Which condition is characterized by spasms and rigidity of the skeletal muscles in horses?

Tetanus is the condition characterized by spasms and rigidity of the skeletal muscles in horses. It is caused by the bacterium Clostridium tetani, which can enter the body through wounds. The infection produces a toxin that affects the nervous system, leading to severe muscle contractions, stiffness, and spasms. Horses may exhibit a specific posture known as "sawhorse stance," where they may stand with their hind legs spread apart and neck extended. Additionally, other symptoms may include an elevated heart rate, sweating, and difficulty swallowing, which can worsen as the condition progresses.

The other conditions mentioned do not share these characteristics. For instance, Equine Herpesvirus primarily affects the respiratory and reproductive systems and does not cause the specific muscle spasms seen in tetanus. Choke refers to an obstruction in the esophagus, leading to difficulty in swallowing, rather than muscle rigidity. Laminitis is a painful condition affecting the hooves of horses and does not involve the muscular symptoms associated with tetanus. Understanding these distinctions is crucial for accurate diagnosis and treatment in equine health.