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