18 months Dogs not heat

Question
Hi, my two dogs_Alsatians(both 18 months old) have never been on heat (to the very best of my knowledge, at least i pay close attention to them), what could be the cause? is this normal, as there mother is not like this, she ovulates every six months.

Answer
Well it's kind of hard to believe that both of them could have a hormonal imbalance causing them not to cycle. Even people who pay very close attention can miss a dog in heat if the dog is very clean. Plus some dogs have silent heats and are EASY to miss. You can have them vetted and hormone levels done to be sure their ovaries are functioning, but I am pretty certain you just missed their cycles. If they are grumpy and grouchy with each other, more so then usual it's often a symptom of cycling. The only way to know for SURE is to expose them to a male dog frequently or, do the tissue test on a weekly basis. Having the vet rule out function issues at least will put your mind at ease.
Cindi