LEG AND HOOF CONFORMATION

Quarter cracks are a common cause of foot lameness or decreased athletic performance in race and sport horses. They typically originate at the coronary band and continue distally. A true quarter crack is full thickness, extends into the dermis of the hoof often leading to instability, inflammation, and infections. Quarter cracks can be painful due to infection or instability caused by movement of the hoof wall posterior to the crack. The vertical movement of the heel bulb on the affected side further complicates this instability. Causes of quarter cracks may include trauma to the coronary band; preexisting damage to the corium from infection; abnormal hoof conformation, especially the long toe underrun heel; and focal foot imbalances, such as sheared heel, short shoes, or an abnormal landing pattern when the foot strikes the ground.

Often the problem facing equine practitioners is that many of the horses that develop quarter cracks must continue to perform. For this to occur it is essential for the repair to provide strength and stability to the hoof wall defect, which allows the horse to perform without pain while the quarter crack heals.

The goal of any repair process is to stabilize the motion at the site of the crack. Each horse's situation is unique and should be assessed by a competent farrier and sometimes a veterinarian as well. Factors that dictate the course of treatment include the depth and placement of the crack, whether it is infected, if the horse is lame, as well as the general health of the foot, such as the thickness of the hoof wall.

What is often not understood or appreciated is that the crack isn't straight into the underlying tissue. Hoof cracks are directed at an angle, and invariably there is considerable wall separation along the line of the wall failure. So what looks reasonably simple externally may be further complicated with more extensive wall separation.

The farrier or equine practitioner explores the crack site to assess the degree of damage, to determine the choice of repair and help owners or trainers understand what's going on. A horse may need both repair and time off work, and something like an infection can complicate the situation further. If infection is present, the crack should be opened and bandaged with 2% iodine, or a similar disinfectant agent, for at least 48 hours before the repair.

The importance of determining the underlying cause, trimming the feet properly, and applying the correct shoe cannot be over emphasized when repairing a quarter crack. Correcting any existing hoof imbalance along with palmar/planter support provided by the appropriate shoes is as important as the repair itself.

• Determine the underlying cause and correct where possible
• A full thickness quarter crack that warrants repair should be placed in a bar shoe if possible
• Glue-on shoes is an option
1. Allows the foot to be trimmed and shod to a more suitable foot conformation.
2. Gluing allows for more expansion to be provided under the quarter and heel of the affected side to increase support.
3. When shoes are glued on, there is no concern with nail placement in the affected quarter.
• O'Grady method of lacing - Holes are drilled on either side of the defect, and two sets of wire with small steel tabs are laced through the holes. The wire is then wound together and pulled tight. The tabs are placed against the hoof to prevent the wire from pulling through the hoof. Tubing can be placed within the hoof to allow for drainage if necessary, especially if there is any sign of infection. A composite patch can then be placed over the crack.
• Other methods include using staple or screws to hold the hoof together.
• Horses with hoof walls that are too thin and weak to support wire or screws can use acrylic patches, that properly applied can allow support of the foot without the invasive procedures.

Some horses only suffer one crack in a lifetime, while others - especially racehorses - have constant battles with quarter cracks. Is there any way to prevent them?

• The first thing you should ask is why is he getting these quarter cracks. If you do not address that question, then all you are going to be is a repairman.
• You can contribute to the prevention and reoccurrence of quarter cracks by employing regular good horse management
• After treating a quarter crack, employ a carefully planned work schedule until the crack grows well past the coronet - you'll see the progress as it's replaced by good, solid hoof wall.
• Feed correctly, and use supplements to assist in making up deficiencies
• Treat the feet with good quality hoof ointments - a bad hoof dressing does more harm than good.
• Keep the hoof walls moist - especially in dry conditions
• Look out for injuries and warning signs

A successful quarter crack repair should be simple, strong, safe to apply, and durable. It must be emphasized that the cause of the crack must be addressed in order to prevent reoccurrence.

Reprinted with permission from the June newsletter from C. Jarvis Insurance Agency