Meconium Impaction - Horse

Also known as:

Meconium Retention

Colic in foals
Impaction
Simple Obstruction
Large Intestinal Simple Obstruction
Small Colon Impaction
Descending Colon Impaction

Description

Meconium impaction or retention is the most common cause of colic in the first 24 hours of life. Meconium is mucilaginous material in the intestine of the term fetus containing a mixture of cellular debris, secretions of the intestinal glands, bile and amniotic fluid. Meconium usually begins to be evacuated from the newborn foal within 3 h after birth, and is considered retained if the foal makes frequent attempts but fails to produce meconium by age 12 h.(Pusterla)

Signalment

Newborn foals. More common in colts than fillies, particularly if they are overdue. This may be related to a narrower pelvic inlet.

Aetiology

Meconium is composed of glandular secretions, swallowed amniotic fluid and cellular debris. It is dark brown to black and cement- or pellet-like in texture. Most foals defaecate shortly after their first meal, within 24 hours of birth. Once meconium has been passed, the faeces become a dark yellow, reflecting milk digestion. Meconium retention may result from a lack of colostrum ingestion, since colostrum is a natural laxative. Thus foals with meconium retention should also be checked for failure of passive transfer (FPT). Intestinal dysmotility may also be an indication of perinatal asphyxia.

Clinical Signs

Colic (due to gas accumulation within the bowel)
Continuous straining
Classic 'arched back' stance
Foal depressed or remains bright
Normal or reduced level of suckling
Tail swishing and elevation
Restlessness

Diagnosis

CAREFUL digital examination per rectum (for diagnosis only)
Abdominal palpation (meconium may be palpable if abdominal tympany is not too advanced)
Abdominal ultrasound
Abdominal radiography

Differential Diagnoses

Uroperitoneum: the foal may assume a more extended stance (NB: a ruptured bladder may occur simultaneously with meconium retention)
Gastrodudodenal ulceration
Impending enteritis
Obstructive gastrointestinal lesions
- Small intestinal intussusception
- Torsion
- Atresia coli

Treatment

Enema: warm soapy water made with a mild soap that can be administered through soft rubber tubing by gravity.
Liquid praffin: 300ml by nasogastric tube for foals that do not respond rapidly to an enema
Muzzling and maintenance rate fluids IV: for persistent meconium retention resulting in significant abdominal distension. A constant rate infusion of 5-10% dextrose will provide some calories in addition to the free water needs. Dextrose should NOT be given as a bolus.
Retention enema: a more aggressive treatment may be required using acetylcysteine which is an irritant and increases secretion. 20g baking soda and 8g acetylcysteine are added to 200ml water to create a 4% acetylcysteine solution of pH7.6. A 30-french Foley catheter is inserted 2.5 to 5cm into the rectum and the bulb slowly inflated to occlude the rectum. 100-200ml of the solution is adminstered under gravity and retained for 30-45mins by occluding the catheter.^[1]
Surgery: may be required for extreme cases
Analgesia: may be needed for some foals. NSAIDs have deleterious effects on renal function and gastric mucosal blood flow, so they should be avoided if possible. Butorphanol given IM at 0.05 to 0.1mg/kg^[2] may help to prevent straining. Hyoscine (Buscopan-Boehringer) may alleviate the colic.
Intranasal oxygen: is useful for foals with significant abdominal distension.^[3]

Prognosis

Most cases resolve with medical management within 12-24hrs.

Complications

Foals with meconium retention may be at risk of sepsis because bacterial translocation may occur across the disrupted intestinal mucosa. Blood cultures are thus advisable and foals should be monitored closely for clinical signs of sepsis. Continuous straining may lead to patent urachus.

References

Wilkins, P.A (2010) 'Diseases Of The Gastrointestinal Tract' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) Equine Internal Medicine (Third Edition), Saunders, Chapter 21.

↑ Pusterla, N, Magdesian, K, Maleski, K, et al. (2004) Retrospective evaluation of the use of acetylcysteine enemas in the treatment of meconium retention in foals: 44 cases (1987-2002). Equine Vet J, (6):170-174. In: Wilkins, P.A (2010) 'Diseases Of The Gastrointestinal Tract' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) Equine Internal Medicine (Third Edition), Saunders, Chapter 21.
↑ Arguedas, M.G, Hines, M.T, Papich, M.G et al. (2008) Pharmacokinetics of butorphanol and evaluation of physiologic and behavioural effects after intravenous and intramuscular administration to neonatal foals. J Vet Intern Med, 22(6):1417-1426. In: Wilkins, P.A (2010) 'Diseases Of The Gastrointestinal Tract' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) Equine Internal Medicine (Third Edition), Saunders, Chapter 21.
↑ Wilkins, P.A (2004) Respiratory distress in foals with uroperitoneum: possible mechanisms. Equine Vet Educ, 16(6):293-295. In: Wilkins, P.A (2010) 'Diseases Of The Gastrointestinal Tract' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) Equine Internal Medicine (Third Edition), Saunders, Chapter 21.

[1] Pusterla, N, Magdesian, K, Maleski, K, et al. (2004) Retrospective evaluation of the use of acetylcysteine enemas in the treatment of meconium retention in foals: 44 cases (1987-2002). Equine Vet J, (6):170-174. In: Wilkins, P.A (2010) 'Diseases Of The Gastrointestinal Tract' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) Equine Internal Medicine (Third Edition), Saunders, Chapter 21.

[2] Arguedas, M.G, Hines, M.T, Papich, M.G et al. (2008) Pharmacokinetics of butorphanol and evaluation of physiologic and behavioural effects after intravenous and intramuscular administration to neonatal foals. J Vet Intern Med, 22(6):1417-1426. In: Wilkins, P.A (2010) 'Diseases Of The Gastrointestinal Tract' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) Equine Internal Medicine (Third Edition), Saunders, Chapter 21.

[3] Wilkins, P.A (2004) Respiratory distress in foals with uroperitoneum: possible mechanisms. Equine Vet Educ, 16(6):293-295. In: Wilkins, P.A (2010) 'Diseases Of The Gastrointestinal Tract' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) Equine Internal Medicine (Third Edition), Saunders, Chapter 21.

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