On the subject of kidney failure, this is what I ordered today:
I've wanted this for about two years, and I am very excited to finally be getting it. With this, I can easily measure my dogs' urine specific gravity (from first morning samples) at home without having to rush urine samples to the lab. With multiple senior dogs, it will pay for itself. My friends with dogs are also pretty excited that I've finally ordered one.
You can purchase less expensive refractometers that are not digital, but I thought this one was so cool that I waited until I could get what I really wanted!