LARYNGEAL PARALYSIS

About the Diagnosis

Laryngeal paralysis is a condition that affects dogs and, very rarely, cats. The larynx is commonly called the voice box. It is situated in the neck near the beginning of the windpipe (trachea), which carries air to and from the lungs during breathing. The larynx also contains the vocal cords. As air moves over the vocal cords, sound or voice is produced. The opening of the larynx consists, in part, of two "gates." These gates are pieces of cartilage that open to allow air into the lungs when a dog inhales. When exhaling air, these cartilages open slightly to let air out of the body. When a dog swallows, the cartilages close tightly to prevent food and water from entering the lungs.

In a dog with laryngeal paralysis, one or both of the cartilages (the "gates") responsible for opening and closing the larynx are unable to open properly when the dog inhales. The amount of air reaching the lungs is decreased. Breathing is labored, especially after exercise or in hot weather, when very labored breathing and even respiratory distress, accompanied by loud wheezing sounds during inhalation, may be present. This problem most commonly occurs in large breed, older dogs. Rarely, in some breeds such as the Bouvier des Flandres, the condition can be present at birth (congenital).

The cause of laryngeal paralysis is usually unknown (idiopathic). Other diseases have been linked to this condition, although a true cause-and-effect relationship has not yet been proven. These diseases include hypothyroidism (decreased thyroid gland activity) and hypoadrenocorticism (Cushing's disease, which is an increased amount of certain hormones responsible for metabolism). A rare cause of laryngeal paralysis is the presence of a tumor near the nerve(s) that control the movement of the cartilages or nerve injury from trauma. In most cases, however, no cause is found.

Outward symptoms (clinical signs) of laryngeal paralysis include the development of breathing problems when the dog exercises, becomes excited, or if the dog becomes overheated. The dog may gag or cough when eating or drinking. Because movements of the larynx are uncoordinated in dogs with laryngeal paralysis, food can slip through to the lungs and cause pneumonia (aspiration). The dog's voice can change, and a change in the sound of the bark is often one of the early markers of laryngeal paralysis (though not necessarily indicating an immediate need for intervention/surgery). During a severe episode, so little air may reach the lungs that the dog may faint.

Laryngeal paralysis is often suspected based on symptoms, the breed and age of the dog, and the history (presumptive diagnosis). The condition is definitively diagnosed with a procedure called laryngoscopy. The dog is lightly sedated for this procedure. Either through direct visualization or using a small tube that has a camera attached to its end (endoscope), the movement of the cartilages is observed as the animal breathes; limited movement indicates laryngeal paralysis. An ultrasound examination of the larynx is a novel approach that can also help to diagnose this disease in some dogs.

Your veterinarian may take x-rays of your dog's neck and chest to help determine if pneumonia or any other respiratory problems may be present simultaneously. A blood sample may be taken at several points in time to help to determine if the thyroid and adrenal glands are functioning properly.

Living with the Diagnosis

Laryngeal paralysis is a progressively worsening, potentially serious condition. When a dog suffers a sudden breathing crisis as a result of this condition, it is an emergency. Try to keep the dog as calm as possible. If the dog has become severely overheated, cool damp cloths can be placed on the footpads and belly. If outside, the dog can be hosed down with cool water. DO NOT place the dog in an ice bath because this causes the body temperature to fall too quickly, which can cause other serious problems. If there is labored breathing beyond normal panting, take your dog to your veterinarian or the closest emergency clinic immediately.

Once the diagnosis is made, it is important to keep the dog out of situations that cause excitement. Do not allow the dog to become overheated. For some dogs, a surgical procedure can be performed to prevent the episodes from recurring.

Treatment

Sudden breathing difficulties caused by laryngeal paralysis require immediate treatment. The veterinarian may give a sedative to help the dog calm down and breathe more comfortably. An anti-inflammatory (e.g., a corticosteroid) can be given to help control swelling in the throat. In some cases, a veterinarian will need to insert a tube into the windpipe (trachea) through which the dog can breathe (tracheostomy). Oxygen can be administered through the tube in preparation for surgery.

Long-term treatment involves a surgical procedure. In this procedure, the cartilage that does not open properly to allow air into and out of the lungs is sutured into a permanently open position (tieback procedure). This surgery can be performed by a veterinary surgical specialist. Many factors must be considered before a dog can undergo this surgery; not all dogs with laryngeal paralysis are candidates for this surgery. Your veterinarian can discuss this option with you.

DOs

• Give medicines exactly as directed.

• Begin a weight loss program for your dog if there is any degree of overweight or obesity; excess body fat limits the amount of expansion room for the lungs during breathing, increases the work of exercising and therefore the intensity of breathing, and makes dogs prone to overheating, all of which are reversible but otherwise very serious potential triggers for a future laryngeal paralysis crisis.

• See your veterinarian or go to the nearest emergency clinic if your dog is having breathing difficulty.

DON'Ts

• Do not allow your dog to become overheated or overexcited, if possible.
• Do not force your dog to continue exercising if breathing problems begin.
• Do not use an ice bath to cool an overheated dog.

When to Call Your Veterinarian

• If any of the symptoms listed above arises for the first time in your dog.

• If your dog has had laryngeal surgery and develops gagging, coughing, or labored breathing when eating or drinking or signs of not feeling well (lethargy, loss of appetite, etc.).

• If you are unable to give medicine as scheduled.

• If you cannot return for a scheduled visit.

Signs to Watch For

• When giving medication, watch for depression, anxiety, weakness, decreased appetite, hives (bumps under the skin), vomiting, diarrhea, and seizures.