Sick rats tend to hunch up and be unresponsive. Although fear can cause a rat to tense up, in time it should relax. By the way, diarrhea can also be caused by fear. This is a sign of sickness. This is a picture of male versus female babies.
Older rats are easier to check, because the testicles are very prominent.
If you've found a place to buy rats from, you may or may not want to get your rat checked out by your vet . If you do, ask the breeder, owner, pet store employee, etc. if this is okay. Step 6 Choosing your new pet This is by far the most important part of choosing. In order to get the perfect bond between you and your new pet, you're going to want the rat to be curious, friendly, and sweet. Put your hand in the cage and let the rats come up and sniff you.