Tracheal collapse is a condition characterized by incomplete formation or weakening of the
cartilageCartilage is a stiff yet flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
nous rings of the
tracheaThe trachea, or windpipe, is a tube that connects to the pharynx or larynx, allowing the passage of air to the lungs. It is lined with pseudostratified ciliated columnar epithelium cells with mucosal goblet cells which produce mucus...
resulting in flattening of the trachea. It can be
congenitalCongenital disorder involves defects in or damage to a developing fetus. It may be the result of genetic abnormalities, the intrauterine environment, errors of morphogenesis, or a chromosomal abnormality. The outcome of the disorder will further depend on complex interactions between the pre-natal...
or acquired, and extrathoracic or intrathoracic. Tracheal collapse is a dynamic condition. Collapse of the cervical trachea (in the neck) occurs during inspiration; collapse of the thoracic trachea (in the chest) occurs during expiration. Tracheal collapse is most commonly found in small
dogThe dog is a domesticated form of the Gray Wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The domestic dog has been one of the most widely kept working and companion animals in human history...
breeds, including the
ChihuahuaThe ' is the smallest breed of dog in the world and is named after the state of Chihuahua in Mexico.- History :Both folklore and archeological finds show that the breed originated in Mexico...
,
PomeranianThe Pomeranian is a breed of dog of the Spitz type, named for the Pomerania region in Central Europe and classed as a toy dog breed because of its small size...
,
Toy PoodleThe Poodle is a breed of dog, and is regarded as one of the most intelligent breeds of dog. The poodle breed is found in small, medium, and large sizes, and in many coat colors. Originally bred as a type of water dog, the poodle is skillful in many dog sports, including agility, obedience,...
,
Shih TzuThe Shih Tzu is a breed of small companion dog of very ancient type, with long silky fur. The breed originated in China, possibly by way of Tibet...
,
Lhasa ApsoThe Lhasa Apso is a non-sporting dog breed originating in Tibet. It was bred as an interior sentinel in the Buddhist monasteries, who alerted the monks to any intruders who entered...
, Maltese and
Yorkshire TerrierThe Yorkshire Terrier is a small dog breed of Terrier type, developed in the 1800s in the historical area of Yorkshire in England. The defining features of the breed are its small size and its silky blue and tan coat...
. Obesity is a common contributing factor in dogs with tracheal collapse.
Congenital tracheal collapse appears to be caused by a deficiency of normal components of tracheal ring cartilage like
glycosaminoglycanGlycosaminoglycans or mucopolysaccharides are long unbranched polysaccharides consisting of a repeating disaccharide unit.-Production:...
s,
glycoproteinGlycoproteins are proteins that contain oligosaccharide chains covalently attached to their polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending...
s,
calciumCalcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the Earth's crust...
, and
chondroitinChondroitin is a chondrin derivative.Types include:* Chondroitin sulfate* Dermatan sulfate...
. Acquired tracheal collapse can be caused by
Cushing's syndromeCushing's syndrome is a hormone disorder caused by high levels of cortisol in the blood. This can be caused by taking glucocorticoid drugs, or by tumors that produce cortisol or adrenocorticotropic hormone...
, heart disease, and chronic respiratory disease and infection.
Symptoms include a cough (often called a "goose honk cough" due to its sound), especially when excited. This cough is usually paroxysmal in nature. Other symptoms include exercise intolerance, respiratory distress, and gagging while eating or drinking. Tracheal collapse is easily seen on an
x-rayX-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 10 to 0.01 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays...
as a narrowing of the
tracheal lumenA lumen in biology is the inside space of a tubular structure, such as an artery or intestine...
. Treatment for mild to moderate cases include
corticosteroidCorticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
s,
bronchodilatorA bronchodilator is a substance that dilates the bronchi and bronchioles, decreasing airway resistance and thereby facilitating airflow. Bronchodilators may be endogenous , or they may be medications administered for the treatment of breathing difficulties...
s, and
antitussiveA cough medicine is a medicinal drug used to treat coughing and related conditions. Dry coughs are treated with cough suppressants that suppress the body's urge to cough, while productive coughs are treated with expectorants that loosen mucus from the respiratory tract...
s. Medical treatment is successful in about 70 percent of tracheal collapse cases. Severe cases can be treated with surgical implantation of a tracheal
stentIn medicine, a stent is a man-made 'tube' inserted into a natural passage/conduit in the body to prevent, or counteract, a disease-induced, localized flow constriction. The term may also refer to a tube used to temporarily hold such a natural conduit open to allow access for surgery.-Etymology:The...
(inside or outside of the trachea) or prosthetic rings. Extraluminal (outside the trachea) stenting is generally only used for tracheal collapse in the neck region. Intraluminal stenting has shown more promise for success with intrathoracic cases, especially using nitinol, a type of
shape memory alloyA shape memory alloy is an alloy that "remembers" its original, cold, forged shape, and which returns to that shape after being deformed by applying heat. This material is a lightweight, solid-state alternative to conventional actuators such as hydraulic, pneumatic, and motor-based systems...
composed of
nickelNickel is a chemical element, with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. It is one of the four ferromagnetic elements at about room temperature, other three being iron, cobalt and gadolinium...
and
titaniumTitanium is a chemical element with the symbol Ti and atomic number 22. Sometimes called the “space age metal”, it has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color.Titanium can be alloyed with iron, aluminium, vanadium, molybdenum, among other...
. Potential problems include stent migration and fracture.
Tracheal collapse has also been described in the
horseThe horse is a hoofed mammal, a subspecies of one of seven extant species of the family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
, both as a congenital condition and as a result of trauma. It is most commonly seen in the cervical trachea.