The oesophagous is the tube that carries food from the mouth to the stomach. It is normally the same size all the way down and is designed to move the food by muscular contraction. In megaoesophagous (mega=large), the tube becomes enlarged and weakened and food is not moved down it into the stomach
Megaoesophagous can be present at birth but often does not show up until weaning, as liquids can flow down, at least to some extent, to the stomach without requiring any propulsive force from the walls of the oesophagous. Early signs may be regurgitation of food or liquids, or simply a swishing sound in the front of the body as the puppy moves. Sometimes a pouch can be felt as a swelling at the lowest point of the throat where it joins the chest. The puppy may show no other symptoms or it may suffer from oesophagitis (inflammation of the oesophagous) or bouts of pneumonia due to inspiration of food particles into the lungs.
Another cause of similar symptoms in a young puppy is the 'Vascular Ring Anomaly', which is a band of tissue constricting the oesophagus. These tissue bands are remnants of foetal blood vessels which would normally disappear before birth but do not always do so. Improvement is obtained when the band is surgically cut but in quite a few cases some residual regurgitation persists.
Megaoesophagous can also occur later in life, often as a secondary to a variety of diseases which cause neuromuscular dysfunction, but it can also occur as a primary disorder for which the cause is unknown (idiopathic). This is what I believe to be an auto-immune disorder in which the immune system is attacking the muscular walls of the oesophagous. We had it occur in a six year old and the first symptom was regurgitation of liquids when running. Fluid would be propelled from her mouth with a force that sent it several feet in front of her. Later, this became regurgitation of food, to begin with in very small amounts but then, as the disease progressed, in ever larger amounts. In her case it appeared that a smallish area of the oesophagous was first affected and food collecting in this stretched it further and so the condition progressed. At post mortem the whole oesophagous was like a large, papery sack instead of a tube.
As can be imagined, the main problem then becomes a hound that is starving despite eating well, simply because very little of what is eaten reaches the stomach. She did not ever get pneumonia but did suffer frequent bouts of oesophagitis. Sadly, I was unable to do any more than try to manage her condition by liquidising her food, feeding her on the stairs so that she was stretched out as much as possible, and trying to massage the food down the oesophagous and into the stomach. This was back in the early 1980s when I was just starting to look at alternative therapies and was feeding commercial diets and vaccinating every year, and very little seemed to be known about auto-immune disorders. It was also much more difficult then to find details about megaoesophagous and ways to deal with it, but nowadays a vast amount of information can be found on the Internet. [See the Links]
Regurgitation is completely different to vomiting, as it is simply what has been ingested - whether liquid or solids - being deposited back on the floor, whereas vomiting is liquids or solids being forcibly expelled. I presume that Mandy's projection of fluids when running was because she was running and so the powerful movement of the muscles propelling her legs was the cause of the fluids being forcibly ejected. In young puppies, liquids quite often come out through the nostrils.
The most common cause of megaoesophagous in older dogs is Myasthenia gravis, which is a condition in which the nerve/muscle junction is destroyed. Signals from the nervous system sent to co-ordinate oesophageal muscle contractions cannot be received by the muscle. Megaoesophagus is one of its classical signs though general skeletal muscle weakness is frequently associated. This condition is treatable but special testing is needed to confirm it. A really detailed page on diagnostics and treatment can be found at http://www.marvistavet.com/html/body_megaesophagus.html. Thyroid disease is another common cause.
Megaoesophagous can sometimes be linked to laryngeal paralysis, which can also be a symptom or complication of hypothyroidism.
When feeding a dog with megaoesophagous it is best to get it as upright as possible so the food (best given as a liquid or in small balls - which must be swallowed whole and not chewed - can slide down the oesophagous, which is why I had Mandy stand at the bottom of the staircase with her forefeet several steps up, so that she was in at least a reasonably upright position. However, owners of one affected dog put together a chair to keep him upright while being fed and for twenty to thirty minutes afterwards to allow the food to slide down as completely as possible. It's called a Bailey Chair and details can be found at http://www.caninemegaesophagus.org/support.htm.
