My mini dachshunds condition...

Question
I would greatly appreciate your advice.  I have taken my female miniature dachshund to the vet 3-4 times regarding this situation and I'm not satisfied that she's been properly diagnosed.  We have another appointment tomorrow at 4 where I'll insist that further investigation be done.  Here it is:  Our vet says that she has the "reverse sneeze/collapsing trachea" condition.  They did give us some antihistamine to try to prevent allergies from irritating the condition and things have not improved... on the contrary... she has 3-4 per day and they're worsening.  She struggles for breath, it seems, and makes wheezing noises when she tries to recover.  Last night, she had one at 11PM and it took almost 20 minutes for her to recover.  It tears me apart.  I am very concerned that it might be something else.. her heart?  Lungs?  Any ideas other than the present diagnosis?  Thanks so much!  

Answer
I would recommend a chest x-ray to evaluate her lungs and heart.  Collapsing trachea is common in small dogs and often a honking cough will ensue especially when excited.  Asthma can occur in dogs but isn't very common.  She could have allergic bronchitis or a form of COPD.  If she is not on heartworm prevention, have her tested for heartworm.  A bronchodilator such as theophylline may help open up her airways, but I would get an x-ray first.  Also, if there is any dental disease, I would recommend a course of antibiotics in case of secondary infection that has spread to nasal passages.