We live in Uganda. A female cat "adopted" us and presented us with three kittens in December. We had her neutered when she came in heat again. She has been busy grooming and hunting for the kittens. She will wait till they eat before eating what they have left. They have all had their shots.

Last Sunday a 3 month old kitten appeared. This kitten has been well cared for and is very tame.

The mum is now displaying very aggressive behaviour to this kitten but also to her own 3. She still hunts and calls for the kittens to eat. She still waits at feeding time for all of the kittens to eat. But, if she walks buy anyone of the four kittens she attacks them. She is far less affectionate to us as well.

Is this a result of the introduction of the kitten or coincidental? Will it pass? Should we be calling the vet?