How to Compare Fibre Sources in Dog and Cat Food

Fibre is more than a percentage

Fibre is not a single, uniform ingredient category. Two dog or cat foods may show similar crude-fibre percentages while containing fibre sources with different properties and potentially different effects. For that reason, comparing fibre sources in dog and cat food requires more context than ranking foods by one number on the label.

Fibre information can help you ask better questions, but it cannot independently predict stool quality, gastrointestinal response, digestibility, or clinical benefit. A useful comparison considers the complete label, the animal’s needs, and whether the food is being used for general feeding or a therapeutic objective.

Why fibre characteristics differ

These characteristics do not necessarily move together. Fibre sources can differ in physiological effects, digestibility, and fermentability, and these differences may affect other dietary ingredients. Research also supports comparing fibre sources by physicochemical properties and fermentation behaviour rather than treating all fibre as equivalent.

Laboratory or model findings can help describe differences between sources, but they do not guarantee the same gastrointestinal or stool response in every dog or cat. The animal, complete diet, processing, amount of fibre, and clinical goal all matter.

• Solubility: how a fibre behaves in relation to water.
• Viscosity: how it may affect the thickness or flow of material in the digestive tract.
• Water-holding capacity: how much water the fibre can retain.
• Fermentability: how it behaves during fermentation.
• Digestibility: how the fibre and the complete diet are processed by the animal.
• Physiological effects: how the source may interact with the rest of the diet and the animal’s digestive response.

Crude fibre versus total dietary fibre

The guaranteed analysis generally reports crude fibre as a maximum percentage. This is useful label information, but crude-fibre testing captures only part of insoluble fibre and does not quantify soluble fibre.

In trials of six dry dog foods and six dry cat foods, crude-fibre analysis produced the lowest values among the reviewed methods, while total-dietary-fibre analysis produced the highest values. Crude fibre did not correlate with the other fibre methods. The researchers concluded that combining total dietary fibre and crude fibre may help distinguish total, unfermentable, and partially fermentable fibre in pet foods.

This comparison can be more informative than crude fibre alone, but it remains incomplete. Total dietary fibre and crude fibre do not fully reveal fibre fractions, fermentability, viscosity, water-holding capacity, processing effects, or an individual animal’s response. They should be treated as measurements that add context, not as a complete prediction of clinical effects.

Read the complete label

WSAVA’s label guidance recommends looking beyond the ingredient list. Ingredient lists do not provide information about ingredient quality and may be misleading about overall food quality. The presence of a named fibre ingredient, its position in the list, or a particular crude-fibre percentage should therefore not be used alone to judge the food.

A complete-label approach places fibre in the context of the food’s nutritional adequacy, calories, feeding directions, target species, manufacturer details, and available nutrient information. These details may be more useful for deciding whether a food is appropriate for the animal than an isolated ingredient name.

• Nutritional adequacy for the target animal.
• Calorie content, especially when comparing foods with different energy densities.
• Feeding directions and the target species.
• Manufacturer details and available information about its nutrition expertise.
• Specific nutrient information that may be available beyond the basic guaranteed analysis.
• Whether the food is intended for general feeding or a therapeutic objective.
• What fibre information is actually provided, such as crude fibre, total dietary fibre, or other analytical details.

A practical comparison checklist

A practical comparison starts by defining the question. If you are comparing two foods for routine feeding, first determine whether each is nutritionally appropriate for the dog or cat and compare calories and feeding directions. Then examine the fibre information that is available and note what the label does not disclose.

If one food lists more crude fibre than another, that difference may be worth discussing, but it is not a reliable threshold for a particular stool or digestive outcome. Similarly, two foods with the same crude-fibre value may function differently because their fibre sources and complete formulations differ.

Keep a record of the actual label information rather than assuming that a familiar ingredient or a higher percentage tells the whole story. The most useful conclusion may be that the available label data are insufficient to predict how either food will affect a particular animal.

• Record the crude-fibre value, remembering that it is generally a maximum percentage.
• Look for total-dietary-fibre information or other fibre analyses, while recognizing that these measurements still have limits.
• Note whether the label provides meaningful information about the complete food, not only one fibre ingredient.
• Compare calorie content, nutritional adequacy, feeding directions, and target species.
• Consider whether the manufacturer provides useful details about the food and its formulation.
• Ask what the comparison is meant to address: routine feeding, stool observations, weight management, or a medical goal.
• Avoid treating a higher or lower crude-fibre number as proof of better digestibility, fermentability, stool quality, or gastrointestinal benefit.
• If the goal is therapeutic, discuss the comparison with a veterinary professional rather than relying on label data alone.

When to involve a veterinary professional

Fibre decisions deserve professional input when they relate to gastrointestinal disease, obesity, constipation, diarrhoea, diabetes, or another medical condition. A veterinary professional can help place the label information in the context of the animal and the clinical goal.

Do not assume that an ingredient list or crude-fibre percentage can determine the appropriate fibre type or amount for an animal with a medical condition. Condition-specific diet decisions should not be made from label data alone.

The evidence does not support ranking one universal fibre source as best for every dog or cat. Instead, compare the information available, recognize the limits of the analyses, and consider the animal, complete diet, processing, amount of fibre, and purpose of feeding. Fibre is best understood in context—not as a single number.