Quittor in horses is an infection in the collateral cartilage of the hoof, usually caused by a wound that exposes the internal structures of the foot to bacteria. Left untreated, quittor can lead to tissue death, severe pain and other complications.
This condition can be debilitating for affected horses, causing significant lameness and discomfort. Fortunately, quittor is now relatively rare, but it was once commonly seen in working draft horses.
Early detection and prompt veterinary care are critical for the horse’s recovery and long-term health. Surgery is typically required to remove the infected tissue from the hoof.
By understanding the effects of quittor, risk factors and prevention strategies, horse owners and caretakers can safeguard their horses’ hoof health and quality of life.
Quittor in Horses
Quittor is an infection of the collateral cartilage, also known as the ungular cartilage. These are structures located on either side of a horse’s hoof that attach to the coffin bone and provide support and flexibility. [1][2]
Quittor usually develops as a result of trauma or puncture wounds in the area that allows bacteria to enter the internal structures of the foot. [3][4]
Quittor infections typically lead to open draining tracts in the horse’s skin, forming along and just above the coronary band. [5] If the infection is not treated promptly, it can spread to other structures and lead to necrosis (tissue death). [2][6][7]
Other names for quittor include: [5][6][7]
- Necrosis of the lateral cartilage
- Necrosis of the medial or lateral collateral cartilage of the distal phalanx
- Infection of a collateral cartilage
- Septic chondritis of the collateral cartilages
Hoof Anatomy
It’s helpful for horse owners to familiarize themselves with internal and external hoof structures so they can better understand the pathophysiology of quittor and other conditions of the hoof.
External Hoof
The hoof is the hard outer part of the horse’s foot. It is comprised of: [1][2]
- Hoof wall: The hard outer surface of the hoof. Similar to nails or claws in other mammals, the hoof is made primarily of a protein called keratin, and grows continuously.
- Sole: On the underside of the hoof, the area inside the white line (innermost layer of keratin where the soft and hard tissue joins), excluding the frog. The sole is the first layer of soft tissue protecting the inner structures and has a small role in load bearing.
- Frog: The innermost layer of soft tissue makes an angular structure inside the sole. In addition to protecting the inner structures of the hoof, the frog prevents the hoof from distorting during walking, and is involved in the horse’s awareness of where its feet and legs are relative to each other (proprioception).
The function of the external hoof is to protect the internal structures of the foot. It also helps distribute the shock and weight of the horse’s footfalls. The coronary band is the name for the place where the hoof joins the fleshy part of the foot.
Internal Foot Structures
Inside the hoof, several critical structures work together to ensure proper foot function.
- Coffin bone: Also known as the distal phalanx, provides structural support within the hoof. The coffin bone is the primary load bearing bone in the horse’s foot.
- Navicular bone: Sits behind the coffin bone and acts as a pulley for the deep digital flexor tendon, which flexes the hoof.
- Digital cushion: Acts as a shock absorber underneath the coffin bone and helps recirculate blood back up the leg
- Laminae: Interlocking layers of tissue that secure the coffin bone to the hoof wall
- Collateral cartilages: Cartilages on either side of the hoof that provide shock absorption and protect internal structures
Collateral Cartilages and Quittor
The collateral cartilages are attached to the coffin bone. These two wing-like structures are located on either side of the bone within the hoof. [1]
Quittor initially develops in the collateral cartilages after a foot wound opens up the internal structures to bacterial infection. [4] Since cartilage does not contain blood vessels, the infection rarely clears on its own. [6]
Without treatment, it can progress to infect the surrounding soft tissue and bones quickly. Immediate veterinary care is required for horses suspected of quittor. [6]
This condition is more likely to occur in the hindlegs. It occurs most often in the back part of the fetlock but is sometimes found in the sides or front of the coronet. In these less common cases, the pain tends to be more severe. [7]
Risk Factors
The incidence of quittor in modern times is quite low. This is because wound care and surgical treatment have advanced significantly in recent decades. A reduced dependence on draft horses has also had an impact on the prevalence of this condition. [3][6]
Risk factors