Rectal instillation of butyrate provides a novel clinically relevant model of noninflammatory colonic hypersensitivity in rats

BACKGROUND & AIMS

The treatment of irritable bowel syndrome (IBS), characterized by abdominal pain and bloating, is empirical and often poorly efficient. Research lacks suitable models for studying the pathophysiologic mechanisms of the colonic hypersensitivity and new pharmacologic targets. The present study aimed to develop a novel model of colonic hypersensitivity possessing several of the characteristics encountered in patients with IBS.

METHODS

Rats received enemas of a butyrate solution (8-1000 mmol/L) twice daily for 3 days. A time course was determined for colonic hypersensitivity (colorectal distention test) and referred cutaneous lumbar hyperalgesia (von Frey hairs). Macroscopic and histologic analyses were performed on colonic mucosa. The efficacy of morphine, U50488H (a kappa opioid agonist), and trimebutine on the 2 pain parameters was determined. Finally, the involvement of peptidergic C-fibers was evaluated using capsaicin-pretreated animals and treatments with calcitonin gene-related peptide (CGRP) and neurokinin 1 receptor antagonists.

RESULTS

Butyrate enemas induced a sustained, concentration-dependent colonic hypersensitivity and, to a lesser extent, a referred cutaneous mechanical hyperalgesia, particularly in female rats, but no macroscopic and histologic modifications of the colonic mucosa, as observed in patients with IBS. Both pain parameters were sensitive to morphine, U50488H, trimebutine, neonatal capsaicin treatment, and the CGRP receptor antagonist but not to the neurokinin 1 receptor antagonist.

CONCLUSIONS

These results present our noninflammatory model of chronic colonic hypersensitivity as a useful novel tool for studying IBS. The CGRP receptor antagonist-induced reduction of colonic hypersensitivity suggests that CGRP receptors may provide a promising target for treatment of IBS.

Phosphate enema toxicosis in a pygmy goat wether

Phosphate enema toxicity was diagnosed in a 7-month-old, castrated male, pygmy goat. On presentation, clinical findings included mild depression, tachycardia, tachypnea, rumen stasis, muscle tremors, hypocalcemia, hypokalemia, hypochloremia, hyperphosphatemia, azotemia, and metabolic acidosis. Fluid diuresis and parenteral antimicrobial therapy resulted in recovery after 3 d of treatment.

Surgical removal of a seminoma from a black sea bass

An adult black sea bass was examined because of abdominal distention and decreased appetite. A large abdominal swelling was evident and was firm on palpation. Differential diagnoses included neoplasia, abscess or granuloma, hematoma, or swim bladder abnormality. Diagnostic tests included survey radiography, positive-contrast radiography, and computed tomography. The sea bass was anesthetized with tricaine methanesulfonate. A ventral midline abdominal incision was made, and adhesions to the mass were gently dissected. The fish recovered without complications. Radiography was repeated 8 weeks after surgery, and there was no evidence of mass regrowth. To the authors' knowledge, this is the first report of a barium enema being performed in a fish. Although surgical procedures are performed more commonly on fish for research, a few reports of clinical surgical cases have been described. Our experience supports the conclusions of other reports that certain surgical procedures can be performed safely in fish.

[Life threatening metabolic disorders after application of a sodium phosphate containing enema in the dog and cat]

Application of a sodium phosphate containing enema caused life-threatening metabolic disorders in a Dachshund and two cats. Clinical signs were characterised by dehydration and various neurological deficits including seizures. Most striking laboratory abnormalities were hypernatremia, hypocalcemia, hyperphosphatemia, and polycythemia. Despite intensive treatment the dog died, whereas the cats recovered completely. In face of possible severe and potentially fatal metabolic abnormalities sodium phosphate enemas, such as Practo-Clyss, should be used with caution or not at all in cats and small dogs.

Treatment of calcium, phosphorus, and magnesium balance disorders

In food animal practice, the majority of the calcium, phosphorus, and magnesium balance disorders are due to low blood concentrations of one or more of these minerals. The purpose of this article is to review methods that can be used to restore normal blood concentrations of these minerals. Low plasma calcium is often accompanied by changes in plasma phosphorus and magnesium. Initial discussions will consider each mineral separately, followed by pros and cons of combined therapies. In all cases the doses of the treatments described in this article are those appropriate for the 600-kg cow.

Suspected herbicide toxicosis in a dog

An 8-year-old 38-kg spayed female Golden Retriever was admitted for vomiting, signs of abdominal pain on palpation, ataxia, anorexia, and generalized weakness of 2 days' duration. Ten hours prior to onset of clinical signs, the dog was found standing in and drinking from large pools of an accidentally spilled herbicide that contained an octanoic acid ester of bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) and an isooctyl ester of (2-methyl-4-chloro) phenoxyacetic acid (MCPA). Appendicular muscles were firm on palpation and persistent muscle contraction (myotonia > 1 minute duration) was found on muscle percussion, using a reflex hammer. Electrical activity indicative of myotonia was identified on electromyographic evaluation. With supportive treatment, the dog eventually recovered from suspected MCPA toxicosis. Although rare, MCPA toxicosis should be considered as a cause of acquired myotonia in dogs.

