There are alot of things you can do to see if it resolves his weight issues...
Probably firstly..worm him. I don't know if tapeworms are common where you live, you could ask your vet....if they are, you need a wormer with praziquantel/ivermectin combination in it.....
Secondly, since he is ribby...he needs a probiotic. These supplements are rather cheap and they have worked MIRACLES for my OTTB. I reccomend them for EVERY horse, but certainly for senior or ribby horses.
Thirdly, have his teeth checked by your vet and floated if needed.
Foruth, he could certainly benefit from a weight supplement. We used Cool Calories and it made our boy fat...so it does work for some horses. There are many other weight supplements out there.
Free choice hay is good. Our OTTB went from a body score of 2 to being a bit fat pig on probiotics, Cool Calories and free choice hay with NO grazing, as he was in a dry lot. Imagine: going from body score to to fat pig on DRY LOT.
The reason I think you should get a vet in to look at him is that his appearance and overall health seems to have declined since the last pic, which was when you first got him.
I am certainly not suggesting you are doing anything wrong or are not doing all you could....It would just get me mildly concerned to see a decline like the one in the pics, even though it is mild...it is still a decline from what used to be a healthy appearance (last pic) and he may have some metabolic or other issue that your vet can help you resolve.
He's a very beautiful boy. And you are a fantastic horse owner to care so much and to come here asking for opinions and advice. SO many horse owners are neglectful, and wouldn't notice or care if their horse was thin or had a worm belly.
As a matter of sad fact, some horse owners couldn't care less if their horse lived or died.
You are certainly NOT a bad horse mom, you are a great horse mom...because you care. Your boy is lucky to have you!!!
Last edited by Beauseant; 11-11-2011 at 12:23 AM.