Overproduction of Estrogen in Dogs

A dog can overproduce estrogen due to an artificial introduction of hormones or a natural imbalance of hormones. While overproduction of estrogen is more common in female dogs that naturally have higher estrogen levels, overproduction of estrogen may also occur in male dogs. No breed appears to have a higher occurrence of overproduction of estrogen or estrogen toxicity.

• Lethargy
• Pale gums
• Blood in urine, stool and/or vomit
• Fever
• Infections
• Thinning hair and/or hair loss
• Males exhibiting female characteristics
• Infertility
• Prolonged estrus in females
• Enlarge vulva and/or teats in female
• Bleeding from vulva
• Decreased attraction to opposite sex in intact males
• Increased attraction to opposite sex in females
• Tumor on tail in males
• Testicular mass in males
• Testicular atrophy in males
• Prostatic dysfunctions in males
• Prostatic cysts in males

• Artificial estrogen or testosterone supplementation
• Excessive production of estrogen (idiopathic)
• Ovarian tumor
• Ovarian cysts
• Testicular tumor

Diagnosis will depend upon proper reporting of symptoms and your dog’s medical history. A thorough physical examination, followed by a complete blood count to determine your dog’s levels of red and white blood cells, which can decrease as a result of overproduction of estrogen, chemical blood profile, and urinalysis in order to determine your dog’s overall health and identify any issues or irregularities. If your dog’s is losing hair, a skin biopsy will be examined in order to determine the cause of hair loss. An additional biopsy of your dog’s lymph nodes will be conducted, along with an aspirate bone marrow biopsy. These will help determine estrogen levels and their affects on your dog’s health. An x-ray and/or ultrasound of your dog’s abdomen will be taken, and reproductive organs will be examined. For male dogs, testicles will be thoroughly examined, and any testicular masses will be diagnosed through a needle biopsy. For female dogs, ovaries will be examined, and any ovarian cysts will be studied through an ultrasound-guided aspiration.

Treatment will depend upon the cause and extent of the overproduction of estrogen, as well as the sex of your dog. If overproduction of estrogen is caused by hormone supplementation, that therapy will be ceased immediately. The next step will be to stabilize your dog, which may include antibiotic treatment and blood transfusions, depending upon the severity of your dog’s case. Definitive treatment typically involves surgical neutering or spaying in order to stabilize your dog’s sexual hormones and is typically curative. Further treatment of masses or cysts will depend upon their presence and location; masses may be removed via an incision or small scope instrument, testicle(s) or ovaries may be removed completely. If your dog is suffering from decreased blood production, medication may be prescribed to increase production in bone marrow. In some cases of ovarian cysts in female dogs, medication may be prescribed to induce ovulation.

A dog’s hormonal balance is very delicate, and may take months to return to a healthy and natural balance. Monitor your pet’s health and behavior during recovery and carefully follow all of the veterinarian’s instructions for medications. If your dog has undergone surgery, stick to follow-up and wound care instructions carefully and monitor surgical sites. In almost every case, it will be required to bring your dog back to the veterinarian for checkups that will include blood tests and possibly bone marrow biopsies in order to monitor recovery. With proper treatment, recovery should be slow but total. Be sure never to give your dog supplemental hormones without consulting the veterinarian.