You can tell when a dog is in heat by observing a combination of physical and behavioral signs: Physical Signs:

• Swollen, red vulva that is noticeably larger than usual.
• Vaginal bleeding or discharge, which may start as bloody and then change to a yellowish or brownish color.
• Increased urination frequency.
• Licking the genital area more than normal

Behavioral Signs:

• Changes in social behavior, such as being more clingy or nervous.
• Increased receptiveness to male dogs, including allowing mounting and sometimes mounting other dogs or even humans.
• Tail position changes, often held to the side to signal readiness to mate.
• Roaming behavior to find male dogs.
• Possible aggression toward other dogs or anxiety

The heat cycle typically lasts 2 to 4 weeks, with the most fertile period around day 10. The cycle has four stages-proestrus, estrus (when the dog is receptive to males), diestrus, and anestrus-with distinct signs in each phase

. If you notice these signs, your dog is likely in heat. Managing her environment carefully during this time is important to prevent unwanted pregnancy and to support her comfort