Laryngeal and pharyngeal dysfunction in horses homozygous for hyperkalemic periodic paralysis.

This research investigates hyperkalemic periodic paralysis (HPP) in horses, a genetic disorder that affects muscular function, with the goal of understanding its effects on pharyngeal and laryngeal dysfunction. The study consists of a survey of owners, trainers, or veterinarians of horses with HPP, and shows a high occurrence of stridor and other symptoms related to laryngeal or pharyngeal issues in such affected horses.

Study Methodology

• This research was conducted as a cohort study and involved the collection of data from 69 horses that tested homozygous for HPP between October 1992 and November 1994. Homozygous refers to the possession of two identical forms of a particular gene inherited from each parent.
• To gather the data, questionnaires addressing various aspects of the horses’ life such as their medical history, training regimes, physical condition, and current status were sent out to the horse owners, trainers, or attending veterinarians.
• Completed data were then tabulated and evaluated using descriptive statistics.

Study Findings

• Out of the 189 horses that were identified as homozygous for HPP, responses were received from 69 (37%).
• These responses indicated that horses with HPP suffer from a varying degree of muscle weakness or paralysis, which could be mild fasciculations to serious episodes leading to the inability to stand or even death.
• An overwhelming majority (63 out of 68) of the horses with HPP were found to have stridor (a harsh or grating sound during breathing) related to exercise, stress, or during episodes of muscle paralysis.
• The most common endoscopic findings in affected horses were issues related to the pharynx and larynx, such as pharyngeal collapse and edema, laryngopalatal dislocation, and laryngeal paralysis.
• The use of a medication named acetazolamide was noted to decrease the occurrence of stridor in 12 out of 27 horses on this treatment.

Conclusions

• This study concludes that most horses that are homozygous for HPP display clinical signs associated with pharyngeal and laryngeal dysfunction.
• It highlights the importance of considering HPP in the differential diagnosis of horses presented with signs of laryngeal or pharyngeal dysfunction or stridor.
• Furthermore, it suggests that treatment with acetazolamide may help control respiratory symptoms associated with HPP in horses.