The long bones of dogs and cats are almost identical to the bones of the legs and arms of people, and just like people, dogs and cats can break these bones due to vehicular trauma, fight with other animals and some sporting injuries to name a few causes.
A bone can break in many ways; we call these fractures. To make it easier to plan for therapy, veterinary surgeons classify fractures into several categories.
- Incomplete: a fracture that is more like a bend in the bone; the bone may only be broken partway around the circumference of the bone; most commonly seen in young animals (Figure 1).
- Complete: the bone is broken through its full circumference and two or more bone fragments are created (Figure 2).
Complete fractures are further described based on the shape of the break.
- Transverse: the break is straight across the bone at a right angle to the length of the bone
- Oblique: the break is at a diagonal across the bone, creating two bone fragments with sharp points.
- Comminuted: the break is in three or more pieces of varying shapes (Figure 3).
A fracture that results in an open wound in the skin is called an open fracture; these can be created when the broken bone penetrates the skin (from the inside out) or when an object goes through the skin and breaks the bone. If there is no open wound near the fracture, it is called a closed fracture.
When a bone breaks, one of the first things that needs to happen is for the bone fragments to be immobilized so they cannot move. A fracture that is immobilized will hurt a lot less and the sharp ends of the bone fragments will not cause further damage to the muscles, nerves and blood vessels surrounding the bone.
At home, before you can get to a veterinary clinic or hospital, you can confine your pet to a very small space. Ideally your pet is lying down in a box, crate or kennel; movement is limited to only that necessary to go to the bathroom or maintain cleanliness. Seek veterinary care as soon as possible – at least call to receive instruction; a bone fracture is very painful and other dangerous medical conditions may have been created at the same time as the fracture. Do not give any medications or apply any therapy unless you receive clear guidance from your veterinarian.
Closed fractures are ideally treated within 2–4 days; open fractures are best treated with an initial surgery to clean the wound and bone within 8 hours of the injury (a final surgery for open fractures can be delayed for 24–48 hours.)
Usually, the best way to temporarily immobilize a fracture prior to final treatment is to place the leg in a splint. To properly immobilize a bone, the joints above and below the affected bone must be prevented from moving. It is fairly easy to temporarily immobilize bones below the elbow and below the knee; the upper arm and the thigh are more challenging to manage because the shoulder and hip are difficult to splint. Often it is best to put the limb in a sling or simply confine your pet to a small space while plans for definitive treatment are made. Splints and bandages, as well as confinement, are best managed at a veterinary facility.
When a bone is broken, it is unable to resist the normal physical forces that act on bones when a pet walks on a leg. Some of these normal forces are:
- bending (like the force used to break a pencil in half)
- torsion (a twisting force around the bone)
- compression (the force that gravity puts on us when we bear weight on our legs)
- traction (the pulling force applied to a small portion of bone by a muscle at its attachment on the bone)
The strength of normal, healthy bone resists these forces. A bone breaks when it is subjected to a force that is greater than its own strength. Once it is broken, it must be immobilized sufficiently to allow the bone to heal back together. This is where veterinary treatments, like those listed below, are used to ensure quality bone healing and good leg use.
- External coaptation: a splint or cast; applied to the outside of the limb; good at resisting bending forces and fair at resisting torsion and compression forces.
- External fixation: a surgically applied device that is attached to the bone with pins that thread into the bone, but come out through the skin. These pins are connected to a rigid bar with clamps to “splint” the bone on the outside. This method is very good at resisting bending, compression and torsion forces.
- Internal fixation: surgically applied devices implanted inside the bone or on the surface of the bone. Various devices are available and offer different results against the various forces such as plates, screws, nails, pins, wires.
Several factors go into making up a final treatment plan for a fracture. Each factor has characteristics that support easy/rapid fracture healing and characteristics that result in slow/complicated fracture healing. We use a scale of information to come up with the best repair options for an individual pet. Your veterinarian may refer you to CVSS for your pet’s fracture repair because of the experience and training involved in successful fracture fixation.
After all is considered, you may be faced with choices for fracture repair; one option might be best for your home environment, time investment, and possible financial constraints. A splint or cast repair option is not necessarily the “easiest” or “cheapest”. Splints need frequent evaluations and changes and complications may result in a longer overall healing period, whereas some fixation methods improve the chance of successful outcomes without demanding post-operative care. Your active participation in this decision-making process will improve the overall outcome of your pet’s medical condition.
If you have any questions, please give us a call.
Articles and Photos Courtesy of the American College of Veterinary Surgeons