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Basics ⬇

Outline

BASICS

Overview!!navigator!!

  • Tenesmus is a repeated, uncontrollable sensation or need of straining to evacuate primarily the rectum, or bladder, with passage of small amounts of fecal matter or urine, or nothing at all. It is likely induced by constant stimulation of the sacral nerves owing to inflammation or physical stimulation of the organs (rectum, uterus, urinary bladder) that gives the horse a continual sensation of the need to defecate or urinate. Because tenesmus is pathologic, the repeated attempts to evacuate the bowel or bladder persist as the nervous stimulation remain unrelieved by the defecation/urination attempts
  • Stimulation may result from intrinsic disease of the organ involved (e.g. rectal inflammation); therefore, tenesmus may be seen with diarrhea, colitis, or rectal laceration. Stimulation also may result from physical pressure on the organ from within (e.g. constipated feces) or from the pelvic space (e.g. pararectal abscess, pelvic masses, impactions). Tenesmus may lead to rectal prolapse, or in females it may lead to uterine prolapse through the vagina and bladder prolapse through the urethra

Signalment!!navigator!!

More common in adult females.

Signs!!navigator!!

  • Repeated straining in attempts to defecate or urinate
  • Prolapsed rectum, and uterus, or bladder secondary to tenesmus

Causes and Risk Factors!!navigator!!

  • Rectal causes of tenesmus—internal stimulation (pressure) in case of constipation (meconium impaction in foals) or foreign bodies; external pressure on the rectum as in pararectal abscess or neoplasm; intramural stimulation of the rectum in the case of inflammation in proctitis, colitis/diarrhea or rectal tear
  • Uterine causes—more likely during peripartum. Metritis, vaginitis, and retained placenta
  • Urinary causes—ureteritis or urethritis as in lower urinary tract infections or obstruction in cystitis or calculi. Uroperitoneum
  • Neurologic origin—central nervous system diseases such as central hepatic encephalopathy or rabies or peripheral nerve trauma caused by rabies, parturition, or dystocia

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • Tenesmus is a clinical sign that may reflect various underlying diseases or causal conditions that trigger stimuli for defecation/urination
  • Dysuria (painful urination) and stranguria (straining to urinate) are the most important clinical differential diagnoses of tenesmus, which is especially difficult to distinguish in colts
  • Clinical examination should be aimed at identifying which of 4 potential organs/systems (digestive, urinary, uterine, or neurologic) are affected and promote tenesmus
  • Differential diagnoses to consider include colitis (including uncommon severe colonic infarction owing to salmonellosis), proctitis, rectal tears, strictures, polyps, neoplasms, small colon intussusceptions, and, in neonates, meconium impaction or uroperitoneum (ruptured bladder/urachus). Pelvic abscess, lymphadenopathy, neoplasias. Vaginitis or retained placenta. Urolithiasis or lower urinary tract infection. Neurologic origin includes hepatic encephalopathy, leukoencephalomalacia, and rabies (cerebral disease signs), or dietary toxicosis (oak acorn, Psilocybe magic mushroom, or lolitrem B/perennial ryegrass)

CBC/Biochemistry/Urinalysis!!navigator!!

  • Tenesmus is the clinical manifestation of a persistent arc reflex and as such no paraclinical tests are needed to confirm it. Paraclinical analyses are useful to identify potential differential diagnoses
  • CBC may show neutropenia and thrombocytopenia with severe acute inflammatory conditions (rectal tear, retained placenta, colitis, intussusception), or neutrophilia with subacute–chronic inflammation (urolithiasis, colitis). Eosinophilia has been reported in tenesmus owing to eosinophilic proctitis
  • Biochemistry is informative with liver diseases (hepatic encephalopathy; increased bile acids and blood ammonia) and uroperitoneum, or in foals with meconium impaction if repeated water enemas have been administered (hyperkalemia; hyponatremia, hypochloremia)
  • Urinalysis may be abnormal with urinary tract diseases

Other Laboratory Tests!!navigator!!

  • Abdominocentesis for uroperitoneum and rectal tears
  • Serum or urinary phenolic content using gallic acid standards to determine hydrolyzed tanin concentration in acute acorn toxicosis

Imaging!!navigator!!

  • Abdominal radiography for meconium impaction
  • Abdominal ultrasonography for uroperitoneum, intussusception, and pararectal abscess, or lymphadenopathy
  • Bladder ultrasonography for urolithiasis or neoplasia

Other Diagnostic Procedures!!navigator!!

Diagnostic procedures should be aimed at identifying the underlying pathology, or the severity and prognosis of medical complications due to prolapse of pelvic organs. Basic procedures include vaginal and rectal examination to assess organ wall integrity (rectal endoscopy/vaginoscopy for tears, polyps, neoplasia, strictures, proctitis/colitis, or intussusception), and endoscopy of the urethra and bladder for lower urinary tract diseases. Tissue biopsy for proctitis, polyps, or neoplasia.

