Safety and efficacy of oral low-volume sodium phosphate bowel preparation for colonoscopy in dogs

Background: Sodium phosphate (NaP) is a low-volume, hyperosmolar laxative that is an effective bowel-cleansing agent in humans. Hypothesis: NaP will be as safe and efficacious as polyethylene glycol (PEG) bowel preparation for colonoscopy in dogs. Animals: Eight purpose-bred healthy dogs. Methods: In phase I, standard (NaP and enemas; NaP1) and control preparations (PEG and enemas) were compared in a crossover design to determine the safety and efficacy of NaP. Serial clinical and serum analytical evaluations were used to determine the safety of NaP. In phase II, the efficacy of the standard NaP preparation was compared with 3 other NaP variations, which excluded enema or included bisacodyl, with or without enemas in a crossover design. An observer blinded to the bowel preparation assigned a score of 1-4 (1=clean colon; 4=unacceptable colon cleansing preventing adequate endoscopic evaluation) to each of 5 regions of the colon. Results: The mean total colon cleansing score (TCS), defined as the sum of scores from each region, of the control (9.4) was less than NaP1 (13.6) (P < 0.05). There were no significant differences in regional or TCS for the remaining 4 NaP protocols. NaP1 resulted in moderate, but clinically occult, hyperphosphatemia and hypocalcemia, which resolved within 24 hours. Conclusions and Clinical Importance: Despite the safety and ease of administration of the NaP preparations, the NaP bowel-cleansing preparations used in this study cannot be recommended for use because of the inadequate quality of bowel preparation compared with the protocol using PEG-containing fluids.