Acute thallium toxicosis in a dog

A Doberman Pinscher was evaluated for acute onset of gastroenteritis, characterized by anorexia, hematemesis, and hematochezia. The dog had ingested mole bait containing thallium 2 days prior to admission. Thallium toxicosis was confirmed by detection of thallium in the urine, using colorimetric analysis. The dog responded well to administration of antibiotics, fluids administered IV, warm-water enemas, and oral administration of activated charcoal slurries.

Comparison of an orally administered gastrointestinal lavage solution with traditional enema administration as preparation for colonoscopy in dogs

Forty dogs were randomly assigned to be given either multiple enemas (group A) or orally administered lavage solution (group B) before colonoscopy. Dogs of group A (n = 20) were given 3 large-volume warm-water enemas 6 hours apart, with the last enema given 9 to 15 hours before colonoscopy. Dogs of group B (n = 20) were given a total dose of 50 ml of the lavage solution/kg of body weight through an orogastric tube. The lavage solution was administered in 2 doses of 25 ml/kg given 1 hour apart, 12 to 18 hours before colonoscopy. Dogs were monitored for changes in body weight and in serum sodium, potassium, chloride, calcium, phosphate, urea nitrogen, creatinine, and total CO2 concentrations. Colonoscopy was performed on dogs under general anesthesia by an investigator blinded as to the method of preparation, and the quality of preparation was subjectively evaluated. The quality of colon preparation was significantly (P less than 0.005) better after administration of oral lavage solution, compared with that after multiple enemas. There were minimal changes in laboratory values, side-effects were minimal, and biopsy specimen artifacts were not seen. Because proper patient preparation is necessary for complete colonoscopic examination, results suggested that an orally administered polyethylene glycol-containing electrolyte solution is preferable to administration of multiple enemas in preparing dogs for colonoscopy.

Rectal resection in the dog. A new surgical approach and the evaluation of its effect on fecal continence

Thirteen healthy mixed breed dogs (6 female and 7 male) underwent rectal transection and resection of 0 to 6 cm using a dorsal approach. Rectoanal sphincter pressure studies were performed preoperatively and 6 weeks after surgery using a double balloon manometer device. Sphincter pressure profiles were altered in the 6 cm resection dogs. Clinical observations of defecation and degree of continence were made over a 10 week period postoperatively. The transection only and 4 cm resection dogs defecated normally. All dogs in the 6 cm resection group involving the peritoneal reflection were incontinent but retained some normal posturing behavior. Surgical complications included minor infection in two dogs, rectocutaneous fecal leakage in four dogs, breakdown of the anastomotic site in four dogs, and incontinence in all of the dogs that underwent 6 cm resections. Barium enemas were performed on the rectums postmortem to ascertain the degree of stricturing induced by the surgery. The index of stenosis measured did not correlate well with the extent of straining in each group. Histopathologic findings on dogs in the transection only and 4 cm resection groups without dehiscence showed mild granulomatous proctitis with normal myenteric plexi seen. Dogs suffering dehiscence had suppurative proctitis, necrosis, and obliteration of the myenteric plexi.

Electrolyte abnormalities induced by hypertonic phosphate enemas in two cats

Severe electrolyte disturbances developed after the administration of hypertonic phosphate enemas in 2 chronically obstipated cats. Hyperphosphatemia, hypernatremia, and hypocalcemia were detected in both cats. Physical findings included weakness, anxiety, tachycardia, hypothermia, and dehydration. Intravenous fluid and electrolyte therapy led to prompt, dramatic improvement in both cats. Although well tolerated by most healthy animals, hypertonic phosphate enemas should be avoided in small animals, especially those that are dehydrated, severely obstipated, or suffering from renal or colonic disease.

Clinical, biochemical, acid-base, and electrolyte abnormalities in cats after hypertonic sodium phosphate enema administration

Ten clinically healthy cats were allotted into 2 groups. Group A was given the low (60 ml), and group B was given the high (120 ml) recommended dose of a commercial hypertonic sodium phosphate enema. Enema retention was enforced. All cats developed clinical and/or laboratory abnormalities, with group B cats being more severely affected. Clinical signs that occurred rapidly included depression, ataxia, vomition, bloody diarrhea, mucous membrane pallor, and stupor; tetany was not seen. One cat in group B died. Laboratory abnormalities included hypernatremia, hyperphosphatemia, hypocalcemia, hyperglycemia, calculated hyperosmolality, and metabolic acidosis with high anion gap probably due to hyperlacticacidemia. There were no significant gross or microscopic lesions associated with enema administration. Therefore, the use of hypertonic sodium phosphate enema at recommended doses is potentially dangerous to cats.

Enema in the horse. Distribution and rehydrating effect

In the first series of experiments enema containing a water soluble marker was given to two groups of horses fasted for 1 and 18 hours, respectively. The marker was only in 1 out of 14 experiments found orally of the pelvic flexure (Table II). Fasting seemed to facilitate the flow in oral direction. The results were discussed with the possible significance in the treatment of large intestinal impactions. In the second series the effect of enemas on water, electrolyte and acid-base status in the acute furosemide-dehydrated horse was studied. Moderate acidifying and hypokalemic effect was encountered, while no effect was demonstrated on the water balance. The choice of method is questioned, and no conclusion is given with relation to a rehydrating effect of enemas.