During oestrus (which lasts 4-8 days) when the discharge stops and ovulation begins.
No they can not and they will typically not let a male mount them if they are not in heat.
A mare goes into heat, or estrus, as part of her reproductive cycle to attract a mate and potentially conceive a foal. During this time, her hormones fluctuate, causing changes in behavior and physical signs like increased vocalization, swelling of the vulva, and increased interest in mating.
Only humans, apes and some monkeys menstruate. Other mammals like dogs and cats sometimes will bleed a little when they are in heat, which is when they ovulate and mate, but they do not have menstrual cycles. Having a menstrual cycle means you do not go into heat. Because of this, humans are able to conceive during a period every month, whereas dogs only go into heat once or twice a year.
Depends how bad it is.
Pregnancy
Female dogs go through a heat cycle, called estrus, every six months. She will have proestrus, or a bleeding cycle, before her true heat cycle during which she is very receptive to the advances of male dogs. This heat cycle lasts for several days up to three or four weeks. Some female dogs will undergo personality changes during this time, the most common changes being anxiety and irritability.
Female dogs go through a heat cycle, called estrus, every six months. She will have proestrus, or a bleeding cycle, before her true heat cycle during which she is very receptive to the advances of male dogs. This heat cycle lasts for several days up to three or four weeks. Some female dogs will undergo personality changes during this time, the most common changes being anxiety and irritability.
A dog's heat refers to the reproductive cycle when they are fertile and able to mate. This usually occurs every six to twelve months and is characterized by hormonal changes that prepare the dog for breeding. It is important to carefully monitor and manage a female dog's heat cycle to prevent unwanted pregnancies.
Dogs are most fertile around days 11-14 of their heat cycle, but can potentially get pregnant at any point during their heat cycle. It is important to keep your dog away from male dogs before, during, and after her heat cycle to prevent unwanted pregnancies. Consulting with a veterinarian for advice on how to best manage your dog's heat cycle is recommended.
Female dogs go through a heat cycle, called estrus, every six months. She will have proestrus, or a bleeding cycle, before her true heat cycle during which she is very receptive to the advances of male dogs. This heat cycle lasts for several days up to three or four weeks. Some female dogs will undergo personality changes during this time, the most common changes being anxiety and irritability.
This is normal - not all dogs spot or bleed during their heat cycle.
Ponies will have a heat cycle every 2 to 3 weeks during the longer, warmer months of spring and summer. If they are not bred or do not conceive once they are bred they will go back into heat within a week or so.