They say that cases come in threes, but that's not one of my personal superstitions (and I do have a few). On Sunday I saw two hit-by-car cases, both with a broken pelvis. Quite a coincidence, and two was enough for one day, thank you.
The pelvic bones, the pelvis (as in Elvis), the pelvic girdle, the birth canal. Everybody's got one. It's what your legs hook into on the bottom and your backbone on the top. ["The Leg-bone connected to the -- Hip-bone..."] If a dog or cat gets hit by a car on the rear, the pelvis often takes the impact. The patient can't get up and can't walk, even though his legs are okay and his back is not broken.
Here's how it looks from the rear. Notice how irregularly shaped and twisty these bones are. What you can't see on our little plastic skeleton is the tremendous amount of muscle and tendon that surrounds it. Both those factors make it very difficult to approach the bones surgically, or to bend and contour a bone-repair plate to fit it. It takes one heck of a good orthopedic surgeon to get in there and put a pelvis back together.
Fortunately, when the hip joints are intact, you usually don't need to surgically repair things. All those muscles and tendons that make the bones so inaccesible will also act as a "self-cast". They will hold it together well enough that most cases will knit back in two to four weeks. If the spine is okay and the hips and legs are okay, the only treatment needed may be bed-rest and nursing care (including pain control, of course). This is Sunday morning's dog patient.
This is Sunday afternoon's cat patient. These patients need help with their toilet work. Personal hygiene is a little difficult for them. You'll have to bring them their food and water -- we don't want them dragging themselves around the room. You have to be alert to be sure that they are able to eliminate, as some individuals have damage to either the bladder, the rectum, or the nerves that control them. Sometimes the sciatic nerve is damaged along with the bones and the animal loses the use of a hind leg, even though all the bones heal up okay.
Also, while these bones usually knit back together well enough for the patient to walk and go potty okay, the "birth canal" will very likely be deformed. If the pet is an intact female, it's important to have her spayed, as she will probably be unanble to give birth naturally.
It's a pretty tough injury, but the prognosis is usually good.