By Dr Jane C Boswell MA VetMB CertVA CertES(Orth) DipECVS MRCVS

Clinical signs of colic are not uncommon in foals. Causes may vary from transient medical conditions, such as low-grade enteritis, through to rare or complex congenital conditions. For the equine practitioner to decide when surgery is required, a broad knowledge base of the common causes of foal colic is essential.

The entire evaluation of the foal with colic is aimed towards determining a diagnosis so that appropriate medical or surgical treatment can be undertaken. A thorough and careful examination and work up, as outlined below, , may be necessary to determine the cause of colic signs.

Signalment

The age and gender of the foal are important as some causes of colic are more prevalent at different ages as shown in the table below.

 It is important to try to obtain a complete history overing both general and more specific history.

 General history

•       Hypoxia, prematurity

•       Dystocia

•       FPT/ sepsis

•       Diarrhoea- individual and farm

•       Treatments

•       Worming

 Specific history

•       Nature of colic signs

•       Duration and progression of signs. Foals with abdominal pain can display dramatic clinical signs, and have the potential to deteriorate rapidly

•       Nursing / appetite

•       Passage of faeces / urine and consistency

•       Straining

•       Abdominal distension

•       Other signs- tooth grinding etc

Physical examination

• Temperature

                        ↑ Enteritis, sepsis, peritonitis, intestinal compromise, severe colic

• Heart rate

                        persistent > 120 bpm suggestive of a surgical lesion

• Respiratory rate

                        ↑ pain, primary respiratory disease, abdominal distension, fractured ribs

• Mucous membranes

                        Toxic -  enteritis, strangulations, peritonitis, sepsis

• Gastrointestinal motility

                        ↓Decreased with ileus, strangulation, ischemia, early enteritis

                        ↑Increased with enteritis, early strangulation

·       Careful palpation of umbilicus and scrotum for hernias

• Abdominal ballottement/ percussion / palpation - ? fluid or gas

• EPR with a gloved, well lubricated finger

Additional diagnostics

- Ultrasonography

• A microconvex 8 MHz curvilinear probe or linear  transducer >10 MHz are ideal for performing the examination.

• Assess the  small intestine for motility, wall thickness  and diameter. Round, fluid-filled amotile loops can indicate a small intestinal obstruction,  enteritis, or ileus which can be due to electrolyte abnormalities or hypothermia.

• Characteristic “bulls eye” with intussusception

• Enteritis  - usually thick-walled (>3mm), fluid filled, not tightly distended, gas in wall (pneumatosis  intestinalis)

• Marked thickening (>27mkm)  and oedema of SI wall in Lawsonia interacellularis

• The stomach should be visualized to determine size.

• Gas distended colon may be  observed and an increase in wall thickness >5-mm may indicate a large colon volvulus or colitis.  A high meconium impaction may also be evident with ultrasound.

• Additionally, the volume of  peritoneal fluid should be assessed. Foals normally have very little peritoneal fluid, but an  increase in volume of anechoic fluid is readily identified and most often indicates a uroperitoneum. 

- Nasogastric intubation

• Due to the possibility of gastric outflow obstruction secondary to ulcer disease in foals, this is an important part of the evaluation. A stallion urinary catheter is ideal for a nasogastric tube in foals. As  the foal is usually recumbent, it can be difficult to create a siphon with flow alone, so gentle suction using a 60ml syringe can be applied.

• If gastric reflux is present, it may be due to a functional or mechanical small intestinal obstruction or a gastric outflow problem.

• Fluid with a dark “coffee grounds” appearance may indicate ulcer disease.

• If gastric reflux is obtained, the foal should not be allowed to nurse and therefore may require supplementation with 5% dextrose IV. Foal stomach tube

- Bloods

• PCV/TP, haematology, serum biochemistry, electrolytes, lactate, IgG

• Assess systemic condition

• Treatment plan +/- diagnosis

Haematology

• Anaemia - haemorrhage, NI, chronic disease

• Haemoconcentration

• Increased fibrinogen / serum amyloid A - Inflammation/ sepsis

• Leucopaenia / neutropaenia, left shit - sepsis, enteritis, peritonitis

• Leucocytosis - chronic inflammation / sepsis

Biochemistry

• Total protein - intestinal protein loss / FPT

• Urea / creatinine - renal function / uroperitoneum

• Liver enzymes - biliary obstruction, hepatic injury

• Electrolytes - diarrhoea, uroperitoneum, secondary renal dysfunction

- Abdominoparacentesis

• Use teat cannula under US guidance

• Only if you think it will alter your  treatment plan

• Measure WBC, total protein, lactate, cytology, creatinine

- Faecal analysis

• Faecal analysis is important in foals with colic and diarrhoea

 - Radiography

·       Useful in foals

·       Good visualization of gas distended intestine

·       Can aid in identifying type of distension, likelihood of obstruction/  strangulation

·       Can sometimes visualize specific obstructions

·       Barium, administered orally at a dose of 5ml/Kg of 30% W/V via gravity through a nasogastric tube,  can be useful to evaluate gastric emptying, obstruction and  thickened small intestine

·       Stomach should empty in 2 hours

·       Barium enemas can demonstrate rectal strictures, atresia coli, meconium impactions

- Gastroscopy

·       Ulceration of stomach common in foals

·         If gastric or duodenal ulceration is suspected, gastroscopy should be performed. In foals <30 days old, a 1-meter endoscope is usually sufficient to visualize the stomach and duodenum.

