Here’s Why Dog Knee Problems Exist
Dog knee problems are common. There are a few different causes. Two of the most common causes are a luxating kneecap, commonly referred to as a luxating patella or patellar luxation, and the other is a cruciate ligament tear, commonly referred to as an anterior cruciate ligament (ACL) tear. The focus of this article is to understand more about dog knee problems including how the dog knee joint works. We will discuss patellar luxation, treatment options, and costs for treating this disease.
First, it is important to know about the dog knee joint to better understand the common problems and treatment options.
What You Need to Know About Your Dog’s Knee Joints
Your dog’s knees are located on the back legs between the thigh bone (femur) and the lower leg bones (tibia and fibula). The dog knee joint is also called the “stifle” joint.
Between the upper and lower leg bones is a kneecap, commonly called the patella. When the knee functions normally, the patella slides smoothly in a groove called the trochlear groove over the femur. There are strong ligaments in the knee at the top, bottom and on the sides. Ligaments attach thigh muscles to the kneecap on the top end and ligaments attach the patella to the tibia (also called the shin bone) on the lower end. There are also ligaments on each side of the knee called the medial and lateral patellar ligaments. The ligaments on the inside and the outside of the knee help keep the patella smoothly riding in the groove.
Problems can occur when one of the ligaments tear, when a fracture occurs to the bones above, below or to the kneecap itself, or when there are genetic defects in the development of the knee joint such as an abnormal groove where the kneecap rides.
All dogs have a risk of a knee injury but certain breeds are predisposed to the different genetic problems. Small breed dogs are more predisposed to a luxating patella and larger breeds are predisposed to ligament tears. However, any knee problem can occur to any dog.
Here are a few breed predispositions:
- Breeds predisposed to Fractures – Breeds that run free and unrestricted are at higher risk of trauma, such as being hit by a car.
- Breeds predisposed to Luxating Patella – Patellar luxation is common in Yorkshire Terriers, Dachshunds, Pomeranians, Toy and Miniature Poodles, and BostonBulldogss. It is also seen occasionally in other breeds including Lhasa Apsos, Cocker Spaniels, Chow Chows, Bedlington Terriers, Australian Terriers, Japanese Chin, Shar-Pei, Tibetan Terriers, and Labrador Retrievers.
- Breeds predisposed to Cruciate Ligament Tears – Cruciate ligament tears can occur in any breed but predisposed breeds include: Labrador retrievers, golden retrievers, German shepherds, Newfoundlands, Bernese Mountain dogs, Bullmastiffs, Chows, American Bulldogs, Akitas, and rottweilers. For more information and details on cruciate ligament tears – go to Ruptured Cranial Cruciate Ligament (ACL) tears in Dogs.
Signs of knee injuries in dogs can vary. In some dogs, knee problems are identified on routine exams by your veterinarian and others are obvious by lameness.
Knee problems or injuries are the most common reason a dog will limp or be lame on a rear leg. Lameness can be constant or intermittent. It is common for dogs with a cruciate ligament injury to be persistently lame while some dogs with a luxating patella will have intermittent lameness or even seem to “skip”. Some dogs experience little discomfort and are relatively asymptomatic. In fact, some dogs seem unaffected and are diagnosed because their owners feel the kneecap pop in and out, such as when their dog is on their lap.
The best way to keep knee joints healthy is to keep your dog at an ideal weight. Obesity puts dogs at risk for injury and subsequent arthritis. Additionally, if your dog hasn’t exercised for quite a while, don’t let him get extreme exercise. Prolonged inactivity followed by excessive exercise can be associated with knee injuries. Because patellar luxation is considered a genetic condition, breeding dogs with this condition is not recommended.
One more thing about dog knee joints – injury to the knee can be very painful. Your veterinarian will commonly recommend pain medications that may include nonsteroidal antiinflammatory drugs (commonly referred to as NSAIDs). Commonly used NSAIDs include carprofen (also known as Rimadyl® or Novox® among others), Meloxicam (Metacam®), or Etodolac (Ectogesic®). These medications are commonly given with other pain medications including Tramadol or T-Relief (also known as Traumeel).
What is a Luxating Patella in Dogs?
A luxating patella is a condition in which the patella (kneecap) no longer glides within its natural groove in the femur. It is also referred to as a “patellar luxation” or “trick knee”. When the knee becomes displaced to the inside, it is called “Medial Patellar Luxation (MPL) and when it is displaced to the outside, it is called “Lateral Patellar Luxation (LPL)”. The luxation can vary in degrees from mild and intermittent to severe when the luxation is permanent.
