Top 15 Equine Neurological Disorders: A Comprehensive NAVLE Guide (Part 2)
Introduction
This guide continues to explore critical equine neurological disorders, offering in-depth diagnostic and treatment insights essential for veterinary professionals preparing for the NAVLE. Understanding these conditions is crucial for effective management in equine practice.
6. Herpes Myeloencephalopathy
Classic Case:
Herpes myeloencephalopathy is often seen in adult horses and can present as a single case or an epizootic outbreak. Symptoms include acute onset ataxia, urinary incontinence, and ascending paralysis, stabilizing after 24 hours. Other herd symptoms include distal limb edema, scrotal edema, abortions, and respiratory infections.
Diagnosis:
- Etiology: Caused by Equine Herpesvirus 1 (EHV-1), typically the D752 strain.
- Diagnostic Tools: PCR on nasopharyngeal swab, lumbar puncture for CSF showing xanthochromia and elevated protein, EHV-1 serum titer rise.
Treatment:
- Medications: Glucocorticoids for up to 3 days.
- Care: Nursing care and isolation for 21-28 days post-symptoms.
Pearls:
Prognosis is good for horses that can walk well but guarded to poor for recumbent horses.
7. Neonatal Encephalopathy
Classic Case:
Known as perinatal asphyxia syndrome (PAS) or hypoxic and ischemic encephalomyelopathy (HIE), this condition affects foals up to one week old, often following dystocia or premature placental separation. Initial normal behavior may progress to dysphagia, lethargy, opisthotonus, seizures, and abnormal vocalizations.
Diagnosis:
- Etiology: Often due to in utero or peripartum hypoxia.
- Exclusion: Rule out sepsis, trauma, or meningitis.
Treatment:
- Supportive Care: 24-hour nursing and anticonvulsants.
- Antibiotics: Due to sepsis risk.
Pearls:
The prognosis is good with an 80% survival rate if not septic. The Madigan squeeze technique shows promise in treating affected foals.
8. Vestibulopathy
Classic Case:
Characterized by an ipsilateral head tilt, nystagmus, ataxia, and drifting sideways. In central disease, symptoms include vertical nystagmus, somnolence, and hemiparesis.
Diagnosis:
- Central Etiologies: Trauma, EPM, neoplasia.
- Peripheral Etiologies: Temporohyoid osteoarthropathy, otitis, guttural pouch disorders.
Treatment:
- Infections: Treat with antibiotics or antifungals for 2-4 weeks.
- Surgery: Ceratohyoidectomy for temporohyoid osteoarthropathy.
Pearls:
Prognosis depends on the underlying cause. Central lesions causing paradoxical vestibular syndrome lead to a head tilt away from the lesion.
9. Polyneuritis Equi
Classic Case:
Also known as cauda equina neuritis, it affects horses of any age, presenting with urinary incontinence, fecal impaction, tail rubbing, and cranial neuropathies.
Diagnosis:
- Etiology: Likely autoimmune.
- Tests: Antibodies to P2-myelin protein, CSF analysis, and EMG.
Treatment:
- Care: Nursing care with frequent bowel and bladder evacuation.
Pearls:
Prognosis is poor for functional recovery.
10. Meningitis
Classic Case:
Primarily affects neonatal or weanling foals, with symptoms including hyperesthesia, stiff neck, muscle tremors, and concurrent omphalitis.
Diagnosis:
- Common Bacteria: Actinobacillus equuli, Rhodococcus equi, Streptococcus equi equi.
- CSF Analysis: Neutrophilic or monocytic pleocytosis, increased protein, negative glucose.
Treatment:
- Antibiotics: Based on culture and sensitivity for 2-6 weeks.
- NSAIDs: For inflammation and pain relief.
Pearls:
Prognosis is guarded to poor, with failure of passive transfer being a significant risk factor in neonates.