Guinea-pig Diets

Guinea-pigs are completely herbivorous and will spend most of their day grazing on a variety of grasses and weeds. They can be vulnerable to diseases caused by incorrect feeding and should have a high fibre diet to ensure that they maintain a healthy gastro-intestinal system and healthy teeth. Like humans, guinea-pigs are unable to synthesise their own vitamin C and therefore require a regular source of vitamin C in their diets.

Diet Related Health Concerns

Vitamin C Deficiency

A deficiency in vitamin C will lead to loss of energy, swollen joints, skin sores, bleeding, loss of appetite, diarrhoea and eventually death. These problems can occur due to a lack of vitamin C in the diet, or occasionally can be due to an underlying condition which prevents the guinea-pig from absorbing vitamin C from its food.

Dental Disease

Some Guinea-pigs are prone to dental disease. Guinea-pig’s teeth grow constantly, and are worn down naturally through the action of eating hay. Dental disease occurs when the teeth continue to grow- causing pain, sores, abscesses or physical deformities of the mouth.

Dental problems can occur due to poor diet or poor breeding/conformation and will eventually lead to the guinea-pig being unable to eat at all. This can lead to gut-stasis, starvation and death if not treated. A general anaesthetic is required to carry out dental treatment, and some guinea-pigs may require dental work as frequently as every 6 weeks. A correct diet will reduce or sometimes eliminate the occurrence of dental disease.

Gut Stasis (Ileus)

Ileus or gut stasis is the term used to describe a condition where the part of or the entire gastro-intestinal tract ceases to move. It is very common in rabbits and can also occur in guinea-pigs and other small mammals. Movement along the gut (peristalsis) is what is required to pass food along the gastro-intestinal tract during digestion. Cessation of peristalsis can lead to the cecum not emptying quickly enough and can lead to harmful bacteria proliferating within the gut. These harmful bacteria can emit gas, causing severe pain and bloat. Some of these bacteria can also release deadly toxins, potentially leading to liver failure. Ileus can also cause dehydration and anorexia. Gut stasis can occur for a number of reasons and frequently occurs as a secondary condition to dental disease.


Obesity can occur in guinea-pigs that are fed a predominantly high carbohydrate diet such as muesli or pellets. This can lead to a number of different health problems such as heart disease and liver disease. Excess weight can also exacerbate arthritis and hinder the guinea-pig’s ability to groom, which can increase their risk of flystrike.

Appropriate Diet

As mentioned above, guinea-pigs are predominantly grazers and their diet should reflect this. The ideal diet for a guinea-pig should consist of hay, grass, weeds, greens and vitamin C rich vegetables and fruit. With a correct diet, most guinea-pigs do not need pellets, although some owners find they help some outdoor guinea-pigs to maintain their weight during colder months. You should still ensure that your guinea-pig has plenty of bedding to bed down in to protect them from damp and draughts.

Many guinea-pig pellets are marketed as being supplemented with vitamin C – however it is worth noting that in most cases, the vitamin C will degrade after packaging and quickly become ineffective. They should therefore not be a replacement for vegetables and fruit. If you do choose to feed pellets, these should be scattered around the guinea-pig enclosure to encourage foraging.

Key points for correct nutrition

  • As with all animals, fresh water should always be provided. A heavy water bowl offers a more natural way for your guinea-pig to drink than water bottles, however may become easily soiled and should be changed regularly.
  • Ad-lib hay should always be available. Get the best quality hay that you can- it should smell sweet and not be dusty. Types of suitable hay include timothy hay, oat hay or meadow hay. Alfalfa hay is best avoided in guinea-pigs, as it is higher in protein and calcium which can lead to kidney disease and bladder stones.
  • Fresh or growing grass should also be available where possible. This is best supplied by allowing your guinea-pig to use a large outdoor space, giving them the chance to graze naturally and exhibit normal behaviour. Never feed lawn mower clippings, as these can ferment quickly, causing digestive upsets and gut stasis.
  • Foraging should be encouraged – provide a large exercise in an outdoor area where your guinea-pig can explore and graze. Scatter favourite foods around the area rather than feeding from one bowl. There are also a number of feeding toys available, which can provide added enrichment.
  • Weeds and plants – there are many safe weeds and plants that your guinea-pig can enjoy. These include dandelions, plantains, clover and thistles. Many pet shops now sell weeds for guinea-pigs in dry forms too, adding some variety to your pet’s diet throughout the year.
  • Vegetables and fruit. We recommend offering vegetables and fruit as part of your guinea-pig’s daily diet – you should focus on items that contain substantial amounts of vitamin C.

 Foods that are high in vitamin C:

  • Dandelion leaves
  • Kale
  • Brussel sprouts
  • Parsley
  • Broccoli leaves and florets
  • Cauliflower
  • Cabbage
  • Spinach
  • Strawberries
  • Raspberries
  • Blueberries
  • Oranges

The more sugary fruits should be given in moderation, as diets that are high in sugar can lead to digestive upsets in guinea-pigs.

Vitamin C supplementation

There are a number of vitamin C supplements now available for guinea-pigs and supplementation is generally recommended. We can advise you on these or order them in for you – please contact us for more information.

Food to avoid:

  • Muesli diets. These are not suitable for guinea-pigs and will eventually lead to health problems as they are high in carbohydrates. They also allow the guinea-pig to selectively feed, leading to dietary deficiencies.
  • Human food. Guinea-pigs have very sensitive digestive systems; therefore food such as bread, crisps and biscuits can easily cause gastro-intestinal upsets, leading to gut stasis.
  • Commercial treats. These are usually marketed as safe for guinea-pigs, but are often high in sugar and offer no nutritional benefit. We recommend feeding some of the plants or vegetables above as treats instead. There are some companies which now produce treats made of natural grasses or weeds – these can be a suitable option. Please contact us for advice if you have a specific question about a product you’ve seen.

Toxic food – these should be avoided at all costs

  • Any plants, grass or hay that has been treated with chemicals such as pesticides or weed killers.
  • Lawn mower clippings
  • Avocado
  • Anything from the allium family, including: onions, garlic, leeks and chives.
  • Tubers such as potatoes.
  • Any plants grown from a bulb. These include: daffodils, bluebells, crocuses, snowdrops and tulips.
  • Buttercups
  • Primroses
  • Poppies
  • Foxgloves
  • Ivy
  • Holly
  • Human foods such as chocolate, caffeine and alcohol.

The list of plants that are toxic to guinea-pigs is non-exhaustive and there are too many to list here! Please research any plants carefully before planting them in areas that your guinea-pig has access to.