Hello, I am Dr. Peter a licensed Veterinarian. I would like to help. I need to ask you a few questions to be well informed and give you the best advise. There is no additional charge for information request.
1- How long has he had these symptoms?
2- Does he have a head tilt?
1- What are you giving as medication?
2- At any point were his eyes moving like up and down or side to side?
3- It is fair to say he was walking like if he is drunk when he was not sedated?
The symptoms that you are describing could be consistent with vestibular disease. Dogs with vestibular disease after several days will show improvement in their gait and stop walking into objects. Being sedated however, will take the compensation mechanism away and the dog will take longer to recover if this is related to vestibular disease. I would recommend you consider stopping the medication and see how he does after several days; if he begins to show improvement then it is consistent with idiopathic vestibular disease and he will regain all function normally in 2 weeks. If no improvement is seen after 3-4 days, then, there could be a central lesion like a brain tumor. These cases are often best managed by a neurologist where they can do advance imaging (MRI or CTScan) of the brain; consider speaking to your veterinarian about a referral to see a neurologist.
Hope the above helps, if you have additional questions I will be glad to answer them.
Walking into is not indicative of any disease in particular either. If the dog has the head press against the wall or into a corner it could be sign of brain swelling or discomfort. But, walking into a corner does not provide any diagnosis nor does it rule out vestibular disease.