A dog's first heat usually appears between 6 and 12 months—earlier in small breeds, later in large breeds—but the range is wide. It is not a fixed date: observe signs, control escapes and discuss the reproductive plan with your veterinarian.
reproductive health.Bleeding, vulvar swelling, or behavioral changes are not always “just heat.” Smelly discharge, fever, lethargy or abdominal pain warrant an appointment. Related:vaccines · castration age.
Heat (estrus) marks the beginning of sexual maturity, not emotional or bone maturity. A dog can become pregnant in the first cycle even though she still looks like a "puppy." That is why it is advisable to plan in advance: supervision on walks, home management and shared decision on sterilization according to size, breed and health.
Each female has her calendar. Some show an inconspicuous "silent zeal"; others bleed clearly for several days. The useful thing is not to memorize an exact month, but to recognize the pattern and know when something is out of the ordinary.
Base reference:AVMA — dog care; manual for tutors inMerck — reproductive disorders of dogs.
When does it usually start depending on the size
In toy and small breeds, the first heat frequently appears around 6–9 months. In medium and large animals it is usual to approach 10–18 months; in giants sometimes later. There is overlap: a small dog may fall behind and a medium dog may advance. Weight, nutrition and genetics influence more than the social media calendar.
Between one heat and the next there is usually an interval of months (often around six, with a lot of individual variation). Keeping a simple record—dates, intensity of bleeding, attraction of males—helps in future consultations.
Common signs of the cycle
- Proestrus:vulvar swelling, bloody or serous discharge, more marked licking of the area; can even reject males.
- Oestrus:receptivity; often the discharge clears; intense attraction of males and possible mating.
- Conduct:restlessness, more marked marking with urine, changes in appetite or mood—variable depending on the individual.
The entire visible "heat" usually lasts several weeks. Not all phases are equally clear at home; If you need precision (breeding or avoidance), the veterinarian can guide with examination and, if appropriate, tests.
Practical care at home
Walk with control: secure leash, well-adjusted harness and avoid areas with loose males. A brief escape is enough for an unwanted mount. At home, protect sofas and beds if there is bleeding; use washable protectors. Do not introduce human tampons, home remedies or drugs "to stop heat" without clinical indication.
Maintain the routine of mental exercise and rest. Some dogs are more sensitive to handling: respect their space and don't force petting if they seem irritable.
When it's not "just jealousy"
Check for foul-smelling discharge, pain, abdominal distension, fever, vomiting, extreme thirst, or marked weakness. Pyometra and other reproductive emergencies exist and should not be expected "for the cycle to pass." Also make an appointment if the bleeding is abnormally heavy or prolonged, or if you suspect pregnancy after a leak.
Celo, cría y spay/neuter
Wanting to "pass heat" before sterilizing is a clinical decision, not a dogma. It depends on the size, joint or tumor risks, and the family context (other intact dogs, surveillance capacity). Discuss options—ovariohysterectomy, timing, local alternatives—with your veterinarian. Related:best age to castrate.
Based on reference sources.Faunexia editorial guidance. It is not a substitute for veterinary care or individualized reproductive advice.
Frequently asked questions
When does heat start in dogs?
Often between 6 and 12 months; It is usually earlier in small breeds and later in large breeds. Confirm the pattern with your veterinarian depending on the individual.
Can I walk my dog in heat
Yes, with strict control: avoid escapes, loose males and mounting situations. Prioritize safety over freedom in off-leash.
Can you get pregnant in the first heat?
Yes. Sexual maturity is not equivalent to complete maturity of the body; An unwanted mating can result in pregnancy.
How often does jealousy repeat itself?
The typical interval is several months, with individual variation. Keeping dates helps anticipate the next cycle.
Does this replace a veterinarian?
No. When in doubt about diagnosis, breeding or signs of illness, consultation is the valid criterion.
Sources
- AVMA — Dog care / pet owners avma.org· consulted 2026-08-13
- Merck Veterinary Manual — Reproductive disorders of dogs (owner) merckvetmanual.com· consulted 2026-08-13
- AAHA — Canine life stage guidelines (preventive health context) aaha.org· consulted 2026-08-13
