Thanks for the responses re Bob being in season.
 
The first Jab worked but only for a very short period before she lapsed
back.  As I posted before, I am intrigued by the mechanism by which she
would, along with her sister, be pulled out of season and then, unlike
her sister, fall straight back in.
 
Her second jab has now begun to take effect and she is responding.  As
soon as the second jab has had time to run it's course both sisters are
to be spayed.
 
I don't feel that rushing her in for an emergency operation so soon after
the second jab or while she is still in season is necessary given that
she has now begun to respond.
 
The reason for them not having been spayed earlier is that they are young
and Priss in particular is extremely small as the runt of the litter.
 
Thanks again for your help and advice, I will keep you posted.
 
W.
[Posted in FML issue 3850]