| Upper Block | Lower Block |
| Acute vomiting | Gradual intestinal distention |
| Dehydration | Mucosal destruction |
| Alkalosis | Toxaemia |
| Pre-renal azotaemia | Peritonitis |
- Commonly in cattle, horses and dogs.
- The most common sites of obstruction are the thoracic inlet, the base of the heart, and the hiatus oesophagus of the diaphragm, i.e.: the narrowest points.
Clinical Signs
Horse
- With foods that expand in oesophagus such as haylage etc.
- Also seen with whole apples.
Cattle
- May eat a spherical object that obstructs the oesophagus mostly in anterior 1/3rd of oesophagus and can often be palpated in live animal.
- Potatoes can be a cheap source of feed and if fed whole can become stuck in oesophagus.
- If obstruction occurs further down can be difficult to diagnose and remove.
- Cattle develop bloat when oesophagus obstructed.
- Apples fairly easily to dislodge.
Dog
- Usually with small bones
- Animals that feel protective of feed may gulp food down quickly, particularly if given small chops / knuckle bones.
- Knobbly shape may make bone lodge in oesophagus, particularly just anterior to heart.
- Very difficult to dislodge (because of shape).
- Pressure necrosis occurs very quickly around it and can erode through oesophagus within about 24 hours.
- Small bone may also lodge in duodenum if they pass through the stomach.