Sex Hormones

()Map ENDOCRINE SYSTEM (Map)

Sex hormones are produced by the zona reticularis of the adrenal glands in addition to those produced by the ovary and testis:

• Testis: Produces androgens:
  • Increase mitoses in skin.
  • Increase sebaceous secrretion.
  • Increase hair growth.
• Ovary: Produces oestrogens and progesterone. Effects of oestrogens include:
  • Decreased collagen production.
  • Decreased sebaceous secretion.
  • Decreased epidermal thickness.
  • Decreased hair growth.
  • Increased skin pigmentation.

Hyperoestrogenism

Females

Ovarian Imbalance Type 1 Seen in adult bitches who present with alopecia and increased pigmentation round the perianal, perigenital and axillary areas. Caused by:

• Cystic ovaries.
• Ovarian neoplasia.

Males

Dogs present with bilaterally symmetric alopecia, similar hyperpigmentation to that seen with female dogs with ovarian imbalance, loss of libido and gynaecomastia. The dogs become attractive to other male dogs. Caused by:

• Sertoli cell tumour.
• Male feminising syndrome.

Hyperandrogenism

Females

Ovarian Imbalance Type 2 Seen in young bitches spayed early. Develop alopecia of perineum, ventral neck, chest and abdomen. Bitch will have immature nipples and vulva and may diplay incontinence. Treatment: May respond to small doses of oestrogens.

Males

• Perianal gland hyperplasia.
• Tail gland hyperplasia.
• Seborrhoea.