Diagnosing GOLPP
As veterinarians, we are faced with a slowly progressive deterioration of a much-loved family member. It is critical that we are fully aware of the natural history of the condition, how we can best manage the affected dog and help the owners throughout the course of the disease.
Accurate History
A standardized (or at least comprehensive) questionnaire will help to ascertain if, in addition to upper respiratory signs, there is any history relating to esophageal dysfunction (e.g., gagging, regurgitation) or early neurologic dysfunction (e.g., gait abnormality, wide stance, stumbling, unable to get up onto couch, bed, car, etc.). This can sometimes be difficult to clearly distinguish from arthritic conditions, which is why we perform full orthopedic examination. Owners are also questioned as to the onset of signs, and also the perceived rate of progression. The frequency and timing of throat-clearing and/or regurgitation is noted (e.g., associated with drinking, eating, early in the morning, randomly), as this may affect what medications are given at time of surgery and upon discharge.
Physical examination, routine laboratories
Most cases of GOLPP are elderly animals, and may have comorbid conditions, or other medical issues that need to be addressed. A full and systematic physical examination and routine complete blood work should be undertaken. Don’t forget to carefully palpate the neck, as thyroid carcinoma can cause a similar clinical presentation to GOLPP.
Neurologic examination
A complete neurologic examination should always be performed and used as a baseline for follow-up appointments. Even though many dogs will not have obvious neurologic deficits at time of diagnosis of their laryngeal paralysis, over half of them will have signs at 6 months, and almost all will have some degree of neuropathy at 12 months. Neurologic issues need to be discerned from orthopedic issues.
Orthopedic examination
A complete orthopedic examination will help distinguish back pain from joint pain from neurologic signs. It can also help decide which medications may be effective in management of these signs (e.g., carprofen may improve orthopedic signs but will not alter neurologic dysfunction).
Imaging
All cases of GOLPP should receive 3 view thoracic radiographs and one lateral neck radiograph as minimum. Due to the typical age of onset of the condition, additional imaging such as abdominal ultrasound or CT is often performed to rule out any hidden pathology (eg, liver, adrenal, splenic tumors) that could change the surgical plan.
Evaluation of esophageal function can be performed with fluoroscopy – preferably in a standing position. It is not too difficult to design an esophageal stanchion to enable this feeding position. The results of the ‘swallowing study’ will help the veterinarian decide on any prokinetic drugs may help in the perioperative period and long-term, and thus decrease the chances of aspiration. In the face of very poor esophageal function, the degree of respiratory compromise can be weighed against the risk of post-operative aspiration. In most dogs, the risk of asphyxiation outweighs the risk of aspiration, and they will go to surgery.
If an esophagram cannot be performed, then an estimate of dysfunction should be based on clinical signs of regurgitation, gagging and throat-clearing. Often, we presume esophageal dysfunction in all dogs and place them on antacid (omeprazole or famotidine) and prokinetic medications (sildenafil or cisapride) prior to surgery and for life following surgery.
Upper Airway Examination
Laryngeal function should be noted on induction using a standard induction protocol, which includes the administration of doxapram HCl (1-2 mg/kg IV bolus) to enhance respiratory excursions. Alphaxalone and propofol are good induction agents. Ideally, all scopes should be recorded and archived offline to remain part of the patient’s medical record. If an animal has hemiplegia and breathing is not severely compromised, then re-examination in 3 months is recommended (or earlier if owner requests, or summer is coming). In addition to laryngeal function, a complete upper airway examination should include a gag reflex, laryngeal sensitivity, epiglottic and hyoepiglottic assessment, palate assessment, piriform recesses, cuneiform and corniculate mucosal surfaces, vocal folds and ventricles. If using a flexible scope, a retroflexed view will complete the exam. Very importantly the flaccidity/spasticity of the paralysis should be tested with a soft tipped probe, as thyroid carcinoma obliterating the rLNs will manifest as a spastic paralysis. (Laryngoscopy is also repeated immediately post-operatively to confirm adequate abduction).