Tracheal collapse of the dog

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In domestic dogs, tracheal collapse is a collapse of the windpipe ( lat. Trachea ) due to the softening of the supporting cartilage braces . This results in a decrease, especially in the vertical diameter, and thus a narrowing of the windpipe, which can lead to severe breathing problems. In humans, tracheal collapse can occur as a result of tracheomalacia . The tracheal collapse in dogs can usually be managed conservatively with medication for a long time , but it cannot be cured. Surgical therapy is possible, but time-consuming and not always successful.

Occurrence and causes

Tracheal collapse in the neck area of ​​the Yorkshire Terrier (right is in front). The white arrows mark the normally dimensioned intrathoracic trachea, the black arrows show the area of ​​the collapse.

Tracheal collapse occurs mainly in domestic dogs , especially in dwarf dog breeds ( Yorkshire Terrier , Chihuahua , Maltese , Miniature Spitz and Miniature Schnauzer ). Middle-aged animals are particularly affected. Occasionally, tracheal collapse also occurs in domestic horses and cattle , and very rarely in domestic cats .

The cause of the disease has not yet been clarified. The tracheal collapse is presumably genetic ( hereditary disease ). But the genesis through the combination of different factors (multifactorial) is not excluded. A number of other factors can contribute to the disease , including respiratory infections, allergies , narrowing of the windpipe, toxic dusts and fumes, and heart failure .

Pathogenesis

The cartilage softening comes about through changes in the cartilage base substance , especially through a reduced content of glycosaminoglycans (especially chondroitin sulfate ) and glycoproteins , which reduces the water-binding capacity of the cartilage and thus its elasticity . The number of cells in the cartilage is reduced and the basic substance is porous. The decrease in the inner diameter of the trachea is accompanied by an increased flow resistance of the air and leads to turbulence .

Secondly, the tracheal collapse leads to degeneration of the ciliated epithelium , hypertrophy of the glands in the mucous membrane of the trachea, and occasionally polyps .

clinic

Classification of the degree of severity according to Tangner and Hobson, 1982

The clinical presentation is very variable, a tracheal collapse can remain asymptomatic for a long time and the degree of narrowing does not have to correlate with the extent of clinical symptoms. The symptoms develop gradually and the disease progresses slowly.

A typical early symptom is a seizure-like cough , which occurs mainly when you are excited or when you are exercising . If the leash is pulled hard, a collar can also put pressure on the windpipe and thus trigger coughing fits. The cough initially appears as a "dry" cough, with the secondary changes that occur (increased mucus secretion due to the glandular hyperplasia) it can turn into a "wet" cough. In addition, there is a reduced performance of the animal.

Clinically, this results in an increased "tracheal breathing noise " ( stridor trachealis , mostly in the form of humming tones), an increased breathing frequency ( tachypnea ) and increasing breathing difficulties ( dyspnea ). If they are localized in the neck section of the windpipe, they occur primarily during inhalation ( inspiration ), if they manifest in the chest part more during exhalation ( expiration ). The reason for this can be seen in the fact that in the case of instability in the neck area, the collapse is caused by the negative pressure that occurs when inhaling, while instability in the chest area is usually a collapse of the trachea due to the overpressure in the chest cavity during exhalation (based on the pressure within the trachea) is the cause. With increasing dyspnea, there is a lack of oxygen, which manifests itself in a blue discoloration ( cyanosis ) of the mucous membranes.

diagnosis

With localization in the neck part of the trachea, the softening of the cartilage rings can already by scanning ( palpation notice), which usually also cough is triggered. The x-ray of the trachea can provide further information, but since the collapse is a dynamic process, normal findings can also occur in a snapshot such as an x-ray. A clear diagnosis can only be made by endoscopy or a CT scan .

Differential diagnoses

The main distinctions are inflammatory diseases of the windpipe ( tracheitis ) caused by infections or allergies . Even foreign bodies in and tumors of the trachea can cause narrowing and tracheal breath sounds. Finally, a narrowing of the windpipe can also come about through compression from the outside through enlargement of neighboring organs. Organs adjacent to the trachea, such as the deep cervical and anterior and middle mediastinal lymph nodes ( Lnn. Cervicales profundi and mediastinales craniales et medii ), the thyroid and the epithelial cells come into question. Also, abscesses and bruising in the vicinity of the trachea may lead to a compression from the outside.

