This is one of the conditions that affect young foals during their first few days of life. It is potentially life-threatening. Some cases occur when the full urinary bladder wall tears in response to high pressure during delivery whereas others result from incomplete development (closure) of the bladder wall leaving a hole in the wall. Both conditions result in leakage of urine into the abdomen (peritoneal cavity, uroperitoneum). Another type of hole formation, resulting in uroperitoneum occurs as a result of infection of the urachus and is not a truly 'ruptured' bladder. The urachus is the tube that runs from the tip of the bladder to the umbilicus (navel) prior to birth, draining fetal urine into the placental fluids. Infection can result in rupture of the urachus before it fully closes and consequent leakage of urine into the abdomen.
What are the symptoms?
When bladder rupture occurs at birth, signs usually develop within 2 or 4 days of life. Colts are affected more often than fillies. If leakage of urine follows infection of the urachus, signs can develop later, but within a month of birth. Symptoms are caused by the accumulation of urine in the abdominal cavity rather than it being voided normally. This results in pressure on the diaphragm and toxemia as the waste products in the urine are reabsorbed into the foal's blood. Affected foals usually pass smaller-than-normal volumes of urine and adopt a fairly characteristic straining posture with the legs stretched out and the back flat, (compared to straining seen with meconium impaction where the back is usually hunched). The abdomen becomes progressively more distended. The foal usually appears depressed and goes off suck. Respiratory rate becomes more rapid and breathing can become quite labored particularly when the foal lies down as pressure builds up against the diaphragm. The heartbeat can become weak and rapid and cardiac arrhythmias (abnormalities in heart rhythm) can develop due to abnormalities in electrolyte levels in the blood. If left untreated, collapse and death usually follow.
How is the condition diagnosed?
The clinical signs of ruptured bladder can initially be vague. Correct diagnosis requires recognition of clinical signs and the results of one or more test procedures. Ultrasound scan examination of the abdomen may demonstrate a large volume of free fluid and is now the most efficient means of making an early diagnosis. Blood tests can be useful to look for increased levels of toxic substances, e.g., urea, and electrolyte abnormalities. A sample of peritoneal fluid can be taken from the abdomen and tested or compared to a blood sample to confirm that it is urine (has a similarly high urea and creatinine content to urine).
Other tests involve injection of a dye into the bladder via the urethra to see if it then appears free in the abdomen.
Where rupture follows infection of the urachus, or if other problems such as septicemia (blood infection) exist, clinical signs may be more complex. Ultrasound scan examination is the most useful tool when looking for infection or abscess of the urachus.
What treatment is available?
When a ruptured bladder or urachus is diagnosed, the foal must be prepared for surgical repair. However, prior to anesthetizing the foal for surgery it is essential to provide medical treatment to correct electrolyte imbalances, treat concurrent infection and restore fluid levels if dehydration is present. The abdomen may be 'washed' by repeated addition and drainage of sterile saline fluid via needles or catheters, to remove the toxic urine. This is called 'peritoneal lavage'. Once the foal's condition has been stabilized, surgery is performed to remove damaged and/or infected bladder and urachal tissue and then to close the defect. Antibiotics are usually given for several days afterwards to remove infection. The foal can be returned to its dam immediately and should be allowed to suck normally. If it remains off suck, supportive treatment such as intravenous fluids and/or administration of mare's milk or milk replacer by stomach tube may be needed.
Are there any long-term effects?
Normally, provided an accurate diagnosis is made early and once the foal is prepared correctly and the bladder defect is repaired successfully, recovery is rapid and complete. Rarely, adhesions may occur between the bladder and other intra-abdominal organs causing colic symptoms. Full recovery will depend on successful treatment of any other conditions that may also be present such as septicemia and joint ill.
Edited by Kim McGurrin BSc DVM DVSc Diplomate ACVIM © Copyright 2010 Lifelearn Inc. Used and/or modified with permission under license.