You can update your pet's profile picture by following these steps:

1.  Select your Pet's Profile from the upper right corner
2.  If you have multiple pets, select the Pet Profile  for the pet you'd like to update
3.  Select Edit Pet from the upper right corner
4.  Select your pet's image
5.  Select Capture Image  to take a new photo of your pet
OR
6.  Select Choose Image to upload an existing image of your pet from your device's camera roll
7.  Select Save