1. Introduction to Digestive Disorders of Horses
The digestive system includes all of the organs that are involved in taking in and processing food. It
begins with the mouth and includes the esophagus, stomach, liver, pancreas, intestines, rectum, and
anus.
Digestion begins when the horse picks up food with its mouth and starts chewing. Salivary
enzymesbegin breaking down the food chemically. The process continues with swallowing, additional
breakdown of food in the stomach, absorption of nutrients in the intestines, and elimination of waste.
Digestion is critical not only for providing nutrients but also for maintaining the proper balance of fluid
and electrolytes (salts) in the body.
The functions of the digestive system can be divided into 4 main categories: digestion, absorption of
nutrients, motility (movement through the digestive tract), and elimination of feces.
When treating a digestive system problem, the veterinarian's goal is to first identify the part of the
system where the problem lies and then to determine the specific cause and appropriate treatment
Major digestive organs of the horse
Fig. 1 Photo courtesy of http://www.merckmanuals.com/vet/
2. DISEASES OF THE DIGESTIVE SYSTEM
Mouth
Name of
disease/disorder
Other
name/
term
Brief description Epidemiology Brief
summary of
pathogenesis
Clinical
signs
Lesions Diagnosis Differential
Diagnosis
Treatment Control and
Prevention
cleft
palate or cleft lip
harelip defect in the
formation of the
jaw & face during
embryonic
development leads
to a gap or cleft in
the center of the
lip, the roof of the
mouth (hard
palate), or both
defect in the
formation of
the jaw and
face during
embryonic
development
leads to
forming cleft
problems
with
nursing,
milkdripping
from the
nostrils,
difficulty
suckling and
swallowing
Cleft or gap in
the upper lip and
palate
Clinical signs,
Oral
examination
Esophageal
strictures
intensive
nursing care,
antibiotics to
treat
secondary
respiratory
infections,
surgery for
minor cases
affected
animal
should be
neutered,
proper mare
management
during
pregnancy
Brachygnathia parrot
mouth
the mandible is
shorter than the
maxilla
griseofulvin
use during
pregnancy in
the mare
cause
broader
teratogenic
effects leads
to shorter
mandible
restriction
of normal
jaw growth
hard palate
damage
oral
examination
Prognathia monkey or
sow mouth
mandible is longer
than the maxilla
badly
affected
horses
suckling
may be
impossible
oral
examination
finding
mandibular
incisors in
contact with or
rostral to the
maxillary
incisors
if feasible,
rasping or
shearing the
offending
points and
projections
Dental Disorders the teeth are not
worn down evenly
forming sharp
enamel points
loss of
appetite or
weight,
difficulty or
Tooth decay,
cuts inside
mouth, swelling
of face or jaw
physical
examination,
detailed and
thorough
Use of
antibiotic to
treat
secondary
Regular
dental
prophylaxis
(preventive
3. causing functional
loss of the teeth
slowness in
feeding,
reluctance
to drink cold
water,
irregular
chewing,
unchewed
grain,
excessive
drooling,
blood-
tinged
mucus in
the mouth,
examination of
the mouth and
teeth
bacterial
infections,
anti-
inflammatory
medications
care), enamel
edgesfiled
down twice
yearly
Lip Lacerations Wounds of the lips
occur frequently
may be
accompanied by
mandibular or
incisive bone
fractures with or
without dental
fractures and tooth
avulsions
horse grasps
objects with
its mouth
and then
pulls back
when
startled
causing
lacerations
Swelling of
lips,
discomfort
in eating
Wounds and cuts
in lips
Physical
examination
Surgical
suturing,
Proper use of
bits and
restraint
devices,
prevention of
biting vices
Slaframine
poisoning
can occur when
horses eat forages,
particularly clovers,
that are infected
with the
fungus Rhizoctonia
leguminicola
horses eat
forages
infected with
fungi, then
fungi
produces the
toxic alkaloid
slaframine
Profuse
ptyalism
no evidence of
oral ulceration or
other oral
lesions
Chemical
detection
ofslaframine or
in forages,
bluetongue,
vesicular
stomatitis,
vesicular
exanthema, and
foot-and-mouth
disease
Removal of
infected
forage from
the diet
Restriction of
horses in
pasture with
suspected
slaframine,
Proper
inspection of
feed forage
Inflammation of
the Mouth
Stomatitis Inflammation of
the mouth
(stomatitis) has
many possible
causes. Trauma to
Trauma and
irritants to
mouth leads
to
inflammation
Frothy
drooling,
reluctance
to eat, and
resistance
Wounds,
sores/ulcerations
or cuts to the
mouth
Oral
Examination
actinobacillosis,
vesicular
stomatitis, and
malignant
catarrhal fever
removal of
any
embedded
foreign
matter inside
4. the mouth or
contact with
chemical irritants
some may
become
severe
to
examination
of the
mouth
mouth,
change the
quality and
quantity of
hay diet
Papillar
Stomatitis
Viral
papillomas
(warts)
found around the
lips and mouths of
young animals
Warts on lips
and mouth
Used liquid
nitrogen to
burn them
off
Pharynx
Name of
disease/disorder
Other
name/
term
Brief description Epidemiology Brief
summary of
pathogenesis
Clinical
signs
Lesions Diagnosis Differential
Diagnosis
Treatment Control and
Prevention
Pharyngeal
Paralysis
Refers to paralysis
of the upper throat
(pharynx). The
paralysis makes
swallowing difficult
or impossible
nervous
system
disorder (for
example
rabies or
botulism)
causes
collapse,
obstruction,
or
malfunction
of the
pharynx
dysphagia
with oral or
nasal
discharge of
food, water,
or saliva,
coughing,
dyspnea,
ptyalism, or
bruxism,
pyrexia,
coughing,
retching
Based on
history and
clinical signs
treatment
for
pharyngeal
paralysis is
directed
toward
relieving
signs, use of
anti-inflamm.
