Omphalophlebitis refers specifically to infection of the umbilical vein, while the broader term omphalitis describes infection of all umbilical remnant structures.
Overview and Clinical Importance
Omphalophlebitis refers specifically to infection of the umbilical vein, while the broader term omphalitis describes infection of all umbilical remnant structures. These infections represent one of the most common and clinically significant conditions affecting neonatal foals, typically occurring within the first 14 days of life, with the majority presenting within the first week.
The umbilicus serves as a potential portal of entry for pathogens in the immunologically naive neonate. Left undiagnosed, umbilical remnant infections frequently result in life-threatening secondary complications including septic arthritis, osteomyelitis, pneumonia, hepatic abscessation, and systemic septicemia. Approximately 50% of foals with evidence of ongoing infectious processes demonstrate ultrasonographic evidence of umbilical pathology, making this a critical component of neonatal evaluation.
| Structure |
Fetal Function |
Postnatal Fate |
| Umbilical Vein |
Carries oxygenated, nutrient-rich blood from placenta to fetus via the liver |
Becomes round ligament of the liver (falciform ligament) |
| Umbilical Arteries (paired) |
Carry deoxygenated blood from fetus to placenta; branch from internal pudendal arteries |
Become round ligaments of the bladder |
| Urachus |
Connects fetal bladder apex to allantoic cavity for urine drainage |
Becomes median ligament of the bladder |
Anatomy of the Umbilical Remnant
The equine umbilical cord consists of four distinct structures enclosed within an amniotic sheath, each with specific functions during fetal life and different postnatal fates.
High-YieldThe umbilical vein courses cranially from the umbilical stump along the ventral midline to the liver, close to the skin surface. This anatomical location makes it vulnerable to ascending infection that can reach the liver, potentially causing hepatic abscessation - the most severe complication of omphalophlebitis.
Normal Umbilical Structure Dimensions
Understanding normal ultrasonographic dimensions is essential for diagnosing umbilical pathology. The following table presents reference values critical for board examinations.
| Structure |
Normal Diameter |
Clinical Significance |
| External umbilical stump |
Less than 18 mm at 24 hours; less than 15 mm at 7 days |
Enlargement suggests infection or hernia |
| Umbilical vein |
Less than 10 mm (less than 1.0 cm) at 24 hours |
Greater than 10 mm suggests omphalophlebitis |
| Umbilical arteries |
Less than 13 mm each; may be slightly asymmetrical |
Asymmetric enlargement suggests omphaloarteritis |
| Urachus-arteries complex |
Less than 25 mm total at bladder apex |
Collective enlargement indicates infection |
Etiology and Risk Factors
Bacterial Pathogens
The bacteria implicated in umbilical infections are similar to those causing generalized neonatal sepsis, reflecting the potential for hematogenous seeding from systemic infection or ascending infection from environmental contamination.
NAVLE TipE. coli is the most common isolate from umbilical infections in foals, just as it is the most common cause of neonatal sepsis. Mixed infections are common, and anaerobic involvement should be suspected when gas shadowing is visible on ultrasound.
Risk Factors for Umbilical Infection
High-YieldFailure of passive transfer (FPT) is the single most important risk factor for development of neonatal sepsis and associated umbilical infections. Always check IgG levels in any foal suspected of infection - IgG less than 200 mg/dL represents complete failure and is a medical emergency.
| Gram-Negative (60-70% of isolates) |
Gram-Positive (25-40% of isolates) |
| Escherichia coli (most common)
Klebsiella spp.
Enterobacter spp.
Actinobacillus spp.
Salmonella spp.
Pseudomonas spp. |
Streptococcus spp. (beta-hemolytic)
Staphylococcus spp.
Enterococcus spp.
Anaerobes (less than 5%):
Bacteroides spp.
Clostridium spp. |
Clinical Presentation
Clinical signs of umbilical infection vary significantly depending on the severity of infection, whether the foal is septic, and which specific structures are involved. Importantly, external signs are often minimal or absent, and infection may only be suspected due to systemic manifestations or findings on diagnostic workup.
