We have 2 female kittens 5months old, they have been neutured

Question

and we have let them outside, one disappeared for 10 hours and has come back but the other cat is fighting and hissing at her. Does anyone have any advice.

Answer 1

just let it be i think she will be fine but if they start to hurt each other than ask you vet at the next check up

Answer 2

She may have come in contact with another cat while she was out.  If I would you i were you I would go to the pet store and buy kitty wipes and they have a freshen up spray that you can use.  Using these on both kittens will neutralize the smells.  It is the scent on the kitten that is making your kitten mad.

Answer 3

The most likely explanation is that the kitten came home from her adventure smelling different.  Cats rely very heavily on their sense of smell to identify friends and some of them can find unfamiliar scents very intimidating.  Things should settle down once the smell has worn off.

A similar thing happened when our male cat hid inside the engine space of a parked car for 2 hours.  When I brought him inside, our female cat took one sniff and then started hissing and attacking him.  She's a bit on the feisty side and it was almost a week before she could tolerate being in the same room as him.  I swapped their bedding and litter trays over on a daily basis to help mix up their scents so that they both had the same smell.  Thankfully they are back to being friends again.