving the horses ability and confidence in that area. Sometimes professional help is needed for both the horse and rider!
Fixing a bridle lame horse can take a long time and requires lots of patience as you are not just fixing a physical issue and waiting for tissue to repair, but retraining the horse`s psychological response to the rider and tack.