Skinnies most likely are the descendants of a lab guinea pig breed called an IAF Hairless. Which was a spontaneous mutation from PEW (Pink Eyed White) Hartley lab guinea pigs at the Institut Armand Frappier, Montreal, QC, Canada in 1978. IAF Hairless guinea pigs are outbred, euthymic (have a thymus), have a competent immune system and are all PEWs. They were sent to Charles River Laboratories in 1982 to be bred for laboratory use. Some inadvertently entered the pet trade through a breeder in the United States who reportedly crossed the IAF Hairless with Teddies to get the Skinny Pig breed, a variety of colors and broaden the gene pool. Later some breeders started crossing with Americans to improve longevity and health.
Unrelated hairless mutations:
'Skinny' is not a synonym for all hairless guinea pigs, it is a breed that is characterized by hair on the nose and feet and has the same genetic mutation as the IAF Hairless Guinea Pig used in labs. The term 'hairless' does not distinguish a unique animal; it is a descriptive name for a group of different strains of various genetic origin.
(Some have erroneously linked the Skinny to an unrelated hairless mutation that took place at the Eastman Kodak Company in 1979, which had no thymus and were immunodeficient. Those died out years before the introduction of the Skinny. It is also impossible to keep such animals alive outside of strict laboratory conditions).
(The Baldwin breed is another unrelated hairless mutation that originated with a show breeder in San Diego. This breed stems from the White Crested breed, is born with a full coat which falls out completely by adulthood. The Baldwin has a different hairless gene and is not related to the Skinny. The Baldwin was a mutation that took place at the breeder's home).
(There have also been independent spontaneous hairless mutations worldwide in homes as well as in labs).
Average is 4.5 years with a potential of 5 - 6 years with proper care. Some Skinnies have lived to be 7 years old.
It is a common misconception that Skinnies have a weaker immune system than normal. This is not the case. They and their lab ancestors have normal immune systems.
In a lab animal lecture that took place on 11/3/98, Joan Cole, D.V.M., M.S., DACLAM, states: "hairless guinea pig used in dermal studies. normal immune system, just hairless." Official documents from the 1980's also state that the IAF Hairless has a normal immune system. Many documents state that they have had a thymus ever since the strain was first identified in 1978. The thymus is a specialized organ of the immune system.
It has been said that Skinnies have a faster metabolic rate than the haired guinea pigs, this observation may be based on animals that are not healthy or are not kept warm enough. According to Charles River Labs: "We do not have any specific evidence that the hairless guinea pigs is significantly physiologically different than haired animals, but we also have not specifically compared the metabolic rate of the two strains." Consuming more food to maintain body heat is a common phenomenon with some Skinnies, this may be circumstantial (illness or temperature related). One large herd of Skinnies that had been observed over a period of several years was reported to eat twice as much hay during the winter months when temperatures were cooler.
The most important aspect of successful Skinny care (aside from standard guinea pig care) is to keep them warm enough. Other than strong genetics, it is the key to good health and longevity. According to the Ron Banks report, the optimal temperature range for the hairless guinea pig is 75 - 79°F (24 -26°C). According to Charles River Labs, the room temperature should be 70°F, +/- 2°F.
Ceramic heat emitters can be used as an additional heat source. Be sure that they are not positioned too close to the guinea pigs, hay or anything flammable. Also, make sure that your guinea pigs can move away from the heat if they want to.
In addition to this each Skinny should have a cozy sack/sleeping bag. Cozies are essential for Skinnies so that they don't lose a lot of body heat while they are sleeping. This heat conservation cuts down on their calorie burn which helps them to maintain a normal body weight. Plastic igloos do not have enough insulation and are inadequate. Putting clothes on a Skinny (unless it is just for a few minutes to take a picture) is not recommended.
Housing Skinnies above floor level is recommended, because hot air rises it can be cold and drafty on the floor. Always warm up your hands before picking up your Skinny, icy cold fingers and hands on bare skin can be very unpleasant! If your Skinny always sleeps in an upright position with legs tucked in, this can be an indication that he/she is not kept warm enough.
It is a myth that Skinnies need to have their skin oiled. Their natural skin oil is sufficient. It is best to leave the skin alone unless medical treatment is needed. Bathing can dry out the skin and leave it vulnerable. Don't bathe more often than you would a haired guinea pig. Skinnies sometimes get a buildup of skin oil on their backs, removing this can leave the skin underneath dry and chapped. If you do use oil (not recommended), please shampoo it off again, leaving it on does not allow the pores to breathe and could also lead to cysts. Dry skin is not normal for Skinnies and could be indicative of an illness.
Do not use harsh or scented detergents on your Skinnies' cloth accessories, these can cause skin irritations. Running them through an extra rinse cycle will help to remove detergent residue. Since Skinnies have no barrier to protect their skin from urine and dirt, their bedding must be kept clean and dry at all times. It is recommended to use high quality litter/bedding such as Carefresh and spot clean when it gets wet. If you use fleece, be sure that it is the kind that wicks moisture completely. There are different types of fleece and some do not completely wick the moisture/urine and are not the best choice for hairless guinea pigs. You can clean your Skinny with a damp wash cloth if necessary. Using commercial wipes is not recommended because of perfume and other chemicals.
There have been cases of Skinnies that were exposed to heavy
lice infestations yet were unaffected. Theoretically they can get them, but maybe these parasites that lay their eggs on the hair shaft prefer a hairy host. You can treat for lice/mites as you would a haired pig.
Hydration levels can be determined by the skin wrinkles. A few skin wrinkles are normal on Skinnies, a well hydrated Skinny will be mostly smooth, excessively wrinkled skin is a symptom of dehydration.