Treatment ⬆ ⬇

TREATMENT

  • Tenesmus has to be addressed in an expedited manner as it may result in pelvic organ prolapse. If signs of colic are present, refer to appropriate management protocols
  • Treatment depends on the inciting cause and whether organ prolapse has occurred or seems to be imminent. The goal is to eliminate the cause and relieve the tenesmus urgency, and to stabilize the animal (stop the straining, alleviate stress and pain, and prevent violent sudden colic-like behavior) to allow safe treatment of organ prolapse, if present. Prevent recumbence to minimize further tissue trauma of prolapsed organs
  • As diagnostic or therapeutic interventions, local epidural analgesia and/or rectal infusions with local anesthetics can result in the transient cessation of tenesmus and perineal and perianal pain. Unlike other species (e.g. cattle), epidural anesthesia in the horse was earlier perceived as more difficult to perform because of handling-associated risks, and slightly different sacrococcygeal anatomy. However, safer approaches exist; infection and other risks are similar to those in other species
  • Sedation is recommended to facilitate epidural anesthesia procedures, and/or to alleviate uncontrollable tenesmus, or to treat organ prolapse
  • α2-Agonists, opioids, and dissociative drugs have been studied as epidural anesthetics with great safety margins. Although the addition of xylazine to epidural injection reduces the dose of local anesthetic required to avoid postepidural hindlimb ataxia and paresis, morphine-like opioids for spinal use have the safest margin as they produce long-lasting analgesia without motor side effects
  • Use of laxatives and stool softeners in the diet to facilitate fecal bolus passage and defecation. Transition of soft diets rich in fiber to the horse-accustomed regular diet may be considered
  • Surgical management by permanent colostomy if untreatable neoplasia of the perianal region
  • Retention enema in meconium impaction

Medications ⬆ ⬇

MEDICATIONS

Drug(s) of Choice

No specific medication; treatment depends on the inciting cause. In humans, diltiazem (calcium channel blocker, potent inhibitor of intestinal smooth muscle contraction) and tolterodine (antimuscarinic/anticholinergic, reduces bladder smooth muscle contraction) have been shown preliminarily to partially alleviate pain and tenesmus in cancer or overreactive bladder patients. No evidence yet exists to support their use in equine tenesmus.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

Follow-up frequency depends on the inciting cause. Tenesmus has to be addressed in an expedited manner and monitored several times a day until it is resolved because it may result in organ prolapse. Short- and long-term monitoring is desirable in cases of prolapse, as prolapse can recur.

Possible Complications!!navigator!!

Pelvic organ prolapse. Severe septicemia or septic shock if advanced tissue damage originates from repositioning a severely affected prolapsed organ.

Expected Course and Prognosis!!navigator!!

Prognosis depends on the cause, and, if present, prolapse severity.

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

N/A

Age-Related Factors!!navigator!!

Given the wide range of conditions that induce tenesmus, it can be seen at any age depending on the inciting cause.

Pregnancy/Fertility/Breeding!!navigator!!

Tenesmus is more likely to be observed as a consequence of dystocia or retained placenta.

Synonyms!!navigator!!

  • Urgency (human)
  • Dyschezia (painful defecation)

Suggested Reading ⬆ ⬇

Anderson GA, Mount ME, Vrins AA, Ziemer EL. Fatal acorn poisoning in a horse: pathologic findings and diagnostic considerations. J Am Vet Med Assoc 1983;182(10):1105–1110.

Choo MS, Doo CK, Lee KS. Satisfaction with tolterodine: assessing symptom-specific patient-reported goal achievement in the treatment of overactive bladder in female patients (STARGATE study). Int J Clin Pract 2008;62(2):191–196.

Colbourne CM, Bolton JB, Yovich JV, Genovese L. Hamartomatous polyp causing intestinal obstruction and tenesmus in a neonatal foal. Aust Equine Vet 1996;14:78–80.

Duesterdieck-Zellmer KF. Equine urolithiasis. Vet Clin North Am Equine Pract 2007;23(3):613–629.

Frazer GS. Post partum complications in the mare. Part 2: fetal membrane retention and conditions of the gastrointestinal tract, bladder and vagina. Equine Vet Educ 2003;5:118–128.

Gibson K, O'Hara A, Huxtable C. Focal eosinophilic proctitis with associated rectal prolapse in a pony. Aust Vet J 2001;79(10):679–681.

Hubbell JA, Saville WJ, Bednarski RM. The use of sedatives, analgesic and anaesthetic drugs in the horse: an electronic survey of members of the American Association of Equine Practitioners (AAEP). Equine Vet J 2010;42(6):487–493.

Johnstone LK, Mayhew IG, Fletcher LR. Clinical expression of lolitrem B (perennial ryegrass) intoxication in horses. Equine Vet J 2012;44(3):304–309.

Jones J. “Magic mushroom” (Psilocybe) poisoning in a colt. Vet Rec 1990;127:603.

Munday BL, Monkhouse IM, Gallagher RT. Intoxication of horses by lolitrem B in ryegrass seed cleanings. Aust Vet J 1985;62:207.

Natalini CC. Spinal anesthetics and analgesics in the horse. Vet Clin North Am Equine Pract 2010;26(3):551–564.

Stowers KH, Hartman AD, Gustin J. Diltiazem for the management of malignancy-associated perineal pain and tenesmus. J Palliat Med 2014;17(9):1075–1077.

Vigani A, Garcia-Pereira FL. Anesthesia and analgesia for standing equine surgery. Vet Clin North Am Equine Pract 2014;30(1):1–17.

Author(s) ⬆

Author: Alexander Rodriguez-Palacios

Consulting Editors: Henry Stämpfli and Olimpo Oliver-Espinosa

Acknowledgment: The author and editors acknowledge the prior contribution of Gail Abells Sutton.