Equine Fractures

Equine Fractures

                               

Equine fracture diagnosis and repair has seen marked improvement in recent decades. Thanks to advances in surgical techniques, casting procedures and owner education, horses with broken bones, once deemed useless and euthanasia candidates, can (in many cases) go on to lead productive and useful lives.

Pre-hospital care and quick diagnoses are paramount to a successful treatment. Without proper emergency field care, a horse with a simple fracture may sustain irreparable damage. All horse owners should be aware of signs and first aid for broken bones, because, although a rare occurrence, this knowledge is critical to your horse’s survival.

There are three types of fractures:

·         Incomplete (including hairline and stress fractures)

·         Complete – simple or comminuted

o    Simple: broke in two pieces

o    Comminuted: broke in more than two pieces

·         Compund – a complete fracture with bone fragments poking out of the skin

In some cases, fracture may be obvious; in the case of an incomplete fracture only mild lameness may be seen and it may take days or weeks for a fracture to show. Less obvious breaks are seen mostly within small bones, as in the case of hock, knee, and foot fractures, and with hairline fractures in larger bones. Bone may also fragment (“chip”) off in a knee or ankle.  

Equine fractures are often complicated by extensive soft tissue damage, which decreases blood supply to the area and also by the need for immediate weight bearing on the affected limb.

Suspect a fracture when the horse is totally unable to use the leg, a loud crack is heard immediately prior to the lameness, the limb is unstable or at an unusual angle, and the horse is in extreme pain. The horse may attempt to move on three legs; any movement should be immediately halted and your vet should be summoned at once.

First Aid

When the fracture is initially suspected, the main goal is to stabilize the fracture site and to ensure further separation remains at bay. Once the limb is stabilized, usually through use of a splint, the horse’s anxiety level decreases and the horse may rest the leg rather than use it for support. The splint is used to take weight off the broken leg and hold the joints in a straight line. Generally, a vet should put on a splint, but if a vet is unavailable, the owner will have to.

Splints consist of wood, halved PVC pipe, boards, or tool handles and should be placed over a bandage of layered roll cotton, gauze and elastic bandaging. The bandage’s diameter should be three times that of the limb diameter. Any thicker and the bandage may bunch or shift.

Stabilize the joint above and below the fracture and secure the splint with a non-elastic bandage. (An exception to this would be fractures located above the stifle, as there is sufficient muscle coverage to act as a splint.) The splints should be applied at a 90^o angle to prevent bending.

Keep the horse from flailing around while trying to bear weight on the unaffected leg. Not only could this cause further soft tissue damage, but the handler could be severely injured in the process.

Transporting

Unless the fracture occurs at your vet’s clinic, moving the horse will be necessary. If the horse is unable to be transported, it is probable that humane euthanasia will be or may be imminent. 

Bring the trailer as close to the animal as possible. Use a ramped trailer if possible. Utilize the chest and butt bars in supporting the horse and leave his head untied to aid in balancing. Provide him with a haybag to keep him busy.

A rule of thumb is to face backward with forelimb fractures and face forward with hindlimb fractures to help him balance during braking. Provide as smooth and straight a ride to the clinic as you can and unload as close to the exam area as possible.

Diagnosis

Complete fractures are obvious to diagnosis. With less obvious fractures, proper diagnosis can be hard, even in an extremely lame horse. The horse may be moderately to severely lame and it may take up to two weeks for the fracture to be seen. Depending on the suspect area, your vet may use hoof testers, nerve blocks, radiographs, or nuclear scintigraphy (bone scan).

Nuclear scintigraphy uses nuclear scanners that detect radioactive materials which have been intravenously injected. These materials accumulate in diseased or traumatized areas of the body and are very helpful in detecting hidden fractures.

Treatment

Fracture treatments vary, depending on severity and location of the problem, and may range from a few weeks of stall rest and some shoeing adjustments to surgery (or multiple surgeries), casting, use of a sling, long stays in the clinic, months of stall rest and a year or more off.

Treatment plans should be designed to minimize occurrence of laminitis or breakdown in the opposite leg.

Other factors contributing to a successful fracture heal are a competent farrier and the location of the fracture itself.

