Urachal Disorders

Stacey R. Byers

Definition and Etiology

Abnormalities of the umbilicus and umbilical remnants, includ­ing the urachus, are frequently encountered disease conditions of neonatal calves and, to a lesser extent, in other neonatal ruminant species.¹ Infections of the urachus are often associated with omphalophlebitis, which commonly arises from environ­mental contamination of the umbilicus at birth.

Clinical Signs and Differential Diagnoses

Calves with internal urachal abscesses, adhesions, and other sequelae are usually older than 4 weeks of age. A history of umbilical infection during the neonatal period may or may not exist, and external umbilical abnormalities may not be present. Clinical signs may be nonspecific and include fever, lethargy, poor body condition, rough hair coat, and poor growth or productivity. Dysuria, pollakiuria, stranguria, and colic may be evident on examination or in the medical history. When an infection extends into the bladder lumen, hematuria and pyuria are expected. Transabdominal palpation of the umbilicus and abdomen in smaller neonates may reveal painful and enlarged umbilical remnants. Complications from associated septicemia (e.g., lameness and joint distention, pneumonia, hypopyon, meningitis) can occur.

If the urachus fails to regress completely, a persistent com­munication between the bladder apex and the pouchlike urachal remnant occurs.

Rupture of the infected urachal stalk may result in the acute onset of peritonitis. If the urachal remnant communicates with the bladder lumen, rupture of the urachus results in uroabdo­men. Rupture may occur spontaneously or after abdominal trauma or parturition in older animals. A report found a possible inheritance link with abnormal involution in a group of Brown Swiss-Braunvieh cross cattle.⁷

A detailed ultrasonographic examination of the interior of the umbilical remnant and caudoventral abdomen is warranted in cases of suspected urachal or umbilical abnormalities, but adhesions may not be visualized.^7-9 The bladder and other viscera may assume abnormal shape or position as a result of urachal adhesions. The luminal contents of the urachal remnant and bladder may appear flocculent in cases with concurrent cystitis. Uroabdomen is characterized by accumulation of echolucent fluid in the abdominal cavity, with variable amounts of fibrin deposition evident.

Laparoscopic examination can allow a more thorough evaluation of the abdomen and has identified adhesions and focal umbilical artery and urachal enlargements not identified by ultrasonographic examination.⁹

Because of the variable nature of urachal problems, the differential diagnoses will vary according to the organ(s) involved. Urachal adhesions to the intestine or uterus may result in colic, signs of intestinal obstruction, and postpartum peritonitis or uroabdomen. Concurrent signs involving the lower urinary system might indicate the potential for primary ascending infections, such as cystitis or pyelonephritis. In cases of uroabdomen in males, obstructive urolithiasis is an important differential. Urolithiasis, urethritis, or neurologic disease may be included in differential diagnoses of dysuric animals.

Clinical Pathology

Laboratory findings may be variable, but an inflammatory Ieukogram, hyperfibrinogenemia, and Eyperglobulinemia are expected. Urinalysis may be normal or indicative of cystitis if the urinary bladder is involved. Abdominocentesis findings are variable and depend on the presence and extent of peritonitis associated with the urachal lesion. Voluminous blood-tinged abdominal fluid suggests uroperitoneum, and analysis of the fluid and serum creatinine concentration is indicated (see Urolithiasis section earlier).

Pathogenesis

Following bacterial infection of the urachus, the inflamma­tory response within the abdomen precipitates development of fibrinous adhesions between the urachus and surrounding viscera, including the rumen, intestine, uterus, bladder, or ovaries. Abscesses may form in single or multiple locations in the urachal stalk and, if involving the apex of the urinary bladder, can result in concurrent cystitis. Urachal fibrosis and adhesions may cause mechanical interference of bladder emptying. Infrequently, the urachal abscess perforates, with subsequent peritonitis, sepsis, or uroperitoneum.^3,4 Most urachal infections involve Trueperellapyogenes, E. coli, Staphylococcus spp., or Streptococcus spp., but other organisms may be present.^1,5,8,10

Treatment and Prognosis

For early and uncomplicated or congenital persistent urachal disorders, medical management using chemical cautery and antibiotic therapy has been reported.¹ Chemical cautery of the urachus with sedation and analgesia has been performed using silver nitrate sticks, iodine, or phenol. There is a risk of incomplete resolution or other complications, so animals should be monitored to determine if additional surgical management is warranted.

Surgical management is recommended for complicated cases, infected urachal remnants, where medical management has failed, or when complete evaluation of the abdominal cavity is needed. Ventral midline celiotomy, paramedian celiotomy, or laparoscopy under general anesthesia is recommended to enable complete evaluation of the abdominal cavity.^7,11,12 Complete resolution may require resection of the urachal remnants and the bladder apex if the urachus incorporates or communicates with the bladder. Perioperative and postoperative antibiotic therapy is essential, and appropriate antibiotic selection should be based on culture and sensitivity of the abscess(es) or urine.

Outcomes following surgical management are often satisfac­tory, but development of adhesions should always be considered a potential risk. A guarded to poor prognosis is warranted for severe peritonitis or extensive adhesions.