Ask The Vet: Doxepin for Canine Laryngeal Paralysis
Dr. Ivana Crnec
Doxepin for canine laryngeal paralysis: a real treatment to consider or a cure-all that has been deeply overrated? Understanding how this drug may help requires gaining a closer insight into how it ultimately works and how it can benefit dogs suffering from laryngeal paralysis.
Canine Laryngeal Paralysis
The larynx is popularly known as the voice box. The voice box is built of several separate cartilage plates. The voice box is controlled by muscles that regulate its closing and opening.
Namely, the larynx’s primary functions are closing the windpipe while drinking and eating and expanding the windpipe when a heavier breath is needed. When the larynx and its supportive structures function adequately, the dog is able to drink, eat, breathe and vocalize comfortably and effortlessly.
Laryngeal paralysis occurs when the nerves that control the muscles of the larynx weaken to a point they can no longer appropriately control the voice box. When the nerves are weak, the muscles relax, and the cartilages collapse inwards.
Laryngeal paralysis is an unusual condition mainly affecting middle-aged to older dogs (median 9.5 years). It is more common among large breed dogs, particularly the Labrador Retriever. In Bouviers des Flandres, Bull Terriers, Dalmatians, and Siberian Huskies, the condition is thought to be hereditary. In Retrievers and Setters, the cause is unknown (popularly referred to as idiopathic).
Traumas (due to neck surgeries and bite wounds on the neck) and cancerous changes of the nerve controlling the larynx are considered as possible underlying causes. A slow and gradual onset characterizes the condition.
Dogs with laryngeal paralysis develop a progressively weak or hoarse bark, leading to a harsh noise as a dog inhales. Other signs and symptoms include coughing, gagging and voice changes (dysphonia) or even loss of voice (aphonia).
Eventually, the breathing becomes labored and difficult, especially in hot weather. An affected individual has reduced capacity for exercise and may collapse in a faint on exertion. Affected dogs can be asymptomatic while resting. In more severe cases, the paralysis may lead to laryngeal edema. Laryngeal edema is a life-threatening condition that clinically manifests with difficult, rapid, labored breathing, cyanosis (blue gums), and collapse.
Laryngeal paralysis is usually diagnosed with an endoscopic examination, medically known as laryngoscopy. The clinical signs are sometimes enough to set a differential diagnosis, but the definitive diagnosis requires laryngoscopic examination.
Traditional Treatment for Laryngeal Paralysis in Dogs
When managing a dog with laryngeal paralysis, it is important to avoid strenuous physical activities and hot environments. It is also highly advisable to avoid anything that puts pressure on the dog’s neck, including collars. As an alternative, it is better to use harnesses.
These management tips offer temporary relief. The underlying cause needs to be adequately addressed. In the past, the treatment of choice was surgery.
The most frequently used corrective surgery is popularly known as "tieback surgery", while its medical term is arytenoid lateralization. The goal of the surgery is to place several permanent sutures that are supposed to keep the airway open.
The sutures are strategically placed where they are most needed. It should be well-noted that the surgery improves the dog’s quality of life, but it does not restore the laryngeal function as it was before the condition developed.
The surgical procedure developed for correcting laryngeal paralysis has some serious postoperative complications. Some of those complications, such as the increased risk of getting food into the respiratory tract, can be life-threatening. The risk of developing aspiration pneumonia following laryngeal paralysis correction surgery is life-long.
Not to mention that patients with laryngeal paralysis are considered high-risk regarding potential anesthetic complications. Last but not least, surgical correction is quite pricey. Such a procedure may set you back anywhere from $2500 to $5000. The recovery period is challenging and its exact length varies based on the dog’s overall condition before the surgery as well as on the occurrence of potential complications.
In recent years, more emphasis is put on the medical management of laryngeal paralysis. The medical approach includes the use of several different medications such as antibiotics, anti-inflammatory drugs and sedatives. A drug known by the name doxepin (Sinequan®) has been proved as highly efficient.
Doxepin for Canine Laryngeal Paralysis
As mentioned, the use of doxepin has been efficient so far. The drug looks quite promising, but further investigations and experiments are required to confirm its pros and cons.
Generally speaking, doxepin is a human drug classified as tricyclic antidepressant. In humans, it is frequently used to treat psychological problems such as anxiety and depression. Therefore, the drug’s use in dogs is not scientifically approved, but anecdotal reports seem to be more than promising.
The doxepin’s beneficial effect on laryngeal paralysis was an accidental finding. Namely, one vet decided to use this medicine on his dog due to other issues and over time, noticed an improvement in his dog’s laryngeal paralysis related signs and symptoms.
The vet used the drug on his 11-year old mixed breed dog and shortly after noticed remarkable results, including increased appetite, less pronounced panting and less intense inspiratory and expiratory noises.
Since then, a lot of unofficial studies can be conducted, and more and more vets have used this drug in experimental purposes. All results are quite promising. However, it should be noted that because of the doxepin’s very potent antihistaminic effect, dogs receiving this medication are likely to experience dry mouth as a side-effect. This side-effect is minor and worthy of the benefit doxepin entails.
Doxepin is useful and recommended only in cases of mild to moderate laryngeal paralysis. Dogs with severe or complete laryngeal paralysis can only be managed through surgery.
The doxepin can be used alone or combined. Most vets recommend combining the doxepin with acupuncture. Luckily, dogs respond really well to this combination.
When managing laryngeal paralysis with drugs, vets also recommend maintaining optimal body weights (obesity aggravates the symptoms and minimizes the chances of successful medical treatment). They also recommend limiting the dogs’ exposure to scorching temperatures which are known to exacerbate the clinical manifestation.
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.