Medical management and positive outcome after prolonged recumbency in a case of equine herpesvirus myeloencephalopathy.

Medical management of a 17-year-old mare diagnosed with equine herpesvirus myeloencephalopathy (EHM) led to a positive recovery despite initial severe neurological deficits and complications. The comprehensive treatment approach, including fluid therapy, medications, supportive care, and management of secondary infections, resulted in significant neurological improvement and functional recovery.

Case Presentation and Initial Diagnosis

• A 17-year-old mare exhibited acute fever, weakness, and bladder dysfunction.
• Diagnosed with equine herpesvirus myeloencephalopathy (EHM), a neurological disease caused by equine herpesvirus type 1 (EHV-1).
• The mare experienced transient recumbency, indicating severe neurological impairment.

Treatment and Hospitalization

• Initial medical interventions involved parenteral fluid therapy and plasma infusion to support hydration and immunity.
• Anti-inflammatory treatment included both steroidal (SAID) and nonsteroidal anti-inflammatory drugs (NSAIDs), aiming to reduce inflammation of the nervous system.
• Bladder catheterization was performed to manage bladder dysfunction, a common symptom in neurological disease impairing urination control.
• The mare was hospitalized 10 days after symptom onset for intensive care due to inability to stand or walk, despite the ability to maintain a standing posture.

Neurological and Secondary Complications

• Neurologic evaluation revealed ataxia and proprioceptive deficits, primarily affecting the hind limbs—indicative of impaired coordination and sensory deficits.
• Secondary complications arose due to prolonged recumbency and immobility, including:
  • Escherichia coli cystitis (urinary tract infection).
  • Corneal ulcers, likely from decreased eyelid closure or recumbency-related trauma.
  • Pressure sores from sustained contact with the ground.
• A full-body support sling was used for 21 days to aid mobility and prevent further complications from immobility.

Ongoing Medical Management

• Continued systemic antimicrobial treatment addressed secondary bacterial infections such as cystitis.
• NSAIDs were maintained for anti-inflammatory effect, with a careful gradual discontinuation of SAIDs to avoid adverse effects from prolonged steroid use.
• Parenteral fluid therapy was sustained to ensure hydration and support kidney function during infection and bladder issues.
• Bladder lavage was performed regularly to prevent infection buildup and promote urinary tract health.

Diagnostic Findings and Monitoring

• Polymerase chain reaction (PCR) tests detected Varicellovirus equidalpha 1 (EHV-1) DNA in nasal swabs and blood on day 13, confirming viral presence.
• Urine samples tested positive for EHV-1 DNA on days 13 and 25, indicating viral shedding through the urinary tract.
• Monitoring virological status guided ongoing infection control and therapeutic decisions.

Recovery and Follow-Up

• Neurological signs gradually improved over 34 days of treatment and supportive care.
• At discharge, the mare exhibited only mild hind limb weakness and ataxia, a significant improvement from the time of hospital admission.
• Secondary complications, such as cystitis, corneal ulcers, and pressure sores, resolved within two weeks, indicating effective management.
• At 8 months post-discharge, the mare showed marked locomotory function improvement, demonstrating a successful long-term recovery from EHM.