N is for Nutrition

BY EXPERT Katharine Frayling RHA, FBAR, & BAR Trainer

Nutrition is the essential breakdown of vitamins and minerals that your guinea pig requires…

A s guinea pig lovers we are always striving to provide the best diet for our furry friends so that they can live a long and healthy life. A varied, balanced diet can provide all the right nutrients to boost immunity while fighting off infections and diseases. Guinea pigs possess specific nutritional requirements, so care needs to be taken to make sure that they are getting a well-balanced diet which includes all the vitamins and minerals their body requires. A nutritionally balanced diet for a guinea pig consists of around 80% hay, 15% vegetables (one cup) and 5% high quality dry pellets (around 1/8th cup per 1kg guinea pig) along with fresh water on a daily basis. An increased amount of pellet mix is needed when guinea pigs are underweight, sick, nursing or pregnant. Access to fresh hay is needed at all times. Not overfeeding with pellets and vegetables will encourage your guinea pig to graze on more hay, resulting in a well-balanced healthy diet.

A lack of different vitamins can affect the health of your guinea pig, especially a lack of vitamin C, as like humans they cannot manufacture it on their own so require a constant supply in their diet. Vitamin C and Vitamin B complex are groups of vitamins that cannot be stored in a guinea pig’s body, so they must have access to both daily. Complex B vitamins are absorbed through the process of coprophagy, the eating of caecal pellets. A lack of other vitamins and minerals can affect dental growth and alignment, energy, skin and hair health, reproductive ability, efficiency of organ function, and overall growth of younger guinea pigs. Delicate balances are required to keep a guinea pig’s gut flora healthy. This can easily become compromised should their diet contain high doses of fats, carbohydrates and sugars. Malnutrition may also occur in certain housing situations when larger, more dominant guinea pigs may bully smaller ones, keeping them away from food and water supplies. Weighing your guinea pigs weekly will alert you to any disruptions to their eating patterns and possibly the start of an illness.

Guinea pig food pellets, & fresh fruit and vegetables

Choosing a high quality, nutritionally-balanced dry food pellet which is manufactured specifically for guinea pigs, such as Oxbow Essentials, will provide many of the vitamins and minerals needed. Read the label to make sure that the food you are purchasing is made mainly from Timothy hay as often alfalfa (Lucerne) is used – which is higher in protein, calcium and carbohydrates.

 Also, being Timothy grass-based means that the pellets have the correct calcium to phosphorous ratio. This is especially important should your guinea pig have a bladder stone or sludge problem. 

Synthetic colourants, especially sunset yellow, are added to many food items and treats for guinea pigs, making it look appealing to us but which can cause irritations in guineas, especially to the digestive and urinary systems, and can also proffer a false positive reading on a urine test for diabetes. This particular issue can be dangerous, as treatment for diabetes, if not required, can be fatal. 

Carefully read the label for expiry or use by dates to check for freshness. Dried food for guinea pigs needs to be low in protein and high in fibre. When reading the ingredients, see that the fibre content of the food is higher than the protein. A good level is around 15-16% crude protein with the fibre content exceeding 20%; the higher the better. A diet high in carbohydrates and sugar can cause changes to the bacteria culture within the hind gut, causing the gut to slow down. This imbalance can lead to gastrointestinal stasis and/or bloat. Keep your guinea pig’s diet low in fats, ideally around 1-2%. Should the percentage be much higher, then the fat converts to starch and glucose, which can cause upset in the gastrointestinal tract leading to a slowing down of the gut processes. High calcium in the urine of guinea pigs can lead to bladder problems. Checking that their diet has the correct ratio of calcium to phosphorous can help in warding off potential problems. Bladder stones are more likely to form should the diet have an inverse ratio, meaning the phosphorous is higher than the calcium. A good ratio in the overall diet is 1.5 calcium to 1 phosphorous.

Feeding a diet that is well-balanced between phosphorous-high foods such as root vegetables and fruit, with calcium-high foods such as greens, can balance out the ratio. Leafy greens contain many of the vitamins, minerals and trace elements that a guinea pig requires. These should be fed alongside the correct ratio of root vegetables so that the guinea pig’s diet is balanced so will not lead to bladder issues. Should your guinea pig excrete a white substance when they urinate, then there may be an excessive amount of calcium in their urine. Check the nutritional content of their pellets and adjust the ratio in the fresh food that they are eating. There are websites explaining the ratios of Ca:Ph in a guinea pigs’ diet such as http://www.guinealynx.info/diet_ratio.html

Hay & Grass

Guinea pigs are foraging animals so require an unlimited supply of hay, and access to grass, to keep their teeth at the correct length and as an essential part of their digestive health. This high-fibre diet contains lingo-cellulose fibre which is required to assist the movement of food through the intestines. It also assists with keeping the bacteria held within the caecum at the correct balance, which is essential for keeping your guinea pig’s digestive tract healthy. 

