Conformational Disorders

14 Conformational Disorders

3. Into what general categories can conformational disorders be classified?

Disorders can be classified by the presenting signs. The breathing pattern can help localize the disorder. An obstructed breathing pattern is found in cases of upper and lower airway disease, while a restricted pattern indicates disease in the thoracic wall, sternum, or diaphragm. Abnormal breath sounds are common in upper airway disease. Stertor (snore) is found in nasal or pharyngeal disease and stridor (wheeze) in laryngeal or lower airway disease. A voice change and inspiratory dyspnea are often noted in the history of dogs with laryngeal disease. Patients with disease in the lower airways may present with a cough, tachypnea, or varying degrees of respiratory distress.

Conformational changes may be congenital or acquired. Acquired disease may be secondary to physical characteristics such as negative intra-airway pressure generated during inspiration in brachiocephalic airway syndrome, inflammation or infection, nasopharyngeal polyps, or diaphragmatic hernia due to trauma. Changes may be structural or functional, static or dynamic. Having this knowledge helps determine what diagnostic tests are appropriate. For example, a direct examination of the larynx is needed to make a diagnosis of laryngeal paralysis; fluoroscopy or bronchoscopy may be needed to document tracheal or bronchial compression or obstruction due to lymphadenomegaly, which cannot be entirely ruled out by examination of static thoracic radiographs.

4. Name some breeds of dogs known to have predispositions for certain conformational disorders.

Brachycephalic breeds have their own syndrome—brachycephalic airway syndrome—and may be predisposed to pectus excavatum.

As a subset of the brachycephalics, English Bulldogs, Boston Terriers, and Boxers have a predisposition for tracheal hypoplasia.

The Chinese Shar-Pei has a risk similar to that of brachycephalic breeds of airway disease, specifically brachycephalic airway syndrome, and hiatal hernia.

Brachycephalic breeds, including Shih Tzus, Bulldogs, Pointers, and Swiss Sheepdogs, may inherit cleft palates.

Congenital laryngeal paralysis has been reported in Bouvier des Flanders, Bull Terriers, Dalmatians, Rottweilers, Siberian Huskies, and German Shepherds.

Many of these dogs will have other concurrent neurological abnormalities. Heritability has been proposed as the cause of these abnormalities in most cases.

A recent prospective study concluded that Labrador Retrievers and Rottweilers have a significantly higher risk for acquired laryngeal paralysis. Other large breeds including Irish Setters, Golden Retrievers, and Afghans, are also considered to be predisposed.

Bichon Frise, Border Collie, Bullmastiff, Chihuahua, Chinese Shar-Pei, Chow Chow, Dachshund, Dalmatian, Doberman Pinscher, English Springer Spaniel, English Pointer, English Setter, Golden Retriever, Gordon Setter, Miniature Poodle, Newfoundland, Old English Sheepdog, Rottweiler, and Staffordshire Bull Terrier are all breeds with reported cases of primary ciliary dyskinesia (PCD) or Kartagener’s syndrome. With the exception of Newfoundlands, in which PCD shows an autosomal recessive pattern of heritability, sporadically reported cases do not represent specific breed predisposition for PCD. There is a rhinitis/bronchopneumonia syndrome in Irish Wolfhounds that is not PCD and is likely heritable.

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Jul 31, 2016 | Posted by in INTERNAL MEDICINE | Comments Off on Conformational Disorders

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