Compression of the end branch of the windpipe occurs relatively frequently as a result of an enlargement of the left atrium of the heart, which in turn is caused by an insufficiency of the mitral valve of the heart ( valve endocardiosis ). In addition to the narrowing of the lumen, the symptoms are significantly increased by the constant mechanical irritation of the windpipe as a result of the heart's movement.

In some breeds of dogs ( English Bulldog , Boston Terrier ), a hereditary growth disorder of the windpipe (tracheal hypoplasia ) must also be considered.

therapy

X-ray image of a stent implanted in the windpipe.

A causal therapy is not possible. In most dogs, the disease can be controlled conservatively for a relatively long time. Simple measures such as using a harness instead of a collar, avoiding excessive physical exertion and avoiding obesity can be carried out by the dog owner himself.

Cough suppressants such as hydrocodone , butorphanol, or codeine can be used to relieve symptoms . Another conservative therapeutic approach is the administration of parasympatholytics ( atropine , also in combination with diphenoxylate ), which is particularly popular in the Anglo-American language area. Since the tracheal collapse is accompanied by inflammation, prednisolone is also initially indicated, which should be tapered in long-term treatment or administered alternately. Since coughing can also lead to reflux oesophagitis , which in turn can trigger a cough, the permanent administration of proton pump inhibitors has recently been promoted. An antibiotic may also be indicated for the rare concomitant infections, with tetracyclines being preferred because of their effect against mycoplasma . A sedative such as acepromazine can be used for severe acute coughing attacks .

The insertion of stents originally developed for human medicine , which ensure passive support of the trachea, is in the experimental stage . Although this procedure is currently regarded as the most effective treatment method for the disease (almost 70 percent of patients experience a significant clinical improvement after the procedure), it has not yet become established as the standard therapy. The main reason for this is the high cost of the stent; In addition, complications can occur if the parts of the trachea and main bronchi that are not stabilized by the endoprosthesis collapse. In some animals, coughing continues to occur due to the accumulation of secretion in the area of ​​the stent parts that are not fully attached to the tracheal wall. Breathing is rarely impaired due to the excessive formation of granulation tissue; however, these symptoms seem to be correctable with the administration of glucocorticoids. Individual reports mention the collapse of a stent with subsequent narrowing of the trachea. As a surgical alternative to the stent, the fixation of the trachea using a plastic framework placed around the trachea is the most common procedure. Interventions on the upper membrane of the windpipe and direct manipulation of the cartilage braces are described as further possibilities. What these techniques have in common is that they are highly invasive and very surgically demanding procedures.

literature

  • RW Nelson, CG Couto: Small animal internal medicine. 3. Edition. Mosby, 2003, ISBN 0-323-01724-X , pp. 289-291.

swell

  1. ↑ JLBurback et al.: Surgical treatment of tracheal collapse in dogs: 90 cases (1983-1993). In: J Am Vet Med Assoc. 1996 208 (3) pp. 380-384.
  2. ↑ MJ Dallman et al: Histochemical study of normal and collapsed tracheas in dogs. In: Am J Vet Res. 1988 Dec; 49 (12), pp. 2117-2125. PMID 2467593
  3. ^ MJ Dallman et al.: Normal and collapsed trachea in the dog: scanning electron microscopy study. In: Am J Vet Res. 1985 Oct; 46 (10), pp. 2110-2115. PMID 4062014 .
  4. ↑ CH Tangner, HP Hobson: A retrospective study of 20 surgically managed cases of collapsed trachea. In: Veterinary Surgery. 1982; 11, pp. 146-149.
  5. ↑ a b Karsten E. Schober: On the diagnosis and drug treatment of tracheal collapse in dogs. In: fachpraxis Volume 41, 2017, Issue 1, pp. 4–11.
  6. ^ A. Moritz et al .: Management of advanced tracheal collapse in dogs using intraluminal self-expanding biliary wallstents. In: J Vet Intern Med. 2004 Jan-Feb; 18 (1), pp. 31-42. PMID 14765729
  7. ^ A. Moritz: Treatment of tracheal collaps with stents. In: Proceedings 16th ECVIM-CA Congress. Amsterdam 2006, p. 35.
  8. ^ A. Moritz: Tracheal collapse and bronchiomalacia
This version was added to the list of articles worth reading on November 5, 2006 .