My dog had first heat at 10 months. No second heat by 18 months?

She could still go into heat at any time. Some dogs go into heat later than others, although smaller breed dogs tend to go into heat by a year of age. It could also be that she has gone into heat, but it was a silent heat so you didn't notice any signs of it. I'd have her checked out by a vet to be safe. Best of luck.

There first hear cycle can often be missed and be a silent heat since the changes in their body are new. It is common to miss it. At her age a second should be approaching soon. The lager the dog, the later and farther between the cycles can be.

Typically a dog goes into heat once every six months, and dogs can have silent heats where they don't show outward signs of being in heat, so it's possible Daisy had another heat without you knowing it. She could go into heat any day now depending on the date of her last heat. It's impossible to predict without having had a date from a heat later than May of 2016. You can take Daisy into the vet for a health check to make sure everything is ok with her.

They will never ne as large as their brother being female. Sometimes the first heat can be silent in that you dont see any outward sign. I would keep a close eye now as their second heat should be imminent.

Most cats do get into their first heat between 7 10 months but in some cases it can even be 12 months. occasionally the first heat cycle may also be silent, so it basically happens but you would not notice it.

Given that Kisses is eight months old, this would be her first heat. Female dogs can go into heat for the first time anytime after six months of age, and they go into heat once every six months. With her age, there would not be time for her to have had one heat already and then gone into a second. I hope this helps!

It is unusual that Maria hasn't gone into her first heat at her age, and it's possible that she has had a heat but it was a silent heat. I'd recommend a check up with the vet for this problem. It would be rare if she was born without a uterus, but it could be possible. Only a vet can diagnose this. I'd make an appointment for her this week. I hope this helps!