Surgery

The objective for a complete fracture is to bring the bones back into alignment. This is accomplished via intense surgery involving plates, screws, pins and casts.

Equine veterinarians have been repairing fractures with plates and screws for approximately forty years, utilizing the same technology human surgeons do. Generally, the horse is placed under general anesthesia and the bone is fixed in place with the surgeon’s choice of hardware. Depending on the nature of the fracture, an “arthrodesis” (fusion of bones of a joint) may be performed.

When using screws, one screw works to compress the fracture line, while a series of screws lock the bone onto the place. This provides a great degree of stability. The hardware may or may not be left in permanently.

Bone cement is also used to support internal fixations (plates/screws), to bond loose fragments, act as an antiseptic and to provide filler and support in new bone growth.

As with humans, a fiberglass cast will be applied for stability to the healing limb. Casts are changed roughly every six weeks in an adult horse, sooner in foals.

Techniques have improved to prevent reinjury to the leg during recovery. Anderson slings, hydraulic lifts, recovery pools (brought to national attention by New Bolton Center in Pennsylvania during Kentucky Derby winner Barbaro’s treatment), and redesigned locking screws have allowed increased survival rates from fracture repair surgery. However, it can still be an anxious time during the immediate recovery period, as the horse may refracture as he is attempting to rise.

Prior to consent to surgery, an owner should be well informed of the costs, risks and time considerations involved. While surgical repair is more expensive, complicated, and riskier than traditional casting, benefits include a quicker healing time and less of a chance for pressure sores and bony calluses to be formed (which may interfere with tendons sliding over the bone).

Complications

Aside from complications arising from anesthesia or the surgery itself, other complications which can present include joint infection, arthritis, ringbone, dejenerative joint disease, re-breaking, soft tissue injury, laminitis, diarrhea, and death.

Euthanasia

Euthanasia is imminent if any of the following occur:

·         Open fractures with bones sticking through the skin

·         Multiple long bone fractures

·         Complete fractures above the knees, and in the upper hind and forelimbs

·         Severe infections of the bone, joint, synovial sheath or bursa

·         Severe damage and loss of soft tissue

Splint Fractures

Splint bones occur on either side of the cannon and are long, narrow bones which start at the knee and taper down, ending in a small knob 2/3 of the way to the ankle. Splint fractures are not to be confused with “splints”, which is an injury to the periostium (tissue covering the bone). Splint fractures can be due to a kick from another horse, self-interference or from forces sustained during a race. Surgical removal may or may not be necessary. Splint fractures have, for the most part, a good prognosis.

Stress Fractures

Stress fractures are overuse injuries seen in horses which are subject to high-demand repetitive activities. They are the result of long term stress that weakens the bone.

During these periods of overuse there is an accumulation of microdamage to the bone itself. The degree of this damage is related to the number and magnitude of the load cycles on the specific structure that is damaged.

This damage is repaired through bone remodeling, a process where damaged tissue is naturally removed and replaced. A stress fracture occurs when the resorptive phase of bone remodeling dominates the rebuilding process and the weakening can lead to complete fractures. Stress fractures are generally not visible radiographically, and need scintigraphy to diagnose.

The horse may be unstable, have painful lameness, and an incomplete fracture line will be visible on the radiographs. Radiographs will indicate new bone formation by bone increasing in size (a normal part of the remodeling process). A specific training history may aid in diagnosis of stress fractures. If stress fracture is suspected and other methods have been unable to diagnosis, nuclear scintigraphy will be recommended.

Prognosis is good for horses with stress fractures. Recommendations usually involve a course of rest-and-retrain, gradually working back up to previous levels to stimulate bone tissue building.

The ultimate goal of fracture repair is to return the horse to work. Treatments and surgeries can be a long and costly process and a horse that ends up only pasture sound may not be considered successfully treated.

Equine fractures are not as detrimental or fatal as they once were. Simple fractures may be healed in as little as 30 days in a stall and development of surgical techniques has vastly improved survival rates from a generation ago. Often the horse will return to the same activity level as he was previously. Prompt action and treatment on owners’ parts greatly increases the likelihood of survival and the ultimate goal of future use.