Captive naked mole-rats (Heterocephalus glaber) have the highest skin pH among mammals

Skin serves as a barrier against the external environment and is a primary defense against pathogens. Cutaneous pH is part of that defense as pH affects enzyme production, activation, and efficiency within skin. Skin pH is influenced by multiple factors, although little research is available on wildlife. Most mammals have neutral to slightly acidic skin, while increased skin alkalinity is associated with a predisposition to cutaneous infections. The long life span, lack of fur, and eusocial nature of naked mole-rats (Heterocephalus glaber) make them an interesting study species for investigating patterns in skin pH. We measured skin pH over six months in captive naked mole-rats to determine variation among ages, sex, social status, the queen's reproductive status, body parts, and skin health issues. The overall mean skin pH was 8.0 ± 0.8 and ranged up to 10.0, the highest skin pH ever reported among mammals (n = 1807 measurements from 79 individuals, pH range 5.68-10.0). The skin pH of colony members decreased as the colony queen's pregnancy advanced, which may be due to elevated estradiol levels in colony members. The skin pH of the head region was more acidic than the body, which may be due to the presence of skin glands. Skin pH did not vary with social status, age, or sex. Given the alkaline skin observed in naked mole-rats and the fact that skin alkalinity is detrimental in other mammalian species, naked mole-rats present an intriguing study system for future investigations of skin function.