Guinea Pig Factsheet & Diet

Guinea pigs originate from the mountains in South America where they naturally eat a diet of high fibre vegetation. To cope with this diet, guinea pigs have continuously growing teeth and a complex digestive system. Most guinea pig health problems are related to an inappropriate diet.

The plants in South America have a much higher vitamin C content than the vegetation in the UK. It is essential that your guinea pigs diet includes the required amount of nutrients, especially Vitamin C, as, like humans, guinea pigs cannot synthesise this vitamin.

A Vitamin C deficiency will cause your guinea pigs immune system to be less effective and leave them susceptible to infection and parasite infection. It can also lead to dental problems and in severe cases scurvy may develop, which if not treated promptly, could be fatal.

Your Guinea Pig Needs

  • A tablespoon (no more) of good quality guinea pig food – we recommend Oxbow Cavy Performance for you guineas up to a year old and Oxbow Cavy Cuisine or Super Guinea Excel for adults.
  • Ad-lib good quality hay – we recommend Oxbow Alfalfa Hay for guinea pigs up to 6 months of age and the Oxbow Timothy Hay for adults
  • Ad-lib grass, either grazed from the lawn or handpicked, never feed you your guinea pig mower clippings as this can cause colic.
  • A small amount of leafy vegetables, e.g: cabbage, broccoli, parsley, dark green rocket etc. Do not feed your guinea pig spinach as this can cause bladder stones.
  • Occasional treats of small pieces if apple, carrot and tomato 2-3 times a week. Your guinea pig will let you know what they like and dislike, so it’s best to experiment at first to find out what their favourites are.
  • Most treats sold in pet shops are generally high in sugar and low in fibre so are not advised.

The correct diet is essential, not just for the general health of your guinea pig but also its welfare. It is especially important as diet plays a huge role in your pets dental health.


It is a good idea to arrange for male guinea pigs to be castrated. As well as preventing unwanted mating, this can help with behavioural problems such as aggression or fighting. Neutering is available for guinea pigs from 5 months of age and after neutering we recommend regular weight checks as it is common that your pet may gain a few pounds.

Prevention of Dental Disease

Dental disease is an extremely common problem and a very frustrating one to treat, it’s also very complex and can be linked to nutrition and diet. Problems with pet’s teeth can also cause a number of secondary problems such as; anorexia, poor grooming, facial abscesses, eye infections, colic or pneumonia. Your guinea pig may also be more susceptible to Trixacrus Caviae mites due to immune suppression and altered behaviour

Very simply, there are 3 contributory factors to dental disease, the first being that it is generic or inherited. The second is poor nutrition, which relates to growth and development of the teeth as well as the supporting bones of the skull. The third is due to failure to provide enough roughage for your guinea pig to naturally wear down their growing teeth. The first reason can be easily prevented by careful breeding, whilst the second and third can be avoided with responsible pet ownership.

Is it best to feed pelleted food (e.g Supa-Guinea, rather than a coarse mix of cereals? Guinea Pigs tend to leave the parts of the cereal that they aren’t particularly fond of – a bit like when you leave the coffee creams in the bottom of the Quality Street box. A pelleted feed ensures they are receiving a truly balanced diet.

Allowing your pet daily access to sunlight is also a good idea as it provides Vitamin D absorption through the skin, enhancing the strength of both teeth and bones.

Fibrous food such as good quality grass and hay should be fed ad lib to provide dental wear and also improve happiness and welfare by decreasing boredom. Your guinea pigs diet should also be supplemented with non-poisonous weeds and plants such as; dandelions, brambles, tree leaves (good sources of calcium and fibre). Vegetables like broccoli, cabbage and spinach can also be a good addition to you guinea pigs diet, root vegetables such as carrots are not a great source of calcium.

