So I reckon that most farmers keep some cheerful, threadbare animal tucked away round the back, away from the road - that they're slightly embarrassed by but they don't have the heart to sell, put down or get rid.

Thread.

A titchy scrap of lamb is born with some defect - legs aren't straight, blind, wobblier than normal. If it's not in pain and has a chance of survival the convo goes like this

"Well, we'll let it take its chance. See if it strengthens up in a day or two".

In a day or two the titchy scrap is sucking and getting stronger.

"Aye, will give it a week or two and see what happens".

In a week or two titchy scrap is bumbling happily around and it then becomes Part of the Scenery of the Farm.

In a few months the wobbly, blind or just downright odd lamb is happily bobbling round the back field with a resigned Shetland as a companion.

Eventually it:
Dies of something unrelated, or
Becomes a family pet and lives to a grand old age siphoning up expensive sheep feed

If anyone points out the odd lamb the farmer says

"Weeeelll the kids/wife/husband/dog didn't want me to get rid of it. What can you do?"

And the weird misshapen sheep lives in luxury for ever and ever until it finally dies of old age and everyone breathes of sigh of relief

End

We had Blind Sheep that used to happily live with the lambs and bobble unsteadily after them around the paddock and sleep next to the ewes who didn't seem to mind his heavy breathing or general dimness. He finally died of old age & the next year we got Scabby ewe