Hyperestrogenism in Dogs
Estrogen, a hormone naturally produced in female dogs, plays a crucial role in their sexual behavior, development, and reproductive tract function. When estrogen levels become excessively high, a condition known as estrogen toxicity or hyperestrogenism may occur. This can happen spontaneously or as a result of artificial estrogen administration.
High levels of estrogen can lead to the formation of abnormal (cystic) cells lining the uterus, creating an environment where bacteria from the vagina can invade. If the cervix remains closed during the estrus cycle (“heat”), it can result in a severe infection known as pyometra. Moreover, elevated estrogen concentrations can cause infertility and disrupt the balance of hormones in the blood.
Symptoms and Types
Symptoms and Types of Hyperestrogenism in Dogs:
- Lethargy and weakness
- Paleness of gums
- Bleeding from skin, urine, stool, or vomit
- Fever
- Persistent infections
- Hair thinning
- Development of female characteristics in males
- Infertility
- Extended periods of estrus
- Enlarged vulva
- Swollen teats in females
- Reduced interest in the opposite sex
- Increased sexual attraction in females (nymphomania)
- Vulvar bleeding
- Hair loss (alopecia)
- Presence of a tail tumor in males (known as stud dog tail)
- Testicular mass in males
- Testicular atrophy
Causes
- Overproduction of estrogen
- Use of estrogen supplements
- Presence of ovarian cysts
- Ovarian tumors
- Testicular tumors
Diagnosis
- Comprehensive blood count (CBC)
- Bone marrow aspiration biopsy
- Abdominal X-ray
- Abdominal ultrasound
- Detailed examination of intact male testicles
- Aspiration biopsy of testicular masses using a needle
- Ultrasound-guided aspiration of ovarian cysts
- Lymph node biopsy
- Skin biopsy to identify the cause of hair loss
Treatment
- Discontinuation of estrogen supplementation
- Supportive care, which may involve antibiotics and blood transfusions
- Administration of blood transfusions if the dog is anemic
- Antibiotics to address infections if present
- Evaluation of masses using a small scope instrument (laparoscopy)
- Surgical removal of masses through incision (laparotomy)
- Surgical neutering for both male and female dogs if estrogen is not being administered artificially
- Consideration of testicle or ovary removal for valuable breeding animals
- Avoidance of testicular prosthetic devices
- Administration of medications to stimulate blood production in the bone marrow
- Prescription of ovulation-inducing medication in cases of ovarian cysts
Recovery and Management
Expect a prolonged recovery period for your pet, which could extend up to several months. It’s crucial to be ready to offer extended care during this time. Stay attentive to administering prescribed medications and stay alert for any changes in your pet’s condition. Regular blood tests and, in some cases, bone marrow biopsies will be necessary to monitor your pet’s response to treatment.
Only administer estrogen-containing compounds under the guidance of your veterinarian. Female pets will undergo testing to assess ovulation.
Furthermore, after the removal of a testicular tumor, a male dog should not exhibit signs of feminization.