Bisacodyl
**Bisacodyl** is a stimulant laxative used primarily in veterinary medicine for the treatment of constipation or for bowel evacuation prior to surgical, radiographic, or endoscopic procedures. * **Clinical Pearl**: Because it is a stimulant laxative, it should be used for short-term management only. Chronic use can lead to dependency, loss of normal bowel function, and severe electrolyte imbalances.
Mechanism: Bisacodyl acts directly on the **enteric nervous system**. * Stimulates mucosal sensory nerve endings → increases parasympathetic reflexes → enhances peristaltic contractions. * Alters fluid and electrolyte absorption → increases intestinal fluid accumulation, which helps soften the stool and facilitate evacuation.
Dosing by species
- Constipation / Bowel Evacuation · PO · Listed for Dogs (D) in monograph index.
- Constipation · 5-15 mg/dog · PO/Rectal · prn · Empirical dose. Onset of action 6-10 hours (oral) or 15-60 minutes (rectal).
- Constipation / Bowel Evacuation · PO · Listed for Cats (C) in monograph index.
- Constipation · 2-5 mg/cat · PO/Rectal · prn · Empirical dose. Onset of action 6-10 hours (oral) or 15-60 minutes (rectal).
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Intestinal obstruction
- Ileus
- Gastrointestinal bleeding
- Severe dehydration
Adverse effects
- Abdominal cramping
- Diarrhea
- Nausea
- Electrolyte imbalances (with chronic use)
Drug interactions
- Antacids · Premature dissolution of the enteric coating, leading to severe gastric irritation and vomiting.
- H2-Receptor Antagonists (e.g., Famotidine) · Increased gastric pH may cause premature release of the drug in the stomach.
Monitoring
- Fecal output and consistency
- Hydration status
- Electrolytes (if used for prolonged periods)
Overdose
Overdose may lead to severe diarrhea, abdominal cramping, and significant fluid and electrolyte loss (especially hypokalemia). Treatment is supportive, focusing on intravenous fluid therapy and electrolyte replacement.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.