Skin Lesions Associated with Lysine Deficiency in Kittens are Characterized by Inflammation

Processing substantially reduces the bioavailability of lysine in pet foods, and certain populations of cats may be at risk for deficiency. A previous study reported that kittens consuming lysine deficient diets developed facial skin lesions; however these were not characterized with histopathology. The hypothesis of this study was that kittens with lysine deficiency develop histopathologically distinct skin lesions. Twelve, male, 7-to-9 week old, healthy kittens were fed diets either replete (16 g/kg as fed) or deficient in lysine (4 g/kg as fed) in a prospective, controlled feeding trial for 1 week. Standard skin biopsies were examined in a blinded fashion. Plasma was analyzed for amino acid concentrations. The median average daily gain of the control and test group kittens was 37.8 g (range 23.8 to 40.3) and 0.8 g (range -12.7 to 7; p < 0.05), respectively. Five kittens in the test group (5/8; 62.5%) and one in the control group (1/4; 25%) developed facial lesions with dark adherent crusting near the dorsal nasal planum, chin, and/or adjacent to the philtrum. Histopathologic examination revealed superficial and deep perivascular pleocellular dermatitis with mild acanthosis, hyperkeratosis, intra-epidermal pustules, superficial folliculitis, and furuncles. There was no difference in plasma lysine concentrations between groups (p = 0.064). Histopathologic characterization of facial skin lesions suspected to be associated with lysine deficiency in kittens were not consistent with other dermatological diseases, and were not associated with decreased plasma lysine concentrations.