Hay and grass contain highly abrasive silica phytoliths which, when chewed, assist in wearing down their continually growing teeth. Without access to hay the gut may slow down and can even stop, causing a condition called gastrointestinal stasis, which can be fatal. As the fibre passes through the digestive system, water is drawn into the intestines allowing essential nutrients to be drawn from the food and allowing the waste material to continue and pass out of the body as droppings. 

There are two kinds of hay: legume hay, and grass hay, which are both types of grass but nutritionally very different. 

Legume hay, also known as lucerne or alfalfa, is higher in protein, carbohydrates, calcium and phosphorous so therefore provides more calories for energy. The higher energy hay is useful for young pups, pregnant or nursing sows, sick and rehabilitating animals, and elderly guinea pigs who have difficulty maintaining weight. Guinea pigs that have bladder stones or sludge issues need to be fed hay which is lower in calcium. Any guinea pig fed a diet high in protein and carbohydrates is unable to fully metabolise the excess which is not required. 

Grass hay, such as Timothy hay and Orchard Grass, is of lower calorific and energy content but still provides the tough fibrous content needed for their bodies. 

Botanical and Oat Hay also make for a tasty treat. When looking for good quality hay, check to see if it is green, has a fragrant sweet smell, and has little dust, no mould and fibrous stalks that are pliable. Without access to hay the gut may slow down and can even stop!

Vitamin A

Guinea pigs usually receive the correct levels of vitamin A in their commercial feed so rarely is an animal deficient. Carotene is a precursor of vitamin A and is found in green vegetables and carrots. This form is less harmful than artificial vitamin A and is readily converted within the body when it is needed. An excess of vitamin A can cause liver damage and is usually caused by administering multivitamins.

B Vitamins

Guinea pigs re-ingest partially-digested food which has been produced in the caecum of the animal. These caecal pellets are moist and usually eaten straight from the anus. The good bacteria within the gut synthesises complex B vitamins in the caecal pellets along with balancing the gut flora. Should there be a medical or physical reason that the guinea pig cannot eat the caecal pellets, then your vet may prescribe a supplement of complex B vitamins. A dose of vitamin C would be required at the same time as this assists with the uptake of the B vitamins into the body. 

You may notice that a poorly guinea pig will pester a healthy one waiting for a caecal pellet to be produced. Instinctively they know when their own pellets are lacking, so they will wait and consume a fresh one from their cage mate. If they have been separated from their friend, then fresh pellets from another guinea pig mixed in with a little wet food and fed to them can assist with balancing the gut flora and adding beneficial complex B vitamins to their diet. Guinea pigs suffering from anorexia (not eating), dental disease and impaction may not be getting the required dose of complex B vitamins unless being fed a critical care feed. If suffering from impaction, allow the guinea pig time to see if they want to eat what is expressed first before disposing of it. 

There are many different types of B vitamins required in the body and they all have important functions. Vitamin B complex (or complex B vitamins) refers to eight B vitamins which help convert food into usable fuel. Many of these vitamins work together but each has a specific role. Some of the functions of the B vitamins are to work as an antioxidant, red cell production, keeping the skin, eyes and nervous system healthy, along with assisting the body with energy release from the food eaten. Antioxidants help fight damaged cells in the body (free radicals) while the red blood cell production is required for the transportation of oxygen throughout the guinea pig’s body. 

Vitamin C

Guinea pigs, like humans, are unable to manufacture their own vitamin C due to the fact that they lack an enzyme called L-gulonolactone oxidase. This enzyme is involved with the synthesis of ascorbic acid from glucose.

Daily amounts are needed from their diet to supply enough, around 20mg; higher doses of 20-40mg per kg of bodyweight are needed depending on whether they are pregnant, poorly or nursing.

To provide this source, a diet rich in a variety of green leafy and coloured vegetables, grass, and herbage will provide the amount of daily vitamin C needed. Fruits can be added a few times per week. Dry food alone should not be relied upon for all the vitamin C requirements as it is present in varying amounts across the feed, and degrades within 3 months once the bag is opened. Only buy a size of bag that you can use in that time, and turn it over frequently to keep up the vitamin C levels. Make sure the bag is sealed daily or food is stored in a bin with a tight fitting lid. When adding more fresh food, empty out the remains, clean out the bin and place the remainder on top of the newer food so that all of the old is used up first. Food purchased as bulk-buy from a pet shop with open bins will not have a good supply of vitamin C as you will not know how old the stock is. Look for a label that states “stabilised vitamin C” which means it should keep for longer. 

Vitamin C is required to assist the body in forming a common protein called collagen which is made from amino acids, and is necessary for the formation of all your guinea pig’s connective tissues. This tissue is the most abundant type in the body which supports, anchors and connects various parts and includes muscles, tendons, cartilage, ligaments, skin, hair, blood vessels, gastrointestinal tract and bones. Should a guinea pig not have a diet rich in vitamin C, then they can start to suffer from a condition called hypovitaminosis C (lack of vitamin C) or, as it is more commonly known, scurvy. Some guinea pigs may suffer from scurvy even though they are consuming enough vitamin C. This may be happening due to an underlying illness or a physical problem, such as a systemic fungal issue, which is interfering with the absorption of vitamin C into the body.