Local Signs (May Be Absent in 50% of Cases)
- Umbilical swelling: Enlargement of external stump beyond normal parameters
- Heat and pain: Palpable warmth and pain on gentle manipulation
- Purulent discharge: Mucopurulent exudate from umbilical stump
- Periumbilical edema: Ventral edema extending from umbilical region
- Moist umbilicus: Persistent moisture suggesting patent urachus
Systemic Signs (Particularly if Septic)
- Fever: Temperature greater than 39.2 degrees C (102.5 degrees F), though hypothermia possible in severe sepsis
- Depression/lethargy: Decreased mental status, reluctance to rise
- Inappetence: Decreased or absent suckle reflex
- Tachycardia: Heart rate elevated beyond age-appropriate range
- Injected/muddy mucous membranes: Signs of endotoxemia
Signs of Secondary Complications
- Lameness with joint effusion: Suggests septic arthritis/polyarthritis
- Respiratory distress: May indicate secondary pneumonia
- Uveitis: Anterior uveitis from hematogenous seeding
- Diarrhea: Common concurrent finding in septic foals
NAVLE TipA common NAVLE scenario involves a foal presenting with lameness and joint swelling (septic arthritis) where umbilical infection is discovered on workup. Remember: 25% of septic foals have umbilical infection, and 50% of foals with septic arthritis have concurrent umbilical pathology. Always ultrasound the umbilicus in any sick neonate!
| Foal-Related Factors |
Environmental/Management Factors |
| Failure of passive transfer (FPT): IgG less than 800 mg/dL
Prematurity/dysmaturity: Immunocompromised state
Recumbency: Increased exposure to bedding contaminants
Neonatal encephalopathy: Weak suckle, prolonged recumbency
Patent urachus: Persistent moisture increases infection risk |
Manual cord separation: Prevents natural retraction
Unsanitary foaling environment: High bacterial load
Inadequate umbilical care: Using strong caustic agents (greater than 2% iodine)
Dystocia: Increased contamination exposure
Umbilical hematoma: Predisposes to secondary infection |
Diagnosis
Physical Examination
Thorough palpation of the external umbilical stump and, in compliant foals, the internal umbilical remnants through the abdominal wall should be performed. However, externally palpable abnormalities are present in only 50% of foals with umbilical infections, making ultrasonography essential.
Laboratory Findings
Ultrasonographic Examination - Gold Standard
Ultrasound is the gold standard for diagnosing umbilical remnant infections and is the only reliable method to detect infections involving internal structures. The examination is performed with a 5-12 MHz linear probe along the ventral midline.
Ultrasonographic Abnormalities Consistent with Infection
- Vessel enlargement: Diameter exceeding normal reference ranges
- Hyperechoic material: Echogenic material (pus) within vessel lumens
- Arterial asymmetry: Unilateral enlargement of umbilical artery
- Wall thickening: Thickened vessel walls suggesting inflammation
- Gas shadowing: Hyperechoic foci with acoustic shadowing indicating anaerobic infection
- Abscessation: Discrete hypoechoic to heterogeneous masses
- Hepatic extension: Infected vein traceable to liver parenchyma (poor prognosis)
High-YieldThe urachus is the MOST commonly infected umbilical structure. However, omphalophlebitis (umbilical vein infection) carries the WORST prognosis because infection can ascend to the liver causing hepatic abscessation, which has up to 50% mortality even with surgical intervention.
| Parameter |
Expected Finding |
Clinical Significance |
| Fibrinogen |
Elevated (greater than 400 mg/dL) |
Acute phase protein; rises with inflammation |
| Serum Amyloid A (SAA) |
Markedly elevated |
Sensitive marker of inflammation in foals |
| WBC count |
Variable: leukocytosis or leukopenia |
Leukopenia suggests severe sepsis |
| IgG concentration |
Often low (less than 800 mg/dL) |
FPT predisposes to infection; assess for plasma transfusion |
| Blood culture |
May be positive |
Guides antibiotic selection; false negatives common |
Treatment
Treatment decisions depend on the severity of infection, structures involved, presence of systemic complications, and response to initial therapy.
Medical Management
Indications: Localized infection without sepsis, foals that are not surgical candidates, and initial stabilization before surgery.
Surgical Management
Indications for surgery: Substantial abscessation, failure to respond to medical management, venous involvement extending toward the liver, concurrent septic arthritis or septicemia, or persistent/patent urachus unresponsive to medical therapy.
