We call eggs a reference protein for good reason, they contain all essential amino acids. Eggs are a nutrient dense food, not only packed with protein but a range of micronutrients too.
As we work with raw diets as well as cooked, one of the questions we are asked all the time is whether raw eggs are safe for dogs.
So, let’s settle it once and for all.
Eggs are high in quality protein, they contain healthy fats, vitamins, minerals, eye protecting antioxidants and various other nutrients,
One whole, large raw egg contains
· protein: 6 grams
· fat: 5 grams
· magnesium: 6 mg
· calcium: 28 mg
· phosphorus: 99 mg
· potassium: 69 mg
· vitamin D: 41 IU
One large egg also contains 147mg of choline which is the precursor to acetylcholine, a key player in nervous system function. Eggs are high in lutein and zeaxanthin which are antioxidants involved in eye health.
Egg yolks provide a good dietary source of biotin and raw egg whites contain a protein called avidin. Avidin is known to bind to biotin in the small intestine, preventing its absorption.
We first found this in rats in the early 1900s. When rats were fed egg-white protein containing avidin, the biotin was biologically unavailable. This resulted in a syndrome of dermatitis, hair loss, and neuromuscular dysfunction known as “egg-white injury.”
Biotin is an essential water-soluble vitamin. It is also known as vitamin B-7 or vitamin H, in which case the H stands for “Haar und Haut,” the German words for “hair and skin.”
Biotin is necessary for the function of several enzymes known as carboxylases. These are part of important metabolic processes, such as the production of glucose and fatty acids.
Specifically, biotin is involved in:
Gluconeogenesis: This is the synthesis of glucose from sources other than carbohydrates, such as amino acids/ Biotin-containing enzymes help initiate this process.
Fatty acid synthesis: Biotin assists enzymes that activate reactions that are important for the production of fatty acids.
Amino acid breakdown: Biotin-containing enzymes are involved in the metabolism of several important amino acids, including leucine.
Research has shown biotin deficiency will result in abnormal fatty acid metabolism, which may be responsible for the pathogenesis of dermatitis and alopecia. Interestingly, supplementation of biotin-deficient rats with omega-6 polyunsaturated acids prevented the development of dermatitis, which indicated that an abnormality in n-6 PUFA metabolism is involved in biotin deficiency-related dermatitis (and perhaps not completely laying the blame at biotin per se).
Other schools of thought relating to biotin-deficiency alopecia is the role of the microbiota in the gut.
Free biotin may influence the composition of the gut microbiota because biotin is necessary for the growth and survival of the microbiota. Biotin deficiency leads to gut dysbiosis and the overgrowth of Lactobacillus murinus, leading to the development of alopecia. This is further compounded with co-administration of antibiotics.
Furthermore, vitamin B7 production appears to proceed in a cooperative manner among different intestinal bacteria; Bifidobacterium longum in the intestine produces pimelate, which is a precursor of vitamin B7 that enhances vitamin B7 production by other intestinal bacteria.
Based on this data you would be forgiven for thinking that raw eggs are a poor dietary choice because of the potential to cause a biotin-deficiency, but is this accurate?
We established a biotin-deficiency using rats. We must remember that rats have no dietary requirement for biotin because it is provided by intestinal microorganisms through coprophagy. To this end there are four ways to produce a biotin deficiency in rats fed a biotin-deficient diet.
1 – use germ free animals,
2 – prevent coprophagy,
3- feed sulfa drugs,
4- feed raw egg whites,
To achieve a biotin deficiency state, 20% raw egg whites as the source of protein was fed.
Whilst our dogs may like eggs, its unlikely that 20% of their diet will consist of them.
Raw and undercooked eggs may contain Salmonella, a type of bacteria.
Salmonella contamination can happen in one of two ways:
· either directly during the formation of an egg inside the hen,
· indirectly when Salmonella contaminates the outside of the egg and penetrates through the shell membrane,
Indirect contamination can happen during the production process, during handling, or during preparation.
In commercial egg sales, pasteurisation is one method that is often employed to prevent the possibility of Salmonella contamination. This process uses a heating treatment to reduce the number of bacteria and other microorganisms in foods.
But where you source your eggs from is a more obvious consideration to make here.
A review of risk factors for Salmonella in laying hens revealed that overall evidence points to a lower occurrence in non-cage compared to cage systems.
There is also conclusive evidence that an increased stocking density, larger farms and stress result in increased occurrence, persistence and spread of Salmonella in laying hen flock.
So, opt for free range and organic raised hens to source your eggs from to reduce the risk of bacterial contamination.
Eggs are nutritious whether you opt for cooked or raw. There may be compromised nutrient absorption, but this only occurs when significant quantities are eaten. Moderation is key and opt for free range and organic wherever possible.
And yes, the shells can be eaten too.
Thanks for reading,