Laryngeal Paresis and Paralysis in Dogs
Veterinary care should include diagnostic tests and subsequent treatment recommendations.
In-depth Information on Diagnosis
Diagnostic tests are needed to recognize laryngeal paralysis from other causes of respiratory difficulty, including: A complete medical history and thorough physical examination. It is especially important that your veterinarian examine the chest with a stethoscope (auscultation) to listen for abnormalities in the lungs or irregularities in the heartbeat. Thoracic radiographs also may be taken, particularly if auscultation of the chest was questionable or abnormal in order to confirm or refute cardiac or pulmonary causes of the respiratory difficulty. Concurrent hypothyroidism can complicate the treatment and prognosis of a dog with laryngeal paralysis. Thyroid gland hormone levels and function tests may be done to rule out this condition. In order to verify the presence of laryngeal paralysis, the dog must be lightly anesthetized and the veterinarian must watch the motion of the larynx while the dog breathes. The diagnosis is confirmed when the arytenoid cartilages of the larynx fail to abduct (move outward) when the dog inhales.
In-depth Information on Treatment Although most cases of laryngeal paralysis are not diagnosed until the dog is brought to the veterinarian in a state of dyspnea, cases in the early stages of the disease with only mild clinical signs may respond well to conservative medical management. Conservative management is directed at preventing excessive respiratory effort that would require the dog to move air faster than the airways will allow. Obesity makes it more difficult for the dog to move air in and out of his lungs due to compression on the diaphragm and chest wall. Excess fat in the tissues around the airways also impedes airflow through the airways. Obese dogs also have trouble ridding themselves of excess heat and are forced to pant more than usual. These all subsequently cause the dog to have an increased respiratory effort and exacerbate the problem. Excessively stressful situations increase the tissues’ oxygen demands and cause the dog to increase his respiratory effort. This is true of hot, humid weather, so they should be kept quiet in an air-conditioned environment whenever possible. Some mild cases of laryngeal paralysis can benefit from the occasional use of oral sedatives when the dogs become overly excited. Acepromazine given orally is often used for this purpose. A very important management technique to prevent difficult breathing is to avoid the use of a neck collar. When the dog pulls on the collar, it compresses part of the trachea, further exacerbating the airway obstruction. An over-the-shoulders-type harness should be used instead. Because the disease tends to progress over time, it is essential to monitor the dog’s condition closely for worsening symptoms that might indicate the need for surgical intervention. Usually the first the veterinarian sees the dog is often during an episode of severe respiratory distress. Owners frequently do not recognize or consider that the early mild symptoms, such as voice change or noisy breathing, are significant enough to warrant a visit to the veterinarian. When they finally do visit the veterinarian, they must be stabilized before definitive therapy can be undertaken. Supplemental oxygen therapy allows the dog to decrease his respiratory effort and treats cyanosis. Dogs in respiratory distress can easily overheat, as they expend a great deal of energy breathing heavily and are unable to rid their bodies of excess heat by panting. If the animal is hyperthermic (body temperature greater than 105 degrees Fahrenheit) the dog will be cooled with a cool water or alcohol bath. The larynx often becomes edematous or swollen in periods of dyspnea and can further obstruct the movement of air during breathing. The administration of corticosteroids can help reduce this swelling. Very severe cases that do not respond to initial treatment may require a temporary tracheostomy to bypass the non-functional larynx. The tracheostomy is created under the neck and a plastic tube is placed through the opening to allow unobstructed flow of air and facilitate breathing.
After the dog has been stabilized and the crisis situation is over, surgical treatment is recommended. There are several different surgeries that accomplish the same basic thing – to create a larger air passage through the larynx. The two most popular are: Partial arytenoidectomy (also called partial laryngectomy). The dog is anesthetized and a temporary tracheostomy tube is placed if not already present. The larynx is visualized through the mouth and part of the arytenoid cartilage and vocal fold is removed from one side. The tracheostomy tube is removed one to two days after surgery and is allowed to heal on its own (it is not sutured closed). Arytenoid lateralization (“tie back”). The dog is anesthetized and has a tube passed into the trachea in the normal fashion through the mouth. An incision is made on one side of the dog’s neck and the arytenoid cartilage on that side is sutured in an open position.