Isolated goat and sheep milk allergy in an adult in the absence of bovine sensitization.

Cow's milk (CM) allergy is the most common food allergy in children, with cross-reactivity to goat and sheep milk (GSM) representing a common outcome due to high protein homology. However, isolated GSM allergy in CM-tolerant individuals is rare and poorly documented in the literature. We describe a 27-year-old male of Mediterranean origin who experienced two episodes of anaphylaxis after consuming sheep and goat cheese, despite regular CM consumption. Skin prick testing confirmed sensitization to GSM but not CM. This report contributes to the growing evidence of adult-onset isolated GSM allergy. Isolated GSM allergy typically presents later in life and may be underrecognized due to limited clinical awareness. We review the potential for species-specific mammalian milk protein allergy, likely mediated by structural differences in casein proteins. Clinicians should be cognisant to consider GSM sensitization in patients presenting with allergic reactions to dairy products, especially in multicultural populations with increasing GSM dietary exposure.