Page 830 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 805

VetBooks.ir Differential diagnosis of a horse, the infective L3 parasitic larvae migrate
from the mouthparts to the skin of the horse and are
Other causes of chronic colic, weight loss and non-
specific disease must be evaluated. Typically, SCC is
diagnosed during thorough evaluation of weight loss swallowed or, less commonly, the fly is swallowed
whole. Adult worms develop in the glandular portion
or chronic colic. of the stomach over approximately 2 months. The
presence of adult worms in the stomach may induce
Diagnosis mild haemorrhagic gastritis. Nodules of adult worms
Non-specific haematological changes may be pres- and necrotic debris develop with Draschia infection.
ent including anaemia, leucocytosis, hyperfibrino-
genaemia and hypoalbuminaemia. Peritoneal fluid Clinical presentation
is variable, ranging from normal to turbid with an Infection is usually inapparent. In rare instances,
increased total protein and nucleated cell count. nodule formation may affect gastric outflow via
Neoplastic cells are uncommonly identified in peri- physical obstruction of the pylorus.
toneal fluid. Gastroscopy is an important diagnos-
tic tool, allowing direct visualisation of the tumour Differential diagnosis
(Fig. 4.131). Multiple biopsies should be taken to EGUS, gastritis, gastric SCC and other gastric
confirm the diagnosis. The stomach can also be visu- tumours should be considered in severe cases.
alised ultrasonographically, and ultrasound-guided
biopsy can be performed if gastroscopic biopsy is not Diagnosis
possible. Ultrasonographic examination of the liver, Due to the typical lack of clinical signs, diagnosis
spleen and pleura, and thoracic radiography may of gastric Habronema and Draschia infection is often
demonstrate metastatic masses. made incidentally. Mild gastritis (Habronema) or the
presence of nodules (Draschia) is most commonly
Management identified during gastroscopy. Endoscopic biopsy of
There are no viable treatment options. Draschia nodules can be diagnostic.

Prognosis Management
By the time of diagnosis, the prognosis is grave. Ivermectin (0.2 mg/kg p/o) or moxidectin (0.4 mg/
kg p/o) are effective. Measures to control flies are
GASTRIC PARASITISM: HABRONEMA beneficial.
SPP. AND DRASCHIA SPP.
Prognosis
Definition/overview The prognosis is excellent unless gastric outflow is
Gastric parasitism caused by Habronema and Draschia obstructed. If an outflow obstruction is present, the
spp. occurs sporadically worldwide and is of vary- prognosis is unclear and response to treatment must
ing clinical significance. Gastric habronemiasis is be observed.
of lesser significance than cutaneous habronemiasis
(see p. 1255). Draschia infection is more likely to pro- GASTRIC PARASITISM: GASTEROPHILUS
duce clinical gastric disease. SPP. AND TRICHOSTRONGYLUS AXEI

Aetiology/pathophysiology Definition/overview
The parasitic nematodes Habronema muscae, H. micro- Gastric infection by Gasterophilus spp. (bots) or T. axei
stoma and Draschia megastoma are involved. Habronema is very common and typically of little significance.
and Draschia eggs are passed in the faeces of infected
animals, and the L1 larvae are ingested by muscid fly Aetiology/pathophysiology
larvae. As the fly larvae mature, so do the parasitic Multiple bot species may be encountered. G. nasa-
larvae. When the adult fly feeds around the mouth lis, G. haemorrhoidalis and G. intestinalis are most