Lice
There are three types of lice that guinea pigs can get. The first type is a slender wriggly insect, white to pale yellow in color, easily visible to the naked eye. The second type is oval bodied and smaller than the first type, they are harder to detect. Both these species are biting lice, they can cause scratching, loss of hair, and scabs, and are usually found round the ears, head, neck, and hindquarters. A third species of lice are very rare. Light infestations are easily overlooked, heavy infestations cause alopecia and rough coat because of excessive scratching. All types of cavy lice are host specific, meaning they need a guinea pig to survive, therefore you need not worry about your family or other pets contracting it.

Treating lice is ussually an easy task. A thoroughly washing with a kitten formula flea and tick shampoo will do the job.

Advantage for cats has also been found to be effective in killing lice infestations. You can ussually buy this through a vet with no prescription. A drop behind each ear and your problems are more than likely solved.

Scurvy
Scurvy is caused by lack of Vitamin C in the diet. Guinea pigs do not produce it themselves so therefore require a diet rich in this vitamin. Some signs of scurvy are: lethargy, weakness, stiff joints, no appetite, weight loss, diarrhea, rough coat, and tenderness to touch. Average adult guinea pigs require 50mg of Vitamin C daily. Guinea pig pellets ussually have added vitamin C, though not an adequate amount to be sufficient. Most pet stores carry liquid supplement drops to put in their water. You also need to provide a diet rich in fruits and veggies that have a high vitamin C content.