I'm wondering how easy it is for a vet to determine how far along a mare is. Took my mare for an ultrasound today and vet thinks the foal is about the size of a 20lb dog. She was last covered April 12, so should be just under three months along. Vet said she was surprised the foal was that big for the dates I gave. Anybody had a vet wrong before? There are no stallions on the property. 

I saw a 6-7 month aborted foal. It was the size of maybe a large cat, say 12-15 pounds. There was nothing wrong with the foal - it was the mare who came down with a fatal super fast blood disease. 

I've had mares ultrasounded and palped at many stages and they kinda lose the ability to SEE much past 90 days. That's why it's so hard to sex foals. Last January I had to have my (then) 6 month along mare ultrasounded to check for placentitis and all they could tell me was that yes, she was definitely in foal and the foal was alive and ****ed at the ultrasound (the sound?). 

Does anybody else have experience with ultrasounds and preg checking  later along in pregnancy?