Canine Ovarian Imbalances

By | March 6, 2016
  • poorly understood conditions
  • diagnosis is made on clinical grounds only
  • there are two types

Type 1 (hyperoestrogenism)

  • middle-aged to old bitches
  • any breed
  • may be associated with cystic ovaries or ovarian tumours

Clinical features

  • bilaterally symmetrical alopecia in the perineal and genital areas, extending anteriorly ()
  • the affected area often exhibits a secondary seborrhoea and in chronic cases lichenification
  • enlarged vulva and nipples
  • abnormalities of the oestrus cycle

Diagnosis

  • physical examination
  • rule out other differential diagnoses
  • response to treatment

Differential diagnosis

Treatment

  • ovariohysterectomy
  • symptomatic treatment for seborrhoea
  • allow 3-6 months before assessing the response

Type 2 (oestrogen-responsive dermatosis)

  • rare
  • usually seen in bitches spayed before the first oestrus
  • cause is unknown; hypo-oestrogenism has not been demonstrated

Clinical features

  • bilaterally symmetrical alopecia in the perineal and genital regions, which spreads to the medial thighs and the ventral abdomen; the dorsum is spared
  • the remaining coat tends to be soft, like that of a puppy; hair-shedding is minimal
  • pruritus is minimal unless there is a secondary seborrhoea
  • the vulva and nipples are small

Diagnosis

  • physical examination
  • rule out differential diagnoses
  • response to treatment

Differential diagnosis

  • hypothyroidism
  • hyperadrenocorticism
  • disorders presenting with seborrhoea

Treatment

  • no treatment is necessary in many cases
  • 0.1 – 1 mg/kg stilboestrol once daily by mouth for three weeks of each month
  • thereafter maintenance dose of 0.1- 1 mg weekly
  • alternative non-stilbene oestrogens include oestradiol valerate (equal potency to stilboestrol) or ethinyloestradiol (20 times more potent)
  • monitor the dogs due to risk of bone marrow depression and pancytopenia

 

Selections from the book: “Skin Diseases in the Dog and Cat”. D. I. Grant, BVetMed (1991)