A species of parasitic worm that normally only lives in cattle has been found infecting a horse for the first time.
April 26, 2026
Original Paper
First reported case of Parafilaria bovicola infection in a horse (Equus caballus)
SSRN · 6636992
The Takeaway
The nematode Parafilaria bovicola was long thought to be restricted to a very specific group of livestock. This documented case proves that the parasite has jumped the host barrier into horses. It causes bleeding spots on the skin and can lead to significant health issues if left untreated. This discovery means that veterinarians must now look for this parasite in animals they previously thought were safe. It also highlights how parasitic ranges are shifting and expanding into new species.
From the abstract
This study reports the infection, diagnosis and treatment of the nematode Parafilaria bovicola in a horse (Equus caballus) in France. A soft, fluctuated and non-painful subcutaneous nodule was observed under the right eye. Ultrasound revealed a mobile verminous element in a fluid cyst. A nematode was surgically extracted from the cyst and further identified as Parafilaria bovicola by sequencing of cytochrome c oxidase subunit 1 gene. This first report indicates that horses can be accidental host