Aggression?

Question
I have three female guinea pigs two i got at the same time from petco. The other is a week or two younger.(also got from petco) They have been living in the same cage for over a year without problems but recently like within a couple of weeks the youngest one has become aggressive toward the others. She will chace them around the cage and bite at them. She chews on the others ears. They will both open there mouth at one another. I'm worried that i may have to separate them. I Have a two story cage with food and water on both levels at all times. There is housing for each piggie two one the bottom level and one on the top. Do you have any advice on what to do about this if there is anything? ohh and their cage was custom build and is 2ft by 6ft for each level. The piggie that is most aggressive is the youngest and she picks on both other pigs but most so to one.The one she picks on most has had a sore behind her right ear and it has final healed.I do not know what the cause of her sore was if it was from the one pig or what but i separated her to let it heal after asking my vet about it. any help would be very helpful thanks in advance!

Answer
In most herds there is always one alpha female. She will push the others around to assert her authority. That may be what you're seeing now. If she is not drawing blood I would leave them together.

There is another issue that may be going on, causing the bad behavior on this female. That's the possibility that she has mites and is irritated to the point of being a pain to the other two sows.  

Mites are something that every pig gets, but sometimes they get out of hand and cause the poor pig to be miserable from the constant itching. The first sign you may notice is a bare spot on the top of the back, usually shaped like a 'v' where the pig has been chewing at them.  

If that's the case it's an easy fix. Go to your local pet store and buy a bottle of Adams Dip. It's in a blue bottle with a red top.  It says for puppies and kittens and you will see no mention of guinea pigs. But it has been the treatment of choice by breeders for many years.

I've found that the Adams brand is the most reliable and seems to work more effectively with just one use. It also has a very pleasant fragrance rather than smelling like a flea dip. There are sprays as well, but the key to success is to completely saturate the coat and allow it to sit.  Sprays aren't always the best for this.  

Mix the solution as directed. You can use your bathroom sink to do this. Just put about two or three inches of warm water in the sink, sit each pig in one at a time and pour solution all over the pig being careful not to get it in the eyes or ears.

The most important step is this:  Do not towel dry or use a hair dryer. Put the pig in a small box or carrying cage if you one. Let them drip dry. This is important.  It allows each hair follicle to become saturated, thus assuring the solution soaks into each hair.

If one pig has mites, they all do. It's not a big deal, it's just part of who they are. They will NOT get on human skin or other animals other than guinea pigs. It's a good idea to do this ever two or three months just as a precaution.

The other consideration is whether the bitchy sow is in heat. Sometimes they get so aggressive and disagreeable they will go after their cage mates. This will pass. But you have to watch that the offender does not cause any harm to the other pigs. Typically it's just pushing and shoving, but occasionally it turns into more than just that.  

If you ever need to break up a hair flying fight don't ever reach your hand in to grab one of the pigs. You WILL get bitten, badly.  The best way to break it up is to grab a garden glove and simple give a good smack on the head. That gets their attention and diverts their attention long enough to send each one on the other side of the cage.  Once the hair raising and teeth chattering stops you can safely approach each of them.

I hope this has given you some help and suggestions. It's unusual for them to remain in that constant state of aggression towards their cage mates. If it's just a case of quarreling over who will be the boss that should pass. But again, if there is bloodshed and/or injuries you may need to remove the aggressor altogether. However, that's not usually necessary.