Page 829 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

804 CHAPTER 4

VetBooks.ir Clinical presentation disease and can be used to differentiate intesti-
nal neoplasia from IBD. Carbohydrate absorp-
Clinical presentation will vary with tumour type
and location. Weight loss and recurrent colic are
the most common abnormalities. Appetite may be tion tests can be used to assess small- intestinal
absorption but cannot specifically diagnose neo-
decreased, normal or increased. Neoplasia should plasia. Exploratory laparotomy or laparoscopy is
be considered in horses with weight loss in the pres- preferred. Often, a definitive diagnosis is only
ence of a good or excessive appetite. Weakness, acute made at necropsy.
colic, depression or abdominal distension may also
be present. Management
Treatment of GI neoplasia is usually unrewarding.
Differential diagnosis Focal, benign lesions may be removed surgically.
A variety of causes of weight loss and chronic colic Resection may also be successful with some other
must be considered. tumours provided adequate margins are resected.
Prior to surgery, radiographs of the thorax, ultraso-
Diagnosis nographic examination of the liver and, potentially,
Anaemia may be present as a result of chronic bone-marrow biopsy should be considered to ensure
disease, bone marrow infiltration or blood loss. that metastasis has not occurred.
WBC count and morphology are usually nor- Often palliative therapy is attempted. Parenteral
mal. Hypoproteinaemia is common as a result of dexamethasone has been used with variable suc-
maldigestion, protein loss or chronic inflammation. cess in certain neoplasms. A variety of antineoplas-
Elevations in certain enzymes may reflect involve- tic drugs have been tried on limited numbers of
ment of other organ systems. Hypercalcaemia is less horses, with inconclusive results. Nutritional sup-
common in horses than in other species, but it can port is often required in conjunction with medical
occur. treatment.
Specific diagnosis of GI neoplasia may be dif-
ficult. Firm masses or abnormal intestine may be Prognosis
palpable p/r. Oesophageal, gastric and proximal The prognosis is guarded to grave for virtually all
duodenal tumours may be visualised and biop- GI neoplasms. Rarely is complete surgical excision
sied endoscopically. Abdominocentesis may yield a possibility. Neoplasms are usually not detected
neoplastic cells, particularly with mesotheliomas. until a relatively advanced stage. Occasionally, small
Ultrasonography should be performed. Rectal GI tumours may be detected during coeliotomy for
mucosal biopsy may be useful with diffuse or distal other reasons.

DISORDERS OF THE STOMACH

GASTRIC SQUAMOUS CELL CARCINOMA 50–75% of cases, particularly into the thoracic cavity.
Tumour spread may be via direct invasion of adjacent
Definition/overview tissues or through blood or lymphatic vessels.
Gastric SCC is the most common neoplasm of the
equine stomach. Clinical presentation
Signs of SCC are non-specific and include weight
Aetiology/pathophysiology loss, anorexia, chronic colic, pyrexia, halitosis,
The aetiology is unknown. Affected horses are usu- weakness and lethargy. If the oesophagus or cardia
ally ≥6 years of age. Gastric SCC originates from is involved, dysphagia or ptyalism may be present.
the squamous epithelium of the stomach or distal Other clinical signs may be present depending on
oesophagus. Metastasis has been reported to occur in whether the tumour has metastasised.