Our Bitch is 7 and had a litter when 4 years without any problem at all. Her last proper season was 18 months ago when we tried a mating but she did no take. Her last season was in January, followed by a slight phantom.  She is producing a bit of clear fliud in teats at the mo but no other phantom signs.It was not a normal season in thet she went from being fine one day to not being able to run her with a male the next. 2 days later she went back with him and the season came and went in an instant. She jhas not had a 'proper' season in 18 months. Am now wondering if there could be a medical problem causing this, any suggestions would be moat appreciated.
Thansk in anticipation

My advice would be to seek vet help, unless your bitch has always had seasons spaced wide apart or of very short duration there is likely to be something amiss and it is also possible you should not be breeding from her for that reason so I urge you to take advice from a vet who really understands breeding and bitches.

Thats what we planned to do. To be honest, had not thought too much about it until we got talking to someone today. She is otherwise a very healthy and fit bitch so just put it down to irregular seasons. Used to have  another dog that only came in every 9 or 10 months. This converstaion made us think perhaps there is an underlying reason so plan to get vets advice. Cheers

Under-active thyroid can cause infertility, and hormonal imbalance, odd seasons etc.

I would ask for a full thyroid panel.