Laryngeal paralysis is an upper airway disease that is most prevalent in older large breed dogs. The breeds most commonly affected by acquired laryngeal paralysis are the Labrador retriever, Golden Retriever, Irish Setter, and St. Bernard. Dogs with laryngeal paralysis are presented most often in the spring, as the weather becomes more hot and humid, exacerbating their already compromised upper airway.

The most common finding in dogs with laryngeal paralysis is marked inspiratory stridor. This distinctive sound in an older large breed dog should raise the level of suspicion for laryngeal paralysis. Owners may also report exercise intolerance, collapse, difficulty with increased heat and humidity, and signs of pneumonia.

Adult dogs with laryngeal paralysis are most commonly presented in one of two ways. There is a chronic presentation and an acute-on-chronic presentation. The acute-on-chronic presentation is characterized by a respiratory crisis that may be life threatening. Dogs can develop severe laryngeal swelling, non-cardiogenic pulmonary edema, and aspiration pneumonia. Recommended therapies for the immediate crisis include oxygen therapy (an oxygen cage is preferred) and sedation (butorphanol or acepromazine). Corticosteroids (dexamethasone SP) may be utilized for laryngeal swelling. Diuretics may be given for pulmonary edema. For some dogs, a temporary tracheostomy may be necessary if other measures fail to stabilize the patient, though this should be avoided, if possible, as this carries a poorer prognosis.

The chronic presentation is more common and dogs usually have a history of progressive exercise intolerance, increasingly noisy breathing (especially during activity), and worsening clinical signs with heat and humidity. They may also have changes to the sound of their bark and may develop aspiration pneumonia.

Most cases of laryngeal paralysis in older large breed dogs are due to a polyneuropathy that is determined to be idiopathic after failing to find other causes for the polyneuropathy. Other potential causes include conditions that may affect the path of the recurrent laryngeal nerves, including previous neck trauma, thyroid surgery, and cervical or cranial mediastinal masses. Hypothyroidism should be treated if identified, though this will not correct the laryngeal paralysis condition.

The diagnosis of laryngeal paralysis requires a laryngeal exam. This may be performed with a laryngoscope or videoendoscope. A light plane of anesthesia is necessary to evaluate laryngeal function. If necessary, doxapram is given IV to stimulate the respiratory center, so that laryngeal function can be evaluated during sufficient inspiration. If there is no laryngeal abduction during normal inhalation, then the diagnosis of bilateral laryngeal paralysis is confirmed. For dogs that have only unilateral laryngeal paralysis, surgery is not necessary at that time.

Thoracic radiographs are necessary prior to surgery to evaluate for possible  cranial mediastinal masses, aspiration pneumonia, pulmonary edema, megaesophagus (see radiograph) or metastatic disease. If a dog has megaesophagus, unilateral arytenoid lateralization carries a poorer prognosis, as aspiration pneumonia risk is markedly increased. A complete blood count, serum biochemistry and thyroid level (T4 and TSH) are also recommended prior to anesthesia or surgery.

Surgery is the treatment of choice for dogs with confirmed bilateral laryngeal paralysis. Surgery allows these animals to breathe more easily and the benefit is seen immediately following surgery. Surgery involves lateralization of one of the arytenoid cartilages (unilateral arytenoid lateralization or "tie-back"). Other surgical options are available but the arytenoid lateralization is the most commonly performed procedure at this time. Post-operatively there is a 20% chance of developing aspiration pneumonia. Other potential post-operative complications include seroma formation, change in bark, progression of neurologic dysfunction (progression of polyneuropathy), recurrence of respiratory signs, and rarely, failure of the procedure (due to cartilage or suture breakage). The five-year survival rate following surgery is approximately seventy percent. Even though dogs may have concurrent disease, surgery may still be a valid treatment option to provide immediate respiratory relief and potentially avoid a severe upper respiratory crisis. Conservative management of laryngeal paralysis includes weight loss, stress reduction and keeping dogs in a cool, dry environment while minimizing activity. Conservative management will not prevent disease progression and may not prevent a respiratory crisis.

There is also a rare congenital form of the disease that can be seen in Bouvier des Flandres, Dalmatians, Huskies, Rottweilers and Bull Terriers. The congenital form of the disease is associated with degeneration of the nucleus ambiguus and subsequent Wallerian degeneration of the vagus nerve. This rare form of the disease affects dogs before one year of age and is rapidly progressive and fatal. Surgery is not recommended for congenital laryngeal paralysis.

Cats may develop the congenital or acquired forms of laryngeal paralysis, though these conditions are rare in cats. Unilateral arytenoid lateralization has been recommended for cats with acquired laryngeal paralysis; however, surgical outcome information is limited.

Originally from Ann Arbor, Michigan, Dr. Imhoff received his bachelor's degree from Princeton University. He worked as a both an economics consultant and then as a carpenter and cabinetmaker prior to becoming a veterinarian. In 2006, he enrolled at the University of Illinois College of Veterinary Medicine, where he received his DVM in 2010. Dr. Imhoff then moved to Fort Collins where he completed a 1-year internship in small animal medicine and surgery. He stayed at Colorado State University to complete a 3-year small animal surgery residency and Master's degree in Clinical Sciences. Dr. Imhoff joined the VCA Alameda East Veterinary Hospital team in August 2014.

Dr. Imhoff enjoys all small animal surgery, and has a particular interest in minimally invasive procedures for both orthopedics and soft tissue surgeries.

When not working, Dr. Imhoff enjoys spending time playing, hiking, biking, and skiing with his wife and their two sons.