Intracranial myiasis by Hypoderma bovis (Linnaeus) in a horse.

The research article discusses a case of a severe neurological disease in a Quarter Horse gelding, caused by the infiltration of a larva of the warble fly, Hypoderma bovis, into the brain of the horse.

Case Description

• The case under study involved a 14-year-old Quarter Horse gelding in western Montana, who fell severely ill due to the migration of a first instar larvae of a species of warble fly, specifically Hypoderma bovis, into its brain.
• The symptoms observed in the horse were variegated and included impaired coordination of gait, circular movement towards the left, tilting of the head to the right, partial facial paralysis on the right side, and compromised vision in the right eye.
• The disease was acute and progressed rapidly – the horse collapsed after a period of two and a half hours since the onset of the disease was first noticed and was subsequently euthanized.

Post-mortem Findings and Disease Characterization

• A post-mortem examination of the horse revealed a massive hemorrhage in the right side of the midbrain and pons region. This was not accompanied by necrosis or any noticeable cellular response
• The severe and rapid symptoms can be attributed to the intrusion and the subsequent activity of the warble fly larva in the intracranial region which led to the noted hemorrhage.
• Although this species of warble flies are parasitic, they typically infest cattle, and cases in horses are rare, highlighting the unusual nature of this case.

Significance of the Study

• The study underlines the potential for unusual hosts for parasite infestation, in this case, Hypoderma bovis in horses.
• It adds to the evidence linking warble fly infestation to neurological diseases.
• The clinical signs presented by horse could serve as a reference for future diagnostic attempts for similar cases.