He is chasing a toy across the lawn when, in the middle of one of his strides, he yelps in pain and pulls up one of his hind legs. He continues to limp across the lawn while only using three legs. After waiting a few minutes, he eventually put his leg back down and resumed his normal activities with it. This happens somewhere around once a week, but it doesn’t appear to bother him all that much. He cries out in agony for only a split second, and then after a few minutes of being hobbled, he is completely normal again.
Luxating patella, also known as a “trick knee,” is a condition that primarily affects small and toy dog breeds and can be very serious in some cases. They may have to do this for several days, during which time they will experience excruciating pain. Some people may have the condition in both of their hind legs, which can result in a change in their posture, including a sagging of their buttocks and a walking gait that places their hind legs further away from their bodies. Those who are most severely affected may not even be able to use their hind legs. Instead, they may walk by balancing their weight on their front legs and lifting their hindquarters off the ground.
Breeder Ruth Cunningham of YankeeBelle Chihuahuas in Sidney, Maine, shared her experience, saying, “I had 2 dogs with it.” “One underwent procedures on both of their legs. One that I carried with me the majority of the time”
“It doesn’t always present itself straight away. Ruth notes that it may not become apparent in some dogs until they are five years old. Typically, the first sign appears when the dog is running and suddenly stops, whimpers in pain, and is unable to flex his rear leg back for a few minutes. This happens when the dog’s hind leg is extended or bent.
Ruth continues by saying, “Some people say it is genetic, and some people say it “might” be genetic.” Dogs who suffer from this condition should not be bred due to the possibility that they will pass it on to their offspring as well as the additional strain that carrying a pregnancy places on the legs. Ruth affirms, “I would not breed a dog that has it” when asked about the condition. Both of mine have been sterilized. They were the first two Chihuahuas I had ever owned, and at the time, I had no idea what to look for in a canine companion.
“If you put your finger on the kneecap and bend the leg, you can feel the stability or lack of stability,” suggests Ruth. “If you put your finger on the ankle cap and bend the leg, you can feel the instability.” If you are interested in getting a puppy but are unsure of what characteristics to look for, a veterinarian will be able to evaluate the power of the puppy’s hind legs for you.
When a normal knee is bent in and out, the patella, also known as the knee cap, moves up and down in a groove at the end of the femur. This allows the knee joint to move smoothly. The patella directs the movement of the quadriceps muscle in the lower leg and serves as a protective barrier for the knee joint.
The ridges that form the patellar groove are not prominent in some dogs, which causes the groove to be too shallow. This makes it possible for the patella to luxate (jump out of the groove) laterally, typically in the direction of the interior, which causes the leg to become immobile. If the patella dislocates, it will not be able to return to its normal position until the quadriceps muscle has had a chance to relax.
The flexed or bent position of the joint is maintained even though the muscles are being contracted and the patella is being luxated. In most cases, the dog only feels pain during the portion of the procedure in which the kneecap slides across the bony ridges of the femur. The dog does not experience any discomfort once it has been dislocated.
Patella luxation is given a grade between 1 and 4 (See sidebar) based on how easily the patella luxates, with grade 1 being the least severe and grade 4 being the most severe. These grades are determined by how easily the patella luxates. Dogs with grades 1 and 2 may not show any symptoms at all, but dogs with grades 3 and 4 almost always have lameness.
If the condition is not treated after it reaches grade 2, the patellar ridges will continue to wear down, which will cause the groove to become shallower. This will result in the dog becoming progressively leaner. The joint will be affected by arthritis at an earlier age, which will result in knee swelling and mobility restrictions. Because of this, it is essential to have a thorough evaluation performed by a veterinarian at an early stage of the condition in order to reduce the risk of long-term arthritis and joint changes.
There is no treatment other than surgery for a luxating patella; however, therapy can sometimes be beneficial for grade 1 cases. The cost of the surgery varies from case to case, but it is typically between $1,000 and $1,500 for each leg.
There are three distinct approaches that a veterinarian can take when performing surgery. The first step is to enlarge the groove that is located at the bottom of the femur so that it can more securely hold the patella. It is also possible to tie the kneecap down on the outside of the patellar groove in order to prevent it from moving into the groove itself. Additionally, the bony protuberance that is at the site of the attachment of the quadriceps tendon on the tibia can be cut off and then the tendon can be reattached in a position that is more laterally located. These procedures are effective in treating the condition and provide a long-term solution to the problem. The specific operation that is carried out is determined by the patient’s case.
After surgery, the recovery process can take as long as a month and a half. The dog will typically be able to use its leg in a normal manner again within a month, but it will require some additional attention and care during this time, and it will also need to perform some leg exercises while it is recovering. It is important to have a conversation about your dog’s trick knee with your veterinarian to prevent the condition from getting worse. In some instances, your dog may be able to avoid the need for surgery by participating in physical therapy and receiving some basic care.
Grade 1:
Occasional carrying of the leg is observed, which is frequently described as skipping or hopping, and the leg returns to its normal position on its own.
Grade 2:
The frequency of luxation increases, and it is more likely that the condition will become permanent. When the veterinarian palpates the joint, they may feel a dry, crackling sensation (also known as crepitation) in the joint. If surgical treatment is not administered at this stage, the condition may progress to degenerative joint changes.
Grade 3:
It is possible to experience the permanent dislocation that results from weight-bearing. The dog will have an appearance that is similar to crouching or bowleggedness. The surgical procedure shouldn’t be put off any longer than necessary.
Grade 4:
The patient has a bowlegged or crouching stance due to the permanent luxation of the affected limb, which results in the limb always being carried. Because bone deformities of the femur and tibia can occur at this stage, surgery is strongly recommended as soon as possible given the urgency of the situation.