After an accidental mating, protect both dogs and contact a veterinarian promptly. Do not try home methods to prevent pregnancy or wait for a treatment suggestion from an informal message thread.

If the dogs are still tied
Do not pull them apart; forced separation can cause injury. Stay nearby, remain calm and prevent sudden movement. If there is pain or another concerning change, call the clinic and describe what is happening. Frightening the dogs is not a substitute for help. After natural separation, arrange secure separation so another contact cannot occur.
Contact and confirmed pregnancy are different events
Pregnancy can occur without a tie, while a witnessed tie does not guarantee conception. A brief encounter therefore neither rules pregnancy out nor confirms it. Merck advises considering pregnancy confirmation before medical termination unless surgical sterilisation has been chosen separately.
Contact the clinic before confirmation becomes possible. The vet will arrange the sequence according to dates and circumstances. Do not wait for abdominal enlargement or decide solely from contact duration. An unknown partner introduces uncertainty; it does not make pregnancy impossible. Discussing risk and performing an intervention may take place on different days.
[1] Merck Veterinary Manual — Prevention or Termination of Pregnancy · [3] VCA Animal Hospitals — Estrus and Mating in Dogs
Record what you actually know
Write down the details before observations become mixed with assumptions. If part of the encounter was not witnessed, say so. Do not fill in missing events just to offer an apparently complete account. Keep the other owner's contact information and the partner's records if available.
- Date, time and events you personally observed.
- Known heat signs and dates.
- The partner's details, where available.
- Pain, injury or changes in condition.
- Every medicine or other product already used.
Avoid home contraception attempts
Douching does not prevent pregnancy. Estrogen-based approaches can cause serious complications. Do not give human emergency contraception or repeat injections recommended for another dog. If something has already been given, tell the veterinarian its name, amount and timing. Do not conceal this because you fear criticism; it is relevant to selecting appropriate care.
[1] Merck Veterinary Manual — Prevention or Termination of Pregnancy
Discuss the available choices with the clinic
Discuss the female's condition, future breeding intentions, pregnancy confirmation and available management options. The choice of intervention depends on the clinical situation and local availability of medicines. An overseas protocol is not an individual prescription. Ask how the outcome will be checked and obtain written instructions, including whom to contact if her condition deteriorates.
[2] Merck Veterinary Manual — Reproductive Management of the Female Small Animal
How the available interventions differ
Spaying may be an option during pregnancy, but ends future reproduction. Medical termination is a different approach with its own contraindications and monitoring. For example, the official British aglepristone product information lists restrictions involving liver, kidney and certain endocrine disorders. This illustrates one medicine; it is not a prescription for your dog.
The decision involves three questions: whether future breeding is intended, whether the method suits her health and whether required follow-up is available. Check medicine availability where the dog will be treated. A product being available from an acquaintance answers none of those questions.
[4] UK Veterinary Medicines Directorate — Alizin Summary of Product Characteristics, January 2026 · [5] PDSA — Dog neutering: castration and spaying
Why follow-up after treatment matters
A published case described retained fetal tissue after medical termination. One case does not establish complication frequency, but illustrates why outward improvement is insufficient. Official product information also requires subsequent confirmation of the outcome, preferably by ultrasound.
The plan ends with a medically confirmed outcome, not the last injection or disappearance of visible discharge. Arrange follow-up when choosing the method. New discharge or worsening health after treatment calls for veterinary advice, not an independently repeated course. Planned confirmation and urgent assessment of a change in condition serve different purposes.
[4] UK Veterinary Medicines Directorate — Alizin Summary of Product Characteristics, January 2026 · [6] Rigau et al., Reproduction in Domestic Animals, 2011 — Partial foetal retention following aglepristone treatment
Prevent another encounter
Identify where supervision failed: an open door, a handover to another carer, a shared walk or inadequate separation at home. Assign responsibility for each part of care and explain the plan for the rest of the heat to the household. Discuss longer-term breeding or spaying decisions separately with the veterinarian; today's anxiety is not a reason to select a drug yourself.
Sources and further reading
- Merck Veterinary Manual — Prevention or Termination of Pregnancy ↗
- Merck Veterinary Manual — Reproductive Management of the Female Small Animal ↗
- VCA Animal Hospitals — Estrus and Mating in Dogs ↗
- UK Veterinary Medicines Directorate — Alizin Summary of Product Characteristics, January 2026 ↗
- PDSA — Dog neutering: castration and spaying ↗
- Rigau et al., Reproduction in Domestic Animals, 2011 — Partial foetal retention following aglepristone treatment ↗
A reference guide from Bruno ·




