Kvet Forum
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Esophageal obstruction is a common occurrence in cattle and can occur within the proximal cervical esophagus, at the thoracic inlet or within the thoracic esophagus immediately cranial to the heart base.
Etiology
Choke can occur when occurs when the esophagus is blocked by food or foreign objects. It can also occur after recovery from standing chemical restraint or general anesthesia. Cattle tend to obstruct on a single, solid object (eg. apples, beets, potatoes, turnips, cornstalks etc.)
Clinical Presentation
Cattle are frequently distressed and adopt a characteristic stance with the neck extended and the head lowered. There is often profuse salivation with repeated attempts to swallow. Regurgitation of large quantities of clear and slightly viscous saliva, which has collected in the cervical esophagus, occurs in cases of lower esophageal obstruction. There is progressive accumulation of gas within the rumen (bloat) over several hours depending on the nature of the obstruction and the diet. Bloat is much more rapid in cereal-fed cattle.
Differential Diagnosis
Frothy bloat (primary ruminal tympany); Other causes of secondary bloat; Tetanus; Rabies.
Diagnosis
There is an immediate history of access to the etiologies listed above.
An obstruction within the cervical esophagus may be palpated through the skin on the left side of the neck. In cattle over approximately 400 kg, placement of a mouth gag and manual examination of the proximal 20–30 cm of cervical esophagus per os may allow direct identification and retrieval of the obstruction.
A flexible orogastric tube will usually not pass the obstruction and relieve the accumulated gas, but it will confirm the site of obstruction.
Endoscopy
Management
In severe (emergency) cases of ruminal tympany, where the animal is in respiratory distress, it may prove necessary to insert a trocar/canula immediately into the rumen to relieve the gas. A wide-bore needle will not suffice for this purpose.
Hyoscine n-butylbromide can be injected intravenously to relax the esophagus before attempting to massage an obstruction within the cervical esophageal up to a point where it can be grasped per os.
For all other obstructions, either a probang can be used to gently push the blockage into the rumen, or it can be removed with a specially designed retractor, which holds the object within a metal loop while a corkscrew enters the obstruction (e.g. potato); the retractor plus the obstruction are then removed. Excessive pressure must not be used because the probang or retractor may be forced through the esophageal wall.
If the choke cannot be relieved by gentle pressure from a probang, a temporary rumen cannula can be placed to release the trapped gas and allow the obstruction time to degenerate. The obstruction may pass spontaneously into the rumen during the next 12–24 hours. Obstructions that are not cleared within 24 hours carry the risk of pressure necrosis of the esophageal wall and subsequent rupture.
Attempts to retrieve the obstruction via a rumenotomy will not be successful and should not be attempted.
Many farmers feed vast quantities of potatoes without problems; outbreaks of esophageal choke are probably related to those tubers small enough to be swallowed without chewing.