[fbkeays]

First of all there is NO REQUIREMENT under the ADA to have any dog that has been individually trained to assist a person with a disability to be certified. None, zip, nada. So Raven IS an offical service dog. Owner trained service dogs are perfectly acceptable.
The only requirement is that have been trained to do tasks that midigate a person's disability. There is a sub requirement for the dog to be well behaved in public. A store owner has every reason to ask you to remove your service dog if your dog's behavior is disruptive, ie uncontrolled barking, lifting a leg, knocking displays over, etc.
There is no requirement that says you have to show certification to any "gatekeeper", ie the "greeter" at Walmart. That is because certification is specifically not required in the ADA. They can only ask you if the dog is a service dog (yes). What does the dog DO for you? (keeps me upright). You do not need to show a prescription, doctor's note or anything about YOUR medical condition. Remember, medical records are confidential.
Service dogs are nothing more then a piece of medical equipment. Just like a wheel chair, walker or O2 canister. It is not a requirement that the dog be "dressed", ie vest with service dog patches, but it does help to show the dog is a valid service dog.
All certification is is a peice of paper printed by organizations stating that said dog was trained by their organization and passed THEIR requirements. There is no standards of training in service dog training organization. You or I can put out a sign in our front lawns saying ACME Service Dog Academy. We can use our printers to print out spiffy looking pieces of paper that says "This is to certify that Fido was trained at ACME Service Dog Academy and has fillfulled the requirements of ACME Service Dog Academy. That is all that "certification" is. It is only as valuable as the paper it is written on. Paper is cheap. Remember that.