A female intact Chihuahua pup was presented at the age of four months with complaints of vulvar swelling andprecocious sexual behaviour. Both complaints started to develop at the age of 9-10 weeks. During clinicalexamination, inspection revealed swollen mammary glands. The differential diagnosis was gonadotrophinindependent(peripheral) precocious puberty (or precocious pseudopuberty) as a result of the exogenous intake ofestrogens, or intersexuality. The first diagnosis was the most probable one since the female owner of the dog appliedan estrogen gel on face and shoulders on a daily basis. The owner was advised to avoid contact of the pup with thegel. This resulted in a positive evaluation after two months, with a complete disappearance of the complaints fourmonths after the first examination.