Surgical Options
NAVLE TipSurgical resection has a higher survival rate (66.6%) compared to antimicrobial therapy alone (42.9%). Cases with hepatic abscessation have up to 50% mortality. Never ligate the umbilical vein internally without removing infected tissue - this can lead to hepatic abscess formation.
| Treatment Component |
Protocol |
Notes |
| Antimicrobial therapy |
First-line: Penicillin + Gentamicin IV
Alternative: Trimethoprim-sulfonamide IV/PO or Doxycycline PO
Duration: 10-14 days minimum |
Monitor renal function with gentamicin; avoid if azotemic |
| Topical umbilical care |
0.5% chlorhexidine (preferred) or 1% iodine solution applied 2-4 times daily |
Continue until stump is dry; avoid strong caustic agents |
| Plasma transfusion |
IgG less than 200 mg/dL: 2 liters IV
IgG 200-400 mg/dL: 1 liter IV |
Recheck IgG 24 hours post-transfusion |
| Supportive care |
IV fluids, nutritional support, gastroprotectants, nursing care |
NSAIDs (flunixin) for endotoxemia; monitor for GI ulceration |
| Patent urachus treatment |
Chemical cautery with silver nitrate (use sparingly, no deeper than 1 cm) |
Excessive use predisposes to infection; surgical correction if medical treatment fails |
Prognosis
| Procedure |
Description |
Indications/Notes |
| Omphalectomy |
Complete excision of external umbilical stump |
External stump infection; combines with remnant resection |
| Umbilical remnant resection |
En-bloc removal of infected internal structures via ventral midline celiotomy |
Treatment of choice when complete resection possible; 89% survival rate |
| Umbilical vein marsupialization |
Rerouting infected vein from liver to external drainage site when complete resection not possible |
Indicated for extensive omphalophlebitis with hepatic involvement; hernia at stoma site is common complication |
| Laparoscopic-assisted resection |
Minimally invasive approach for umbilical remnant evaluation and resection |
Less invasive; requires specialized equipment and expertise |
Prevention
- Allow natural cord separation: The cord normally ruptures at a point approximately 5 cm from the body wall when the mare rises. Manual separation prevents natural retraction and may predispose to infection.
- Appropriate umbilical dipping: Apply 0.5% chlorhexidine or 1% iodine (NOT 7% tincture) 2-4 times daily until the stump is dry. Avoid caustic agents that can cause tissue necrosis.
- Ensure adequate colostrum intake: Foals should receive 250 mL/hour for the first 6 hours of life. Check IgG at 12-24 hours (goal greater than 800 mg/dL).
- Maintain clean foaling environment: Use clean, dry bedding. Avoid overuse of foaling stalls without adequate cleaning between foalings.
- Early detection: Perform routine physical examination including umbilical palpation. Consider baseline umbilical ultrasound in at-risk foals.
High-YieldThe current recommendation is to use DILUTE antiseptics (0.5% chlorhexidine or 1% iodine) rather than strong iodine solutions. Strong tincture of iodine (7%) can cause tissue necrosis, which paradoxically predisposes to infection. 'Dip, don't scrub' - gentle application is preferred.
| Scenario |
Prognosis |
| Localized infection, good response to antibiotics |
Good - Majority recover with appropriate treatment |
| Surgical resection (uncomplicated) |
Good - 89% survival rate without concurrent disease |
| Concurrent septic arthritis or sepsis |
Fair to Guarded - Survival drops to approximately 60% |
| Hepatic abscessation secondary to omphalophlebitis |
Poor - Up to 50% mortality despite surgical intervention |
| Post-operative complications (incisional infection, herniation) |
Variable - 45% of foals with post-op complications did not survive |
Memory Aids
"NAVEL" for Risk Factors
N - Neonatal encephalopathy (weak, recumbent foals)
A - Antibody deficiency (FPT - IgG less than 800)
V - Very dirty environment (unsanitary foaling conditions)
E - Early/manual cord separation
L - Leaky urachus (patent urachus with persistent moisture)
"4 Structures, 4 Fates"
Vein goes to Liver (becomes round ligament of liver) | Arteries go to Bladder sides (become round ligaments of bladder) | Urachus goes to Bladder apex (becomes median ligament)
"E. coli = Enemy #1"
E. coli is the most common pathogen in BOTH neonatal sepsis AND umbilical infections - if you see a sick neonate on the NAVLE, think E. coli first!