Newer Evidence Points to Generalized Neurological Irregularity as Cause of Laryngeal Paralysis

 |  Jul 25th 2011  |   0 Contributions


A reader named Ann recently left a comment on a post from a couple of years ago about a dog who had a honking cough.

Laryngeal paralysis is another condition in which a dog can honk like a goose. Luckily, a friend recognized some less extreme signs of breathing distress in my dog before it got to the outright honking stage.

And even more fortunately, my dogs tie-back surgery was perfectly executed. He leads a normal, happy life. (After having this procedure, some dogs are so easily prone to aspiration that they have to be hand-feed small balls of food for the rest of their lives.)

Laryngeal paralysis is a syndrome in which the voice box becomes paralyzed; this leads to difficulty inspiring air, because a paralyzed voice box cannot actively open to allow air into the respiratory system (the natural resting state of the larynx is closed). It occurs most frequently in older dogs, and Labrador Retrievers appear to be predisposed. The syndrome can cause the voice to change, and it can cause dogs to breathe with increased noises that can sound harsh, raspy, or perhaps sound like honking. Dogs with laryngeal paralysis can suffer sudden fatal respiratory crises. The crises are most common on hot days, after heavy exercise, in overweight dogs.

Laryngeal paralysis has been on mind lately for a couple of reasons. First, my pal Buster is a Lab who, like his owner, is not getting any younger. Also, I attended a lecture on laryngeal paralysis at my recent veterinary conference (I never, ever pass up a lecture on lar par, as it's known among vets).

Two years ago I attended a lar par lecture at a different conference. The speaker at that time suggested that the use of neck leads may cause inflammation in the nerve that runs to the larynx. I promptly blogged about the lecture, and recommended against neck leads in all dogs.

My more recent lecture, however, provided a different explanation (with a more superior type of evidence -- an actual study, rather than the conjecture of an expert). No link was reported between neck leads and laryngeal paralysis. Rather, laryngeal paralysis appears more likely to be linked to a generalized (body-wide) form of neurological degeneration. The study found that many dogs with laryngeal paralysis later developed hind limb weakness. Many others developed a syndrome called megaesophagus. Megaesophagus is a particularly adverse development for a dog that has undergone laryngeal surgery. As Ann mentioned, laryngeal surgery can predispose dogs to aspirating (inhaling) food, which can lead to pneumonia. Megaesophagus is another major risk factor for aspiration.

I am disappointed to learn of the link between megaesophagus and laryngeal paralysis. However, I am happy that some progress has been made on understanding the syndromes -- hopefully over time this understanding will lead to more effective preventative measures and treatments.

Meanwhile, even though the link between neck collars and laryngeal paralysis appears to have been debunked, I still recommend harnesses instead of neck or choke collars. Neck collars can lead to increases in intracranial (brain) pressure, as well as intraocular (eye) pressure. They're also a bit easier to slip out of.

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