Pet Nutrition Fundamentals: Diet Types, Labels and Supplements by Species

Before you buy food for a new pet, the first thing to know is which feeding group it belongs to. A rabbit, a ferret and a leopard gecko have almost nothing in common at the food bowl. This page sorts the site’s common species by diet type, explains how far a pet food label can be trusted, and lists the few supplements that are genuinely required. Each species page has the full detail.

Diet type by species

Species	Diet type	Staple	Supplement needed?	Must avoid
Rabbit	Herbivore	Hay and grass, about 85% (RSPCA)	Not separately. A measured pellet ration supplies vitamins and minerals (RSPCA)	Muesli mixes, iceberg lettuce, avocado (RSPCA)
Guinea pig	Herbivore	Unlimited timothy or other low-calcium hay (VCA)	Vitamin C, 10–50 mg a day from pellets and vegetables (VCA)	Iceberg lettuce, oats, seeds, nuts (VCA)
Chinchilla	Herbivore	Grass hay available 24 hours a day, plus 1–2 tbsp of pellets (VCA)	None on a balanced diet (VCA)	Seeds, nuts, grains, dried fruit and vegetables (VCA)
Ferret	Strict carnivore	Complete meat-based ferret diet, available at all times (RSPCA)	Not separately. Ask a vet to recommend a complete diet (RSPCA)	Fibre, starches, bread, cereals (RSPCA)
Corn snake, ball python	Carnivore	Whole thawed rodents (VCA)	None as a rule (VCA)	Live prey (VCA)
Leopard gecko	Insectivore	Live gut-loaded insects (VCA)	Phosphorus-free calcium dusting, plus a calcium dish (VCA)	Insects collected outdoors (VCA)
Hedgehog	Omnivore, mostly insects	Hedgehog food mixed with low-fat cat food (VCA)	None on a balanced diet (VCA)	Avocado, milk, nuts, raw carrot (VCA)
Pet rat	Omnivore	Rat pellets (RSPCA)	Not separately. Extras come out of the daily ration (RSPCA)	Onion, citrus, walnuts, rhubarb, grapes, chocolate (RSPCA)
Bearded dragon	Omnivore	About 50% plants and 50% insects for adults (VCA)	Calcium with D3, 2–3 times a week (VCA)	Fireflies, wild-caught insects (VCA)
Budgerigar	Seed-eater fed pellets	Small-bird pellets (VCA)	None if 75–80% of the diet is pellets (VCA)	All-seed diets, honey sticks (VCA)
Sugar glider	Omnivore that feeds on nectar and sap	One-third kibble, one-third nectar or sap mix, one-third insects, produce and a calcium multivitamin (VCA)	Calcium multivitamin (VCA)	Chocolate, dairy, canned fruit (VCA)

Two things stand out in the table. First, appearance tells you nothing about diet. Chinchillas and rats are both small rodents, but a seed-and-nut mix that is a treat for a rat is on VCA’s never list for a chinchilla. Second, feeding amounts are tied to body weight or kept tightly measured almost everywhere. Sugar gliders, for example, eat roughly 15–20% of their body weight a day (VCA).

Reading a pet food label

In the US, label rules are set out in AAFCO’s model regulations, which apply to pet food sold through retailers. Three parts of the label are worth checking:

• The ingredient list. Ingredients must be listed in descending order by weight (AAFCO). For a herbivore pellet you want grass or timothy first. For a ferret food you want named meat first.
• The guaranteed analysis. This gives crude protein, fat and fibre. “Crude” describes the lab method, not the quality of the ingredient (AAFCO). For a rabbit, compare the fibre figure with the advice on the rabbit diet guide.
• The nutritional adequacy statement. AAFCO’s nutrient profiles cover only dogs and cats. A “complete and balanced” claim on a hamster or bird food is therefore not tied to any AAFCO standard. VCA warns the same about bird food: “Complete Avian Nutrition” on a bag can be misleading, because no regulatory body certifies bird diets.

A product name that highlights one ingredient can still be mostly something else, so check it against the ingredient list (AAFCO).

Supplements that are actually needed

Most pets on a correct diet need no supplement. The exceptions are specific:

• Vitamin C for guinea pigs. They can’t make it. Pellets lose vitamin C over time, so VCA says to use them within 90 days of manufacture. See the guinea pig diet guide for vegetable values.
• Calcium for insect-eating reptiles. VCA recommends a light dusting of phosphorus-free calcium powder on a leopard gecko’s insects, plus a shallow dish of calcium powder. Gut-load the insects for at least 24 hours before feeding.
• Calcium with vitamin D3 for bearded dragons. VCA suggests a light sprinkle 2–3 times a week. A dragon also needs UV light to use vitamin D3, so a supplement can’t replace a UVB lamp.
• Calcium-based multivitamin for sugar gliders. This is part of the daily third that also includes insects and produce (VCA).
• Birds that lay eggs. VCA notes that egg laying increases calcium needs. Give any bird supplement only with an avian vet’s advice.

Mistakes that cause problems

• Over-supplementing reptiles. VCA says too much calcium, vitamins and especially vitamin D3 is a common problem in pet bearded dragons. More powder is not safer.
• Letting a budgie live on seed. Budgies pick out millet, which lacks many nutrients. Seed-only diets are high in fat and low in protein and can shorten a bird’s life (VCA).
• Feeding a ferret like a dog. The RSPCA says ferrets can’t be vegetarian and can’t digest large amounts of fibre or starch. Cereal-based treats work against that.
• Adding treats on top of the daily ration. The RSPCA says rats’ fruit, egg and seeds should come out of the daily allowance, not be added to it, or they put on weight.
• Switching food overnight. Guinea pigs may refuse new food entirely (VCA), and rabbit and ferret guts are upset by sudden changes (RSPCA).

Avoid

• Honey sticks and all-millet diets for budgies (VCA)
• Yogurt treats for sugar gliders, which VCA links to dental disease and obesity
• Waxworms and superworms as a daily food for bearded dragons, because they are high in fat (VCA)
• Coarse sand, corncob or walnut-shell bedding for insect-eating lizards that may swallow it (VCA)