guinea pigs biting a large area of hair off of each other

Question
 I have a few guinea pigs and two of them are exhibiting a rapid thinning of hair on their sides and backsides. I have seen them "biting" the hair off of each other and most of the time they are not whining in any way when the other does it to them. It is giving them an "ill" appearance. What could cause this and is it serious?

Answer
Hello C,

I'm very sorry it has taken me so long to respond. I have been very ill the last few days. Again, I am terribly sorry for the delay. What you are describing is called barbering. This is one of the ways piggies express dominance (though some piggies just like to eat hair). It's really not serious, just very stressful for the owners. Giving them more hay may help, but it will depend on the piggies. The main concern is possible blockage. Giving them lots of hay can help prevent this. You can also buy unscented spray on deodorant and lightly spray them. It makes the hair taste bitter and won't hurt them. However, this doesn't always work either. If they start ripping the hair out and hurting each other (they'll scream if this is going on), you should separate them but as long as they aren't harming each other, they can stay together if you can handle bald piggies. Once again, I'm sorry for the delay in answering.

-kkat
www.geocities.com/abyssinianguineapigs