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Guinea Pigs

Things you should know about keeping Guinea Pigs

Guinea pigs originated in South America but were probably introduced into Europe soon after the first Spanish explorers returned from that continent in the 1500s. Even though they came from a sub-tropical area these rodents proved to be hardy and adapted to temperate climates such as that of Britain. They became favourite pets in the early part of this century and are also bred as show animals with a wide variety of coat colours and fur types.

What type of housing should I provide for my Guinea Pigs?

This is not particularly difficult and a large variety of hutches and cages have been used. Guinea pigs can be kept outside in the summer and a good draught-free but well ventilated mobile run on the grass is very acceptable as long as there is also a dry covered area. Pens should be at least 30 cm (12 ins) high to avoid escapes and should be covered with mesh to keep cats out. Indoor cages in the winter should allow at least 0.2 square metres of floor space per guinea pig. Since they are social animals guinea pigs can be kept in small to medium groups, but clearly mating will increase the number of animals so single sex groups are advisable. Temperatures between 12 and 20°C (52-68°F) are ideal. Anything over 27°C (82°F) will lead to heat-stroke, especially in animals that are overweight or pregnant.

They should not be kept with rabbits for two major reasons:

1. Aggression. Rabbits (especially males) may be aggressive to guinea pigs.

2. Many rabbits carry a bacterium, Bordetella bronchisepticum, that may cause severe, often fatal, pneumonia.

Where owners have kept these species together make sure that they are fed a ration containing Vitamin C for the guinea pig and also a small tube or box that only the guinea pig may enter so it can escape the rabbit.

Feeding your Guinea Pig

Guinea pigs are herbivores rather like rabbits, although the physiology and function of their gastrointestinal system is less well understood than that of the rabbit. The critical area of dietary science in guinea pigs which you should be aware of is their requirement for vitamin C, covered further below. Apart from that, the key to a healthy diet in a guinea pig is variety. Imagine what the guinea pig has to eat in its native environment of the South American forests: a bit of everything from fruits through greens to root vegetables. We often feed a dry guinea pig mix with few fresh vegetables and expect that to satisfy the animal's requirements. It does not.

Why is Vitamin C so important?

For every animal there is a set of essential nutrients and another set of non-essential nutrients. Animals need a regular dietary supply of essential ingredients, while they can produce their own supply of the non-essential nutrients. In the guinea pig and man one key essential nutrient is vitamin C. The vast majority of other animals can produce their own vitamin C from their intestinal bacterial flora but for some reason guinea pigs and human beings are not able to do this. This is why eighteenth century sailors developed scurvy when not able to eat fresh fruit. Vitamin C is vital in the normal development and maintenance of skin and mucosal surfaces like gums. It is also important in the healing of wounds to these structures. As well as predisposing to skin problems, a lack of vitamin C seems to make the body more prone to other diseases, infections and poor condition. A guinea pig which is reluctant to walk, has swollen feet or haemorrhages and ulcers on its gums or elsewhere is likely to be deficient in vitamin C. It is also important in bone and joint development. Young guinea pigs that are deficient may develop sore backs and swollen stifles. Older guinea pigs may appear to have breathing problems but actually have very swollen joints in the ribs due to Vitamin C deficiency. Urinary disease, too, may stem of lack of this vitamin.

Vitamin C is often added to Guinea Pig mixes. However, it is unstable and has often been lost by the time the food is given. Therefore any food greater than 3 months after manufacture should be regarded as being potentially deficient. Vitamin C may be found in fresh fruit and vegetables with pepper being among the best sources. However, it is hard to make up for a deficient dry mix in this manner.

Vitamin C may be given as a supplement. This should never be added to the water as it may be denatured. It is best given as tablets that can be given directly or crumbled over food. 50 mg per guinea pig per day is advised.

Vitamin C is non-toxic so overdosage will not cause a problem.

What else to feed?

The other main problem in the diet of the guinea pig is lack of fibre. This is one of the main contributors to dental disease. Therefore the staple of the diet should be hay or grass with much less reliance on commercial rations. Like the rabbit, guinea pigs are coprophagic (eat their own faeces) and fibre is essential in regulating this process.

They will also need a good source of calcium and Vitamin D (best accomplished by keeping outdoors!).

In essence they should be fed much as rabbits with high fibre rations. The difference is the importance of Vitamin C to the guinea pig.

Can I breed from my Guinea Pig?

Guinea pigs are one of a group of rodents called the hystricomorphs with an unusual reproductive physiology and breeding strategy. Chinchillas are another member of this group and the others, like the plains vichaca are not kept in captivity so will not worry us here!

Guinea pigs mature at around 3 months but should not be used for breeding for another three months. After about eight months of age the female guinea pig's pelvic bones become more tightly fused and if she has not had a litter by that time, producing young may be more of a problem. You might ask why that is a problem since animals of most species can delay giving birth until they are older. The difference with the guinea pig is that she gives birth not to a large litter of tiny immature young (as the rat or mouse does), but to between two and four fully developed well furred offspring. The average gestation period is 63 days. These large babies have a hard time getting through the pelvic canal unless the mother's pelvic bones are relatively immature and malleable. These large offspring predispose the mother to pregnancy toxaemia, where the metabolic load on the mother is too high resulting in low blood glucose and formation of ketones. This is especially the case where dams are given low fibre diets high in cereals. It manifests as loss of appetite in the early stages, deteriorating to muscle twitching and coma. Prompt veterinary attention (often involving emergency caesarian) can save animals but the problem can be reduced to a minimum by providing plenty of water and green foods during pregnancy, as throughout life.