Prepubic tendon: rupture in Horses (Equis) | Vetlexicon
equis - Articles

Prepubic tendon: rupture

ISSN 2398-2977

Contributor(s) :


Introduction

  • Separation of ventral abdominal musculature including from its attachment to the pelvis.
  • Cause: heavy pregnant uterus in light breed mare; prolonged excessive ventral edema; hydrops of placental membranes, trauma, twinning.
  • Signs: sudden ventral displacement of caudal abdomen with edema and cranial displacement of the udder, with painful ventral edema cranial to udder and elevated tail head.
  • Diagnosis: physical examination, rectal palpation, ultrasonography.
  • Treatment: support abdomen until parturition; induce parturition when appropriate.
  • Prognosis: poor to grave for mare. Prognosis for future fertility if mare survives also grave, unless embryo transfer allowed by stud books.

Presenting signs

  • Tearing of ventral musculature resulting in ventral displacement of caudal abdomen.
  • Cranial displacement of mammary gland (udder).

Acute presentation

  • Ruptures usually present acutely.

Geographic incidence

  • Worldwide.

Age predisposition

  • Older, unfit multiparous late-pregnant mares.

Breed/Species predisposition

  • Lighter breeds.
  • Draught breeds.

Cost considerations

  • May result in loss of mare and foal.
  • Treatment costs.

Pathogenesis

Etiology

Predisposing factors

General

  • Draught breeds.
  • Old mares, often multiparous.
  • Prepubic tendon rupture can be a sequel of hydroallantois, hydroamnios and twinning.
  • Trauma.
  • Abdominal wall infection.
  • May occur spontaneously, without any predisposing factors.

Pathophysiology

  • Rupture of prepubic tendon and/or abdominal muscles can occur together or separately in late-pregnant mares.
  • Heavy pregnant uterus → increased weight on ventral abdomen → separation of ventral abdominal musculature from its attachment to the pelvis via the prepubic tendon or internally → sudden appearance of ventral displacement of caudal abdomen → accompanying edema.
  • Mare becomes progessively more uncomfortable and unable to move.
  • Rupture of the uterine vessels can occur.

Timecourse

  • Acute.

Diagnosis

Presenting problems

  • Ventral edema.
  • Obviously abnormal and enlarged (ventral) abdominal silhouette.
  • Mare unwilling to move/uncomfortable.
  • Cranial displacement of udder is pathognomic for rupture of the prepubic tendon rupture, and helps to distinguish prepubic tendon rupture from other causes of enlarged (ventral) abdomen/abnormal abdominal silhouette in mid-late pregnant mares.

Client history

  • Pregnant mare in late gestation; often older and unfit.
  • Sudden appearance of ventral displacement of caudal abdomen and cranial displacement of udder.
  • Mild colic.
  • Prolonged excessive ventral edema that is painful.
  • Difficulty in moving and reluctance to lie down.

Clinical signs

Ventral ruptures and rupture of the pre-pubic tendon often present in similar ways and can occur together but they should be differentiated if at all possible.

Abdominal wall ruptures

  • Large swelling at flank or caudal ventral abdomen. Palpation per rectum may reveal a rent in the body wall.
  • Abdominal pain, usually mild to moderate but increasing if structures pass into the rupture.
  • Progressive thick plaque of painful ventral wall edema - more obvious than the mild ventral edema commonly seen in mares close to term, which is not usually painful.
  • The mare may lie down or stand unusually in order to relieve pain.
  • Mares can still walk and pelvic/mammary gland orientation are normal.

 Prepubic tendon rupture

  • Severe ventral abdominal swelling Abdomen: muscle rupture 01 - late gestation Abdomen: muscle rupture 02 - late gestation Abdomen: muscle rupture 03 - late gestationAbdomen: muscle rupture 04 - post-foaling.
  • Cranial positioning of mammary gland.
  • Abdominal pain.
  • Progressive generalized ventral wall edema.
  • Reluctance to walk and lie down.
  • May assume 'saw-horse' stance-cranial pelvis tilted ventrally (tailhead and tuber ischii elevated) from abdominal viscera weight and inability of lumbar muscles to maintain normal orientation of back/pelvis.

Diagnostic investigation

2D Ultrasonography

  • Distinguish ventral abdominal wall rupture from pre-pubic tendon rupture.
  • Identify site, size and type of ventral abdominal wall rupture.
  • Identify possible contents of rupture (i.e. structures which have herniated through the ruptured abdominal wall).

Other

  • External palpation:
    • Painful.
    • Occasionally abdominal defect can be palpated in cases of ventral abdominal wall rupture (but not with simple cases of prepubic tendon rupture).
    • In cases of both ventral abdominal wall rupture and prepubic tendon rupture extensive severe edema makes accurate palpation difficult.
  • Rectal palpation Urogenital: rectal palpation:
    • May help differentiate different causes of abnormal abdominal silhouette.
    • May be possible to palpate rent in body wall in cases of rupture of the ventral abomdinal musculature.
    • May be possible to palpate entrapped viscera in cases of rupture of the ventral abdominal musculature.

