Dcat1 is a very quiet, quite timid little tabby. Yesterday DH noticed she was licking her leg a bit but it was all v busy last night and because she was eating fine, using the cat tray and coming to sit on my lap for purry cuddles I didn't think anything of it
She was holed up in one of her favourite resting spots this morning, hopped out for breakfast then went straight back for a snooze
When we came back home at lunchtime ds1 said it looked like there was something wrong with her leg. She's got a deep, jagged cut on her hind leg (on the equivalent of her shin) and has managed to lick all the fur off it. It definitely wasn't like that last night as she was playing a rolling around wrestling game with one of the dc and there's no way we could have missed it
Anyway, rushed her off to the emergency vet - somehow she's managed to get her leg caught on something (vet said it looked like barbed wire!), it's infected and she might need surgery 
She's home at the moment after having had ABs and anti-inflammatory injections and I have the joy of trying to give her tablets plus bathe her leg with salt water 
Back to our usual vet on Tuesday to see if they need to operate
The silly thing didn't behave any differently at all - she's not been limping, not off her food, wanting cuddles - if she'd just let me know there was something wrong it wouldn't have had to get so bad :(