Senokot, Fletcher’s Castoria


  • Tablets: wide range of dose strengths available.
  • Liquid: 3 mg/mL
  • Syrup: 8.8 mg/5ml


A vegetable based laxative that increases peristalsis by its direct effect on smooth muscle in the intestine.

It is believed that the drug either irritates the musculature or stimulates the colonic intramural plexus, and promotes accumulation of fluid in the colon and small intestine.

Senna can be passed in small amounts in breast milk. Avoid giving to lactating rats.


Used in constipation to help improve intestinal motility.

Drug Interactions or Contraindications

  • Senna should be used with caution if the rat is taking digoxin and / or diuretics (e.g., Lasix, hydrochlorothiazide) as the combination can decrease potassium level in blood.
  • Contraindicated in intestinal perforation.

Adverse Reactions

GI: anorexia, malabsorption of nutrients, severe cramping, diarrhea

GU: pink discoloration in alkaline urine and yellow-brown discoloration in urine that is acidic.

Metabolic:  hypokalemia(low potassium level in blood), protein losing enteropathy, electrolyte imbalance with too much use.

Dosage Recommendations

1/8th tab/lb SID; PO  3, 12


  • Ensure rat has adequate fluid and diet intake.
  • Store at cool room temperature in a dry place, and away from direct heat and light.


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