Confirmation of diagnosis

Discriminatory Diagnostic features

  • Cranial displacement of the udder in cases of prepubic tendon rupture.

Definitive diagnostic features

  • Physical examination.
  • Ultrasonography.

Gross autopsy findings

  • Rupture of prepubic tendon or abdominal musculature.
  • Ventral edema.

Differential diagnosis

  • Other causes of ventral edema.

Treatment

Initial symptomatic treatment

  • To save the mare, treatment of choice for pregnant mare with prepubic tendon or ventral wall rupture is parturition. In mares close to term this can be natural, or if earlier in gestation this may be induced Reproduction: parturition - induction.
    Note high risk to mare and foal.
  • In cases not close to term, owners may wish to try and enable the pregnancy to continue in order to facilitate the birth of a viable foal nearer to full term. This is a high risk strategy for the survival of both the mare and the foal.
  • Where attempts are being made to support the pregnancy until parturition:
    • An abdominal support or bandage can be used to help maintan support to the abdominal muscles/prepubic tendion (and use may be continued post-foaling).
    • Laxative diet.
    • Anti-inflammatory and analgesic drugs Therapeutics: anti-inflammatory drugs to control pain and edema.
    • Restricted gentle exercise.
  • The mare should be observed extremely closely for signs of progression of the problem/initiation of partruition.
  • Where partruition (spontaneous or induced) is anticipated:
    • The mare should, if it is reasonable to do so, be carefully moved to a facility where surgical and neonatal intensive care provision are available in anticipation of foaling/dystocia
    • Induced or naturally foaling mares should be monitored closely and usually require manual foaling assistance:
    • Fetal wellbeing should be monitored ultrasonographically Fetus: stress/distress/viability with increased fetal distress acting as an indicator for induction of parturition.
    • Monitoring of mammary secretion electrolytes Fetus: stress/distress/viability assist with determining readiness for foaling, ie determination of when it is appropriate to induce parturition.
  • Surgical treatment of pre-pubic tendon rupture/rupture of the ventral abdominal musculature:
    • Emergency ventral midline laparotomy if ruptures in ventral muscles lead to bowel incarceration.
    • Possibly terminate pregnancy by Cesarean section Uterus: caesarean section at same time.
    • Ventral ruptures can be surgically repaired if limited in size and edema has subsided.
Repair of prepubic tendon ruptures are not possible.

Subsequent management

Treatment

  • Maintain the mare until a live foal can be delivered.
  • Euthanasia Euthanasia is common (any may be necessary on welfare grounds) in mares with prepubic tendon rupture or large abdominal wall ruptures.

Prevention

Control

  • Feed appropriately for condition and growth of fetus.
  • Regular exercise is important to keep mares fit.
  • Early detection and resolution of twin pregnancies.

Outcomes

Prognosis

  • Prepubic tendon rupture: poor to grave.
  • Large abdominal wall rupture: poor to grave.
  • Small abdominal wall rupture: fair to good for mare:
    • Some repair spontaneoulsy following foaling.
    • Can be repaired surgically.
    • Prognosis for return to breeding remains poor as structures are likely to fail again during subsequent pregnancies - use embryo transfer.
Where previous rupture of the ventral abdominal wall/prepubic tendon rupture makes it impossible for a mare to carry a foal to term herself, future reproductive capacity might be salvaged by using embryo transfer Embryo transfer, ie recovering an embryo form the mare at day 7-8 of pregnancy, and transferring it to a healthy recipient mare.

Expected response to treatment

  • Attempt to salvage mare.
  • Attempt to salvage foal.
May be necessary to make a choice between salvaging the mare and foal e.g. attempting to increase the foal’s chances of survival by supporting the pregnancy until closer to the full term date of gestation will reduce the mare’s chances of survival by increasing the chances of the rupture progressing.

Reasons for treatment failure

  • Often results in loss of mare due to evisceration during delivery, internal hemorrhages Uterus: uterine artery / vein rupture, bowel rupture or post-partum colic associated with intra abdominal adhesions Abdomen: adhesions.
  • Inadequate nursing care or failure to induce parturition at appropriate time may also result in loss of foal (depends when in pregnancy the rupture occurs).

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Dolente B (2004) Critical peripartum disease in the mare. Vet Clin North Am Equine Pract 20 (1), 151 -165 PubMed.
  • Santschi E M & LeBlanc M M (1995) Fetal and placental conditions that cause high-risk pregnancy in mares. Comp Cont Educ Pract Vet 17 (5), 710-720 VetMedResource.
  • Troedsson M (2007) High risk pregnant mare. Acta Veterinaria Scandinavica 49 (1), 59 VetMedResource
  • Perkins N R et al (1994) Reproductive emergencies in the mare. Vet Clin North Am Equine Pract 10 (3), 643-670 PubMed.
  • Jackson P G (1982) Rupture of the prepubic tendon in a shire mare. Vet Rec 111 (2), 38 PubMed.