When they are being carried. Guinea pigs generally do not like to be carried or held in certain ways. They do not feel safe and may try to bite the person carrying them to communicate to the person they are not happy. Usually, this bite is just a little nibble. But, if there are additional stressors present, such as children, noise, unusual activity adding to an increased level of unfamiliarity, the bite may be more than a nibble.
	If you are holding them and they have to urinate. Guinea pigs like to potty in private! They do not want to get you wet. If you are holding them, they will generally make their 'need' known. Some will start to fidget; some will try to get away or wriggle off of your lap or towel. Others will give you a nibble on a near-by body part, such as a hand or finger. If you ignore their signal, that signal will usually increase in intensity, such as a stronger nibble, until they give up and do what they have to do, much to their and your chagrin! Guinea pigs average about 15 to 20 minutes before they need to relieve their bladder. Some can go considerably longer, but start paying attention to "signals" at about 15 minutes.
	If you've been holding them a while, they may want to go back! Guinea pigs get tired of being held. They just want to go back to their cage. Respect their wishes.
	When they have mites or some other skin, parasite, or ill condition. Mites make a guinea pig very sensitive to touch. They are in pain from the mite infestation and touching, picking them up, and petting them can cause much discomfort. Their natural reaction is to lash out at the source of the pain and they may try to bite you. If your guinea pig exhibits this behavior coupled with scratching, please take your guinea pig to a vet.

	Some are sensitive in certain areas. Many guinea pigs don't like being touched or petted on their rumps. Just be diligent in determining if this is due to mites or illness rather than a general sensitivity.
	He may be trying to groom you. Guinea pigs groom each other. They will bite or nibble at the other guinea pig. Try offering your guinea pig the flat palm of your hand when he tries to bite. He won't be able to bite the tight skin and you and he may be able to figure it out.
	Children holding a guinea pig improperly. While they may not have done anything wrong, per se, many children lack the right touch with guinea pigs or don't realize that a certain touch or pet or position is uncomfortable or painful for the guinea pig.
	Petting a guinea pig against the lay of their hair. Guinea pigs, like most pets and people, do not like their hair pushed or petted in the opposite direction in which it grows. It can feel anywhere between annoying to painful.

May be unhappy in his housing. If your cage is too small, too confining, your guinea pig may just be unhappy and grumpy. A bored guinea pig stuck in a small cage might resort to chewing anything he can find. Please see Guinea Pig Cages for proper cage size and very inexpensive ways to improve their cage and environment.

In their adolescence as they progress to adulthood.  This is the difficult case, because it takes patience and time. Guinea pigs who exhibit this behavior tend to be between 4 months to 1 year old or young babies. Once they reach maturity, the biting behavior usually fades--usually after about 12 months old. They turn into sweet lap piggies and they are well worth the investment in love and patience. Babies tend to grow out of it in a few weeks to a few months.

Assuming you have ruled out any health or stress reasons for biting, then here are some suggestions:

	DO NOT PUNISH or DISCIPLINE! Guinea pigs will not understand the good and bad cause and effect. Do not tap them on the nose. Do not squirt them with water. Do not yell at them. Do not blow in their face. Do not pinch them on the back of their neck. You will only serve to make them afraid of you. Your reaction of pain is the only signal that is needed to the guinea pig. Follow a number of these suggestions and over time, you should be able to convert a biter into a sweet, lovable lap piggie.
	Make sure there is a wooden hidey hole in the cage for the guinea pig to gnaw on. This can help alleviate the need to bite. Wooden 'chew sticks' are usually ignored and therefore useless. A wooden hidey hole or wooden tunnel is best.
	Make sure your cage space is adequate. Pet store cages are all too small. Please see Guinea Pig Cages for proper cage sizes and very inexpensive ways to improve their cage and environment. Proper cage size can go a long way to making your guinea pig happier and more well-adjusted. If your cage is on the floor, try putting it at table height. Floor cages can be more stressful for guinea pigs.
	Make sure you supply the guinea pig with an UNLIMITED amount of Timothy hay available ALL the time. For young cavies under 4 months old and pregnant or lactating sows, you can mix in 1/2 Alfalfa hay with the Timothy. The Timothy hay also provides the guinea pig with something to chew all day and is needed for their nutrition, gut motility, and grinding down the molars.
	Stuff hay inside a cardboard toilet paper tube, but slit it lengthwise so the pig cannot get his head stuck inside. Some pigs will like challenge of trying to get the hay out of the tube, and they like chewing on and playing with the tube. A good boredom-buster for your cage.
	Don't put them back down after they bite. That will only reinforce the behavior--biting to get their way. Continue holding your guinea pig and pet him calmly. Put him down later.
	Bitter Apple is an anti-chewing spray which can be found in most pet stores and rubbed on whatever body part or place the cavy usually bites. This might discourage the guinea pig from biting.
	Make sure you wash your hands before picking up your guinea pig, especially if you have been handling food. Sometimes they confuse the smell of food on your hands as a snack!
	Pet your guinea pig in the cage without picking him up. Make sure he understands that not all contact is the same, and not as stressful. Start out just by putting your hand in the cage for a while. Let your guinea pig come up to you. Graduate into petting him in the cage. Then, gently corner him and scoop him up. Sit down in a secure place with your guinea pig for lap and petting time.
	When you pick up a guinea pig, wrap him in a towel loosely and make him feel secure. Make sure they cannot see that they are in the air. Provide as stress-free of a situation as possible when handling them (calm and quiet).
	You must give it time. Guinea pigs require patience. You will not see improvement in days. It usually takes weeks and months. Don't expect major changes overnight. Patience, love and tolerance will come back to you many times over.

What can you do to live with biting behavior?

Give your guinea pig a well-behaved non-mating friend to live with. Guinea pigs learn from each other in all manners of behavior. This may help change your cavies' behavior. Not all piggies are meant to be lap piggies.

Little Nippers