Thanks for the additional information. It is helpful. I'd like to point you to a wonderful resource by a therapy dog trainer and evaluator:
It should help you with training your him.
As to your issue right now, you have to be training as consistently as possible on a daily basis. The following site is helpful in helping owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
The earlier training is done, the faster it goes usually. He is already almost 5 months but it does sound like you have done a lot of work with him but still have to work on distraction training and general behavior as well. Use the site I gave to help you with an alternate technique to what you may already be using.
Socialization is going to be very important if he is to do therapy work. So I do suggest that you have him around a varied group of people as well and try and make the situation a positive experience using hot dog sliver or other high value treats. You can do the same with your training. He is food motivated so use that to your advantage. Stinky hot dog slivers are usually more of a draw than what might be on the counter so when you have him sit or lay down and reward him for staying with the stinky treat, he'll learn he gets better food by staying down rather than jumping up.
You can also leave a leash on him to provide a short tug to break his concentration before a verbal reprimand of "NO". It can also be used to hold him in place by slipping it under your foot. They also make a no jump halter that will stop his ability to jump up to the counter and help him learn not to in the first place even if you are not right there to reprimand him. See one here:
You might also consider purchasing some training vests for him so you can alert others to his future occupation so they won't be interferring with your training by petting him inappropriately. They have "Therapy Dog in Training" vests here.
There are many places to purchase these and some places are cheaper. You want to limit his interaction with untrained dogs if possible. It only takes one aggressive dog attacking him at a dog park for him to become fearful of other dogs and potentially start showing aggression before another dog has a chance to attack first. It is better to find some well adjusted friendly adult dogs for him to have play dates with where you know he won't be exposed to aggression and he can learn from well adjusted adult dogs. You will likely find other dogs in the training class and puppies that will be a good choice for playmates. Their owners obviouslly want their dogs to be well adjusted as well.
If you still want to take him to a dog park, be sure you have several tools on hand in case a situation occurs. An airhorn can be used to startle a dog that is lunging at yours. An umbrella hooked handle can be used to grab an attacking dog's collar and pull them off of your dog if it gets to that point. You can also open an umbrella and use it as a barrier if you see a dog getting ready to attack yours. Pepper spray can also deter an attacking dog as well. Right now your dog is being treated as a puppy, but he is maturing fast and other dogs at the park will start challenging him.
That brings me to an understanding of dog body language. It is a great thing to learn so you can tell if an approaching dog is friendly, dominant or even aggressive by the body language they display. That can allow you to head off an attack or even move away from the other dog. It can also help you not expose him to those aggressive dogs at all.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer so I am compensated for my time.
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Since there have been recalls on certain foods, please check the following site to be sure the food your animals eat is not affected. If it is affected, contact your vet as soon as possible. Have your dog seen if they have any symptoms.