Your horse has been doing some pretty intensive speed, jumping or cross-country work, and you know he’s hurting up front. He’s reluctant to take one lead, feels different at the trot on that diagonal, sometimes seems to take a bad step. He’s not quite lame, but he’s not right either. He also rests the leg a lot in the stall.
But you can’t find anything wrong. If anything, he looks puffy on the opposite front leg. The leg you suspect has no heat, swelling, or pain on palpation. Examination with hoof testers and flexion tests are negative.
Your vet agrees it’s something in that foot, but nerve blocks through to the ankle are negative. Your vet starts palpating up the back of the leg, along the tendons and suspensory. With the knee slightly flexed and the vet palpating deeply at the junction of the top of the cannon bone and back of the knee, the horse flinches. Diagnosis: A high suspensory problem or a blind splint.
Problems with the suspensory occur more commonly lower in the leg. Overflexion at the ankle — as occurs at speed, landing after a jump, and with hill work — strains the suspensory and its attachment sites. The splint may be involved secondarily because of local inflammation, but the mechanism is probably concussion and/or stretch to the interosseous ligament of the splint bone when the horse bears weight. This is also why the inside splint bone is usually involved. It actually forms part of the knee joint and is subjected to more force.
Some horses develop problems high in the suspensory or splint rather than low, possibly because the ankle has better shock absorption. The reaction in the interosseous ligament of the splint is called “blind” simply because you can’t see it. Likewise, the tight bands of fibrous connective tissue surrounding the knee often prevent visible swelling when there’s suspensory damage high in the ligament, where it attaches to bone.
If the suspensory is involved, jogging the horse off after you stand him with his toe on a block and the ankle dropped down may aggravate the soreness. Ultrasound is difficult to do in this area but will show any damage. Thermography may be revealing, with an obvious area of increased heat noted “bleeding” down the back of the leg from the back of the knee.
Although some vets use local steroid injections for rapid inflammatory control — and in some cases these are warranted — we believe intensive cooling and icing with adequate rest can be equally effective and less potentially problematic in terms of healing.
Give the horse lots of rest and quiet turnout, alone in a small paddock. Aggravation of high-splint problems can begin to involve the knee, and ligament injuries that involve the attachment to bone are slow to heal. Premature work will damage it further.