Chin sister spraying each other

[Sage]

I have two sister chinis that are about 4yrs and I have had them 3 yrs. Recentlly thy have been barking at night at each other, run crazy in the cage and spraying more then usual. Its crazy behavior for them. It has been hotter then usual up here but I thought our place was pretty cool. Im not sure if thats effecting them.
Any suggestions on what could cause this? I got them from a friend and was thinking maybe seprating them for another family member. They have always been fighting just not this bad. And one always has missing hair chunks every couple of months.
With our state move soon I worrie about them.

 

[Stackie]

You are receiving some pretty vivid warning signs that it is time to separate them. They are obviously not getting along anymore and this could escalate into something much worse- serious injury or death.

Sometimes chins can be together for years just fine, then decide one day they no longer like each other and turn on one another.

 

[Cuddlebug]

I agree. They probably should have been separated a while ago. Missing large patches of fur is not normal for chins that are bonded. Please, separate them before they really hurt or kill each other.