I think my dog or cat is pregnant but I'm not sure
 

This topic is best covered by 2 articles that describe pregnancy signs:

For dogs
[url]http://www.pets.ca/articles/article-dogpregnant.htm[/url]

For cats
[url]http://www.pets.ca/articles/article-expecting.htm[/url]

This article discusses the birthing process in cats
[url]http://www.pets.ca/articles/article-catbirth.htm[/url]