Lactulose

Lactulose In Dogs & Cats: Uses, Dosage and Side Effects

Overview

• Metabolized by colonic bacteria resulting in the formation of low molecular weight organic acids (lactic, formic and acetic acids).
• These acids increase osmotic pressure, causing a laxative effect, acidifying colonic contents and thereby trapping ammonia as ammonium ions, which are then expelled with the faeces.

Uses of Lactulose

• Used to reduce blood ammonia levels in patients with hepatic encephalopathy.
• Treatment of constipation in dogs and cats.

Dose of Lactulose in Dogs and Cats

Dogs:

• Constipation: 0.5–1.0 ml/kg p.o. q8–12h.
• Acute hepatic encephalopathy: 18–20 ml/kg of a solution comprising 3 parts lactulose to 7 parts water per rectum as a retention enema for 4–8 hours.
• Chronic hepatic encephalopathy: 0.5–1.0 ml/kg p.o. q8–12h.
• Monitor and adjust therapy to produce 2 or 3 soft stools per day.

Cats:

• Constipation and chronic hepatic encephalopathy: 0.5–5 ml p.o. q8–12h.
• Monitor and adjust therapy to produce 2 or 3 soft stools per day.

Side Effects of Lactulose in Dogs and Cats

• Excessive doses cause flatulence, diarrhoea, cramping and dehydration.

Contraindications of Lactulose in Dogs and Cats

• Do not administer orally to severely encephalopathic animals at risk of inhalation.
• Do not use in animals with GI obstruction or those at risk of perforation.

Some Notes:

• Synergy may occur when lactulose is used with oral antibiotics (e.g. neomycin) and other laxatives.
• Oral antacids may reduce the colonic acidification efficacy of lactulose.
• Lactulose syrup contains some free lactose and galactose, and so may alter insulin
  requirements in diabetic patients.
• With increasing doses, the pH of the colon decreases, and therefore drugs which are released in the colon pH-dependently (e.g. 5-aminosalicylic acid) can be inactivated.