The MPL is more common in small breed dogs and the LPL is more common in larger breed dogs such as St. Bernards, Irish Wolfhounds, and Great Danes.
Patellar luxation is a common genetic problem in dogs. It can be caused from an abnormally shallow groove that the patella sits in, which allows the patella to move outside the groove (luxate). It can also be caused from lateral ligaments that are stretched, which allow the patella to shift one way or the other.
Over time, the luxating patella affects the joint by causing pain and progressive arthritis. Symptoms of patellar luxation can range from constant lameness consisting of holding the leg up and being totally non-weight bearing, to toe touching with the leg or an intermittent lameness. Some dogs will walk or run normally (when the patella is in the normal location) and appear to skip or run holding that leg up when it pops out of the groove. Many dogs will resume normal use when it pops back in. The patella can pop in and out of the correct location in many dogs in a few seconds, and it can pop in and out many times in a minute.
The symptoms associated with patellar luxation will be determined by how severe the luxation (how easily it pops in and out), the amount of arthritis in that joint, and the individual dog. Your veterinarian can evaluate your dog’s knee and often will “grade” the severity of the patellar luxation. The grading system is as follows:
- Grade 1 – Most dogs with grade 1 patellar luxation are not in pain. Their patella pops out intermittently but can be easily manipulated back into place when the leg is extended. If the kneecap pops out, it will pop back in on its own.
- Grade 2 – Dogs with grade 2 patellar luxation have kneecaps that are less stable. The kneecap pops out and can be manipulated back into place when the leg is extended, but generally pops back out when the knee joint is flexed. Dogs with grade 2 patellar luxation will generally develop pain and joint inflammation (arthritis) over time.
- Grade 3 – Grade 3 patellar luxation is a progression of grade 2 and associated with persistent pain or arthritic changes.
- Grade 4 – Grade 4 patellar luxation is the most severe luxation. Dogs with grade 4 patellar luxation have kneecaps that won’t stay in their normal position even for short periods of time, and it is generally associated with lameness and pain.
Generally the luxation will be progressive over time, starting often as a grade 1 and advancing to a grade 3 or 4.
The best thing to do if your dog has a patellar luxation is to see your veterinarian as soon as possible. The longer the luxation exists and the more severe the luxation, the worse the pain and arthritis. Surgical success can vary once severe joint changes have occurred. Your veterinarian can help you determine the best therapy, which may include surgery.
What’s the Cost of a Dislocated Knee Surgery for Dogs?
Diagnosis of a patellar luxation is often confirmed by the physical examination findings. Your vet will feel your dog’s kneecap and determine if it is in or out of the normal position. There is a distinctive pop that occurs as the kneecap goes in or out. Your vet can manipulate the kneecap out and evaluate how easily it pops back in …or out. They can also determine to some degree the amount of arthritis in that knee joint. Radiographs (x-rays) are also useful to help evaluate the severity of existing arthritis.
Your dog’s physical examination findings, ability to use the leg, and the amount of arthritis all help to determine if surgery is the best option to correct the patellar luxation. If surgery is recommended, your vet may do it or refer you to a board certified veterinary surgeon. The cost can vary drastically depending on your geographical location and the particular surgeon. Dog dislocated knee surgery cost estimates range from $1,500 to $7,200. Costs may include the examination, radiographs, anesthesia, pain control, hospitalization, the surgery and the follow-up examinations.
Not all dogs with patellar luxation will require surgery. The low grade 1 dogs may not need surgery. Dogs with grade 2 may benefit from surgery before they progress to grade 3 or grade 4. Surgery is generally very successful if done before significant joint changes and arthritis develop. Surgery can be done on both legs at the same time or one leg at a time. Your veterinary surgeon will give you his or her recommendations. Most often surgery is performed on one leg at a time.
There are different types of surgery depending on the severity of your dog’s problem, the underlying cause, and your dog’s breed and size. For more information, please read these articles: “Medial Patellar Luxation (MPL) or “Lateral Patellar Luxation (LPL) in dogs.
Luxating Patella Braces for Dogs: Do You Need One?
There are patellar luxation braces for dogs commercially available. In theory, the braces are designed to stabilize the knee. Although marketed thoroughly on the internet, patellar luxation braces for dogs are generally not recommended.
The brace won’t change the underlying problem and stabilize the joint. In fact, most dogs dislike the brace and it can rub on the skin causing skin injury.
How do you find out if you need a patellar luxation brace? Ask your veterinarian. He or she will likely tell you that they don’t help. They can examine the knee and help you determine if surgery is right for your dog.
We hope this article gave you more information on dog knee problems, the function of the dog knee joint, and the common knee problems including a luxating kneecap and cruciate ligament tear.