Not all puppies/dogs have what it takes for the rigors of service work. It is estimated that only an average of 30% of dogs who begin service training are able to complete it.
To give you the best chance of having a successful partner, there are several things to look for including aspects of drive, biddability, intelligence, problem solving and human connection.
I have developed a 21 exercise test based off of a combination of the Volhard test, Puppy Culture and Puppy Prodigies to give some insight when trying to choose a candidate. I offer litter temperament testing or testing just for an individual candidate. It looks at what makes these guys tick, what peaks their interests, what they need to work on and how they cope with problem solving.
Areas covered include:
Redirection from Distraction
Follow Me Engagement
General Handling - ears, eyes, mouth, feet, tail
Positional Changes - mild restraint, supported on back, elevated
Visual - umbrella opening + flapping material
Sound - sudden sound - metal + firework/storm/vacuum
Flip the Switch
Turn on Taplight
What I am looking for is NOT completed behaviors but when introduced to a new situation or obstacle - how does the pup or dog learn, how eager are they to try new things, how aware are they of their surroundings, how connected are they to people vs the environment and how do they like to problem solve.
It is by no means a precise science, nor can it - or any test - guarantee that the pup/dog you choose will make it as a service dog. It does however increase your chances of finding the right combination of energy level, confidence, compatible training style and partner connection.