Service dog to SMA

http://aeromexico.com/en/travel-with-ae … s/?site=us

"•Certified, professionally trained service animals that assist customers with disabilities. In some cases, a certificate stating that the animal is trained to assist the customer with a disability may be requested. These animals can travel on board next to the customer with a disability. According to applicable Health and Aviation regulations, transportation of animals in the passenger cabin is allowed only for guide dogs and some service animals accompanying customers with disabilities. Animals that may pose a threat to the health or safety of passengers and crew are not permitted, such as reptiles, ferrets, spiders, rodents, ponies, pigs and/or monkeys that, because of their size or health restrictions, cannot be admitted in the passenger cabin.

Guide dogs traveling with a passenger with a disability must be vaccinated, clean and on a leash. If you are traveling with a service animal, you must provide a certificate on your doctor's letterhead, stating that you require the services of this animal due to your condition. This certificate must be issued no more than a year before your travel date. You must also consider that your service animal must fulfill local requirements or your destination(s)."

My guess about entering businesses is if you translate into Spanish your documents and if someone tells you pets are not allowed inside give them the Spanish copy of your documents for your service dog and they will left you in with him/her. Here I see service dogs with a Mexican government department logo and  "dog of assistance" in Spanish on a yellow vest that indicates it is a certified servide dog.