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Dysphagia in Dogs

Dysphagia, the medical term given to difficulty swallowing, can occur anatomically as oral dysphagia (in the mouth), pharyngeal dysphagia (in the pharynx itself), or cricopharyngeal dysphagia (at the far end of the pharynx entering the esophagus).

Symptoms and Types

Oral dysphagia can be caused by paralysis of the jaw, tongue paralysis, dental disease, swelling or wasting away of the chewing muscles, or by an inability to open the mouth. Animals with oral dysphagia often eat in an altered way, such as tilting the head to one side or throwing the head backward while eating. Food packed in the cheek folds of the mouth without saliva are also typical signs of oral dysphagia.

Pharyngeal dysphagia is when the dog can grab food, but must repeatedly attempt to swallow while flexing and extending the head and neck, chewing excessively and gagging. While food is retained in the cheek folds of the mouth, it is saliva-coated. There is a diminished gag reflex and there may be snotty discharge from the nose.

With cricopharyngeal dysphagia the dog may succeed at swallowing after several attempts, but afterward it gags, coughs and forcibly throws its food back up. Unlike pharyngeal dysphagia, the gag reflex is normal. Animals suffering from cricopharyngeal dysphagia are often very thin.

Causes

Anatomic/mechanical causes:

• Pharyngeal inflammation
• Due to abscess
• Inflammatory growths
• Tissue in the mouth filled with white cells and modified macrophages (the body cells that eat bacteria)
• Enlargement of the lymph nodes behind the pharynx
• Cancer
• Foreign body
• A pocket of saliva that is draining into the body
• Jaw joint disorders due to fracture or luxation (where the jaws slip out of joint)
• Lower jaw fracture
• Cleft palate – malformation in the roof of the mouth
• Lingual frenulum disorder – a small fold of tissue on the tongue
• Trauma/injury to the mouth

Dysphagia caused by pain:

• Dental disease(e.g., tooth fractures, abscess)
• Mandibular trauma
• Inflammation of the mouth
• Inflammation of the tongue
• Pharyngeal inflammation

Neuromuscular causes:

• Cranial nerve deficits
• Damage to trigeminal nerve (the nerve that stimulates the muscles for chewing)
• Paralyzed tongue – damage to the seventh nerve, the nerve that controls facial muscles
• Inflammation of the chewing muscles

Pharyngeal weakness or paralysis causes:

• Infectious polymyositis (e.g. Toxoplasmosis, Neosporosis)
• Immune-mediated polymyositis (hereditary muscle inflammation caused by an immune disease)
• Muscular dystrophy
• Polyneuropathies – problems with multiple nerves
• Myoneural junction disorders (when the nerves don’t receive the signal to trigger the muscles to act); i.e., Myasthenia gravis, tick paralysis, botulism)

Neurological causes:

• Rabies
• Other brain disorders

Diagnosis

You will need to give a thorough history of your dog's health, onset of symptoms, and possible incidents that might have led to this condition, such as recent illnesses or injuries. Your veterinarian will order standard tests, including a chemical blood profile, a complete blood profile and a urinalysis. These tests will indicate if your pet has an infectious disease, kidney disease or a muscular injury. During the physical exam it is crucial that your veterinarian distinguish between vomiting and dysphagia. Vomiting involves abdominal contractions while dysphagia does not.

Your veterinarian may also draw blood to run laboratory tests for inflammatory disorders of the chewing muscles, like masticatory muscle myositis, as well as for myasthenia gravis, immune-mediated diseases, hyperadrenocorticism and hypothyroidism.

Your veterinarian will take X-ray and ultrasound images of your dog's skull and neck to inspect for any abnormalities. An ultrasound of the pharynx will help your veterinarian to visualize masses and help take tissue samples if needed. If your veterinarian suspects that your dog has a brain tumor, a computed tomography (CT) scan and/or magnetic resonance imaging (MRI) will be used to locate the tumor and determine its severity.