Guinea pig

A silver agouti guinea pig eating grass

Grass is the guinea pig’s natural diet. Their molars are particularly suited for grinding plant matter, and grow continuously throughout the animal’s life. Most grass-eating mammals are quite large and have a long digestive tract; while guinea pigs have much longer colons than most rodents, they must also supplement their diet by coprophagy, the eating of their own feces. However, they do not consume all their feces indiscriminately, but produce special soft pellets, called cecotropes, which recycle B vitamins, fiber, and bacteria required for proper digestion. The cecotropes (or caecal pellets) are eaten directly from the anus, unless the guinea pig is pregnant or obese. They share this behaviour with rabbits. In older boars (the condition is rarer in young ones), the muscles which allow the softer pellets to be expelled from the anus for consumption can become weak. This creates a condition known as anal impaction, which prevents the boar from redigesting cecotropes, though harder pellets may pass through the impacted mass. The condition may be temporarily alleviated by carefully expelling the impacted feces.

Guinea pigs benefit from feeding on fresh grass hay, such as timothy hay, in addition to food pellets which are often based from timothy. Alfalfa is also a popular food choice; most guinea pigs will eat large amounts of alfalfa when offered it, though there exists some controversy over the feeding of alfalfa to adult guinea pigs. Some pet owners and veterinary organizations have advised that, as a legume rather than a grass hay, alfalfa consumed in large amounts may lead to obesity, as well as bladder stones due to excess calcium, in any but pregnant and very young guinea pigs. However, published scientific sources mention alfalfa as a source for replenishment of protein, amino acids and fiber.

Like humans, but unlike most other mammals, guinea pigs cannot synthesize their own vitamin C and must obtain this vital nutrient from food. If guinea pigs do not ingest enough vitamin C, they can suffer from potentially fatal scurvy. Guinea pigs require about 10 mg (0.15 gr) of vitamin C daily (20 mg (0.31 gr) if pregnant), which can be obtained through fresh, raw fruits and vegetables (such as apple, cabbage, carrot, celery, and spinach) or through dietary supplements. Healthy diets for guinea pigs require a complex balance of calcium, magnesium, phosphorus, potassium, and hydrogen ions; adequate amounts of vitamins E, A, and D are also necessary. Imbalanced diets have been associated with muscular dystrophy, metastatic calcification, difficulties with pregnancy, vitamin deficiencies, and teeth problems. Some sources also suggest that guinea pigs are especially susceptible to gall and kidney stones, making it important to limit calcium intake in their diet. This may involve limiting or eliminating multi-vitamin supplements and calcium-rich foods (like commercially-produced yogurt drops, spinach or very high proportions of alfalfa). Guinea pigs tend to be fickle eaters when it comes to fresh fruits and vegetables, having learned early in life what is and is not appropriate to consume, and their habits are difficult to change after maturity. They do not respond well to sudden changes in diet; they may stop eating and starve rather than accepting new food types. A constant supply of hay or other food is generally recommended, as guinea pigs feed continuously and may develop habits such as chewing on their own hair if food is not present. Because guinea pigs’ teeth grow constantly, they routinely gnaw, lest their teeth become too large for their mouth, a common problem in rodents. Guinea pigs will also chew on cloth, paper, plastic, and rubber.

A number of plants are poisonous to guinea pigs, including bracken, bryony, buttercup, charlock, deadly nightshade, foxglove, hellebore, hemlock, lily of the valley, mayweed, monkshood, potato, privet, ragwort, rhubarb, speedwell, toadflax and wild celery. Additionally, any plant which grows from a bulb (e.g., tulip and onion) is normally considered poisonous.

The scientific name of the common species is Cavia porcellus, with porcellus being Latin for “little pig”. Cavia is New Latin; it is derived from cabiai, the animal’s name in the language of the Galibi tribes once native to French Guiana. Cabiai may be an adaptation of the Portuguese çavia (now savia), which is itself derived from the Tupi word saujá, meaning rat. Guinea pigs are called quwi or jaca in Quechua and cuy or cuyo (pl. cuyes, cuyos) in the Spanish of Ecuador, Peru and Bolivia. Paradoxically, breeders tend to use the more formal “cavy” to describe the animal, while in scientific and laboratory contexts it is far more commonly referred to by the more colloquial “guinea pig”.
How the animals came to be thought of as “pigs” is not clear. They are built somewhat like pigs, with large heads relative to their bodies, stout necks, and rounded rumps with no tail of any consequence; some of the sounds they emit are very similar to those made by pigs, and they also spend a large amount of time eating. They can survive for long periods in small quarters, like a ‘pig pen’, and were thus easily transported on ships to Europe.
The animal’s name carries porcine connotations in many European languages. The German word for them is Meerschweinchen, literally “little sea pigs”. (The Polish świnka morska and Russian морская свинка mean exactly the same.) This derives from nautical history: sailing ships stopping to reprovision in the New World would pick up stores of guinea pigs, which provided an easily transportable source of fresh meat; Schweinswal (pig-whale) is German for porpoise, which was another food source for sailors. The French term is Cochon d’Inde (Indian pig); the Dutch used to call it guinees biggetje (Guinean piglet) or Spaanse rat (Spanish rat) in some dialects, and in Portuguese the guinea pig is sometimes referred to as porquinho da Índia (little Indian pig). This is not universal; for example, the common word in Spanish is conejillo de Indias (little rabbit of India / the Indies).
The origin of “guinea” in “guinea pig” is harder to explain. One theory is that the animals were brought to Europe by way of Guinea, leading people to think they had originated there. “Guinea” was also frequently used in English to refer generally to any far-off, unknown country, and so the name may simply be a colorful reference to the animal’s foreignness.Another theory suggests the “guinea” in the name is a corruption of “Guiana”, an area in South America, though the animals are not native to that region. A common misconception is that they were so named because they were sold for the price of a guinea coin; this theory is untenable, because the guinea was first struck in England in 1663, and William Harvey used the term “Ginny-pig” as early as 1653.Others believe “guinea” may be an alteration of the word coney (rabbit); guinea pigs were referred to as “pig coneys” in Edward Topsell’s 1607 treatise on quadrupeds.