Fact checked by Dr. Antoinette Martin, DVM

Guinea pigs have plenty of qualities that make them appealing pets. Because they are small, gentle, personable, and undeniably cute, many people choose guinea pigs as the first pet for themselves or their children.

While there is no denying that guinea pigs make excellent companions, even for inexperienced pet owners, they do require special care and attention. One area often overlooked is guinea pig nutrition. Most of the health problems guinea pigs suffer from can be traced back to flaws in their diet.

To help you keep your fuzzy little friend feeling happy and healthy, we are going to go over everything you need to know about a guinea pig’s diet and its nutritional needs. If you are unsure what to feed your guinea pig or want to ensure you’re providing your pet with everything it needs, you have come to the right place!

What Type of Diet do Guinea Pigs Need?

Guinea pigs are true herbivores, which means they require a strictly plant-based diet. Just like rabbits, guinea pigs get all of the vitamins and minerals they need from plant-based foods, like vegetables, leafy greens, dried hay, hay-based pellets, and fruits.

You mustn’t feed your guinea pig any animal-based proteins, like dairy products, eggs, meat, or even insects. Not only will the guinea pig be unable to digest these foods and absorb nutrients from them, but animal-based proteins can also actually make your guinea pig quite sick.

To make things simple, we will now go over each of the main types of food you can feed your guinea pig.

Vegetables

While vegetables should not be the primary type of food you feed your guinea pig, they can offer variety and be a healthy alternative to the hay and pellets that will most likely make up the bulk of the animal’s diet.

Leafy green vegetables, in particular, are an excellent source of fiber, and they offer healthy nutrients that cannot be found in hay. When you provide your guinea pig with vegetables, make sure they are fresh. It is also a good idea to wash any vegetables first to ensure they are free from dirt and pesticides.

Diversifying the types of leafy greens you offer will keep things exciting and make sure your guinea pig has a more balanced diet. Since each type of vegetable has its own nutritional content, food variety will help you avoid imbalances.

Appropriate types of leafy green vegetables for your guinea pig include lettuce, parsley, dill, coriander, basil, dandelion leaves, celery leaves, kale, brussels sprouts, and carrot greens.

When feeding a guinea pig leafy greens, aim for about a cup per day. If the guinea pig does not eat the vegetables, remove them before they have the opportunity to rot and spoil. Eating wilted and rotten vegetables can lead to stomach issues and sickness.

You can also offer your guinea pig some types of non-leafy vegetables, but you should do this less frequently, as most of these vegetables contain high amounts of sugar. For example, guinea pigs enjoy carrot and bell pepper pieces, but they should be treated more like a treat than a staple food.

Fruits

Just like non-leafy green vegetables, fruit tends to be high in sugar. While fruit can contain many nutrients a guinea pig needs, the high sugar content can negate the benefits. This is why fruit should be given as a rare treat rather than as a primary food source.

Small pieces of raw apples, pears, strawberries, blueberries, peaches, apricots, and kiwi can be OK occasionally. But remember, these should be given as occasional treats, so make sure you do not overdo it. You can offer your guinea pig some small pieces of the fruits mentioned above roughly once per week, but it is also OK to avoid fruit altogether.

Hay

Grass hay is a requirement for guinea pigs and should be made available at all times. This is because guinea pigs need a significant amount of fiber in their diets to maintain a balanced bacterial flora in their guts. Chewing hay also helps keep their teeth at a healthy length, which will be explained in greater detail later.

There are different types of hay that guinea pigs can consume, and each offers a slightly different nutritional content. Grassy varieties of hay, like Timothy hay and Brome hay, are ideal for guinea pigs. Hays derived from legumes, such as Alfalfa hay, tend to be high in calcium, which can lead to kidney and bladder stones. Not only are calcium stones painful and often require surgery to remove them properly, but they can also be fatal.

While the extra calcium and protein in legume-based hays can be beneficial for pregnant and lactating guinea pigs, it is best to avoid them outside of these situations. If you are unsure if your guinea pig is pregnant and should be eating a diet that has a higher concentration of calcium, you can speak with a Hello Ralphie virtual veterinarian. An online vet appointment is one of the easiest ways to get answers about your specific guinea pig’s needs without having to leave the house.

While calcium stones are the main reason you should avoid giving your guinea pig hays high in calcium and protein, they can also lead to excessive weight gain and serious urinary issues.

When providing your guinea pig with hay, avoid giving it compressed hay cakes. The non-compressed form is easier for the guinea pigs to chew. Remember, make sure that healthy grass hays are made available to your guinea pig at all times.

Pellets

Guinea pigs should also be given healthy pellet food. Choose guinea pig pellets that are flavorless and do not contain added grains or dried foods. If you give your guinea pig flavored pellets, it may turn down the non-flavored varieties in the future, which tend to be healthier.

Pellets are made from hay and provide guinea pigs with many of the same nutrients, but in a more convenient form. To make sure your guinea pig is consuming the healthiest type of pellets possible, look for brands made from grass hays.

