Human artificial selection and breeding practices have, for better or worse, created a huge variation within domestic species. We’re all familiar with different breeds of dogs and cats, but did you know there are different types of guinea pigs? Today we will discuss one of the more unusual types, the skinny pig, and ask if they make good pets. Unfortunately, there are few reliable peer-reviewed sources for information on skinny pigs, and many links to sources are not active anymore. We will thus compile the available information as best we can but take it all with a pinch of salt and refer to your vet if you are unsure. 

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The Origin of Guinea Pigs and Skinny Pigs

Guinea pigs (Cavia porcellus), or cavies, are domesticated rodents originating from South America. Their wild ancestors were first domesticated for food by people living in the Andes mountains around 7000 years ago. Guinea pigs are still commonly raised for food in South America to this day. Their popularity as pets began with the European colonisation of the Americas from the 1500s. (It has been claimed that English Queen Elizabeth I had guinea pigs as pets. And guinea pigs are visible in a 1613 painting by Flemish painter Jan Brueghel the Elder called ‘The Entry of the Animals into Noah’s Ark’). 

Guinea pigs were also popular laboratory animals until the late 20th century. (Hence the term ‘guinea pig’ for something used for experimental purposes). In fact, it was in a laboratory that skinny pigs were first developed.

Skinny pigs are a variety of guinea pig 

Interestingly, most organisations do not list skinny pigs as a distinct breed of guinea pig. They are, of course, best known for their hairless appearance. Reliable sources on their origin are scarce, but most websites claim they were developed in a laboratory in Montreal, Canada. In 1978 the lab bred a group of guinea pigs carrying a genetic mutation for hairlessness. These hairless guinea pigs were bred with normal haired guinea pigs to create skinny pigs in 1982. 

The hairless trait was desirable as the guinea pigs could be used for dermatological testing. Eventually, these guinea pigs were bred privately, and skinny pigs became available on the pet market. It has been claimed that earlier skinny pigs were often unhealthy due to high rates of inbreeding, but that today’s skinny pigs are healthier. There is another type of guinea pig that is hairless, known as the Baldwin guinea pig; which carries a separate genetic mutation that renders them hairless.

It is important to note that abnormal hair-loss (alopecia) can also occur in hairy guinea pigs as a result of diseases like skin infections, over-grooming, parasites, overactive adrenal or thyroid glands, low vitamin C, or bites from other guinea pigs. If your normally hairy guinea pig is starting to lose its fur it isn’t becoming a skinny pig! We recommend speaking to your vet instead. 

Differences in Skinny Pigs 

Temperature and Metabolism

In many ways, skinny pigs are the same as normal guinea pigs – remember they are the same species after all. This means their basic physiological needs are much the same as regular guinea pigs. The one commonly reported exception is their optimum body temperature (20 to 26 °C), which is higher than in normal guinea pigs, owing to their lack of insulating body hair. This means they are also vulnerable to cold snaps, so ensure your house is kept warm. If you don’t want to heat the whole house, their enclosure may benefit from a heat lamp. 

It has also been reported that their metabolisms are higher, owing to the need to stay warm. However, the laboratory that first bred them claims there is no evidence for this (primary sources quoting the lab are not available). 

Hairlessness 

Their most striking feature is their hairlessness. In actuality, the coverage of fur varies. Most skinny pigs will have hair on their nose and feet, while some can have fur extending onto their backs and bottoms. Because most of their skin is hairless, they are more vulnerable to damage, especially sunburn. It is recommended that skinny pigs should be kept indoors in safe enclosures free of sharp corners or anything that could cause damage. If you wish to take your skinny pig outside, this should be done carefully and limited. Some skinny pig carers advise using sunscreen on their skin. Ideally this should be a pet-specific crean; however, avoiding the sun is the safest option, as any chemical not designed for guinea pig skin could cause irritation. 

Skinny pigs should not need to be cleaned any more frequently than normal guinea pigs. Regular shampooing or oiling their skin is not needed – their natural oils and grooming should be sufficient. However, it is important to keep their enclosure as clean as possible to minimise anything that could cause damage or infection to the exposed skin.

The most common skin cancer in hairy guinea pigs are cancers of the hair follicles. It would therefore not be wrong to assume that skinny pigs face a lower risk of this kind of cancer, though there is no evidence of this currently. Other skin cancers are still possible. Being hairless they may be more vulnerable to UV-related cancers, such as melanomas – again, this is just speculation. Avoidance of the sun is still recommended. 

Eye Issues

One study of 10 skinny pigs and 10 hairy guinea pigs found that skinny pigs were significantly more likely to have thick discharge from the eyes, and certain bacteria were isolated from their eyes more commonly than haired guinea pigs. They also found that skinny pigs were more likely to have abnormally facing eyelashes that rub the surface of the eye, inflammation of the cornea of the eye, and debris stuck in their eyes. However, these latter results were not considered significant. 

Thus, it was concluded that skinny pigs are more likely to have bacterial conjunctivitis than normal guinea pigs, and they may be more susceptible to other eye issues. Bear in mind this study was small, and further studies may be needed to prove some of the non-significant data. 

Hypoallergenic?

Some people claim that because skinny pigs lack hair, they can be considered hypoallergenic and thus appropriate pets for people with fur allergies. This is sadly false for two reasons. Firstly, skinny pigs are not hairless, as they have some fur on their faces and feet, so anyone with sensitivity to it will still be vulnerable. Secondly, allergens (the agents causing an allergic reaction) are found in more than just hair; dead skin cells, urine, faeces, saliva, or even guinea pig food or litter can all cause allergic reactions. As with dogs and cats, there is no true hypoallergenic guinea pig.

Breeding

Many websites displaying information on skinny pigs advise that they should not be bred by non-professionals, and not directly bred with another skinny pig over multiple generations. Because of small populations, this form of breeding may result in high levels of inbreeding; thus an increased risk of genetic mutations, illness and premature death. This is why the first generations of skinny pigs were reported to be unhealthy. One website reports that to maintain healthy populations skinny pigs should regularly be bred with haired guinea pigs that carry the hairless gene – this will result in a mix of haired and hairless pups.

We don’t know much about them!

Because skinny pigs are a relatively new creation, and there is little literature investigating their health, there may be other differences between skinny pigs and normal guinea pigs that have not yet been identified.

Do Skinny Pigs Make Good Pets?

Based on the current evidence available, it seems that skinny pigs are not dramatically more difficult to care for than normal guinea pigs. Aside from being mindful of their temperature requirements, avoiding direct sun as much as possible, and keeping their enclosure clean and safe, the care requirements should be the same. If you are a capable guinea pig owner, keeping skinny pigs should not be a challenge. 

Saying that, guinea pigs in general, haired or not, can be more complex than people think. Guinea pigs are often given to children as first pets, but their care can be as complicated as dogs and cats. We’ve written many articles about guinea pig care before, so we won’t go into detail here. Remember that guinea pigs need high fibre diets with lots of vitamin C, companionship (always keep guinea pigs in pairs or more), and room to exercise. Please do your research if you’re a first-time guinea pig owner, particularly if you are choosing a skinny pig.

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