So if two dogs give birth on the same day, that counts as "1" or "2" in your count?
I read that request as wanting a 1, in other words, a count of the number of unique dates.
One method uses summary fields and calculation fields to produce that count: How to count the number of unique occurences in field.
another method is to use ExecuteSQL() with the DISTINCT keyword: A new way to count unique values in FileMaker 12
Thx PhilModJunk! I indeed meant to count that as "1". I recognized the same question in your first link and will try that out.
I created the fields mentioned and I got a result for my complete unfiltered database when sorted on DoB. But as soon as I filtered a selection the result disappeared. Also after sorting again. Is there a solution for this? I have FM11 and I think ExecuteSQL is of FM12 and higher.
I have it working! I created my selections with a search but found that opening and closing the sUniqueCount summary the field was suddenly updated and filled. Now I create my selection with a script and all works fine. Thanks for your help!