Neonatal foals are small in stature, but they can develop big problems needing immediate veterinary attention. Several of these issues center on the bladder, urachus, and umbilicus, and some are possibly life-threatening if not diagnosed and treated promptly. Robert L. Linford, DVM, PhD, Dipl. ACVS, a professor in the Department of Clinical Sciences at the Mississippi State University College of Veterinary Medicine, discussed some of these problems at the 2012 Western Veterinary Conference, held Feb. 19-23 in Las Vegas, Nev.
"Problems associated with the urinary bladder, urachus (the fetal tubelike structure in the umbilical cord that connects the urinary bladder to the placental cavity known as the allantois), and umbilicus in neonatal foals can produce career-limiting and life-threatening injuries," Linford began. He discussed the clinical signs, implications, and treatment options available for three disorders found in neonatal foals.
A ruptured bladder and subsequent uroperitoneum (urine accumulation in the abdominal cavity) should be considered a medical emergency for neonatal foals, Linford said, as without treatment, affected foals will die. A relatively uncommon disorder in foals (the reported prevalence is between 0.5% and 2.5%), ruptured bladders are thought to occur during birth when the bladder is full and result from increased pressure associated with uterine contractions or a strenuous birth, he relayed. Other potential causes include tissue damage in the urachus or bladder wall, ureteral tears, and congenital defects, he added. When the bladder ruptures, urine accumulates in the foal's abdomen.
Linford said clinical signs of uroperitoneum typically appear two to five days after birth and include:
- Rapid, shallow breathing;
- Appetite loss;
- Abdominal distention with or without abdominal pain;
- A "fluid wave" during abdominal palpation;
- Minimal gastrointestinal sounds; and
- Urine dribbling as the foal strains to urinate.
Veterinarians can confirm diagnosis via abdominal ultrasound, abdominocentesis (a belly tap), and increased blood-serum potassium levels in conjunction with decreased serum sodium and chloride levels, Linford said. The elevated serum potassium levels put the foal at risk for cardiotoxicity (heart muscle damage), he noted.
Prior to carrying out the required surgical repair of the bladder, the veterinarian must lower serum potassium levels (to reduce the risk of cardiac arrest during surgery) and place a urinary catheter to keep the bladder drained and prevent additional urine from pooling in the abdomen, he said. Linford gave the veterinary audience tips on the best way to lower potassium levels and place the urinary catheter.
He also noted that it is best to drain much of the urine from the abdomen prior to surgery. To accomplish this, he said, the veterinarians should make an ultrasound-guided stab incision, generally along the midline of the abdomen, and insert a fenestrated tube (one with multiple small openings) to allow the fluid to drain. At this point, the foal should also be started on broad spectrum antibiotics, Linford said.
Once the foal has been stabilized, he can be taken to surgery to repair the ruptured bladder. Linford explained that the procedure is carried out with the foal under general anesthesia and involves examining the damaged organ carefully prior to suturing it back together. He gave veterinarians in attendance a step-by-step tutorial on performing the surgery.
Post-surgery, the foal's urinary catheter should remain in place until he is able to urinate consistently, which typically takes several days, Linford said. Additionally, he said, veterinarians should provide anti-inflammatory drugs for three to five days following surgery and continue administering broad-spectrum antibiotics at least two to three days after removing the urinary catheter.
"The prognosis is generally good if the ruptured bladder is the primary problem and surgery is not delayed," Linford said. "If the foal is septic or sick for other than uroperitoneum prior to surgery, the prognosis is guarded to poor."
In most cases the umbilical cord stretches and breaks about three to five centimeters from the foal's belly shortly after birth. "This stretching is usually sufficient to promote closure of the urachus and umbilical vessels," Linford noted.
As with most normal procedures, however, things don't always go as planned; in these cases the urachus can tear either within the abdominal cavity or subcutaneously (i.e., just under the skin).
