Like most animals, guinea pigs generally aren't comfortable when they're shivering -- in fact, it usually means that something is wrong. Just like you do, guinea pigs tend to shiver when they're cold, so if yours are doing it, it could be a sign that you need to adjust the thermostat. If it isn't a response to the room temperature, though, you may need professional help.
Guinea pigs are warm-blooded, of course, but that doesn't mean that they can comfortably live in just any temperature. A guinea pig's environment should never be below 65 degrees Fahrenheit -- 65-75 is the ideal range. If the temperature is much higher, he'll be susceptible to heat stroke. Lower, and he could develop a respiratory problem. Carefully monitor the temperature in his room to make sure that it's healthy.
Bathing a Pig
If your guinea pig is shivering after a bath, you should change the way you bath him. Wash him in a shallow bowl of warm water in a warm room -- since water carries heat away from the body, washing him in a cold room is like getting out of the shower and standing in front of a box fan. When you're done washing him, dry him off immediately and thoroughly, as any water left on his body is likely to cool him down, and can make him shiver.
When your guinea pig shivers and you can't regulate the temperature of the room, it's time to move him. It could be an environmental factor -- for example, your guinea pig should never be placed in a drafty area, like near an open window or air conditioning vent. Conversely, he can't be placed in direct sunlight, which makes him and his cage too warm. A shivering guinea pig needs to have his cage placed in an area with consistent temperature and still air.
Getting Checked Out
If your guinea pig is shivering, but the room is the right temperature with no environmental factors, it's time to see a veterinarian. Shivering is a symptom of conditions like respiratory infections, so your pig is probably as uncomfortable as he looks. Getting him checked out ensures that everything is OK, and that if need be, he can take some medicine to help him make a full recovery.
Tom Ryan is a freelance writer, editor and English tutor. He graduated from the University of Pittsburgh with a degree in English writing, and has also worked as an arts and entertainment reporter with "The Pitt News" and a public relations and advertising copywriter with the Carnegie Library of Pittsburgh.