PHARYNX, LARYNX AND TRACHEA | Lesson 4
Congenital and Developmental Anomalies
Congenital anomalies of this area are not very common in animals.
Excess soft tissue at the back of the soft palate is seen in some breeds of dogs.
TRACHEAL COLLAPSE
Tracheal collapse consists of dorsoventral flattening of the trachea and occurs in miniature breeds of dogs. It causes death from hypoxia. Diagnosis at postmortem can be challenging because the trachea has a certain amount of dorsoventral "give" anyway. It helps to look closely for signs of abrasion on the mucosal surface.
Collapsing trachea is a congenital deformity - the tracheal rings become flattened ovals.
EVERTED LARYNGEAL SACCULES
Brachycephalic dogs have a variety of upper respiratory problems – including stenotic nares, elongated soft palate, and everted laryngeal saccules. The laryngeal saccules are small bags of tissue that normally sit in a recession just in front of the vocal folds.

If the upper airway is compromised in any way, dogs have to work harder to fill their lungs with air. This effectively pulls the saccules out into the airway, further complicating the process of getting air into the lungs.

When everted, the saccules sit just in front of the opening to the trachea and block the flow of air. The treatment for this problem is excision of the saccule tissue.

LARYNGEAL PARALYSIS
Here is the larynx from a horse that was a "roarer". What is the lesion, and how does the pathogenesis work?
LARYNGEAL EDEMA
The whole larynx is swollen with edema fluid and there is a particularly big pocket of edema at the arrow. What could cause such a thing to happen?
LARYNGEAL OBSTRUCTION
This dog died shortly after eating. Looks like it ate something way too big and the big bolus of food lodged at the larynx.

Equine pharyngeal lymphoid hyperplasia is a fairly common disorder in horses. Grossly and histologically, it consists of tremendous lymphoid hyperplasia in the dorsolateral pharynx. It can be mistaken for lymphoma. The lymphoid tissue gets so proliferated that it actually interferes with exercising horses getting enough air.

Equine lymphoid hyperplasia, it is all the lympy-bumpy tissue just adjacent and cranial (to the left of) the epiglottis.

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