A urachal tear in the abdominal cavity will result in the same clinical signs as a ruptured bladder and uroperitoneum and will require the same diagnostics and treatment methods. With a subcutaneous tear, however, the foal will develop a typically nonpainful swelling in the umbilical region (similar to that of an umbilical hernia; however, these swellings can't be pushed back into the abdomen) 10 to 24 hours after birth.
A veterinarian should surgically correct a subcutaneous urachal tears as quickly as possible, Linford said. "When the condition is not promptly recognized and treated, or if surgery is delayed for more than 24 to 48 hours, (pooled) urine will devitalize the skin and subcutaneous tissue, resulting in a massive tissue slough."
Linford said these defects are corrected surgically by resecting umbilical structures, which he reviewed with the veterinary audience.
Foals develop this condition when the urachus doesn't close properly once the umbilical cord is torn. "If the urachus does not close, the umbilicus will remain moist, intermittently dribbling or passing a thin stream of urine when the foal voids the bladder," Linford noted. "This is common in foals that are born weak or septic, or foals that cough excessively or strain to defecate because of retained meconium."
He explained a patent urachus is a "convenient portal for bacteria entry" to the body, so this condition should be treated promptly. Foals with a patent urachus are also at risk for developing sepsis, he noted.
Many foals respond well to conservative treatment, Linford said, which includes antibiotic administration, silver sulfadizine salve application on the navel, and careful silver nitrate stick use to cauterize the opening. This combined treatment generally stimulates the urachus to close, he said.
In some cases, however, foals need a little something extra to close the urachus. In these cases, Linford said, surgery is indicated: "Surgical resection of the umbilical structures is recommended ... when there are signs of sepsis, the urachus fails to close with conservative treatment, or there is persistent inflammation or prominent infection of the umbilical structures."
Linford stressed that after a foal is born, as soon as the foal's umbilical cord has ruptured it should be dipped in a .5% chlorhexadine tincture to keep the opening as sterile and healthy as possible. This procedure should be repeated two to three times daily for three to five days, he said, as failure to do so can put a foal at increased risk for developing an umbilical infection.
Linford explained that umbilical infections can manifest as swelling and inflammation of the visible part of the umbilicus, much like an umbilical hernia. However, in many cases these infections involve the internal structures that form the umbilicus (the urachus, the umbilical arteries, and the umbilical vein). "Commonly, bacteria from the infected internal umbilical structures are picked up in the bloodstream and lodge downstream to cause painful or swollen joints, or physes, prompting a veterinary evaluation," he said.
"Any time a foal presents with lameness and fever, septic arthritis/physitis should be suspected, and the umbilical structures should be examined carefully with ultrasound," Linford said, adding that if the umbilical structures are infected, they need to be surgically removed promptly.
Linford stressed, "Delay in evaluation and treatment of lameness in a foal--for even 24 hours--may mean the difference between eventual soundness or crippling and persistent lameness."
In addition to prompt surgical removal of the infected umbilical structures, treatment for an umbilical infection should include the administration of broad spectrum antibiotics, he said. It's also advisable to run a culture and analysis of the infected umbilical structures to be sure the most appropriate antibiotics are used. When a joint is involved, additional culture and analysis of a synovial or physeal sample should be done. The veterinarian or caretake should lavage the affected joint every other day until lameness is resolved, Linford said, and instill a dose of an appropriate antibiotic in the joint after each treatment. If extensive fibrin (a light, fluffy, cotton candylike substance that is one of the components of a blood clot and is a precursor to a dense connective tissue scar) accumulation is found in the joint, he recommended removing it via arthroscopy.
If only one joint is affected and the infected umbilical structures are removed promptly and the joint is flushed and treated as soon as swelling and lameness develop, the prognosis for complete soundness is generally good. If several joints are involved and the infection and joint swelling and lameness have been present for more than 24 to 48 hours, the prognosis is poor.
Neonatal foals are delicate creatures, and a veterinarian should evaluate any issues that arise with the bladder, urachus, or umbilical cord immediately. Many foals recover without ill effects; however, delayed treatment typically reduces the chance of a favorable recovery.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.