Please bear with me. This isn’t going to be comprehensive or universal, no matter what I do. Service dogs come in all shapes, sizes, and personalities. There is no “one size fits all” and sometimes the dog you never even thought of turns out to be the best fit. Other times, the dog you thought would be perfect will wash out (that’s trainer speak for not making it) in the least expected circumstances.

Let’s begin with physical attributes. No matter what dog you start with (shelter rescue, puppy from a service dog line, mutt found in a ditch), you must ensure that your dog is or will be physically sound enough to perform the work you’ll ask of him. Every service dog prospect should be evaluated thoroughly by a veterinarian to ensure that their work will not cause any undue harm. Puppies bred by a breeder should come with a full genetic history and a reasonable assurance of physical soundness with a a guarantee that the financial investment of that puppy can be transferred if the puppy is less than sound within a time frame. (Please look here if you’re considering buying a puppy from a breeder.) Dogs and puppies being adopted from a rescue or a shelter can often be taken by the prospective adopter to a vet for an evaluation before adoption. Alternatively, the adoption fee may be paid and a clause written into the contract specifying the stipulation that the vet must find the dog suitable for the work expected.

As far as describing exact physical attributes, that’s nearly impossible for the purposes of this article. A diabetic alert dog can be a dog of literally any size. But a dog expected to sometimes perform momentum pulls or other heavy weight bearing work should be very large and the amount of weight the dog is expected to carry should not exceed a percentage (determined by an orthopedic veterinarian) of the dog’s body mass… There’s a shocking lack of literature and research that has been done to determine the safety and impact that any weight bearing work might have on a dog. While it is easy to recognize the need for a disabled person to get this type of assistance from a dog, minimally relying on a dog is best for the dog. No working dog should be expected to work with disabilities of their own. Blindness, deafness, compensation for a missing limb, and even the complications arising from a brachycephalic condition (bulldogs, boxers, shih tzus, etc) can make service dog work unreasonably onerous for a dog. A dog who is expected to learn, work, cope, and enjoy their life for extended periods each day cannot be expected to do so when they’re struggling with their own physical limitations.

Tangentially, age is a physical factor that is often forgotten in selecting a prospect: Puppies should not be worked to the exclusion of their very much full-time developmental needs and adult dogs have their own complications. Adult dogs tend to be fairly established in their personality, can come to a working situation with a good deal of very solid training under their collars, and are often a good choice for someone who needs a service dog sooner rather than later. But the dog’s history plays a significant role and we’ll get to that… Young puppies are often considered a blank slate and that’s not QUITE true, but is often more true than any adult dog that might be considered for the same role. Puppies require extensive time investments and training before any service dog work might actually begin (2 years ish). Not everyone has the energy and patience that should go into rearing a puppy, never mind the type of dog traditionally bred for service dog work. That said, a young adult dog (16-24 months) has a veritable lifetime to learn and work. A mature adult large breed dog (over 2.5 years) on the other hand, may only have 6 reasonable years to learn and work before retirement. A three year old small breed dog, however, has a considerably longer life expectancy and it might be more reasonable to consider a mature adult of a smaller breed in some situations. Unless a dog is already alerting naturally to a medical condition, any dog over the age of 3, especially without previous training, is usually considered unsuitable as a prospective service dog.

Which brings us to psychological and temperament considerations of any given prospect.

Service dogs MUST be mentally sound. This is probably the most common reason that a dog will wash out of training. An overwhelming majority of dogs are unsuitable to working in unpredictable environments without significant, accumulated stress. Imagine the straw that broke the camel’s back. The straw is perhaps someone dropping a box of macaroni at the grocery store and the camel is your prospect dog. No one wants to break a dog in any way, but this is often the result with dogs who were a) inherently unsuitable to the work for any of a million reasons, b) worked too much or too early, c) exposed to some trauma preventable or otherwise in the course of (life, training, working, any circumstance really). Dogs bred from working lines for service dog work often have the best chance for overcoming these odds. Thoughtfully reared puppies from any reasonably healthy background (we’ve taken our prospect to the vet, remember) often have a pretty good chance of being psycho-socially sound as well. Adult dogs can usually tell you pretty immediately and honestly how they feel about any given circumstance or situation and are actually easier to evaluate (in my opinion). We’re looking for a dog that is human-centric, enjoys play, is social with other dogs, animals, and people, and is not so sensitive as to be easily damaged. Many dogs, especially herding breeds, tend to be very easy and enjoyable to train, but that very ease of trainability can become a liability when the dog begins to learn unexpected things. I’ve never seen a herding dog work well as a psychiatric service dog for this reason. They learn things like “handler becomes anxious when we go into this building, thererore this building is bad and we should prevent handler from entering.” Intelligent disobedience is a life saving tool in some service dog work, but if the dog is actively preventing the handler from completing necessary tasks due to an unintentionally learned behavior…the dog will often become a hindrance instead of an asset. If you won’t need your service dog to work outside of the home, these specifications can be considerably more loose. All prospects and working dogs should be able to allow emergency personnel to assist their handler in an emergency.
Now we find ourselves in kind of a loop, dumped back at the starting point of “physical” traits: breeds. Breeds of dogs have been selectively altered for hundreds of years to behave in very specific ways. The breed of your prospect will absolutely have a measurable impact on how your dog learns and works (or doesn’t). Service dog trainers have the “fab four” which are most commonly trained as service dogs. These breeds are usually Labrador, Golden Retriever, Standard Poodle, and (I think) German Shepherd Dog. Breed mixes (while I tend to favor them) are verifiably an unpredictable mix of genetic predispositions. Purebred dogs have very reliable tendencies, mannerisms, and preferences. This makes them the “superior” choice for specific types of work. I say “superior” because while breeds can be generalized, individuals are often a happy surprise. If you’re a person who needs help with routines and memory, herding dogs or terriers are often a good choice. People who need help picking up dropped items due to balance problems might consider a retriever of some kind. I find happy go lucky type dogs like bully breeds and goldens to be the perfect fit for anyone who has psychiatric concerns because the dogs tend to be very emotionally resilient. Canine hybrids are specifically and very reasonably excluded from coverage under the ADA and should not be considered for service dog work. Outside of that consideration, any breed of dog MIGHT be a good service dog, but make sure that the potential breed traits you might need are likely to present in your prospect. Training behaviors that are not instinctive takes much more time and effort and is often not worth the trade off.
I’m sure I have left out important considerations. Maybe I should mention things like “make sure the grooming is something you can handle” and “be sure you LIKE the dog”. Choosing a service dog is a monumental decision, even when you have specific needs. It feels like writing a guide to choose one that might help every owner is even more daunting. If you’re unsure of how a service dog might help your disability but just have this vague idea that one will, ASK. Ask your trainer. Ask your friends. Ask a doctor. Ask a facebook group. Describe your specific disability and ask “can a dog help me”.  If the answer is “no”, chances are someone will be able to direct you to some other resource or assistance. If the answer is yes, ask HOW the dog might help. From there, determine what type of dog might be good at those behaviors (or have a trainer help you). Whatever you do, do not be discouraged. This article was written to give potential handlers an IDEA of what to look for. It is not intended to make any definitive declarations. If I cannot help, I hope that I can always point you in the direction of help.