Guinea Pigs should be handled with care. They have delicate bones and if dropped would cause them an injury. However Guinea Pigs are not like smaller animals such as Hamsters because they are much bigger you can hold them with confidence. I feel Guinea Pig's shouldn't be handled by small children. However if the adult holds the Guinea Pig then guides the child's hand to stroke him gently the Piggy shouldn't come to any harm.
You should handle all of your Guinea Pigs as often as possible to build up a bond between you. I handle each Piggy at least once a day. Kornage and Nutmeg love being stroked. Millie, although it would look like she doesn't like it by her shaking of her head and the fact she bites, I like to believe this is all fake and really she does like it. She seems to forget she's being handled after a while and settles down.
As a rule Guinea Pigs do not bite. I just seem to have the nawtiest of all Guinea Pigs and when I say she bites, its more of a nibble than sinking her teeth in.
If you do own a Guinea Pig that shows this kind of behaviour my suggestion to you is to persist but at the same time try to respect that this Guinea Pig just doesn't like being handled. Millie is very timid, I have owned her for 6 months now and over the time her trust in me has grown.
When I am placing my Guinea Pig's back in their cage I find Millie Moozer She tends to try and leap out of my hand. I have found the best way around this is to hold her in my hands so she is facing my stomach, so she goes in backwards. This way she can not see where she is going and doesn't try to leap. We had a nasty experience like this one day when she leapt from about 2ft high and landed on her face. She hurt her face that time but still attempts to leap. The other two are much more calmer about it unless of course they are excited.
I have noticed when handling my Guinea Pigs they become fidgety. This can be after 5 min's or an hour. They start off licking me. Other times they lick me and settle down. However when they lick me and start to fidget and wont rest I put them back in to the cage and 9/10 they have a pee. So I use this as an early warning sign. On occasions when I have had all 3 on me and one does this and I haven't got up fast enough they have then peed on me. As a rule if I keep to this I do not get peed on. Guinea Pigs seem to have some hygiene awareness.
You may notice your Guinea Pig likes to hide inside his house. In the wild they can live in a maze of tunnels and travel from one place to another underground. When you cuddle your Guinea Pig you may find he will like to climb inside your top or dressing gown. You will notice they just hide their face. His theory is if he can't see you then you can't see him. Shh don't tell him that his huge bum is sticking out and the cute squeaking noise he makes when cuddled will give him away! When I have owned new piggie's I have used a lightweight cotton cover to offer them to hide under when being cuddled. You may notice they like to sit on your shoulder and hide in your hair? This is for the same reason as mentioned.
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Article By : http://www.kornage.co.uk/how_to_hold_a_guinea_pig.htm