Sudden and severe aggressive behavior.

[DriftyAlison0]

Once clinical signs of Rabies appear there is nothing you can do because Rabies is always fatal. I would do a rabies test asap and if it is positive then you would need to have to put her to sleep. But if she had her rabies vac. then it could be due to age.

http://www.cfsph.iastate.edu/FastFac...s/rabies_F.pdf

[*LabLoverKEB*]

Unfortunately, you cannot do a rabies test unless you look in brain tissue. So obviously the animal has to be already dead. There is no blood test to check for the rabies virus.

[Alysser]

She is 10 years old, which is pretty old. She might be showing the early stages of dog alhemizers. I knew a dog who had that, she got it when she was 11 and it got progressively worse. She didn't remember her family members and became quite aggressive too. I am not vet, but this is a serious issue especially seeing as how it came up out of no where. I would get her to a vet.