It might be your graphics card.
so if you are not sure go to
http://www.systemrequirementslab.com/
and choose the sims 3 pets.
it will tell you if your graphics card is bad or if you are out of the minimum requirement.
that way you wil know if its your computer or if its the game itself.
Comments
Looking at the results was interesting - I didn't think my computer was so good! Not shabby at all for a 3-year-old laptop. :P
Yayyyy I have faith! Perhaps this is why the update didn't destroy my game?
http://crinrict-help.blogspot.com/
(It's further down that page)
Fun, yes. Accurate, no.
Are your pets distorted like mine?
http://forum.thesims3.com/jforum/posts/list/449131.page