Hi Isles,
I'd be very much glad to help. How many years has Rex had asthma?
So since you are the mom of Rex, id like to give you a little info on asthma (tho i know you read into it already); asthma is due to the continuous constriction of the vascular smooth muscle that is found around the respiratory tubules (normally, these smooth muscles are able to constrict and relax , however, in asthma, the smooth muscles fire at a rapid rate and significantly decrease the amount of air to the respiratory system).
I'm no way a specialist in animals, but humans and dogs do share the fundamentals of physiology and anatomy. I would recommend you give Rex some kind of asthma medication that can treat the constriction of the smooth muscle. I would recommend you get a medicine called Albuterol or Salmeterol (do note that these drugs are inhalants, so you would have to open Rex's mouth and spray it into his mouth). If you would prefer oral medication (capsule or tablet form), you can get theophylline, montelukast.
You can get these in your local pharmacy. Ask the pharmacist for children's preparation.
I do not know why the doctor you talked to recommended Tuseran when that is used only for cough and cold.
Another quick question, how much does Rex weigh? Repost it here so i can do a proper calculation in how much of the drug should you ask the pharmacy to prepare.
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