My bitch is 5 weeks pregnant and seems to be drinking excessively. This has come on gradually and she is now drinking twice her normal amount. I am taking her to the vet this afternoon.  She does not appear to be ill in any other way, just the drinking. How much increase in drinking is normal ?

Have you changed her food at all?

Thanks for your response. No, I have not changed her food at all.

Could be due to pyo, or could be just due to the extra weight that she's carrying around.

Hello...Being very thirsty is a classic symptom of diabetes. Sometimes it can be brought on by pregnancy but it is quite rare so please do not panic. Another clue maybe her breath. Does it smell of pear drop??
If it does not stop or her breath smells of pear drops (acidity), she has a voracious appetite or, she becomes very lethargic , then I would pop her to the vets. It can be monitored very easily.

If you have the book doglopedia (you can get it from Pets at Home - ISBN 1-86054-074-0) it tells you all about it  .

or THE BEST BOOK EVER FOR BITHES - BOOK OF THE BITCH  ISBN 978-1-86054-023-3
AN ABSOLUTE MUST FOR BREEDING INFO.

My girls drink more when pregnant, I think it's because they pant more due to the extra body weight they are carrying.

Also, if they are eating more dried food maybe they get thirstier ;) 

Thanks for responses. I have been to the vet, he is not unduly concerned. Urine tests are normal, no signs of diabetes or infection. He says up to 100ml per kilogram body weight is OK. I have to measure her water intake accurately and take in another sample next week.
I have got The Book of the Bitch to hand.
Many thanks.