Guinea pigs are unique among pet rodents in one critical way: like humans, they cannot synthesize their own vitamin C. This single fact makes their dietary requirements distinct from other small pets. But vitamin C is just the beginning—guinea pigs also need specific amounts of hay, vegetables, and carefully portioned pellets to thrive.
The Vitamin C Imperative
Guinea pigs require 10-30 mg of vitamin C per kilogram of body weight daily. For an average 1 kg guinea pig, this means 10-30 mg daily—with pregnant, nursing, young, or ill guinea pigs needing amounts at the higher end of this range.
Without adequate vitamin C, guinea pigs develop scurvy—symptoms include rough coat, lethargy, joint swelling and pain, loss of appetite, weight loss, diarrhea, delayed wound healing, and eventually death. Even mild deficiency causes subclinical problems that weaken the immune system.
Best Sources of Vitamin C
The best way to provide vitamin C is through fresh vegetables. Unlike supplements added to water (which degrade quickly and may alter the taste, causing reduced water intake), fresh foods provide stable, reliable vitamin C along with other nutrients.
Vitamin C Content in Guinea Pig Foods
- • Bell peppers (red): 190 mg per cup — Highest vitamin C; feed daily
- • Bell peppers (green): 120 mg per cup — Excellent daily staple
- • Kale: 80 mg per cup — High vitamin C but also high calcium
- • Parsley: 80 mg per cup — Good source but feed in moderation
- • Broccoli: 81 mg per cup — May cause gas; introduce slowly
- • Strawberries: 85 mg per cup — Treat only due to sugar
- • Kiwi: 167 mg per fruit — Excellent but high sugar; occasional treat
- • Orange: 70 mg per fruit — Some piggies dislike citrus; high sugar
Should You Supplement?
If your guinea pig eats a good variety of vitamin C-rich vegetables daily, supplements may not be necessary. However, many owners choose to supplement as insurance, especially for picky eaters or during times of stress or illness.
Best supplement options: Liquid vitamin C syringes administered directly (most reliable), or vitamin C tablets made specifically for guinea pigs. Avoid: Vitamin drops added to water (vitamin C degrades rapidly in water and light).
Hay: The Digestive Foundation
Like rabbits, guinea pigs need unlimited access to grass hay. Hay provides the long-strand fiber essential for proper gut function and helps wear down their continuously growing teeth. A guinea pig should eat a pile of hay equal to their body size daily.
Types of Hay
Timothy hay is the ideal staple for adult guinea pigs—high fiber, appropriate protein, and low calcium. First and second cutting are both suitable.
Orchard grass is an excellent alternative or mix-in. Some guinea pigs prefer its softer texture and sweeter taste.
Meadow hay provides variety with its mix of grasses. Quality varies by supplier.
Alfalfa hay is appropriate only for guinea pigs under 6 months, pregnant/nursing sows, or underweight adults. Its higher calcium and protein content can cause bladder stones in healthy adults fed long-term.
Fresh Vegetables: Daily Essentials
Guinea pigs should receive approximately 1 cup of fresh vegetables per day per pig. Include a variety of vegetables, with an emphasis on vitamin C-rich options and leafy greens.
🥗 Safe Vegetables for Daily Feeding
Daily Staples:
- • Bell peppers (all colors)
- • Romaine lettuce
- • Green leaf lettuce
- • Red leaf lettuce
- • Cucumber
- • Cilantro
Rotate Through Weekly:
- • Tomato (small amounts; no leaves)
- • Zucchini
- • Carrot (limit due to sugar)
- • Endive
- • Parsley
- • Celery (cut to prevent strings)
High-Calcium Vegetables: Feed in Rotation
Guinea pigs are prone to bladder stones, making calcium intake an important consideration. High-calcium vegetables aren't forbidden but should be rotated rather than fed daily:
- • Kale
- • Spinach
- • Parsley
- • Dandelion greens
- • Collard greens
Offer these 2-3 times per week rather than daily, and balance with lower-calcium options like bell peppers and lettuces.