Skin cancer is very rare, there have been only four cases of skin cancer reported in Skinnies worldwide (Melanoma/skin cancer is not exclusive to Skinnies, any guinea pig can get skin cancer). Their skin may be slightly more sensitive to carcinogens. Thoroughly research the ingredients of any product before applying it to your Skinny's skin. In a recent study moisturizers have been linked to increased incidence of skin cancer in laboratory animals. The use of sunscreens on Skinnies is not recommended, keeping them out of direct sunlight is. Lufenuron accumulates in the fat cells and is the sister drug to a known carcinogen.
Exposed skin makes Skinnies susceptible to ringworm. Bathing can strip off the natural skin oil which forms a protective barrier, leaving the skin more vulnerable to fungal infections. Ringworm can look powdery, flaky, crusty or cause peeling skin. It does not always have the characteristic 'ring' and is usually very itchy. A lab culture done by your vet can help determine if it is ringworm. Small spots can be treated with topical Miconazole 1% or Nizoral shampoo. If your Skinny has spots that recur, spread or cover a large area, take him/her to the vet.
Oral Fluconazole has been used on hairless lab animals and is considered a safe treatment.
Caution: Use of Lufenuron (Program) or Chlorhexidine Gluconate are not recommended for the hairless breeds of guinea pig. The best defense against ringworm is to maintain excellent husbandry.
Most scratches can be avoided. Don't house your Skinny with an aggressive cage mate. Keep nails trimmed as you would any guinea pig. Also use an emery board to smooth off any rough edges of the nail to prevent self inflicted scratches from grooming. Vertical hay racks reduce the possibility of hay pokes to the skin which can lead to abscesses. Make sure there is not anything sharp in your Skinnies' environment, such as zip ties, splinters in wood or grass houses and flashing inside plastic igloos or anything else that you use. If your Skinny does get a minor scratch, use an animal safe antiseptic solution.
The author does not encourage anyone to breed their pet Skinny, this is for information purposes only. There is no money to be made from breeding Skinnies, breeders that have gone into it for that purpose have failed sometimes leaving behind neglected and unwanted animals. To do this properly you would need to keep a large number of animals, which would cost you a lot of time and money to maintain (proper care, housing, food, litter and veterinary care). To maintain integrity Skinnies are out crossed to haired carriers at least every other generation. This is an important step in the breeding process which cannot be overlooked without serious negative consequences. Successive multiple hairless to hairless breeding can produce animals that are smaller, weaker and have a shortened life expectancy due to remutation. Some of these animals may appear healthy at first, but can decline suddenly and rapidly. Inbreeding and close line breeding are very risky and increase the chance of remutation as well. Animals with unknown backgrounds or known genetic faults should not be bred. Cutting corners is unfair to the animal and your carelessness could end up being someone else's heartache and high vet bills.
Skinnies are not hypoallergenic animals. Allergies can be caused by saliva, skin, dead skin debris, hay, litter and proteins in the urine.
Some hairless animals are sensitive to chemicals. Avoid pellets that have additives. Feed organic produce as much as possible. Avoid tap water. Lean toward products/shampoos that have natural ingredients as much as possible. Regular Carefresh is treated with fewer chemicals than the Ultra. However the Ultra does seem to be more absorbent and suppressive of ammonia odor. You can check with your hay and feed company regarding pesticide/herbicide use in their products.
As a breed Skinnies are not predisposed to any particular genetic defects or illnesses. Healthy Skinnies are similar to normal haired guinea pigs except for their hairlessness, with a normal activity level and normal food/water consumption. Even though they may look smaller because of their lack of hair, healthy Skinnies should have a comparable weight to that of haired guinea pigs.
Skinnies can get any illnesses that haired guinea pigs can; after all they are first and foremost still guinea pigs. Not meeting their temperature requirements will cause them to be more susceptible to illness. Just like their haired counterparts Skinnies can be healthy or sickly, this depends on individual genetics, competent veterinary care and you.
Just as the Skinny came about as a spontaneous mutation, the gene responsible for its hairlessness has the capability of another spontaneous mutation or expression of an alternate allele. These spontaneous allelic mutations are responsible for many of the otherwise unexplained illnesses and early deaths that have surfaced in Skinnies.
The hairless gene for Skinnies is harmless in its stabilized form, but Skinnies that have been inbred or bred hairless to hairless over multiple generations have an increased chance of having another allelic mutation of the hairless gene. Other mutations at the hairless locus produce various effects affecting: life span/ageing, growth/size, skin, nervous system, digestive system. It is NOT normal for Skinnies to be small, hyperactive, nervous, eat or drink excessively or have a rapid heart rate. Skinnies that have a strong odor to their feces with no medical cause cited, may have a genetic weakness in the GI system and should avoid hard to digest (chunky) or gas causing vegetables and fruit. Probiotics may also be beneficial to them. However, this can also be caused by the over-consumption of food which can be stimulated by cooler temperatures.
History of the IAF Hairless Guinea Pig:
IAF Hairless used in experiments:
Link between moisturizers and skin cancer:
Causes of animal allergies:
Baldwin pups losing hair:
Lufenuron injection site sarcomas:
More on Lufenuron:
Unrelated hairless mutation in Iran:
British Small Animal Veterinary Association Manual of Exotic Pets, fourth edition, 2005
The Laboratory Guinea Pig, Lizabeth A. Terril, Donna J. Clemmons 1998
Handbook of Toxicology, Michael J. Derelanko, Mannfred A. Hollinger, 2002
R. Banks, USAMRIID Series 17, 1989
Laboratory Animal Management, Rodents, ILAR, 1996
Patricia A. Mirley, Manager, Technical Services, Research Animal Diagnostic Services, Charles River Labs
Guy B. Mulder, DVM, MS, DACLAM, Charles River Labs
Charles W. Parady, Senior Specialist, Technical Services, Charles River Labs