Page 845 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

820 CHAPTER 4

VetBooks.ir other causes of colic may produce similar clinical beneficial to deworm initially with slower-acting
anthelmintics (e.g. fenbendazole), as opposed to
signs to those of ascarid impaction.
Diagnosis avermectins, to reduce the chance of ascarid impac-
tion. Deworming programmes for yearlings and
Faecal flotation should be performed and ascarid adult horses are variable and should be designed for
eggs are readily identified after the 10–12 weeks pre- the individual farm based on farm type, horse num-
patent period. In foals with ascarid impaction, signs bers, horse movement, pasture crowding and ability
of small-intestinal obstruction are present. These to properly manage pastures.
include gastric reflux and ultrasonographic identi- Ascarid eggs can remain viable on pasture for
fication of distended small intestine. Occasionally, years, so prevention of pasture contamination is
ascarids are identified in gastric reflux, on gastros- important. Proper pasture management, including
copy or via ultrasound (Fig. 4.144). avoidance of overstocking, removal of faeces, pasture
rotation and routine deworming of all animals with
Management access to the pasture, is essential. Faecal egg count
Routine deworming should be started in foals reduction tests are useful for evaluating the effec-
at 6–8 weeks of age and repeated every 8 weeks tiveness of the deworming programme.
for the first 6–12 months. Broodmares should be Emergency surgery is usually required in foals
dewormed regularly, including during the third with ascarid impaction and signs of intestinal
trimester, to decrease environmental contamina- obstruction (Fig. 4.145).
tion. Ascarid resistance to various anthelmintics
is widespread, and knowledge of regional patterns Prognosis
is essential for adequate control. Further, faecal The prognosis with ascarid infestation is excellent.
egg reduction tests should be regularly performed. The prognosis for ascarid impaction is guarded
If a large ascarid burden is suspected, it may be because of the frequent requirement for emergency
surgery and the complications that can ensue with
small-intestinal surgery in young horses. Intestinal
4.144 rupture secondary to ascarid impaction is rare but
can occur (Fig. 4.146).

4.145

Fig. 4.144 Cross-sectional ultrasound image of a foal Fig. 4.145 Enterotomy to remove ascarids in a foal
with ascarid impaction. Note the two cross-sectional with an ascarid impaction.
images of ascarids within the intestinal lumen.