Guinea pigs eat for around 16 hours a day: make sure it’s the right stuff! The key to a good diet is variety. Guinea pigs thrive on a varied, quality diet consisting of 80% hay, a variety of vegetables, a little fruit and a chemical-free dry feed.

For a quick reference guide to what vegetables your guinea pig should eat, keep a copy of our handy feeding guide.

Their teeth, all 20 of them, grow throughout their lives. They therefore need to be kept ground down with an abundance of abrasive food like hay.
In addition to the correct diet, allow daily exercise in a secure grass run (where he is safe from predators). This is hugely beneficial to his well-being, and the bigger the run, the better.

Dry food

The dry food should not contain chemical colourants as they can give symptoms of diabetes (very high blood sugar readings) amongst other abnormalities. We would never feed our guinea pigs or yours with anything which is not first approved by us and second, free from chemical colourants. At the time of writing, they are: Wagg Guinea Pig Crunch, Wagg Optimum, Burgess Excel and Pets at Home Museli.

Many of the popular food brands are the equivalent of junk food for your guinea pig and just as you would not thrive on eating fast food for every meal, neither will your guinea pig. The ingredients list has to, by law, state whether this chemical is included.  Once you have found a supplier of chemical colourant free food you will need to check each purchase as companies sometimes change suppliers which could mean the addition of chemical colourants.

If you buy your guinea pigs dry feed loose from a bin, you need to know if the chemical colourants are included from the analysis on the back of the bag that the feed was in, before being tipped into the bin.  We would be very sceptical about buying dry feed if the analysis is unknown.  The bin and scoop should also be clean and dry. It should not have feed stuck to the sides indicating old feed or damp which probably harbours bacteria.

How much to feed

This is a difficult question as every guinea pig is different and appetites and needs vary.  However, this does not apply to the amount of hay they eat which should be around his own bodyweight daily. You will soon be able to gauge how much dry feed your guinea pig likes to eat, therefore avoiding too much waste.


The dish should be cleaned regularly.  Do not put fresh feed on top of old feed: to avoid waste, tip the previous days feed to one side, add fresh to the other but clear out completely on a regular basis. This does not apply if the guinea pig uses his dish as a toilet.


Like humans, guinea pigs need vitamin C daily and rely on you to be the provider. Fresh vegetables are critical to the well-being of your guinea pig and the amount of fresh mixed vegetables required for each guinea pig is approximately one cupful once or twice per day. Get a good balance by ‘being creative and colourful’. The key is not to feed too much of the same thing too often! We give once daily in the morning and a handful of Spillers Readigrass later on in the day but ALWAYS ensure there is an abundance of good quality hay in a rack off the floor and heaped on the floor.

  • Feeding veg direct from the fridge  or unwashed vegetables can cause diarrhoea.
  • Beware of accidentally feeding pieces of cellophane wrapped around some cucumbers.
  • Never feed veg which is past its best.
  • Remove uneaten veg from the cage after 24 hours
  • Feeding veg in the morning is preferable to it lying in their gut all night.
  • See your local farm shop for what they call “the rubbish” (don’t forget to wash it first).  Your guinea will think Christmas has come early!
  • Limit fruit and tomatoes (also a fruit!) due to the acid content.
  • Beware of feeding too much kale, spring greens, carrot tops, dandelion leaves, beet leaves, lamb’s lettuce, parsley or spinach, due to the high calcium content. This often leads to renal or gastric problems where the guinea pig is weeing frequently, is wet underneath, loses form and weight, and often contracts urine infections including the very painful cystitis and ultimately BLADDER STONES. Refer to the guinea lynx website for more details.


Poor quality hay can harbour a variety of parasites, including lice and mange mites.  Mange is usually fatal if left untreated and is a horrendous, agonising death. The result of an inadequate hay supply will be an underweight, miserable guinea pig with overgrown teeth who has difficulty eating and no muscletone.

  • DON’T feed your guinea out of vacuum packed, exorbitantly priced, plastic wrapped hay. It is likely it has been swept off the barn floor and washed.
  • REPLACE floor hay regularly as it will get urinated and defecated on.
  • DON’T use straw instead of hay. It is nutritionally inadequate and too harsh
  • DON’T use one of those hanging balls.  They don’t hold enough and how would you like to eat your dinner with your hands tied behind your back?
  • DON’T feed your guinea pig hay that smells musty or looks mouldy or dirty (even if it was a freebie!)


The bottle should be out of the sun and refilled daily. Do not put fresh water in with old.  Keep the bottle free from algae (the green stuff) with a bottle brush.  Do not bother putting vitamin C drops in the water as after a few hours there is a chemical change in the spout making this addition a waste of time and money.

Make sure the spout is at a comfortable height for the guinea pig. We find a thick elastic band is preferable to the bottle wire that is used to secure the bottle to the cage.  Some people like to use a trumpet head brush cleaner on the spout.

Don’t waste money on a thermal cover to prevent ice forming as we assume you wont be keeping your guinea pigs in freezing conditions.If their water bottle is frozen, what’s to stop their bedding freezing where they have urinated? The older they get, the worse the problem. Their natural habitat is a warm, dry climate, not damp or freezing conditions – frozen drinking water is an indicator that your guinea pigs are in danger of freezing to death.

If your guinea pig isn’t eating or drinking, or you have any other health concerns, please consult a vet. You might also find our  Emergency Medical Guide useful, for reference.