Eggs, particularly chicken eggs, are now being used increasingly often as an addition to BARF diets and can also be found among the ingredients of commercial pet foods. Egg yolk can add valuable nutrients to our cat’s meal, but it must be offered in moderation and with due care. It is best to avoid the egg white.
Nutritional value
100 g of chicken egg (without the shell) provides 143 kcal. In terms of macronutrients, it contains 12.6 g of protein, 9.51 g of fat, and only 0.72 g of carbohydrates. Eggs have a high water content, amounting to 76.2 g/100 g. Above all, they are rich in fat-soluble vitamin A and water-soluble vitamin B4 (choline). To a lesser extent, they are a source of vitamin D, vitamin B9 (folic acid), and vitamin B7 (biotin). Eggs also contain minerals, mainly phosphorus, chloride, sulfur, sodium, potassium, and calcium. They additionally contain large quantities of Omega-6 and Omega-3 fatty acids. Their cholesterol content is 372 mg/100 g. Leucine, valine, and arginine are amino acids that are also present in significant amounts in eggs.
How should eggs be served?
Despite its wealth of nutrients, vitamins, and minerals, an egg does not, of course, contain these substances in proportions suitable enough for it to constitute a complete and balanced meal for a cat. There are no detailed recommendations regarding how many eggs may be given, but moderation is necessary because of the relatively high number of calories in the yolk that come from fat (with a risk of obesity if consumed too frequently) and its substantial phosphorus content. It is always worth considering the overall diet so as not to disrupt, for example, the proportions of amino acids.
Are there any risks?
As for the form in which eggs are served, raw egg yolk is often added to the bowl in a BARF diet. In that case, attention must be paid to the origin of the eggs to avoid bacterial infection, most commonly with Salmonella or E. coli, which primarily cause gastrointestinal symptoms. If we are concerned, we can also serve a hard-boiled (approx. 65°C) and cooled egg. It is important that it contain no seasonings, salt, oil, or butter. An egg fried in any type of fat is unhealthy, while the addition of onion, chives, or garlic may even cause fatal poisoning. Some cats may have a food allergy; if we notice any worrying symptoms, consultation with a veterinarian will be necessary.**
What about egg white?
Egg white is not recommended in a cat’s diet because it contains avidin. This compound belongs to the glycoproteins. It poses a risk in the body because it binds biotin permanently, making the biotin unavailable for use. Studies induced biotin deficiency in young female cats by feeding them diets containing 18.5% or 32% dried egg white. Symptoms included dried discharge around the eyes, nose, and corners of the mouth, scaly skin lesions, inflammation of the skin around the nose, upper jaw, and lower jaw, excessive salivation, and hair loss. The symptoms intensified, and bloody diarrhea, anorexia, and general body wasting also developed; these resolved after biotin was administered orally. Even if the biotin content of our cat’s diet is adequate, feeding egg white can significantly reduce its availability and cause a deficiency. It is also worth mentioning that avidin is relatively resistant to high temperatures (it remains active after an egg has been cooked at 90°C for 3 minutes), so in this case it makes no difference whether the egg is served cooked.
Benefits of egg yolk in a cat’s diet
Egg yolk can improve the palatability of a cat’s meal and encourage the cat to eat, which is one reason why it is present in some commercial pet foods. By offering egg yolk occasionally to add variety to our cat’s meal, we provide high-quality protein with a high amino acid content; these amino acids are building blocks of tissues and support tissue regeneration. We also provide a concentrated dose of energy and fatty acids that are necessary for the entire body to function properly. Choline is another valuable component: it forms part of cell membranes and has a positive effect on nervous system function and fat metabolism. Egg yolk contains the fat-soluble vitamins A, D, and E, which are essential for healthy vision, bone health, and immunity. At present, not all the components found in eggs have been scientifically confirmed in terms of their direct effects on a cat’s body.
Sources:
- Beasley, S., & Hiidenhovi, J. (2024). The use of egg and egg compounds in companion animal health (Version 2). Preprints.org.
- Pastoor, F. J. H., van Herck, H., van ’t Klooster, A. T., & Beynen, A. C. (1991). Biotin deficiency in cats as induced by feeding a purified diet containing egg white. The Journal of Nutrition, 121(11 Suppl.), S73–S74.
- WSAVA Global Nutrition Committee. (2024). Feeding treats to your cat (Version 2). World Small Animal Veterinary Association.