Some breeds require more grooming than others. Long-haired varieties need the most attention, but short-haired breeds enjoy regular grooming too. Also, grooming involves handling, and this is the best way to keep a close look out for skin problems or other health issues.
This Sheltie is one of the long-haired guinea pig breeds. Grooming required!
Guinea Pig Grooming Kit
Longer-haired breeds such as the Sheltie and Peruvian need a comb and a soft brush in their hairdressing kit. Daily grooming is best, and a serious keeper of Peruvian guinea pigs intended for shows will keep their pets' flowing locks in wrappers to keep then clean and tidy.
For an Abyssinian guinea pig, with rosettes of hair that grow out in different directions, an old toothbrush is the best grooming tool.
Long haired breeds all benefit from having the hair around their bottoms trimmed short, otherwise they are forever 'peeing their pants' and looking unsightly!
You don't need to regularly bathe your guinea pigs, whatever the breed, unless you want an extra smart finishing touch before a pet show. However, all guinea pigs have a grease gland in the region where their tail would be, if they had one, and in older GPs, especially males, their coats can become covered in dark grease from this gland. The grease can be loosened with a lubricant such as swarfega (ask your vet, local expert, or pet store about it), and the guinea pig can be shampooed and rinsed afterwards, dignity intact!