5 Year old Pitbull Mix Aggression

[K8Ash]

I have a 5 year old Pitbull/Jack Russel mix. She has become increasingly aggressive towards dogs while on a leash, and when cornered in an elevator actually bit the neighbor dog - bad enough for the vet, but not maiming, surgery,etc. Two days later, this morning - she snarled an almost attacked our older lab because he got too close to the kitchen.

She has a history of being possessive but never before has she bitten a dog or human. I don't allow her to play with other dogs or go to dog parks, although she really needs a lot of exercise. She is friends with a cat at my mom's house, and usually likes the other dog too.

Why might her aggression be increasing and what can I do?

[Ghilly]

You need to consult a canine behaviorist ASAP.  Your dog is a mix of two breeds that have both been bred to display aggression toward other animals.  It is dangerous enough to have an animal-aggressive small dog, but when a breed with the strength and tenacity of a pit bull is involved in the mix it becomes a real liability.  You have the makings of a real problem on your hands so please don't waste time trying home-grown solutions, get with a real behaviorist as soon as you can.

Ghilly

[Margot49]

JGF gave you good advice.  You do have to be careful as an aggressive dog can be a liability issue!  Trying a Gentle Leader may be a good idea but you will have to be vigilant knowing your dog may be aggressive.
Consulting a trainer is a good idea.
Read up on NILF dog training.
Try to avoid letting her have eye contact with other dogs.
Also, has she had a bad experience with another dog?
Is she spay?
Vet check and blood work is a good idea and ask that her thyroid be checked.
Good luck and please update

[JGF25]

First of all, no dog should be out unless they are on a gentle leader.  Are you using a gentle leader to walk your dog?  It gives you much more control over them.  Second, you need to see a trainer.  Yes, dogs can become possessive and exhibit guarding behavior.  A certified trainer will be able to help you with this problem.  I also wonder about illness since this has kind of come on all of a sudden.  YOu may want to take your dog in for a check up as well.  Right now, at home, your dog should be on a leash and with you at all times.  He/she has lost the right to be free to roam the house right now.  

As for exercise, if you feel your dog needs a bit more than you can muster up to give them, then get a used treadmill and walk the dog on it.  It is not very hard to train a dog to walk on a treadmill.  Both of mine do it.  Again, a certified trainer can help you with this.