Author: Tarra Freel, MS | Nutrition & Research Manager – Specialty Pets, Compana Pet Brands
In the wild, ancestors of pet guinea pigs spend many of their waking hours foraging for food and consuming large amounts of diverse vegetation . In fact, guinea pigs must have a steady supply of fiber from plant materials to keep their gastrointestinal tracts functioning properly and this applies to domestic guinea pigs as well .
Guinea pigs are concentrate selectors, meaning they will choose to consume the most energy-dense plant material available as quickly as they can. This behavior of selecting energy-dense foods stems from evolving as a prey species with the drive to minimize the time spent being vulnerable out in the open. It’s important to keep this in mind when feeding our pets as this could lead to the unhealthy behavior of selective feeding, which can be prevented by offering a uniform pellet.
The diversity of plant material and nutrient profile of a wild guinea pig’s diet is something we can try to mimic to some degree for our pets. A good, balanced (yet diversified) daily diet for pet guinea pigs should look something like:
- 70% grass hay, always available, offer a variety
- Young guinea pigs (<6 months) can eat alfalfa, but it should be offered only in small amounts as an occasional treat for adults.
- 20% fortified food (uniform pellets prevent selective feeding)
- 8% greens
- 2% treats
- Unlimited fresh water
A disruption in normal gastrointestinal function can be detrimental to guinea pigs and can be caused by many things, some of which are specific food items.
The list below outlines some foods that may threaten guinea pig health. While this is certainly not an exhaustive list of foods that are toxic or unhealthy for guinea pigs, it highlights some of the more common foods to avoid feeding your pet.
If your guinea pig ingests one of the items below, call your veterinarian immediately. Of course, if you wish to introduce any new food items into your guinea pig’s diet, it’s always best to consult your veterinarian for that as well.
Foods Guinea Pigs Should Never Eat Include:
- Animal proteins
- Chives, Garlic, Leeks, Onions
- Fruit seeds/pits
- Highly processed foods such as bread, pasta, chips, rice, and crackers
- Peanut butter
- Raw potatoes
- Hot peppers
- Certain parts of tomatoes
- Some house plants
Can Guinea Pigs Eat Animal Proteins?
As herbivores, guinea pigs do not have adequate enzymes to properly digest and utilize animal protein as omnivores and carnivores do. Thus, it is not recommended to feed your guinea pig meat, eggs, dairy, or other animal-derived proteins. Doing so could cause digestive upset, dysbiosis (a shift in the microbiome -microbes live in the gastrointestinal tract of guinea pigs and many help with digestion), and increase the risk of obesity.
Can Guinea Pigs Eat Avocados?
Avocados contain a compound called persin which can be toxic to guinea pigs. Persin is found in all parts of the avocado including the fruit, skin, seeds, stem, and leaves. Toxic amounts of persin can damage a guinea pig’s heart muscle within 24 to 48 hours, potentially leading to congestive heart failure if not promptly treated . For these reasons, guinea pigs should never eat avocados.
Can Guinea Pigs Eat Chives, Garlic, Leeks, or Onions?
Allium spp of plants include garlic, onions, chives, and leeks with garlic and onions being most reported for toxicosis. These plants contain sulfur-containing oxidants that are thought to be the cause behind hemolysis (destruction of red blood cells) that may occur after ingestion.
Hemolysis usually occurs 3-5 days after ingestion, and unfortunately, physical signs of Allium toxicosis are generally not noticed until significant hemolysis has occurred.
Symptoms of Allium toxicosis in guinea pigs may include:
- Abnormally rapid breathing
- Rapid heartbeat
Fatality may occur if hemolytic anemia is not treated promptly .
Can Guinea Pigs Eat Chocolate?
Similar to the risk in dogs and other mammals, chocolate can be fatal to guinea pigs and should be altogether avoided.
The toxic substances in chocolate are theobromine and caffeine. The lighter the chocolate, the lower the risk of toxicity, but for pigs, all chocolate should be avoided. White chocolate contains insignificant amounts of these compounds but still shouldn’t be fed to guinea pigs due to its high sugar and fat content.
Toxic amounts of chocolate can result in central nervous disturbances and life-threatening heart rhythm abnormalities, as theobromine is a cardiac stimulant and diuretic.
Symptoms of toxicity in guinea pigs may include:
- Difficulty getting comfortable
- Tachycardia (elevated heart rate)
- Hyperthermia (elevated temperature).
Signs of chocolate toxicity usually appear 6-12 hours after ingestion and it can be fatal if not treated promptly .
Can Guinea Pigs Eat Fruit Seeds or Fruit Pits?
Guinea pigs can eat apples and other fresh fruits in small quantities as an occasional treat. Before offering your guinea pig his favorite slice of green apple, however, make sure to remove all seeds and pits.
