Short answer: A complete heat cycle (estrus) lasts about 21-28 days, with the receptive/fertile window of 5-9 days in the middle (estrus stage). Most dogs cycle twice yearly. Spaying eliminates the cycle completely.
What you should actually do
- Proestrus (7-10 days): bloody vaginal discharge, vulvar swelling, attracting but not accepting males.
- Estrus (5-9 days): straw-colored discharge, will accept males – the fertile window.
- Diestrus (60+ days): pregnant or ‘false-pregnant’ – hormonal phase.
- Anestrus (4-6 months): reproductively quiet.
- Cycle frequency: ~6 months between cycles; varies with breed (Basenji once yearly).
First heats can be irregular (silent heats, prolonged bleeding) until about the third cycle. Track each heat in a calendar or app – patterns emerge that help with future planning.
Spaying eliminates heats and dramatically reduces mammary cancer risk if done before the third heat. Timing of spay should be discussed with your vet – for some large breeds, post-puberty spay reduces joint disease risk.
Dig deeper
⚕️ Medical Disclaimer
The information on this page is intended for educational purposes only and does not replace a hands-on veterinary examination. Drug doses depend on your dog’s complete clinical picture, concurrent medications, and the exact product formulation. Always confirm dosing with your veterinarian before administering any medication, and contact a 24-hour veterinary emergency service or animal poison control immediately if you suspect a medication overdose or adverse reaction. Editorial standards: every drug dose published on PuppaDogs is cross-checked against multiple authoritative veterinary references and reviewed by PuppaDogs Veterinary Editorial Team before publication.