There are many vegetables that are high in vitamin C, such as bell peppers, coriander, kale, romaine lettuce and dandelion greens, so it is usually not a problem for a guinea pig to receive their daily quota if given a mixed variety of fresh food each day.

Vitamin D

This vitamin is required to elevate the calcium and phosphorous in the blood plasma so that it will support mineralization of bones along with other body functions. There are two types of vitamin D: D2 and D3. Vitamin D3 is synthesised within the body when they are exposed to ultraviolet rays from sunlight, and D2 is found in sun-dried forages and hay which have been exposed to sunlight. Most guinea pigs receive enough vitamin D from access to sunshine, the eating of hay and with vitamins in their dry food pellets. Animals kept in dark sheds or in poor light may suffer from vitamin D deficiency

Vitamin E

Vitamin E is especially important for a healthy heart and good physical condition of pregnant guinea pigs. When breeding, sows can have vitamin E oil; it can be added to the diet should the commercial guinea pig food be less than 50mg of vitamin E per kilogram of food.


Minerals that guinea pigs require are usually found in the correct dosages in the commercial food provided. A diet that may have an imbalance of calcium, phosphate and magnesium along with a deficiency in vitamin D can lead to a condition called metastatic calcification. Mineral deposits can sub-clinically show up as irregular grey patches on tissue surfaces. Symptoms may show as muscle stiffness, bone deformities and poor growth, but internally these mineral deposits can occur throughout the body.

  • Issue 34 - PRINT ONLY
    Issue 34 – PRINT ONLY
  • Issue 34 - DIGITAL ONLY
    Issue 34 – DIGITAL ONLY

Will she get better on her own?


My guinea pig is eating and pooping normally, wheeking and running around as normal. However, she is also sneezing a lot, sometimes gets crusty eyes and a chest rattle. I did some research online, and the advice was conflicting. I can’t afford to take her to the vets at the moment as I lost my job during the lockdown. Does she have a cold, similar to a human cold? She doesn’t look like she’s suffering and hasn’t been getting any worse. Will she get over this on her own?

A: Dr Alison Wills

It sounds like your guinea pig may be suffering from a respiratory infection that will not resolve on its own. It is positive that she hasn’t deteriorated further, but she may be entering a chronic disease course (where the problem goes on for a long time), which won’t get better without treatment. It would be cheaper and easier to treat this respiratory infection now rather than leave it, and the problem becomes persistent. You may find that she is intermittently ill for the rest of her life, which would not be a nice way for her to live.

 Unfortunately, she could die from this, and it is not uncommon for guinea pigs to die from respiratory infections even if veterinary care is sought straight away. It might be the case that you can take her back to the pet shop you purchased her from (if you acquired her recently), and they may cover the costs of as much treatment as she needs to get her better. If you have had her longer, it might be the case that the veterinary care she needs is not as expensive as you think. 

Perhaps phone a local vet and ask how much a small animal consultation is and what they estimate it could cost with some medicines on top of that. Pets do, unfortunately, cost some money in terms of vet bills throughout their lives. 

So whilst it is very sad if this is something you are unable to afford, it might be best to relinquish your guinea pig to a charity or rescue centre who will look after her and get her the veterinary care she needs. I wish you all the best and hope you can get your pet to a vet and that she gets better.

A: Wiebke Wiese Thomas

Please have your girl vet checked. She needs an antibiotic to get on top of her well-developed bacterial upper respiratory tract infection (URI), which she is obviously not getting on top of on her own. 

A human cold is viral, so they are not the same at all. Not all untreated URIs are deadly, but they can leave permanent scarring in the airways and a reservoir of bacteria which can flare up much worse again later in life.

 I have looked after a guinea pig with upper and lower lung disease due to an undertreated UTI earlier in life before I adopted her. It was not fun, and it was a lot more expensive than the appropriate initial treatment would have been. I wish she could have been spared her breathing problems in later life! In newly bought guinea pigs where exposure and infection have happened at the pet shop, you can reclaim any vet fees from the pet shop based on a diagnosis and by presenting the vet bill together with your purchase receipt. 

US chain pet shops will cover illnesses in the first month after purchase; this goes for 2-3 weeks in the UK. It is part of your regular customer rights for having been sold damaged ware. The right to medical care is part of the five basic animal rights (the freedom from pain and suffering). Please always save up for a vet fund as part of the weekly/monthly maintenance cost. 

When things go wrong with guinea pigs, they very often do very suddenly and very badly. I hope you will give your little piggy the care she needs right now and a happy and healthy long life. All the best!