Laminitis is the result of systemic disease with local consequences in the feet–including mismatch in growth between toes and heels. Ponies on rich pasture seem especially vulnerable to laminitis. The end result is often a discrepancy in hoof growth, in which the heels grow faster than the toe due to compromised blood supply to the inflamed laminae in the toe. This mismatch in hoof growth initially causes an excessively long heel. If the hoof is not trimmed appropriately, and often, the extra heel horn collapses and the heels become under run. If affected feet are left untrimmed for many months, support literally grows out from under the animal and he is walking on the collapsed heels; the hooves become shaped like Aladdin’s slipper, turning up at the toes.
During the summer of 2007 I worked with a rescued 10-year-old laminitic Miniature pony gelding in which all four hooves were severely overgrown. His feet had gotten to the point that he was uncomfortable standing. He spent most of his time lying down, reluctant to get up and walk to water. When he did walk, it was very slowly and cautiously. He had chronic laminitis and reportedly had several episodes believed to be associated with grass overload. The pony displayed a characteristic laminitic stance with forelimbs placed out in front and hind limbs positioned under his body.
The left front foot was most severely affected. All of his heels were underrun, and he was walking on the exterior hoof wall. The sole and frog of the front hooves were visible from the front of the pony.
After an examination to determine his health status and radiographs of his feet, I felt we could help him. Radiographs showed the bones had minimal changes. There was very little degenerative joint disease in the coffin joint; there was minimal bone deformity, even though the alignment was completely off since the hooves were so overgrown. The hoof-pastern axis was broken backward in all four feet.
The next step was to start the pony on medical therapy to reduce pain and inflammation and to help increase blood supply to the feet. He was placed in a deeply bedded stall and maintained on a low carbohydrate diet of orchard grass hay with no grain and supplemented with Farrier’s Formula to promote better-quality hoof growth. Medical treatment consisted of acepromazine twice a day, aspirin orally once a day, and phenylbutazone twice daily. The acepromazine was given for one week, the aspirin for six weeks; then the pony was slowly weaned off phenylbutazone.
When we began working with the pony we contacted farrier Jim Brocato, and we used a radiograph system in which we could take an image and put it on the screen immediately so we could know whether to trim the feet more or not. This enabled us to see whether to take more off one side or the other, or off the toe or heel.
The pony was initially trimmed three times at three-week intervals. Trimming was aimed at correcting the coffin bone alignment relative to the ground, hoof capsule and bony column, and to relieve tension in the deep digital flexor tendon by getting the hoof and pastern angle more normal. In the first and second trimmings we tried to take as much of the excess hoof off as reasonably possible without causing the pony discomfort. Most of the excess hoof grown was trimmed using hoof nippers, with intermittent (and cautious) use of a blow torch to make the dry, hard sole more flaky and easier to remove with a hoof knife.
Results of the first trimming were remarkable. The feet looked much better than we’d hoped. We didn’t want to be too aggressive with that first trim because we didn’t want to make him more sore, but the farrier did a great job. Radiographs showed that more trimming was needed, but we deliberately halted the trim at that point. His feet didn’t become that overgrown in a day, so we weren’t going to try to correct it all at once.
After the First Trim
The transformation was rewarding, however. The pony was able to stand with his legs positioned directly under his body, thus more evenly distributing his weight on all four feet. Mechanically he was walking much better. The hind hooves were close to normal. The front feet were also much better, but evidence of the severe overgrowth was still present and a small amount of sole was still visible, viewed from the front. He continued to rock over the outside edge of the underrun heel of the left front.
We trimmed him three weeks later, again using radiographs to guide us and help us determine the necessary adjustments. The third trimming, three weeks after the second, was more aggressive, focusing on returning the hooves to as normal (angles and appearance) as possible, again using radiographs. After that third trimming he was mildly uncomfortable and we treated him with phenylbutazone twice daily for three days. It took him a few days to bounce back and walk at his previous comfort level, but all four hooves resembled normal hooves. He no longer had underrun heels and for a few days stopped rocking over the outside edge of his left front hoof. Radiographs showed hoof conformation was close to normal, with more normal balance and function. The degree of rotation and sinking of the coffin bone was determined to be mild to moderate in all four feet.
The front hooves, being more adversely affected, will probably never resume their original function and appearance because the rotation and sinking of the coffin bone is largely irreversible, but with proper trimming, they were dramatically improved after just a few weeks and his life was no longer in danger.
Radiographs were performed throughout the first three trimming sessions to help determine necessary adjustments.
Two months after the pony was rescued he was walking very well and appeared to be comfortable with no sign of lameness. He was gradually reintroduced to turnout in a small paddock. He continued to do well and nine months later can walk and trot and is definitely what we would call pasture sound. He is happy and comfortable, walking around nibbling grass, and has been off medication since the first three months.
The hind feet are very close to normal, but his fronts could not be completely reversed because they had been deformed for so long. He walks a little crooked, rolling the left front foot over the outside edge. The farrier still works on him every three to four weeks because if we let him go any longer, the feet get worse and start to develop Aladdin-slipper shape again. The toes of his front feet still want to point up, and that’s how they try to grow. If he wasn’t being trimmed regularly, he would soon have problems again. Keeping his feet trimmed at least once a month is the key to keeping him comfortable. He still walks very carefully and slowly and will never be normal, but his condition is acceptable and humane.
This case summary was written by Dr. Cassar and Heather Smith Thomas. Also contributing to this article were Jim Brocato and Robert J. Hunt, DVM, Dipl. ACVS