And
antibiotics
Esophagus
Name of
disease/disorder
Other
name/
term
Brief description Epidemiology Brief
summary of
pathogenesis
Clinical
signs
Lesions Diagnosis Differential
Diagnosis
Treatment Control and
Prevention
Obstruction of
the Esophagus
Choke a condition in
which the
esophagus is
obstructed by food
masses or foreign
objects. It is by far
horse quickly
eats dried
grains or hay
then
obstruction
happens/
nasal
discharge of
feed
material or
saliva,
dysphagia,
Physical
examination
and Endoscopy
examination
Repeated
pumping and
siphoning of
warm water,
Oxytocin
(0.11–0.22
Proper
monitoring
of horses
husbandry
practices
5. the most common
esophageal disease
in horses
diseased
teeth can’t
chew food
masses
properly
causes choke
coughing, or
ptyalism,
horse
stretch and
arch its neck
mg/kg, IV)
relax
esophageal
smooth
muscle
Esophageal
strictures
Esophageal
narrowing
Esophageal
strictures of
unknown cause are
sometimes seen in
foals
Healing
process of
mucosal
defect or
congenital or
may occur
after external
neck trauma,
as a sequela
of previous
esophageal
surgery, or
after
esophageal
rupture leads
to stricture
problems
with
nursing,
milkdripping
from the
nostrils,
difficulty
suckling and
swallowing
mucosal
ulceration of
esophagus
Endoscopy
examination
harelip dietary
manage-
ment and
Surgical
treatment
(esophago-
tomy or
esophageal
myotomy)
Stomach
Name of
disease/disorder
Other
name/
term
Brief description Epidemiology Brief
summary of
pathogenesis
Clinical
signs
Lesions Diagnosis Differential
Diagnosis
Treatment Control and
Prevention
gastric ulcer Equine
gastric ulcer
syndrome
[EGUS]
this syndrome is
most closely
associated with
horses involved in
performance
disciplines;
changes in housing
or social
interaction; and
illness
periods of
eating or
nursing and
makes higher
secretion of
hydrochloric
acid in the
stomach or
intensive
exercise
(pressure)
collapsing the
Foals-
diarrhea,
grinding of
teeth, poor
nursing,
lying down,
and
excessive
drooling
Adult-
abdominal
discomfort
Sores most
common on the
upper part of
stomach,
thickening and
contracture of
the stomach
Endoscopy is
the only
reliable
method of
diagnosis
antacids,
histamine
type-2
receptor
antagonists,
and proton
pump
inhibitors
medications
- omeprazole
(4 mg/kg,
PO, sid)
Proton pump
inhibitors ,
managing the
risk factors
(feeding
schedule,
stall
confinement,
travel, and
training) and
using
medication
6. stomach and
forcing the
acid gastric
contents
upward
results in
ulcers
(colic), poor
appetite,
mild weight
loss, poor
body
condition,
and attitude
changes
-Ranitidine
(6.6 mg/kg,
PO, tid),
designed for
ulcer
prevention
(omeprazole)
1 mg/kg, PO,
sid
Colic Abdominal
pain
a broad term for a
variety of
conditions that
cause horses to
experience
abdominal pain
inflammation
or ulceration
in the
stomach
results to
colic
pawing
repeatedly
with a front
foot, looking
back at the
flank region,
curling the
upper lip
and arching
the neck,
repeatedly
raising a
rear leg or
kicking at
the
abdomen,
lying down,
rolling from
side to side,
sweating,
stretching
out as if to
urinate,
straining to
defecate,
distention
of the
abdomen,
loss of
appetite,
Physical
examination,
history and
clinical signs
Pain Relief
Fluid
Therapy
