- Definition
- Pathophysiology
- Systems Affected
- Genetics
- Incidence/Prevalence
- Geographic Distribution
- Signalment
- Signs
- Causes
- Risk Factors
BASICS
- Obstructive GI conditions, such as meconium impaction, cause gas and fluid distention proximal to the obstruction, and subsequent abdominal distention and associated pain due to stimulation of intestinal wall stretch receptors within the GI tract. Prolonged/severe distention or direct compression by an intraluminal mass (e.g. impaction) can lead to reduced intestinal wall perfusion and ischemic injury, leading to secondary reperfusion injury when blood flow is reinstituted
- Enteritis and enterocolitis (see chapter Diarrhea, neonate) can be caused by a variety of bacterial and viral organisms. Small intestine and colon can become distended with fluid and gas secondary to enterocolitis and may also have spasmodic contractions, leading to colic pain
- Strangulating lesions of the small or large intestine (such as small intestinal volvulus) generally cause acute, severe pain, and rapid hemodynamic deterioration
- Duodenal stricture or obstruction can occur secondary to gastroduodenal ulceration, usually in foals 1–4 months of age
- Damage to the intestinal wall secondary to enterocolitis, obstruction, or strangulation can lead to bacterial translocation and subsequent endotoxemia. Endotoxin is responsible for many of the clinical signs (fever, tachycardia, leukopenia, injected mucous membranes)
- Adhesions are a relatively common complication of abdominal surgery in neonatal foals. They form as fibrin adheres to areas of serosal injury
- GI
- Cardiovascular—decreased fluid intake, third spacing of fluid in the intestinal lumen, abdominal effusion, and losses via reflux or diarrhea can lead to hypovolemia, hypovolemic shock, and dehydration. Endotoxemia will compound the effects on the cardiovascular system and may lead to decompensated shock
- Generalized abdominal pain or colic does not have a genetic predisposition
- Specific causes of colic, such as lethal white syndrome, do have a genetic basis
The incidence of colic in foals appears to be lower than that in adult horses; however, there are causes of colic that are specific to or more common in foals.
No specific geographic distribution, although sand colic is more prevalent in coastal areas or local turnout areas with high levels of sand.
- Miniature horses have a higher incidence of fecalith formation
- Overo-overo cross Paint foals are at risk of intestinal aganglionosis (LWFS)
- Foals 24–48 h of age are most commonly affected by meconium impaction and enterocolitis. Less commonly, atresia coli, LWFS, GI ulceration, and congenital inguinal hernias are causes of neonatal colic
- Foals 2–5 days of age—enterocolitis, ruptured bladder, atresia coli, atresia ani, gastric ulcers
- Foals 5 days to 6 months of age—enterocolitis, gastric ulcers, duodenal ulcers and stenosis, small intestinal volvulus, intussusception, hernias (inguinal, scrotal, diaphragmatic), phytobezoar, drug-induced colic (antimicrobial-associated enterocolitis, NSAID-associated GI ulcerative disease), abscessation, and ascarid impaction
- Colts are at risk of inguinal hernias and appear to be at higher risk of ruptured bladder and meconium impaction
Signs of colic in neonatal foals can be inconsistent, and may be complicated by concurrent disease states (e.g. septicemia). Foals may be depressed and anorexic rather than displaying “classic” colic signs such as pawing or rolling.
- Not nursing well—foal may have dried milk on its head, and mare's udder will be full
- Decreased fecal passage
- Persistent posturing to urinate/defecate
- Poor weight gain, unthrifty appearance
- Previous gastric ulceration can predispose to gastric outflow obstruction in older foals
- Depression, lethargy
- Abdominal distention
- Reduced nursing
- Tachycardia, tachypnea
- Tail flagging, straining/tenesmus
- Decreased or increased borborygmi
- Rolling, lying on back, restlessness, persistent recumbency, stretching out of limbs
- Signs of self-trauma (e.g. abrasions over the eyes) indicate colic pain prior to presentation
- Bacterial—septicemia can lead to enterocolitis. Other common causes of enterocolitis in foals include Clostridium difficile and/or perfringens, rotavirus, corona virus, Escherichia coli, Actinobacillus equuli, and Salmonella spp.
- Congenital—intestinal atresia, LWFS, and hernia are congenital problems in foals
- Intussusceptions are associated with tapeworm infestations in older foals and adults; this is not a common cause of colic in neonates, but may be related to altered peristalsis
- Small intestinal volvulus can occur secondary to enteritis or may be idiopathic—progressive fluid distention and altered motility may contribute to volvulus at the base of the mesentery
- Diaphragmatic hernias are uncommon in neonatal foals but may be congenital or traumatic in origin
- FTPI places foals at higher risk of septicemia (and therefore enterocolitis) and might predispose to meconium retention
- NSAIDs and stress contribute to formation of gastric and duodenal ulcers in foals
- Neonatal maladjustment syndrome can result in localized ischemic perfusion injury to the intestinal mucosa, resulting in generalized small intestine ileus, mucosal injury, and bacterial translocation
DIAGNOSIS
TREATMENT
MEDICATIONS
FOLLOW-UP
MISCELLANEOUS