Estradiol Benzoate/Oestradiol Benzoate
Why has my veterinary surgeon prescribed this medicine?
Estradiol benzoate (also called Oestradiol benzoate) is a synthetic oestrogen. Estradiol is used for prevention of pregnancy after mismating (misalliance) in female dogs; the drug needs be given soon after the mismating to be effective. Pregnancy may continue in 5% of dogs, despite treatment.
Continual hormonal control of pregnancy and seasons may cause side effects in your pet. If your dog is not intended for breeding, think about having her spayed (sterilised).
How does this medicine work?
Estradiol inhibits the transport of fertilised ova down the oviducts and also causes hypertrophy of the uterine mucosa.
How do I give this medication?
- Your veterinary surgeon will administer this medicine to your pet by injection.
- A course of injections may be necessary.
Potential side effects
- Although a drug has potential side effects, it does not mean that there is necessarily a high risk of any of these occurring.
- This medicine does not cause abortion in a small percentage of dogs.
- Repeated use of this medication may result in an increased risk of your pet developing an infection in the uterus.
- Your veterinary surgeon will monitor your pet's blood parameters because your pet may experience some abnormalities in the blood. Contact your veterinary surgeon if you notice any unusual behaviour in your pet.
- Other side effects may occur. If you notice anything unusual, contact your veterinary surgeon.
Possible drug interactions
- Make sure to tell your veterinary surgeon what other medication you are giving to your pet.
- Quite often your veterinary surgeon may prescribe two different medications and a drug interaction may be anticipated. In this case, your veterinary surgeon may vary the dose and/or monitor your pet more closely.
- Drugs may interact such that they can cause an increased or decreased effect or side effects. Although drug interactions may occur, it does not mean that there is necessarily a high risk of any of these occurring.
- Contact your veterinary surgeon if your pet experiences any unusual reactions when different medications are given together.
© Copyright 2025 LifeLearn Inc. Used and/or modified with permission under license. This content written by LifeLearn Animal Health (LifeLearn Inc.) is licensed to this practice for the personal use of our clients. Any copying, printing or further distribution is prohibited without the express written consent of LifeLearn. This content does not contain all available information for any referenced medications and has not been reviewed by the FDA Center for Veterinary Medicine, or Health Canada Veterinary Drugs Directorate. This content may help answer commonly asked questions, but is not a substitute for medical advice, or a proper consultation and/or clinical examination of your pet by a veterinarian. Please contact your veterinarian if you have any questions or concerns about your pet’s health. Created on Jul 27, 2015.