·         Foals should be sedated for the procedure and care taken not to overinflate the stomach with air. The region of the margo plicatus should be visualized for ulcers and the scope allowed to pass through the pylorus into the duodenum to determine the presence of a stricture at either location.

·         Air should be removed from the stomach prior to withdrawing the endoscope.

Treatments

•   Sedatives

• Butorphanol   0.1mg/kg IV

• Diazepam        0.1 – 0.2 mg/kg IV           

• Xylazine           0.2mg/kg IV

·     Analgesics

• Buscopan        0.2mg/kg iv

• Meloxicam      0.6mg/kg iv BID

• Flunixin           1.1mg/kg iv BID

• Xylazine           0.2  to 1 mg/kg iv

• Others:            carprofen, firicoxib

Enemas

• Treatment of meconium impaction / constipation

• Fleet enema

• Soapy water (~ 300-500 ml)

• Acetyl cysteine enema

• Sedate foal if necessary (diazepam/ butorphanol)

• Raise bottom on towel

• Insert Foley catheter into rectum (~ 6”) , inflate balloon

• Mix 40mls Acetyl cysteine (200mg/ml) + 160mls warm water

• Infuse by gravity flow

• Clamp for 20-30 mins

Fluids

•       Fluid & electrolyte therapy is often required for cardiovascular support to correct deficits associated with loss of fluid into intestinal tract & from inadequate intake

•       Initial bolus 10 - 20ml/kg Hartmanns over 15 – 20 mins

•       Formulate plan for ongoing fluids if necessary

•       For younger foals that are not nursing, the addition of 5 - 10% glucose to fluids should be considered to provide for an initial energy source. However, some caution is needed with glucose containing fluids as, over time, they may result in hypernatremia from increased free water loss in urine with varying degrees of hyperglycemia.

Oral fluids

• Oral rehydration with electrolytes for mild cases

• Relies on successful absorption across GI tract

• Not suitable for severely affected foals

• Contra-indicated in foals if reflux is obtained on nasogastric intubation

• 500 – 1L via nasogastric tube every few hours

Intravenous fluids

- Consider foal’s specific requirements

• Maintenance (ie low sodium) fluids must be used in young foals without diarrhoea

• Diarrhoea often associated with sodium & electrolyte loss

• Intermittent boluses for ambulatory foals

• Consider nutritional requirements

• Check acid base and electrolyte status

• Strong ion acidosis common

• Hyponatraemia with relative hyperchloraemia common in foals with diarrhoea

• Use sodium bicarbonate if volume replacement fails to fix acidosis

• Isotonic solution = 150mls 8.4% sodium  bicarbonate plus 850mls sterile water

• Bicarbonate requirement =Body weight (kg) x Base Deficit (mEq) x 0.5

• Give half deficit as a bolus

• Remainder over 6 – 12 hours

• Care in foals with concurrent respiratory disease

• Can give orally (1g = 12mEq)

Colloids

·       The neonate may require plasma for its immunoglobulin (IgG) content in an effort to correct failure of passive transfer of colostral antibodies but plasma can also provide albumin for its colloid effects.

·       Foals with profound enteritis with infections such as Clostridium perfringens or Clostridium difficile can lose significant amounts of plasma proteins across the intestinal mucosa and often require colloid replacement.

Treatment of hypoproteinaemia

• Rapid resuscitation

• Gelafusin (2 - 4ml/kg)

• Hetastarch (10ml/kg max daily dose)

• Plasma (20 – 40mlg/kg)

 Anti-diarrheal agents

Intestinal protectants/ bind toxins

• Biosponge has been shown to absorb clostridial toxins (30ml PO BID)

• Bismuth salicyclate (1ml/kg PO TID to QID)

• Kaolin-pectin

Gastroprotectants

Treatment of known gastric ulceration

• ? prophylaxis in foals with other types of colic 

• Omeprazole 

• 4mg/kg PO SID

• effective acid suppression in healthy and ill foals

• Sucralfate

o   20mg/kg PO TID

o   binds to ulcers and promotes mucosal blood flow

•  Ranitidine

o   1.5mg/kg IV or 6.6mg/kg PO TID

Antimicrobials

• Should be used in young foals with diarrhoea to prevent bacteraemia

• Broad spectrum therapy

• Metronidazole for clostridial infections  (15 mg/kg PO TID or 20mg/kg PO BID)

• Antimicrobial choices recommended for treating Lawsonia  intracellularis include oxytetracyclines, macrolides, or chloramphenicol.

• Antibiotic treatment in foals with known Salmonella infection is indicated due to the risk for bacteremia and sepsis. Treatment should be continued beyond clinical recovery to prevent secondary seeding.Antimicrobials effective against Salmonella spp include extended-spectrum cephalosporin or ampicillin-sulbactam alone or in combination with an aminoglycoside (gentamicin or amikacin) or fluorquinolones.

Gut Rest

• Consider in foals with severe enteritis, marked abdominal distension

• Muzzle and strip mare or separate

• 6 hours +

Surgery

The entire evaluation of the foal with colic is aimed towards determining what the potential problem is and if surgical treatment is necessary. The biggest dilemma is distinguishing a surgical lesion of the small or large intestine from enteritis and colitis. Unnecessary surgery should be avoided because of the high risk of postoperative adhesions, however, early surgical intervention prior to the onset of shock and sepsis results in an overall improved outcome in those foals that need surgery.

Indicators for surgery include

·       progressive increases in pain,

·       persistent tachycardia (>120 beats/min)and

·       increasing abdominal distention.

Evidence of a surgical lesion on transabdominal ultrasound