Ask the Vet: Why is My Dog Coughing and Collapsing?
Dr. Ivana Crnec
Being a responsible pet parent is a full-time job. We all want to know what our beloved canine babies are doing, and we carefully monitor every change in their behavior. It goes without saying that when they are sick, we are sick with worries as well.
Watching a dog only cough is already troublesome, so imagine how a dog parent would feel watching his/her dog coughing and then suddenly collapsing. Even the most experienced dog parent will find this event mortifying, at least.
Why is My Dog Coughing and Collapsing?
Sadly, a coughing bout followed by collapsing is always a sign of a more serious underlying issue. All underlying issues are potentially life-threatening and require prompt and adequate veterinary attention.
If you witness the above-explained situation, do not assume it is a one-time event, and wait and observe your dog for a couple of days. Your dog does not have that much time. Instead of ignoring the problem or waiting for future development, be proactive and act quickly – take your dog to the vet’s office.
For a dog that was coughing and then collapsed, without veterinary attention, things could only become worse than before. Each episode is likely to be more severe and more prolonged than the previous. Therefore, the sooner the dog receives veterinary attention and care, the better its odds.
What Happens When Dogs Collapse After Coughing
The fancy medical term for fainting or collapsing is syncope. In medical textbooks, it is defined as a temporary loss of consciousness that occurs when the brain is suddenly deprived of energy. More precisely, syncope occurs when the brain is deprived of either glucose or oxygen.
Simply put, as an organ, the brain is addicted to oxygen, and even a slight deprivation of no more than 10 seconds is enough to trigger a syncope episode.
On the bright side, most syncope episodes are short-lasting – usually, the dog regains consciousness within a few seconds.
When a dog experiences a syncope episode, it falls on one side and stiffly extends its legs. The dog may yelp due to a lack of control over the nervous system while falling. More often than not, during an episode, the dog may urinate or defecate. These actions occur without control.
It should be well-noted that syncope is not a disease. It is a symptom that develops due to an underlying condition. The first step towards dealing with a fainting dog is determining the underlying issue.
Syncope vs. seizure
Sometimes, it is hard to differentiate between a syncope episode and a seizure. Both events are quite similar and hard to distinguish.
However, if the dog coughs before the bout, chances are it is going through a syncope rather than a seizure.
Causes for Dogs Coughing and Collapsing
The following are only some common causes of dogs coughing and collapsing and therefore they are not for diagnosis purposes. Only your veterinarian can diagnose your dog through a hands-on examination and batteries of tests.
1) Cough and Drop Syndrome
It may sound like a surprise, but fainting after coughing is quite common in the canine world. So much so, it even has its name among veterinarians – "cough and drop syndrome" or, more scientifically, "tussive syncope".
The "cough and drop syndrome" usually occurs due to the so-called "vaso-vagal response". In plain terms, strong coughs stimulate the vagal nerve, and this nerve's stimulation results in decreased heart rate and blood pressure. Consequently, there is a blood flow shortage.
Once the blood flow is restored correctly, and the brain receives energy, the dog regains consciousness.
If this is the case, the vet will prescribe medications that suppress the coughing. Additionally, the vet will determine what causes the coughing in the first place.
Other underlying causes of coughing and collapsing are heart murmurs and irregular heart rates. In fact, coughing, if reviewed on its own, is among the most common signs indicative of a heart problem.
Sometimes, certain heart conditions cause the heart to enlarge in size, and if enlarged, the heart exerts pressure on the trachea (windpipe). When the trachea is pressured, coughing is likely to occur.
If a vet examines a dog that is coughing and fainting, and suspects heart disease to be the underlying cause, he/she will perform several diagnostic procedures.
The vet will perform chest x-rays, an EKG, a heart ultrasound, and if needed, Holter monitoring. If the vet determines the problem is heart-related, but cannot make an accurate diagnosis, the dog will be referred to a canine cardiologist.
Finally, coughing and fainting can be triggered by an underlying tracheal issue. Among the more common tracheal issues is a collapsed trachea. Collapsed trachea usually occurs in smaller dog breeds.
The trachea, or as we commonly know it – the windpipe, is a long and narrow tube built from cartilage rings and muscles. Under normal circumstances, in healthy dogs, those rings are rigid and do not flatten due to external forces. In such normal conditions, they actually aid the air passage to the lungs.
In dogs with collapsed trachea, the rings are not flaccid instead of rigid and cause the trachea to flatten instead of maintaining its round lumen. In such a case, the air finds it hard to pass through.
Dogs experiencing this problem will produce a honking cough in an effort to inhale as much air as possible. Because of the overexertion the impaired inhalation causes, the dog may accidentally trigger its vagal response and experience fainting as previously described.
Usually, long-term management is achieved through a surgical procedure that includes the insertion of a so-called "tracheal stent" to hold the windpipe wide open. After the procedure is performed, dog parents are advised to use a harness instead of a regular collar to avoid pressuring the trachea. In fact, all dogs predisposed to collapsing trachea should be walked with a harness.
Coughing and collapsing, mostly if seen one after the other, should not be taken lightly. In some cases, the solution is simple, but it can be life-threatening in others.
However, you cannot distinguish between a standard and simple problem and a potentially life-threatening condition. Therefore, if you saw your dog coughing and collapsing, take him to your trusted vet’s office as soon as possible.
About The Author
Dr. Ivana Crnec is a graduate of the University Sv. Kliment Ohridski’s Faculty of Veterinary Medicine in Bitola, Republic of Macedonia.