This is probably the reason for the foal's abandonment, take a look at the off hind, he is dragging his leg.
Those Gypsy Cob feathers don't make it that easy to see but he is suffering from a locked stifle.
If you compare these two photographs, above and below, of the hind leg you'll see that he has dragged his leg along the ground and in the above picture is standing with a bent fetlock.
"Sticky stifles" aren't uncommon at certain stages of a foals development, usually when they are "bum high".
Eggsy 's is exacerbated by his conformation having a rather straight stifle.
Eggsy now has plenty of room to move and as you can see once the stifle unlocks he is perfectly able to get around. Backing a pony up will release the stifle and building his muscles will help improve the condition, 80% of foals that suffer from a locking stifle grow out of it. We're hopeful that with a suitable exercise routine, good nourishment and time Eggsy will recover.
Would you like to help Eggsy?
Eggsy has a GoFundMe campaign to help raise funds for his care, we'd be really grateful if you'd go take a look, share it far and wide via your social media and of course if you can spare some money please donate.
Help Raise Abandoned Foal Eggsy ~ GoFundMe
Thank you, Eggsy and I really appreciate it x