This paper describes the structure of the otter anal scent sacs. The deposited secretion contains apocrine gland protein and polymucosaccharide and sebaceous gland lipid. Chemical analyses by gas-liquid chromatography and acrylamide gel electrophoresis revealed individual differences in the composition of secretion. The individual differences in protein bands as revealed by electrophoresis were stable with time and may be useful in following the movements of wild otters in the field.
A captive pair of otters produced deposits of secretion with a periodicity similar to that of the female oestrous cycle, with both sexes producing deposits around oestrus.