Parasites and lameness in domestic animals

Lameness is a significant welfare issue in domestic animals, and it may also result in productivity losses in farm animals. While traumatic injuries are the primary cause of lameness in animals, parasitic infections may be a potential factor in cases where the underlying cause of lameness remains unclear. Parasites may cause lameness in animals by inflicting extensive pathological damage to various organs and tissues, inducing severe anemia, producing endo- and exotoxins that act on the host, and more. However, the mechanisms by which many parasites induce lameness remain unknown. This review summarizes the literature on parasitic-induced lameness, which is classified as direct or indirect. Direct lameness occurs when parasites damage tissues such as muscles, bones, joints, tendons, and nerves, leading to a loss of function in these structures and subsequent lameness. Neurotoxins produced by some parasites may also cause coordination disorders, paralysis, and lameness in animals. Indirect lameness is caused by Égaré parasites-misplaced parasites that reside in tissues unrelated to their typical target location. These parasites may be found in the central nervous system, muscles, nerves, tendons, interdigital region, or femoral artery. Some endoparasites may cause tissue damage during migration, while others may induce lameness by affecting the circulatory system through blood parasites.