A Happy New Year to all the readers from the far north. We seem to have missed most of the bad weather up here, which has plagued the west and south of the country. Here’s hoping to get the worst over now and not in April and May as happened last spring.

One Sunday afternoon just before Christmas, I received a phone call from an owner who was quite distressed. The object of his angst was a young coloured cob called Billy. Billy had a sad past even though he was only about two years of age. He had been bought by another local horse owner who was looking for a companion for his thoroughbreds. That was all fine and well at the outset. However circumstances changed and this owner found that he had no further need of Billy. Sad to say, that left only two options for Billy; namely to sell him if a buyer could be found or send him to the factory.

Billy had been grazing a field beside my client’s house and my client and his wife had become very fond of Billy. When they heard that Billy was for sale, or worse, heading for his waterloo, they decided they might intervene. Standing at a height of 14.2hh now, it was felt he would probably make almost the 15hh and as his temperament was excellent they made the owner an offer he couldn’t refuse. The offer was gratefully accepted and Billy became the pride and joy of my clients next door.

Billy therefore moved across the fence and continued to be spoiled by his new owners. He was a bit on the thin side when they got him and they immediately set about reversing that situation. I was called to check and rasp his teeth. A faecal worm count was performed which revealed a moderate worm burden. We passed a tube and wormed him and advised an improved diet. My clients increased his fodder intake and gradually built up the level of hard feed to supplement him. This was done ever so carefully and sensibly.

Thus when they went out to feed him on this particular afternoon, they were very distressed to find that their cob was in a very sorry state indeed. Although he appeared to be absolutely fine that morning, he now seemed to have had a catastrophic injury and could hardly move at all. The call to me was made and as they do not have any stable with lights, I headed off as soon as I could, so as to avail of the remaining daylight.

When I pulled into the street (that’s what we call the area around a house or yard up here in Inishowen), I could see Billy grazing quite contentedly in the corner of the paddock and I wondered what the panic was. I soon found out. As soon as Billy started to move, the diagnosis became very obvious. I shall try to describe how he walked. Billy’s front legs were unaffected but with each movement of either of his hind limbs, the leg would lift only a few inches off the ground. It would then appear to be stuck and suddenly with quite an audible “clunk”, it would release and the rest of the step would continue quite normally. The whole sequence would be repeated by the other leg at the next step, thus making the usually smooth act of walking a jerky, seemingly painful procedure for the poor animal.

LOCKED PATELLA

The diagnosis as I said was obvious as this type of gait is characteristic of a locking patella or knee-cap (Fig 1).

The knee-cap or patella (good to know if you are a cross-word fan) is held in place by three large ligaments and it should glide nice and smoothly up and down the groove made for it on the lower end of the femur.

What happens in a case like this is that the ligaments and bone are developing at different rates and the patella becomes temporarily locked over the enlarged end of the femur for an ever so brief period of the horse’s step. The joint is therefore not functioning as it should, and with an awkward movement, the patella locks over the femur and the joint locks in a semi-extended state. When another movement is attempted, the ligaments can suddenly free themselves and the leg jerks back into its correct position. This can happen at every step or at other times the animal may go for several steps before being caught again. It looks quite dramatic, but actually the condition is not at all painful for the horse.

Billy was certainly the youngest horse I had seen with this condition and as both of his hind legs were affected, you would definitely not want to be on his back!

The owners were initially very disappointed when I told them what was wrong but the news was not all that bad in the end. As he is so young and had been poorly done when younger, I feel that the new owners’ good feeding and care would help Billy pull through.

He had gone through a growth spurt but his ligaments had not quite matched his bone growth. The joints were just growing in size and the ligaments needed to stretch a little. I consulted a colleague and then suggested to the owners to keep Billy in controlled work for the present.

That entailed hand walking and slowly starting to get him fit. The purpose of this is to build up the muscles of the hindquarters and allow the bones and ligaments time to adapt to each other’s growing size. As he still had a considerable amount of growing to do, it is hoped that he will grow out of this and will go on to give his owners plenty of fun and enjoyment as they ride him.

So it is nice to start off the year with a good news story and I can report that even with a few weeks of strengthening exercise, the owners are seeing a good improvement in Billy’s condition. We expect him to make a full and uneventful recovery. One note of caution though is that if this condition were to develop later in life then the outcome can be different.

In certain cases surgery is performed but we usually try to avoid this if at all possible. In this case, Billy needs no surgical intervention and continues to go from strength to strength on a daily basis.

Anne Scott MVB MRCVS is a member of Veterinary Ireland Equine Group and is in practice in Inishowen Equi-ai Centre, Tulnaree House, Carndonagh, Co Donegal

Email: hq@vetireland.ie

Telephone: 01- 4577976