Breeds sited as being predisposed genetically are young Siberian Huskies and Bouvier des Flandres, and they tend to be afflicted 4-6 months of age.
Bouvier des Flandres
Dogs can also acquire this condition from injury and lead poisoning, and paralysis of the larynx is also what animals suffering from Rabies end up dying from (Rabies ultimately kills from ascending paralysis). Like many diseases, there is an idiopathic form. Idiopathic, meaning "we don't know why" it happened. This form is the form your middle-aged to older large and giant breed dogs are prone to.
Signs include strange sounds as they breathe in, overall breathing distress and/or difficulty breathing, changes in their 'voices', and also cyanosis. Cyanosis is when mucous membranes turn blue due to not getting enough oxygen. The most common treatment is surgery, but if it were me I'd also consult specialists, as veterinary medicine is constantly evolving! While the prognosis is good, I'm not familiar with if there are varying degrees of severity, but I can only assume there is. There are many disease conditions which may impact the throat and it's components, so always see your veterinarian if you notice any changes in sound, breathing, exercise intolerance, or changes in eating habits.