It’s a classic situation. "Hey Doc, can you come and look at my new colt? I think the old mare stepped on him ’cause he’s a bit gimpy today." When the foal is evaluated, you find a swollen joint or two, and the colt also has a slight fever. At this point, you’ve most likely got your diagnosis–septic arthritis. In foals, it often is called joint ill, and it is seen commonly in neonatal foals less than one month of age.

This is not to say that mares don’t step on their foals, because some do. However, the most common cause of lameness that veterinarians see in neonatal foals is caused by septic arthritis, not careless mares. Septic arthritis also can be seen in older foals and adult horses, but the cause usually is quite different from that in neonatal foals. In this article, we will discuss the cause, clinical signs, and treatment options for septic arthritis in foals and adult horses.

What Is Septic Arthritis?

Septic arthritis is infection within the joint. Simplified, arthritis means joint inflammation, and septic means infection caused by microorganisms. Therefore, septic arthritis is joint inflammation caused by microorganisms