The diabetes mellitus (DM) is disease of animal metabolism, secondary to absolute or relative deficiency of insulin, which is characterized by hyperglycemia after jejunal and the tendency to develop lipid and protein catabolism. Young dogs (juvenile diabetes) rarely presents this illness, usually insulin-dependent, affecting less than 1.5% of racial bias in dogs with golden retriever, west terrier, miniature Schnauzer, among others. In the same way, the pituitary dwarfism is a rare manifestation of endocrinopathy and its diagnosis is established when there is low concentrations of growth hormone (GH) and consequently, somatomedins (IGF1), with racial bias in German shepherd, Weimaraner, Spitzer and pincher toy. Cases of congenital hydrocephalus due to a structural defect of the ventricular system within the skull, which blocks the flow of cerebrospinal fluid (CSF) or hinders its absorption, causing an abnormal dilation and compression of adjacent structures. There is a racial bias in dog race Maltese, Yorkshire, English bulldog, Chihuahua and Lhasa Apso. The report case refers to a male dog, breed Chihuahua, 5 months old, treated in the Anhembi Morumbi Veterinary Hospital, with a history of polyuria, polydipsia, polyphagia, weight loss, slow growth, delayed tooth eruption, increase of skull, the presence of fontanelle open with no history of neurological disorders. The additional tests revealed adequate renal and hepatic function and normal thyroid and adrenal function, but, hyperglycemia (268 mg/dL), glycosuria, fructosamine elevation of serum (545 umol/L), in addition to not closing the growth of cartilage (physeal areas) and decreased levels of somatomedin (IGF1 < 25 ng/mL) and protein carrier somatomedin (BP3 < 0.5 mcg / mL) were found. No reports of simultaneous occurrence of juvenile diabetes, dwarfism and hydrocephalus in the same animal were found in veterinary literature so far. The hydrocephalus could justify the hyposomatotropism by compression and consequent reduction in hypothalamic GHRH, but the occurrence of diabetes is not justified in this context, suggesting a polygenic inheritance. The treatment so far was intermediate-acting insulin canine (Caninsulin^® 0.5 IU/kg every 12 hours), with the patient's clinical improvement.