I wanted to bring some awareness to another health issue I have dealt with and witnessed as a severe and devastating case first hand.
About this time last year I had a beautiful young female that I was so excited about. She was gorgeous, passed all her health tests including a pennhip with a score of .27 .28, she breathed well, moved well, had a great temperament, she did well at her first show, and looked to have a bright future.
Well around 7-8 months of age she started having a random limp in her front legs and after a few weeks of being kept quite in a crate and a few vet visits we determined it was most likely Panosteitis aka pano and so we treated her accordingly. Well, finally the limp in the front legs stopped and then she was limping on both rear legs and I was thinking "what the heck?" So I called my vet to discuss what he thought and he basically told me that pano can affect any of the limbs although it is most common in the forelimbs so just keep doing what I was doing and we would have to wait it out.
So now I am just waiting for her to outgrow this odd limping that she was going through.
I would watch her carefully when she went outside for her potty breaks and she would trot along smelling the grass and I noticed that she would hop along on three legs occasionally and then go back to her normal gate and this would happen on both rear legs randomly. I also noticed that when she was standing she seemed to be losing all her angulation in her rear and looked like she was bowing her legs outward. So, I brought her over to a flat area of my yard and stacked her up and she locked her rear legs straight and stood on her toes which I thought was wierd. So, I was running my hands down the front side of her rear legs from her tuck to her feet gently feeling around and I had both hands over her knees and she leaned back onto her toes and I felt a pop under both of my hands like something moved. My heart sank. I knew exactly what it was.
I brought her to my vet the next morning to confirm what I knew in my heart was wrong with her. You could litterally pick up her knee caps and slide them in either direction off of her knees and she hardly even noticed we were doing it. My vet said if it had been from an injury she would have been in pain when we were manipulating her patellas and it wouldn't be in both knees. She was diagnosed with congenital bilateral luxating patellas at 8 1/2 months of age.
She never seemed to be in any pain only slightly bothered when her knee caps would slip out of place and then she would limp a few steps until they realigned and she would be fine. So I made the decision to spay her and see if I could find someone who was willing to take her on. After she was spayed she seemed to be getting worse, within a few weeks should could no longer get up or walk. I would help her get onto her feet and she would stand akwardly with all four feet under her and look at me with the most misserable eyes I have ever seen. At that point I made the decision that it would be more humane to end her suffering. I cried all the way to my vet and bawled my eyes out on her shoulders while she fell asleep in my arms. She was 10 months old when I put her down. My vet said her case was one of the more severe that he had seen and it affected her one leg way worse than the other but both were pretty bad. Typically dogs can live a mostly normal life with this condition but may eventually need surgery to realign the knee caps by carving out a deeper grove in the knees for the tendon and patella to sit in but this in not always a permanent fix. I still miss her to this day. She was a great dog.
WHAT IS PATELLAR LUXATIONS?
The patella, or knee cap, is a small bone buried in the tendon of the extensor muscles (the quadriceps muscles) of the thigh. The patella normally rides in a femoral groove within the stifle (Figure 1). The patellar tendon attaches on the tibial crest, a bony prominence located on the tibia, just below the knee. The quadriceps muscle, the patella and its tendon form the “extensor mechanism” and are normally well-aligned with each other. Patellar luxation is a condition where the knee cap rides outside the femoral groove when the stifle is flexed (Figure 1). It can be further characterized as medial or lateral, depending on whether the knee cap rides on the inner or on the outer aspect of the stifle.
Figure 1: Three-dimensional computed tomography illustrating the anatomy of a canine limb with medial patellar luxation, viewed from the front (left) and the outer side (right) of the leg. The extensor mechanism originates from the hip area, includes the quadriceps muscle, knee cap and patellar tendon, and attaches on the tibial crest. The knee cap rides out the femoral groove.
Incidence of Patellar Luxation
Patellar luxation is one of the most common congenital anomalies in dogs, diagnosed in 7% of puppies. The condition affects primarily small dogs, especially breeds such as Boston terrier, Chihuahua, Pomeranian, miniature poodle and Yorkshire terrier. The incidence in large breed dogs has been on the rise over the past ten years, and breeds such as Chinese shar pei, flat-coated retriever, Akita and Great Pyrenees are now considered predisposed to this disease. Patellar luxation affects both knees in 50% of all cases, resulting in discomfort and loss of function.
Causes of Patellar Luxation
Patellar luxation occasionally results from a traumatic injury to the knee, causing sudden non-weight-bearing lameness of the limb. It may also develop subsequent to cranial cruciate deficiency in dogs that will typically have a chronic history of lameness. However, the cause remains unclear in the majority of dogs. The femoral groove into which the knee cap normally rides is commonly shallow or absent in dogs with non–traumatic patellar luxation. Early diagnosis of bilateral disease in the absence of trauma and breed predisposition supports the concept of patellar luxation resulting from a congenital or developmental misalignment of the entire extensor mechanism. Congenital patellar luxation is therefore no longer considered an isolated disease of the knee, but rather a component/consequence of a complex skeletal anomaly affecting the overall alignment of the limb, including:
- Abnormal conformation of the hip joint, such as hip dysplasia
- Malformation of the femur, with angulation and torsion (Figure 3)
- Malformation of the tibia
- Deviation of the tibial crest, the bony prominence onto which the patella tendon attaches below the knee
- Tightness/atrophy of the quadriceps muscles, acting as a bowstring
- A patellar ligament that may be too long
Signs and Symptoms
Clinical signs associated with patellar luxation vary greatly with the severity of the disease: this condition may be an incidental finding detected by your veterinarian on a routine physical examination or may cause your pet to carry the affected limb up all the time. Most dogs affected by this disease will suddenly carry the limb up for a few steps, and may be seen shaking or extending the leg prior to regaining its full use. As the disease progresses in duration and severity, this lameness becomes more frequent and eventually becomes continuous. In young puppies with severe medial patellar luxation, the rear legs often present a “bow-legged” appearance that worsens with growth. Large breed dogs with lateral patellar luxation may have a “knocked-in knee” appearance, combining severe lateral patellar luxation and hip dysplasia.