6 days box rest

My poor baby has done something to his left knee. It's hot and swollen and even with 3 days of box rest it didn't go down and he was getting more and more lame and had developed lameness behind and was very reluctant to walk out of his stable which is so unlike him so last night I called the vet. She was concerned that with 3 days box rest and cold hosing the swelling, heat and lameness hadn't gone. What was also worrying was that he was now lame behind and showing signs of tying up including tight muscles on his quarters and muscle tremors even though he's done no exercise for about a week.

She injected him with a strong pain killer and anti inflammatory, said to keep him in for another 6 days and has given me bute to give him in the morning and evening. If, after the 6 days are up, he's still got heat/lameness then he has to go for x-rays to see if they can see what's wrong.

After his bute he's more or less sound but the swelling/heat still hasn't gone at all and he's definitely not right but fingers crossed it goes back to normal before the 6 days are up.