I am trying to download paws and claws pet vet 2 but your computer said pixel shader unavailable what do you do

Pixel shader technology is hard-coded into your video card and its drivers. While it is possible to emulate pixel shader using software like 3danalyze or swiftshader, these programs only shuffle the workload off to your CPU. Unless you have a hugely powerful system, emulating pixel shader will most likely result in uacceptably low performance and/or system instability.

Therefore, your best option is to upgrade your system with a new video card which has pixel shader support built-in.