What Causes Chronic Coughing in Small Dogs?
I received the following question from Jo Ann a while back:
I have a Maltipoo, and she has been coughing on and off for years. The medicine the vet gives her works to counter the cough. This time she was also put on antibiotics and after four days got real lethargic. I took her off of the meds. I want her to get an X-ray by someone who specializes in small dogs' tracheas. She is 9 years old.
This question was triggered by my article on "Big Dog-Little Dog" syndrome, in which I describe the various forms of trauma that small dogs can suffer when they are in altercations with much larger members of their species. In the article, I mentioned collapsing trachea as a common cause of coughing in mature Maltipoos (and other small dogs).
Collapsing trachea is a condition that affects the firm structures that hold the windpipe (trachea) open during breathing. The structures become weak, and the windpipe collapses during breathing -- especially rapid or hard breathing during exercise or excitement.
Heart disease in small dogs is usually linked to leaking valves in the heart. This, in turn, causes fluid to back up into the lungs (a condition called congestive heart failure), which can cause coughing or more serious breathing troubles.
Chronic bronchitis is a condition, common in older small dogs, in which the routes through which air flows in the lungs (called airways) become chronically inflamed. The inflammation leads to irreversible scarring and slowly progressive symptoms.
The three problems are not mutually exclusive, and many dogs suffer from more than one at a time. Heart disease and collapsing trachea especially tend to go together, and they play on each other. Heart disease causes the heart's size to increase; this, in turn, can cause the heart to compress the trachea inside of the chest -- a form of tracheal collapse.
All three of the conditions can lead to crises that cause severe, life-threatening respiratory distress. All three can be exacerbated by unrelated viral or bacterial infections.
Although the treatments for the conditions are different, three commonalities can be addressed to reduce symptoms and the risk of life-threatening crises. First, obesity markedly exacerbates all three conditions. Therefore, weight management is crucial for any dog with coughing and breathing issues. Second, inhaled irritants, most notably smoke, also make all three conditions worse, so smokers should pursue their habit outside and away from their dogs. Third, activity or excitement often triggers coughing. Owners of dogs with any of the conditions should be especially wary of heavy activity on hot days -- this is a recipe for a serious crisis.
Note that antibiotics don't treat any of the three conditions. However, antibiotics may occasionally help treat secondary bacterial infections that can cause acute exacerbation of symptoms. Cough suppressants, on the other hand, may be useful (especially in collapsing trachea and bronchitis) because coughing tends to cause a feedback cycle of inflammation which results in even more coughing.
Jo Ann, I recommend that you find out why your dog is coughing. Only after you have a diagnosis will your vet be able to implement appropriate treatment. The treatments for the three conditions are different, and the treatment for bronchitis can exacerbate heart failure, so it's important to figure out what's going on.
You probably don't need to see a specialist yet. Any vet should be able to take and read chest radiographs (X-rays). Radiographs that are not conclusive can be sent electronically to a specialist in veterinary radiology for more detailed assessment.
However, if the X-rays are equivocal or don't show significant irregularities, then you should consider consulting a veterinary cardiologist or internist to discuss ultrasound of the heart as well as more advanced diagnostics such as bronchoscopy.
In my opinion, the best way forward is to identify the source of the coughing.
Got a question for Dr. Barchas? Ask our vet in the comments below and you might be featured in an upcoming column. (Note that if you have an emergency situation, please see your own vet immediately!)