Page 98 - JSOM Spring 2018

TABLE 1 Normal Operational K9 Vital Signs Parameters FIGURE 1 Normal dog stomach (reproduced with permission of
Parameter Normal Range a Veterinary Information Network and www.VeterinaryPartner.com).
Respirations 10–40 per minute
Normal heart rate 60–80 bpm
Postexercise pulse ≤130 pulses/min
Capillary refill time <2 seconds
Mucous membrane color Pink (black pigment is normal)
Normal rectal temperature: 37.8°C–39.2°C (100°F–102.5°F)
Postexercise rectal temperature 39.4°C–41.7°C 103–107°F
a Normal values are for a resting state. Exercise, increased activity,
pain, and stress will influence parameters.
abdomen in conjunction with nonproductive retching (an in-
dicator of an esophageal or gastric outflow obstruction), and
a distended, tympanic abdomen places gastric dilatation and
volvulus (GDV) as the most likely differential diagnosis. GDV
is an acute, rapidly progressive, life-threatening condition
characterized by accumulation of gas, fluid, and ingesta in the
stomach with varying degrees of gastric malposition (volvulus
or torsion). Left untreated, the condition rapidly leads to car-
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diorespiratory dysfunction, circulatory shock, and death. Even
with prompt and aggressive treatment, GDV-associated mor-
tality rates may exceed 60%. Although used synonymously,
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bloat and GDV are not the same:
In a normal canine without volvulus, the pylorus lies ventral
• Bloat or gastric dilatation (GD): simply the distention to the fundus and right of the median plane. In the presence of
of the stomach owing to accumulation of gas, food, volvulus, the pylorus is displaced craniodorsal to the fundus
froth, and/or fluid within the stomach lumen, but the and left of the median plane. 4-7
stomach is not malpositioned 4
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• Gastric volvulus (GV) or gastric torsion: involves at Although rare in humans, GDV is considered a high risk for
least a 90° rotation of the stomach around its axis creat- select canine populations (discussed later in this article). The
ing a closed-loop gastric obstruction along with incar- higher risk in some canines may relate, in part, to the gastric
ceration and strangulation of the stomach. In canines, ligaments formed by the omentum. The omentum is an apron-
the stomach may rotate from 90° to 540°; rotation of like extension of the visceral peritoneum. It arises from the
220° to 270° is most common. 4–6 both the greater and lesser curvature of the stomach form-
• GDV: involves gastric distention with volvulus ing the greater and lesser omentum, respectively. The greater
omentum spans from the stomach, attaching to the hilus of
Differentials other than GDV and GD for an acute abdomen the spleen, forming the gastrosplenic ligament. In humans,
in OpK9s include intestinal volvulus (mesenteric or colonic), the greater omentum also attaches to the transverse colon,
splenic torsion, gastrointestinal obstructions, peritonitis, and forming the gastrocolic ligament; canines do not have this at-
diaphragmatic hernia. tachment. The lack of tethering to the transverse colon may
make the canine stomach prone to greater instability and risk
for volvulus. The lesser omentum attaches to the liver form-
Anatomy of the Canine Stomach and Omentum
ing, the hepatogastric ligament (HGL). The HGL helps secure
Canines are monogastric animals (i.e., stomach with a single and stabilize the pylorus within the right cranial abdominal
compartment) that have similar stomach anatomy to that of compartment. Stretching or laxity of the HGL may predispose
humans. The canine’s stomach is a C-shaped structure with the canine at higher risk for GV. A small case-control study
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a greater curvature (convex surface) that faces caudoventral demonstrated that the HGL in GDV-affected dogs were signif-
and to the left side of the body, and a lesser curvature (con- icantly longer than those in control dogs. However, the investi-
cave surface) that contains the angular notch (Figure 1). The gators also stated that it was not known whether the ligaments
stomach’s cranial aspect, the cardia, houses the inlet opening were lengthened as a result of GDV or whether the lengthened
from the esophagus and lies left of the body’s median plane; ligaments predisposed dogs to GDV. Laxity in gastric liga-
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the caudal end (pylorus) contains the outflow opening into ments (i.e., gastrosplenic, gastroduodenal, gastrophrenic, and
intestinal tract and lies slightly right of the median plane. The gastrohepatic ligaments) is reported to account for up to two-
stomach has three main sections or regions: 7 thirds of cases of idiopathic GV in humans. 8
• Fundus: Large outpouching located dorsal and cranial Pathophysiology of GDV
to the cardia and lies left of midline
• Body: Middle and largest section of the stomach It remains unclear whether gastric distention precedes GV or
• Pyloric region: Irregularly, funneled shaped distal third vice versa. GD (simple bloat) may occur in the absence of vol-
region of the stomach. It contains the pyloric antrum, vulus, and GV may occur in the absence of dilatation. Regard-
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pyloric canal, and pylorus. This region connects the less of which event develops first, once combined to produce
body of the stomach to the first portion of the small GDV, the result is hemodynamic and respiratory compromise.
intestines (i.e., the duodenum). Both gastric distention and volvulus cause occlusion of the

92 | JSOM Volume 18, Edition 1/Spring 2018