Pellets: Supplementary Nutrition
Pellets provide convenient supplemental nutrition and are fortified with vitamin C. However, they should not be the main component of the diet. Guinea pigs fed too many pellets often neglect hay and become overweight.
Choosing Quality Pellets
Select plain timothy-based pellets formulated specifically for guinea pigs—not rabbits, which have different nutritional needs. Avoid mixes with seeds, nuts, dried fruit, or colorful pieces, which encourage selective eating and often contain unhealthy ingredients.
Look for pellets with:
- • Stabilized vitamin C (check expiration dates—vitamin C degrades over time)
- • Timothy hay as the primary ingredient
- • 16-18% fiber minimum
- • 14-16% protein
- • Low calcium (under 1% for adults)
How Much to Feed
Adults: 1/8 cup (about 2 tablespoons) of pellets per pig per day. This is less than many owners expect—the emphasis should be on hay and vegetables.
Young guinea pigs (under 6 months): Can have unlimited alfalfa-based pellets to support growth, then transition to limited timothy pellets.
Treats: Small Pleasures
Guinea pigs can enjoy small amounts of fruit as treats—limit to 1-2 small pieces a few times per week due to sugar content.
Safe Fruit Treats
- • Strawberries (a favorite for most piggies)
- • Apple (remove seeds)
- • Blueberries
- • Watermelon (remove seeds)
- • Cantaloupe
- • Banana (small amounts—very high sugar)
- • Grapes (cut in half to prevent choking)
⚠️ Foods to Avoid
- • Iceberg lettuce: Low nutrition, can cause diarrhea
- • Potatoes: Toxic to guinea pigs
- • Onions, garlic, leeks: Toxic, can cause blood disorders
- • Avocado: Toxic
- • Rhubarb: Toxic, including leaves
- • Chocolate, caffeine: Toxic
- • Bread, crackers, cereals: Digestive upset, no nutritional value
- • Seeds and nuts: Choking hazard, too high in fat
- • Dairy products: Guinea pigs are lactose intolerant
- • Commercial "treats": Most contain harmful ingredients like seeds, honey, or artificial colors
Water: Clean and Constant
Fresh water must be available at all times. Most guinea pigs drink from water bottles with sipper tubes, though some prefer bowls. If using bottles, check daily that the ball bearing mechanism is working properly.
Change water daily and clean bottles/bowls regularly. Algae and bacteria can build up in water bottles, so thorough cleaning with a bottle brush weekly is important.
Daily Feeding Schedule
Guinea pigs do best with consistent feeding times. A typical schedule might look like:
Sample Daily Feeding Schedule
- Morning:
- • 1/8 cup pellets per pig
- • Refresh hay pile
- • Fresh water
- Evening:
- • 1 cup mixed vegetables per pig
- • Check and replenish hay
- • Refresh water if needed
- Throughout day: Ensure hay is always available
Signs of Nutritional Problems
Watch for these warning signs that may indicate dietary issues:
- Weight loss or gain: Weigh guinea pigs weekly to track changes
- Rough or dull coat: May indicate vitamin C deficiency
- Joint stiffness or reluctance to move: Possible scurvy
- Dental problems: Often from insufficient hay
- Soft or watery stool: Too many vegetables too fast, or inappropriate foods
- Bloody urine: Possible bladder stones (seek vet care immediately)
Multiple Guinea Pigs
Guinea pigs are social animals and often kept in pairs or groups. Ensure each pig gets adequate nutrition by:
- • Providing multiple food stations to prevent resource guarding
- • Spreading vegetables around the enclosure
- • Monitoring that all pigs are eating and maintaining weight
- • Watching for bullying at feeding time
Proper nutrition is the foundation of guinea pig health. By providing unlimited hay, daily vitamin C-rich vegetables, limited quality pellets, and clean water, you'll give your guinea pigs everything they need for a healthy, happy life. Remember that guinea pigs are creatures of habit—maintain consistent feeding times and introduce new foods gradually to keep their sensitive digestive systems running smoothly.