Locking stifle

[Nakipa]

I have a nearly 4 yr old ID. He is in light work and is going very nicely.
When we bought him from a very reputable breeder 4 months ago she told me that he had locking stifle. I researched it and he passed the vetting easily and I was not at all worried about it.

A few times when he is going out of the stable first thing his stifle locks but if you give him a second it relaxes and he can then walk normally. I have never seen it lock at any other time.

For the past 8 days he has been at a local livery yard with my other horse on grass turnout whilst we have been away on holiday. They were out day and night on good grass, with small feeds and ad lib hay provided but not eaten because they had plenty of grazing.

Today we went to collect them and the ID would not load into the trailer which has never happened before, he is always a very good loader. As I was standing watching I noticed that as he approached the trailer his stifle locked a couple of times. Eventually after about 15 tries to load he went in.

Since he has been home and turned out he is very uncomfortable on the side with the locking stifle and dozens of times I have seen it lock. This has never happened before when he is out.

I have contacted the livery yard and they say that he was fine whilst there and though he and my other horse did have a bit of fun and were playing a lot as they do at home, nothing untoward happened.

Does anyone have any suggestions as to why it should suddenly be so bad or what might cause it to be so chronic?

Any thoughts welcome.

 

[teddyt]

I expect its because of the time off, even for only a week. Hes also still growing, so its likely that changes in muscle tone are the cause from either or both of these reasons.