How long for shaved patch to grow back?

[Toddlerteaplease]

Cheddar had her dental a month ago. And the hair where they put the cannula in has not grown back at All. It's on her leg. Is this normal?

Sushi was spayed at the end of February and although the op site is covered by fur now, you can see a definite patch where she was shaved. It seemed to take forever to grow to that stage then it all of a sudden grew really quickly.

Sorry that meant to say end of January

Magic had surgery the day after abs she has a thin coating on her face. Though it's easier to see with her as she's black. cheddars undercoat is white.

Wanda has blood tests every 6 months because she has epilepsy. Her fur is shaved again at exactly the point it's completely grown back!
Last lot of bloods was 31st Jan, fur is about a quarter back now.

Decided that I can't relax until she's had her kidneys checked, especially as there had been a change in her vomiting pattern. I think she's ok, but I've got her booked in for bloods this evening. She's not acting like any cats I've known with kidney issues.

Bloods fine!