Most fruits are safe in small amounts, but the seeds and pits from many fruits contain trace amounts of cyanide. While amounts of cyanide in seeds/pits may be very low, it’s best practice to avoid feeding them all together as they can also pose a choking hazard.
Can Guinea Pigs Eat Rhubarb?
Rhubarb contains a high concentration of oxalic acid which, if consumed in high quantities, can interfere with calcium absorption and have other toxic effects. In guinea pigs, the oxalate can bind to calcium and potentially form bladder stones which can be very painful. Avoid feeding rhubarb to your guinea pig at treat time and opt for a small amount of more guinea pig-friendly dark leafy greens instead.
Can Guinea Pigs Eat Processed Foods?
While not necessarily toxic, many highly processed human foods such as bread, pasta, chips, rice, crackers, and cookies can still pose a threat to your guinea pig and are not nutritionally appropriate. Many of these foods are very high in the type of carbohydrates that should be kept to a minimum for guinea pigs – starches and sugars. Feeding these types of foods to your guinea pig can cause digestive upset and increases the risk of obesity.
Fortunately, there are more species-appropriate treats to share with your guinea pig such as small amounts of fresh fruits, and good quality manufactured treats that contain fruits and veggies. Avoid treats that contain artificial colors, flavors, or preservatives.
Additionally, there are a variety of leafy greens and leaf lettuces that guinea pigs can and should eat daily. Many guinea pigs love greens so much they will consider these healthy foods a treat when offered alongside their grass hay and guinea pig pellets!
Can Guinea Pigs Eat Peanut Butter?
There are several reasons that you should not offer peanut butter to your guinea pig. For one, peanut butter is high in fat, making it less than ideal for your guinea pig, and in many cases is also high in sugar. Peanut butter also presents a choking hazard due to its thick, sticky consistency. Similarly, whole peanuts are also not recommended for your guinea pig.
Can Guinea Pigs Eat Raw Potatoes?
Raw potatoes contain an alkaloid called solanine which can be toxic to some small mammals. Ingesting solanine can lead to digestive upset, abdominal pain, decreased appetite, and lethargy. Potatoes are also very high in starch which can potentially lead to serious digestive issues in guinea pigs when consumed in significant quantities.
Can Guinea Pigs Eat Hot Peppers?
The compound capsaicin is what makes hot peppers hot and it can also irritate the digestive system. You should never intentionally subject your guinea pig to hot peppers such as chili peppers or jalapeno peppers as this could lead to digestive upset. Bell peppers of all colors, on the other hand, are a great choice for guinea pigs!
Can Guinea Pigs Eat Tomatoes?
Unripe tomatoes, tomato leaves, and tomato stems all contain tomatine which is a glycoalkaloid poison that can lead to diarrhea and other ill effects in guinea pigs. Even with fresh, ripe tomatoes, stick to low quantities as the high oxalic acid can cause cheilitis (scabs on the mouth).
Can Guinea Pigs Eat House Plants?
Though not something humans view as food, house plants can look very appetizing to guinea pigs. In fact, some devoted guinea pig owners grow pig-friendly varieties of houseplants specifically for their pets to enjoy. With that said, some species of house plants are toxic to guinea pigs, so it’s best to keep all house plants out of the reach of your pet unless you’re well-researched in which varieties are safe .
Holowaychuk, M. K. (2006). Renal failure in a guinea pig (Cavia porcellus) following ingestion of oxalate containing plants. The Canadian Veterinary Journal, 47(8), 787.
Kohles, M. (2014). Gastrointestinal anatomy and physiology of select exotic companion mammals. Veterinary Clinics: Exotic Animal Practice, 17(2), 165-178.
Lord, E., Collins, C., deFrance, S., LeFebvre, M.J., Pigière, F., Eeckhout, P., Erauw, C., Fitzpatrick, S.M., Healy, P.F., Martínez-Polanco, M.F. and Garcia, J.L. (2020). Ancient DNA of guinea pigs (Cavia spp.) indicates a probable new center of domestication and pathways of global distribution. Scientific reports, 10(1), 1-9.
Merck & Co., Inc. (2006). The Merck Veterinary Manual (8th edition). Whitehouse Station, NJ: Merck & Co., Inc.
Navia, J. M., & Hunt, C. E. (1976). Nutrition, nutritional diseases and nutrition research application. In Biology of the Guinea Pig, J. E. Wagner and P. J. Manning (Eds.), (pp. 235-265). New York: Academic Press.
Weir, B. J. (1974). Notes on the origin of the domestic guinea pig. In The Biology of Hystricomorph Rodents, I. W. Rowlands and B. J. Weir (Eds.). New York: Academic Press.