Thrush in horses

Thrush is a common bacterial infection that affects a horse’s hoof, particularly the frog area. Studies show that about 45% of horses experience thrush at some point, making it one of the most prevalent hoof issues. While thrush can result from environmental factors, it may also occur in horses with well-maintained hooves. So, what exactly is thrush, how can you recognize it, and how can you effectively treat it in your horse?

What is the frog, and what is its function?

The frog is the V-shaped, central part of the underside of a horse’s hoof. The middle of the frog contains the digital cushion, flanked by lateral grooves. The groove in the center of the digital cushion is known as the central sulcus. The frog serves as a shock absorber, helping the hoof to maintain grip and reduce slipping. It’s also a tactile organ, similar to the sensation humans feel in the soles of their feet, allowing horses to feel the ground better and avoid tripping.

A healthy frog should be firm yet flexible. It should be free of odor, and the central sulcus should not be deeper than the lateral grooves. If these conditions are not met, your horse may be at risk for thrush.

What is thrush in horses?

Thrush, also known as hoof rot or frog rot, occurs when a horse’s frog becomes infected, typically by bacteria or fungi. Most often, thrush begins in the central sulcus, which provides an ideal environment for bacteria to thrive. The infection causes the frog to become soft, and a foul-smelling, moist substance is often released. As the infection progresses, the frog may shrink, and the grooves deepen, causing the frog to essentially rot away.

How to recognize thrush in your horse

Thrush is a common problem. But what does thrush actually look like? Thrush in a horse can usually be recognized by the following symptoms:

• A thick, blackened frog
• The frog appears soft or no longer flexible
• The frog looks “loose” with flaps of tissue
• The frog is small and recessed deeply into the hoof
• The central sulcus appears as a deep groove when viewed from behind
• A strong, foul odor from a moist substance around the frog

What causes thrush in horses?

One horse will be more susceptible to thrush than another. However, many other factors can contribute to thrush. You can therefore take into account the following risk factors that can cause thrush in your horse:

• Poor hygiene: Horses living in dirty stables or environments are at a higher risk of thrush. Ammonia from urine and manure can damage the frog. Always ensure a clean stable with proper ventilation.
• Moist environment: Horses that stand in wet conditions for extended periods are more likely to develop thrush, as moisture softens the frog, making it easier for bacteria to thrive. Aim to keep your horse in a dry, clean environment.
• Lack of exercise: Regular exercise promotes good blood circulation, which helps keep the hooves and frog healthy. Without sufficient exercise, hooves can become weak, increasing the risk of thrush.
• Poor nutrition: Nutritional deficiencies can weaken a horse’s immune system, making the frog more vulnerable to infection.
• Insufficient trimming: Regular hoof trimming, every 6 to 8 weeks, helps maintain healthy hooves and ensures the frog stays in good condition. Neglecting trimming can contribute to thrush development.

How to treat thrush in horses’ hooves?

To treat thrush and ensure that it does not keep recurring, it is important to have a farrier visit every 6 to 8 weeks. The farrier can properly trim the hooves with thrush, exposing the frog grooves again. After this, you can follow these steps yourself:

• Thoroughly clean the hooves with disinfectant soap. Make sure to dry the hooves well afterwards and use a drying spray if necessary.
• Keep the hooves clean and dry. Therefore, ensure a clean, dry stable and pick out the hooves daily.
• Give your horse plenty of exercise. Choose a good surface and do not let your horse walk for hours in a muddy paddock.
• Ensure a high-quality ration where your horse receives all the necessary nutrients. To support the hooves from the inside, you can also opt for a supplement to support the hooves with, for example, biotin or MSM. These are nutrients that naturally occur in a horse’s hooves and are therefore essential for healthy hoof growth and a strong frog.