How to Stop Dog Pregnancy: Options and Considerations
Unplanned dog pregnancies can cause stress for pet owners, but there are several methods to prevent or terminate pregnancy in dogs. Understanding the options—and their risks—helps you make the best decision for your dog's health.
Understanding the Canine Reproductive Cycle
Female dogs typically go into heat (estrus) twice a year, though this varies by breed and individual. During heat, they're receptive to males and can become pregnant if mating occurs. Accidental matings are common, especially if the dog isn't confined during this fertile period.
Detecting Pregnancy in Dogs
- Abdominal palpation: Most accurate between 4 and 5 weeks after mating, but challenging in larger or overweight dogs.
- Relaxin blood test: Detects pregnancy hormone from about 22 days post-mating. A negative result should be retested after 10–14 days.
- Ultrasound: Reliable from 3.5 weeks post-mating; also assesses puppy health.
- X-ray: Used later in pregnancy to count puppies once skeletons are visible.
Permanent Prevention: Spaying
The most effective and permanent way to prevent pregnancy is spaying (ovariohysterectomy), which removes the uterus and ovaries. Spaying before a dog's first heat offers extra health benefits, like lowering the risk of mammary cancer and preventing uterine infections (pyometra). Even if a dog is already pregnant, spaying is possible, though it becomes more complex as pregnancy advances.
Medical Prevention and Its Risks
Hormonal drugs can temporarily suppress estrus or prevent pregnancy, but they're rarely recommended due to significant side effects. Some options include:
- Megestrol acetate (progestin): Approved for short-term heat suppression, but increases risk of pyometra, diabetes, and mammary tumors. Not for use in pregnant pets or those with uterine disease.
- Mibolerone (androgen): Formerly used for estrus suppression; can cause masculinization of female puppies and other adverse effects. Rarely available and not licensed for breeding animals.
- Testosterone: Rarely used due to side effects and limited access.
Postcoital douches don't prevent pregnancy. Injectable or oral estrogens are not advised due to serious side effects like uterine infection and bone marrow suppression.
If Accidental Mating Occurs
If your dog mates accidentally, absolute confinement during her heat is the only immediate preventive measure. There is no "morning-after pill" for dogs and no safe over-the-counter solution. If pregnancy is suspected, prompt veterinary consultation is crucial.
Medical Termination of Pregnancy
If pregnancy is confirmed and unwanted, several medical options exist. All require veterinary supervision and carry risks:
- Prostaglandin F2α (dinoprost or cloprostenol): Induces uterine contractions and abortion or embryo resorption, depending on stage. Cloprostenol is preferred for fewer side effects.
- Misoprostol: Sometimes used with prostaglandins to improve effectiveness and shorten treatment.
- Cabergoline (with prostaglandin): Inhibits prolactin; used with prostaglandins for more reliable termination and fewer side effects.
- Dexamethasone: An oral corticosteroid used after 30 days gestation. Side effects include panting, increased urination/thirst, and immunosuppression.
- Aglepristone (Alizin): Progesterone receptor antagonist given as two injections 24 hours apart between day 10 and 45 post-mating. Causes embryo resorption or abortion. Ultrasound follow-up is recommended.
- Bromocriptine (with prostaglandin): Used early in diestrus; daily treatment over five days showed high success rates in studies.
Surgical Abortion
Spaying a pregnant dog is effective at any stage and prevents future pregnancies. However, it's riskier and more expensive as gestation advances.
Aftercare and Monitoring
Medical abortion or mismating treatments can cause side effects like lethargy, vomiting, diarrhea, or behavioral changes. Repeated veterinary visits may be needed for injections or monitoring. Provide a quiet environment and watch for complications such as infection or heavy bleeding. Report any concerns promptly to your veterinarian.
The Importance of Veterinary Guidance
All interventions should be discussed with a veterinarian, considering your dog's health, age, and breeding plans. Early action increases options and reduces risks. Permanent sterilization is recommended for those not intending to breed their pets.
