At what age do mares usually go in heat for the first time?

Question

I should know this but when do mares go in heat for the first time?

Answer 1

Hi,

My 14 month old yearling filly has started her seasons already.  She had her first one last month (July). Wondered why she was suddenly hot headed and unreasonable and bingo! She came into season. I was surprised, I must admit. On average, a filly will start to cycle in the Spring of her second year, but as I can confirm, this is NOT always the case!  

  

Answer 2

Usually around their late 2nd to 3rd year. At least thats when I start noticing the boy babies trying to breed them.

Answer 3

it's usually right around 24 months old but it can happen earlier. normal is anywhere from 18-24 months. 99% have their first cycle right around their 2nd year. it's not uncommon to see bred 2 year olds for sale but it's NEVER a good idea to breed a mare before she's physically mature (5-6 years old)

Answer 4

the horses i know started going into heat at between the ages of one and two.

Answer 5

Some of our girls start cycling as yearlings... usually in the later part of the summer.

Answer 6

Like a girl getting her first period, there are a lot of variables.  Previously (based on wild herds) a filly would come into estrus at about 2 years.  

Given the additives and meds that our horses are fed a steady diet of, that has changed. ( We had two yearling fillies come into heat in April and May.  Both were May foals.)

There was no doubt about it as the two 'rigs' at the barn were constantly courting them and they (fillies) were responding.

Doctors have been calling this early onset 'Precocious Puberty', thanks to the growth hormones we ingest as milk, meat, eggs.

Answer 7

It really depends. My filly started her heat at 10-11 months old. Some horses go earlier some go later. Just keep them separated earlier rather then later as you don;t want a unwanted pregnancy at such a young ago. That's what happened with my filly. The previous owner never even saw her in heat and she still got pregnant. No one knew she was though till after the baby was born! (she never got an udder, yes she got bigger but i thought it was just fat lol) Luckily everything went well and the colt is perfect!  But just make sure if there is a stallion or dad around, to separate them early on!