Even though pellets are mostly made from hay, guinea pigs usually favor them over raw hay. If you provide your guinea pig with a constant source of pellets, there is a good chance it will overeat and become overweight. It may also neglect its raw hay, which can lead to digestive issues, as well as excessively long teeth and other dental problems. This is why portion control is essential.

For most guinea pigs, it is recommended that you limit pellet consumption to roughly 1/4 cup per day.

Specific Dietary Needs for Guinea Pigs

While guinea pigs have relatively simple dietary needs, there is one type of nutrient in particular that guinea pigs struggle with.

Vitamin C

Guinea pigs, like human beings, cannot manufacture their own Vitamin C. This is why most owners will provide their guinea pigs with a Vitamin C supplement.

Not only is Vitamin C essential for normal development and the maintenance of the guinea pig’s skin, joints, and gums, it also plays a vital role in the healing of wounds. Without Vitamin C, the guinea pig is also much more prone to diseases, infections, and a variety of skin and fur issues.

In most cases, you can tell if a guinea pig has a Vitamin C deficiency because their coat will feel excessively rough and look patchy. They will also eat less of their food, have frequent cases of diarrhea, lack energy and walk around less, give off the impression they are in pain, show visible signs of swollen feet and joints, and even have open wounds and ulcers on their gums and skin.

If your guinea pig is showing any of these clinical signs, it is a good idea to book an online vet appointment with one of our qualified Hello Ralphie veterinarians. While the cause is likely a Vitamin C deficiency, it could be a sign of another issue and should be examined to make sure.

While some of the pellets made for guinea pigs contain Vitamin C, it is good to add a supplemental source to ensure they are getting enough. Natural sources of Vitamin C, found in various fruits and vegetables, can be healthy, but it isn’t easy to get the balance right. Guinea pig-specific Vitamin C supplements are available in the form of tablets and powders, and they can ensure the guinea pig has enough in its diet to live a healthy life.

How Much Vitamin C Do Guinea Pigs Need?

In general, guinea pigs need between 10 and 50 milligrams of Vitamin C per day. The exact amount your particular guinea pig will need depends on a variety of factors. Since age, health, stress level, pregnancy status, and more can all impact Vitamin C requirements, it is always a good idea to speak with a veterinarian to develop a specific supplement routine.

Even if you give your guinea pig plenty of vegetables and fruits that are rich in Vitamin C, as well as pellets that have added Vitamin C, it can be challenging to make sure it has enough. Vitamin C is a relatively unstable compound, so it tends to break down and oxidize pretty quickly. Once this occurs, it cannot be absorbed through the digestive system of a guinea pig, so it will not satisfy the animal’s Vitamin C requirements.

Supplementing Vitamin C is particularly important for older guinea pigs, as their digestive systems become far less efficient as they age. This means older animals often struggle to absorb appropriate amounts of the vitamin from the food they are given. If you have any questions about Vitamin C supplements, speak with a Hello Ralphie online vet.

Fiber

As mentioned earlier, guinea pigs require a significant amount of dietary fiber. Aside from the fact that it helps maintain a healthy balance of gut bacteria, guinea pigs need fiber for their teeth. This is because guinea pigs have constantly growing teeth. While our teeth stay a specific size and length, guinea pig teeth keep growing, posing health risks if the growth is left unchecked.

Chewing fibrous materials, such as hay, helps grind the teeth down. While chewing hard pellets can help, they are usually not enough on their own to grind the teeth down and keep them at a healthy length. Again, this is why you must provide your guinea pig with a constant source of fresh and healthy hay.

Final Tips for Guinea Pig Diets

Now that we have gone over foods and supplements appropriate to feed your guinea pig, we will go over some final feeding tips.

Stability

It is essential that you keep your guinea pig’s diet reasonably stable and that you do not make changes abruptly. Even if you are transitioning your guinea pig to a healthier type of food, it is crucial to make sure this change occurs slowly. While some level of variety is good, too abrupt of a change can cause your guinea pig to stop eating or even become sick. For more information about changing your guinea pig’s diet, feel free to reach out to a Hello Ralphie online vet.

Water

Your guinea pig should also have access to fresh, clean water at all times. If you are using a sipper bottle, you should clean it regularly. Water and food bowls should also be cleaned often.

Food Volumes

Ensure you provide your guinea pig with an unlimited quantity of hay, about a 1/4 cup of pellets per day, a limited variety of fresh produce, specifically leafy greens, and an appropriate Vitamin C supplement.

In Summary

Providing your guinea pig with a healthy diet rich in the nutrients it requires is one of the best ways to ensure it lives a long and healthy life. You should also remember that it is a good idea to check in with a vet at least once per year to ensure that your guinea pig’s diet provides it with all of the nutrients it needs! If you have any questions, you can book an appointment with a Hello Ralphie online veterinarian at your convenience.