Don't you just LOVE IT when your dog takes off on a Hot Lap! They leap into top gear and race off at great speed, often with their back arched a bit and their tail sometimes even tucked up between and under their back legs. AND THEY RUN...run like a Greyhound! It brings a smile to my face just picturing it!
Well, Blacky's mum was in the kitchen and looked up to see Blacky have that spur-of-the-moment-spark-of-life, and take off on a Hot Lap of the backyard. A joy to behold...but just after Blacky ran out of her view, she heard a thud and a yelp! She raced outside to find Blacky looking a bit sheepish... possibly a small look of guilt. You know the look in their eyes when they aren't sure if they've done something wrong or not.... or wondering how you are going to react to something they've done.
Mum couldn't work out what had happened, but a day or two later started to notice Blacky's face looking a bit "out-of-shape"... maybe a bit swollen. But she was eating and drinking OK, even though she was a little bit quieter than usual.
They re-traced her Hot Lap to see if they could work out what had happened, and that's when they found her tooth!
AND NOT JUST ANY TOOTH...it was her canine tooth, complete with its entire root intact and lying on the ground next to the tow-bar of the family car. What you see in a dog's mouth is probably only 1/3 of the tooth, the root is enormous and accounts for 2/3 of the tooth's size.
The canine tooth has evolved for gripping onto prey and not letting go. It is extremely strong, and its root massive, so that it won't break even when holding onto a struggling large prey. Imagine a wolf grasping a large buck (male deer), and hanging on to bring it down. It takes a strong set of teeth, and the canine is the largest grasping tooth. SO, to knock a canine tooth out, COMPLETELY and in one piece, requires a HUGE amount of force.
Blacky must have hit the tow bar at full speed. She mustn't have seen it at all...and WHACK! It must have really shocked her and this may have masked some of her immediate pain.
"I am SO sorry Dad...I just didn't see that damn Tow-bar on the car ! OMG !!! Is THAT MY TOOTH?!"
Blacky's owners brought her in to see us straight after the weekend (they found the tooth on Sunday). There was a foul odour eminating from her mouth, and her lower jaw did look swollen. Gently opening her lip showed that not only was there a hole where her canine had come out of, but the jaw bone was broken and the loose/mobile end piece of jaw had a few teeth in it. The odour was from infection in the bone and torn tissues, in which was rotting debris, even a bit of food.
In the Left photo you can see food and debris trapped in the hole where the canine tooth used to be.
After the wound had been thoroughly flushed and before being prepared for surgery, You can clearly see the large bone fragment with both intact and fractured incisor teeth in it and the torn tissues.
We booked her straight in for X-rays and surgery. Because of the infection in the area, the bone fragments could not be saved and used in any reconstruction. Also root tips of the teeth of the bone fragment were exposed, so even if we could save the bone, these teeth would have had to be removed. AS it was the adjacent and last remaining front incisor tooth and the right side adjacent premolar had to be removed due to some exposure of their roots, and thus infection.
These X-rays clearly show the damage BLacky had done to herself. The remaining lower canine can be seen on the other side, and in the middle X-ray the root of the canine extends right down to where you can see the first bit of fractured bone super-imposed over the jaw bone, directly above the "L"in Blacky. You can see the faint "shadow", slightly darker area, where the canine root was. There are multiple fractures!
Luckily the remaining jaw bone, the mandible, was solid - a great relief! The exposed infected bone had to be removed by curetting and the area flushed with sterile saline. Because there was no tissue to suture to, all of the sutures had to be placed through holes drilled all the way along the upper bone, and also holes lower down to help close the deeper tissue. In this way, the lip was re-attached to the bone.
The bone fragments including the incisor teeth. The small tooth to the left is the first premolar tooth. 
The completed surgery.
Strong pain relief and IV antibiotics were given, and a combination antibiotic course given for an extended time to combat the nasty bugs we tend to find in dog's oral infections, and in particular, bone infections (osteomyelitis). The malodourous smell is usually an indication of an anaerobic infection, which can be devastating. Bone infection can sometimes take 2-3 months on antibiotics and need repeated swabs and culture and sensitivities done with changes in the antibiotics used, as indicated. Fortunately in Blacky's case, the "aggressive" curetting of the infected bone removed it, leaving healthy bone, which resulted in a rapid healing.
Fully Healed! The Left photo shows Blacky's right side of her jaw, and you can compare that to her normal left side of her jaw in the far right photo. With her lip down, you cannot tell she has suffered a major injury and loss of multiple teeth and bone. Even from front on, the middle photo, you cannot tell! Blacky's cosmetic result is excellent. Blacky also has no trouble eating - a VERY important consideration for a healthy Labrador!!!
Because we used strong slowly disolving sutures in her mouth, by the time we were confident she had healed, the sutures were still present and starting to trap material and smell a bit, so a short anaesthetic was given to remove all of those that were visible along the gum margin, and to check the wound healing. Blacky had healed beautifully! And if you didn't know what to look for, you wouldn't have known she had lost a lot of jaw bone and EIGHT teeth!
However, a few weeks later, it was noticed that she had an unusual eye-movement when she moved her head to the right to look at her owners ...
As Blacky moved her head to the right, her right eye retracted into its socket, and this pushes across the Third Eye Lid (the nictitating membrane). Also, on examination, it was noted that the muscles around the right side of her face had atrophied (shrunk in size, withered away), leaving her eye socket bone protruding, and the muscle hollowed out behind her eye. When you look back at an earlier photo, the face-on middle photo above, you can notice the early changes as the right eyebrow (left side of the picture) is lower than her left side.
In the left photo you can see that as Blacky looks to her right, the third eyelid comes across. You can also see her eye socket bone protruding due to muscle wasting.
The Trigeminal Nerve (the seventh cranial nerve) is the most likely nerve to have been damaged as it has a major branch called the Mandibular Nerve that supplies the large masticatory (chewing) muscles. This branch may have been ireversibly traumatised at the time of the accident as it passes over the jaw bone right at the back at the angle of the jaw...but we didn't note any sores or soreness here. Another possibility is that the force of the jolt to the front of the jaw transmitted force to the back and possibly fractured the deep petrous bone - pure speculation on my behalf - and as the Trigeminal Nerve comes out of a hole in this particular bone, fractures to the Petrous bone are known to damage the Trigeminal Nerve (and the other Facial Nerve which is Cranial Nerve 5)...
The chewing muscles of dogs are HUGE! The back of the mandible actually is under the side bone protecting the eye, the zygomatic arch. When the chewing muscles lose their nerve's function, they shrink or atrophy, and it becomes obvious when you compare one side of the face to the other. As the muscles are on the side of the top of the head, this reduces in size, as you can see on Blacky. Coupled with loss of muscle size below the zygomatic arch bone, this bone becomes much more obvious as it now sticks out more. As the muscles atrophies behind the eye, under the zygomatic arch, it causes the eye to become shrunken in.
The third eyelid is moved across the eye whenever a dog pulls its eye backward by contracting a specific muscle behind the eye. Because there is already some pulling back of the eye due to shrinkage of the muscle there, it now only takes minor movement of the eye muscles to cause the eye to be pulled in enough to easily push the third eyelid across the eye!
Blacky continues to have no trouble eating as the healthy normal chewing muscles on the other side of her head provide that function. Her wounds all healed well and it will be the unusual muscle wastage and consequent prominent bones of her face that will be the only signs of her Hot Lap mishap.