Thanks for that additional information. She is obviously a dominant female. She likely was close to being in heat when she was spayed or was spayed shortly after. Femalse are quite aggressive during their cycle so it may take about a month to get the hormones stable.
What she needs is extensive obedience training. Until then you should muzzle her to prevent injury to your other dogs. They make basket muzzles that allow a dog to eat and drink and breath relatively normal while preventing bites. Use this when she is around the other dogs or outside with them unsupervised.
Start obedience training. It has to be formal training but not necessarily in a class setting initially though you will want at least one class after she is trained so a trainer can correct any issues that still remain or can fine tune the training methods. The following site is helpful in helping owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
Training helps you gain control over her. The other thing to learn is dog body language. This will help you determine how each dog is feeling and hopefully stop fights before they start. For instance, you notice her hair up and gaze fixed on another dog. Before she acts on her intent, call her to you and then reward her for coming to you You will also need to change how you treat the dogs. Since she seems to be the dominant dog, you need to treat her like the dominant dog. Geed her first, let her out first, show her attention first, etc. Only show the other dogs attention after she has had her fill. I know it isn’t fair to your own dogs, but when you do anything else, it creates conflict between the dogs.
Additional training can also help. Both dogs should be leashed and if one dog even looks at the other dog, a correction should be done. Any sign of aggression including a prolonged look, hair raised on the shoulders, a growl or even a stiff legged walk, should be corrected. A correction is a quick tug of the leash and a firm low toned "NO". Once you have done this couple of times, you should notice the dogs ignoring each other. When that happens, you will want to reward them for the desired behavior. Again, use tasty treats like the hot dog slices. This teaches the dogs that you WILL not tolerate fighting in YOUR pack.
You can start this with her wearing the muzzle but eventually it has to come off, but hopefully by then you will have already got her to the point where you can control her.
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Since there have been recalls on certain foods, please check the following site to be sure the food your animals eat is not affected. If it is affected, contact your vet as soon as possible. Have your dog seen if they have any symptoms.