Keeping Guinea Pigs & Rabbits Together

It is not recommended that guinea pigs and rabbits are kept together in the same hutch. Rabbits tend to bully guinea pigs and they have the capacity to inflict a lot of damage by kicking with their powerful hind legs. Also as they are different species, they both carry different bacteria in their lungs which increases the chances of infection that could lead to pneumonia.

Guinea Pig Diet

Guinea pigs (also known as cavies) are a popular pet, originating from the mountains and grasslands of South America. Guinea pigs are highly social animals, and should be kept in single—sex groups, pairs or harems. Guinea pigs are nervous animals and can be frightened easily. They are not hardy and therefore should not be exposed to extremes of temperature or humidity. Guinea pigs should not be housed with rabbits, as rabbits tend to bully them and they have very different nutritional requirements.

Guinea pigs are herbivores and their diet should be high in fibre. The ideal guinea pig diet comprises a mixture of commercial pelleted food plus free access to good quality hay and fresh leafy green foods such as grass, dandelion, groundsel, cow parsley and broccoli. Food is primarily eaten in the late afternoon and evening. Guinea pigs, like other rodents are coprophagic — eating caecotrophs (special faecal pellets) directly from the anus


Unlimited high quality hay (timothy and orchard grass are popular) should always be available. Eating the long hay strands keeps their digestive system moving and helps prevent their teeth from over growing. Guinea pigs are able to digest hay more efficiently than rabbits, so they eat hay slowly. However, a hay-only diet is inadequate for a guinea pig.


As guinea pigs can be selective feeders (ie picking out their favourite flavours from the mix), complete pelleted diets are preferable as they ensure your pet has a balanced diet. Commercial diets have vitamin C added, however this does reduce in the food over time due to oxidisation. Purchase pellets in small quantities and store in a dry cool dark place to preserve the potency of the vitamin C (check expiration date for freshness).

And remember, pellets are not a substitute for hay! Be sure to provide high quality hay all the time for your guinea pigs.

Vitamin C

(Ascorbic acid): Guinea pigs cannot manufacture their own vitamin C, like humans and are only able to store vitamin C for a short period of time. The average vitamin C daily requirement is 10mg/kg, increasing when they are growing, ill or pregnant. If the diet is low in vitamin C then scurvy will develop. While many guinea pigs receive adequate vitamin C from fresh vegetables and pellets, you may wish to ensure your guinea pig gets adequate vitamin C by giving a quarter of a 100 mg chewable or plain vitamin C tablet, or provide a small amount of liquid vitamin C drops. Vitamin C degrades rapidly once added to water — so change daily. Excess vitamin C is harmlessly excreted in the urine.

Do not give multivitamins! Plain vitamin C is fine, but multivitamins are not. Excessive amounts of vitamins like A and D can cause serious problems for your pet.


Fresh water should always be available and changed daily. Any changes in watering system or water should be gradual, to allow your pet time to get adjusted to the new source initially.

If water bottles with metal drinking tubes are used, these can oxidise the vitamin C rapidly (50% is lost in 24 hrs) so will require daily changing of the supplemented water.


Vegetables high in vitamin C are recommended and for their high fibre content. Some vegetables that are high in vitamin C are green or red pepper, asparagus, tomato, broccoli and spinach, as well as all leafy green vegetables — such as parsley, kale and chicory are also good. Wash vegetables thoroughly. Do not feed wilted or spoiled food. Vegetables must be introduced slowly, to avoid digestive upsets. Once introduced, you can supply a variety of them to your pet. Variety is the key to maintaining your pet’s health. Be creative.

Not Recommended in Diet

  • Commercial diets with multi coloured mixes — as this is when they can selectively feed.
  • Nuts can be a potential source of mould and then cause illness.
  • Dairy and meat products (guinea pigs are herbivores).
  • Rabbit pellets (they do not contain Vitamin C).
  • Seeds in husks an be a choking hazard.
  • Commercial treats marketed for guinea pigs (like yoghurt drops) as they are high in fat, sugars and calcium, which can lead to reduced intake of the correct diet and can predispose to dental disease.