Overproduction of Estrogen in Ferrets

By PetMD Editorial on Jun. 20, 2010

Hyperestrogenism in Ferrets

Produced by the ovary, testes, and adrenal cortex (endocrine gland at the top end of the kidneys) for the purpose of regulating the menstrual cycle (estrus), estrogen is vital. However, an overproduction of estrogen can result in estrogen toxicity, or what is known as hyperestrogenism. This can happen without any outside interference or it can occur when estrogens are being introduced artificially, but typically occurs in sexually mature females (greater than 8 to 12 months of age).

Severe aplastic anemia (bone-marrow disease) and blood loss due to abnormal clotting from estrogen-induced bone marrow suppression is the most common and severe effect of hyperestrogenism.

Symptoms and Types

In intact females, severe hyperestrogenism can lengthen the duration of estrus, causing severe bone marrow suppression and subsequent blood loss due to deficiency of platelets in the blood stream. If not treated, the condition may become fatal within two months. Symptoms and signs to watch out for include:

  • Fever
  • Darkened skin
  • Depression
  • Lethargy
  • Lack of appetite (anorexia)
  • Bilaterally symmetric hair loss, usually beginning at the tail base and progressing forward
  • Blood in the urine (sometimes black in color)
  • Rear limb weakness, unsteadiness, partial or complete paralysis
  • Pale mucous membranes
  • Red pin-dots or splotches, or other signs of hemorrhage
  • Vaginal discharge
  • Large, turgid vulva
  • Cyst or abscess around the urethra


Proliferation of cells on the kidney lining or cancer causes increased production of sex steroids and is one of the most common diseases of ferrets. The bone marrow suppressive effects of hyperestrogenism in ferrets with adrenal disease is usually mild. Other organs affected include the skin and urogenital tract.

Hyperestrogenism due to prolonged estrus is less common in the United States because most ferrets are neutered before arriving at pet stores at approximately five to six years of age. Hyperestrogenism is also occasionally seen in neutered male ferrets, especially those with ferret adrenal gland disease.


Your veterinarian will first conduct a thorough physical exam and perform a variety of blood tests and a urinalysis to rule out other diseases and conditions that may cause similar symptoms. He or she may then recommend taking a sample of vaginal discharge for microscopic examination and/or bacterial culture. If the veterinarian still does not have success identifying the underlying cause, X-rays or and ultrasound may be necessary.


Because hyperestrogenism is a life-threatening condition, your ferret will probably require hospitalization, especially if the animal has anemia or is hemorrhaging. Immediate intravenous fluid therapy and antibiotics may be used to stabilize the animal. Typically, your veterinarian will recommend spaying (or neutering) your ferret.

Living and Management

Your veterinarian will recommend regular follow-up examinations to monitor its progress, and will give you instructions as to a proper diet during recovery.


If your ferret is intact, she should not be allowed to remain in heat for longer than two weeks without inducing ovulation by breeding or administration of appropriate medication.

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