Bilateral laryngeal paralysis associated with hepatic dysfunction and hepatic encephalopathy in six ponies and four horses.
Authors: Hughes K J, McGorum B C, Love S, Dixon P M
Journal: The Veterinary record
Summary
# Editorial Summary: Bilateral Laryngeal Paralysis and Hepatic Disease Between 2009 and its publication, Hughes and colleagues documented an unusual clinical presentation in ten equines (six ponies, four horses; mean age 15.9 years) where sudden-onset bilateral laryngeal paralysis coincided with significant hepatic dysfunction, challenging the conventional understanding of BLP aetiology in these species. Nine animals presented with respiratory distress whilst one presented with weight loss, and investigations revealed clinicopathological and histological evidence of liver disease in nine cases, with eight showing hepatic encephalopathy, six demonstrating hyperammonaemia, and nine having endoscopic confirmation of BLP; notably, three animals also had concurrent pituitary pars intermedia dysfunction. Despite thorough post-mortem examination of the intrinsic laryngeal muscles, recurrent laryngeal nerves, and nucleus ambiguus regions in affected individuals, no structural neuropathological abnormalities were identified, suggesting a metabolic or functional mechanism rather than degenerative nerve disease. The prognosis proved uniformly poor, with only one pony surviving after temporary tracheostomy; this case series highlights that unexplained BLP, particularly in older equines, warrants investigation for hepatic disease and metabolic encephalopathy rather than assuming idiopathic or genetic origins. Clinicians encountering sudden bilateral laryngeal dysfunction should perform liver function screening and ammonia testing as part of their diagnostic protocol, recognising that management may require addressing the underlying hepatic pathology rather than focusing solely on airway management.
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Practical Takeaways
- •Investigate liver function and hepatic encephalopathy in horses and ponies presenting with sudden-onset bilateral laryngeal paralysis, as this may indicate systemic hepatic disease rather than primary laryngeal pathology
- •Assess ammonia levels and neurological status in cases where bilateral laryngeal paralysis occurs unexpectedly, as hepatic encephalopathy may be the underlying cause
- •Be aware that temporary tracheostomy may provide short-term relief but prognosis is guarded; only 1 of 6 animals receiving tracheostomy recovered, with most subsequently euthanased or dying
Key Findings
- •10 equines (6 ponies, 4 horses) with sudden-onset bilateral laryngeal paralysis presented with concurrent hepatic disease and dysfunction
- •9 of 10 animals had hepatic encephalopathy and/or hyperammonaemia associated with the laryngeal paralysis
- •3 animals had concurrent pituitary pars intermedia dysfunction diagnosed by clinical signs and/or endocrine testing
- •Histopathological examination of laryngeal muscles and recurrent laryngeal nerves revealed no abnormalities, suggesting neurological dysfunction rather than structural pathology