Sheep milk by-products are commonly consumed in Western Europe, mostly cheese made from sheep milk like feta and ricotta.
The allergenic proteins in sheep milk are generally split into albumins (commonly called whey) and casein. In human milk the split is usually 60% whey to 40% casein. In sheep milk the split is 20% whey to 80% casein. This is a very similar composition to cow's milk. This massive difference in composition is thought to be the cause of what causes IgE allergic reaction to mammalian milk, with most people being allergic to casein proteins in the milk.
Sheep milk or cheese are not suitable alternatives for people suffering from cow’s milk allergy.
Sheep milk allergy is not currently associated with any syndromes.
Cow, goat and buffalo milk could all be cross reactive with sheep milk due to similar composition.