Homeopathic remedies which could fit the megaoesophagous symptom picture are Alumina, Arsenicum album, Plumbum metallicum, Stramonium, Veratrum album
http://www.caninemegaesophagus.org/
- Canine Megaesophagus org website
http://www.caninemegaesophagus.org/resources.htm
- additional resources page, including a yahoo group
http://www.akcchf.org/canine-health/your-dogs-health/disease-information/megaesophagus.html
- The American Kennel Club page on megaoesophagous
http://pets.webmd.com/dogs/dog-enlarged-esophagus-megaesophagus
- The Pet WebMD page on megaoesophagous
http://www.petmd.com/dog/conditions/digestive/c_dg_megaesophagus
- The Pet MD pages on megaoesophagous
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The larynx is an organ in the neck. It is the point at which the aerodigestive tract splits into two separate pathways: the inspired air (air being breathed in) travels through the trachea, or windpipe, into the lungs, and swallowed food enters the oesophagous and passes into the stomach. Because of its location, the larynx has three important functions: control of the airflow during breathing, protection of the airway, production of sound for barking.
The larynx consists of a framework of cartilage with surrounding soft tissue. At the top of the larynx (sometimes considered part of the larynx itself) is a U-shaped bone called the hyoid. The hyoid bone supports the larynx from above and is itself attached to the mandible by muscles and tendons. These attachments are important in elevating the larynx during swallowing and barking. The lower part of the larynx consists of a circular piece of cartilage called the cricoid cartilage. This cartilage is shaped like a signet ring with the larger portion of the ring in the back. Below the cricoid are the rings of the trachea.
In the centre of the larynx lie the vocal cords, which are made of muscles covered by a thin layer of what is known as mucosa. There is a right and left fold, forming a "V" when viewed from above. At the rear portion of each vocal cord is a small structure made of cartilage called the arytenoid. Many small muscles are attached to the arytenoids. These muscles pull the arytenoids apart from each other during breathing, thereby opening the airway. For barking the arytenoids and therefore the vocal cords are brought close together.
Laryngeal paralysis in animals is a condition in which the nerves and muscles that control the movements of one or both arytenoid cartilages of the larynx cease to function, and instead of opening during inspiration and closing during swallowing, the arytenoids remain stationary in a somewhat neutral position. Specifically, the muscle that causes abduction of the arytenoid cartilage, the cricoarytenoideus dorsalis muscle, ceases to function. This leads to inadequate ventilation during exercise and during thermoregulatory panting as well as incomplete protection of the airway during swallowing. Affected animals thus have reduced tolerance for exercise and heat and an increased risk of aspiration pneumonia. Laryngeal paralysis is fairly common in large breed dogs. Laryngeal paralysis can be unilateral or bilateral depending upon dysfunction of one or both arytenoid cartilages.
Symptoms of laryngeal paralysis include voice change (the dog's bark becomes hoarse-sounding), gagging or coughing (often during or after eating or drinking), exercise intolerance, inspiratory stridor (noisy breathing on inspiration), difficulty breathing, and in severe cases cyanosis or syncope (fainting). Secondary problems may also occur, including aspiration or oedema in the lungs, though often the problem remains an upper respiratory problem. Affected dogs are vulnerable to heat stroke and heat exhaustion due to their limited ability to cool themselves down by panting, but the disorder itself can be mistaken for heat stroke. Symptoms may occur at any time, but initially it may only seem that the dog's bark sounds different, that the dog can't run as much as before. In unilateral cases the unaffected side can compensate for the paralysed side and so problems may only appear in hot weather. However most unilateral cases will eventually progress to include both sides of the larynx, a more serious problem with symptoms appearing more often. Symptoms are usually worse in hot and humid weather, during exercise, during times of stress or excitement, and in overweight dogs. Acute or severe symptoms require immediate emergency treatment.
Some of the symptoms seen in laryngeal paralysis - such as gagging, coughing, exercise intolerance, difficulty breathing - can occur because of heart disease, lung worm, heart worm. Laryngeal paralysis can also be secondary to neuromuscular disorders, neuropathies and other disorders.
LINKS
https://www.acvs.org/small-animal/laryngeal-paralysis - The American College of Veterinary Surgeons page on laryngeal paralysis
http://www.veterinarypartner.com/Content.plx?A=2331- A Pet Health Library article on laryngeal paralysis
http://en.wikipedia.org/wiki/Laryngeal_paralysis - the Wikipedia page on laryngeal paralysis
http://www.animalmedcenter.com/faqs/category/laryngeal-paralysis-in-dogs - Animal Medical Center of Southern California page on laryngeal paralysis
http://www.petpathics.com/products_petpathics_other.html - page on homeopathic products for treating animal ailments, including TrachiAid for laryngeal paralysis. Petpathics are in Western Australia
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Updated 8/14/2015