Medial Patellar Luxation (MPL) in Dogs
“Trick knees”, more properly termed medial patellar luxations, are a relatively common finding on physical examinations here at OCVH and in most veterinary practices of small breed dogs. In many cases, it is an incidental finding during a routine exam, while in other cases it is found when a dog comes in for sudden limping. When found on routine physical exam, veterinarians will mention it as a finding but may not go into much detail since it is not usually a cause for concern. But since it is so common, here is some additional information about the condition and what, if anything should be done about it.
What is it?
The patella is the fancy name for the knee cap. It is attached to the tendon of the quadriceps muscle in the front of the thigh and sits in a groove of the femur (thigh bon
e). The function of the patella is to act like a pulley and to facilitate the bending actions (flexing and extending) of the knee. The term “patellar luxation” means that the knee cap has slipped out of its normal position within the groove of the femur, most often toward opposite leg (medially). Sometimes it may slip toward the outward direction, which would be called lateral patellar luxation, but this is much less common. While patellar luxation can be seen in any breed, smaller breed dogs are much more prone to it. About 50% of affected dogs have the abnormality in both knees.
What causes it?
Medial patellar luxation (MPL) is most often due to a congenital (inherited) abnormality and is usually present from a young age. The groove in which it resides may be too shallow or an abnormal rotation of the shin bone may cause the attachment of the tendon to be more to the side. In either case, the patella is tends to pop out of place with normal motion of the leg. Trauma or injury can also cause luxation but this is relatively rare.
Clinical signs
In most cases, there is no obvious sign to the owner that a pet has this condition. Some owners will note that the pet will occasionally hop or skip on one leg when running and then return to normal without ever acting painful, indicating that the patella has shifted out of groove but then popped back into place. Some dogs may become lame during exercise if the patella shifts and does not return to normal position, causing discomfort and inflammation. Long term effects of frequent displacements can lead to arthritis in some pets and may make them more prone to injury of ligaments in the knee.
Types of Luxation
Patellar luxation is graded on a scale of 1 to 4, with higher numbers indicating more severe luxation.
–Grade I – Patella can be manually moved out of groove during examination but immediately returns to normal position. These dogs are unlikely to show lameness.
–Grade II – Patella is able to be easily manipulated out of place but does not return to correct location once pressure removed. These cases are more likely to show mild signs of lameness.
–Grade III – Patella is always luxated, can be slipped back into place but immediately re-luxates. These dogs show more persistent lameness.
–Grade IV – Patella always out of groove and cannot be put back in place. These dogs will have significant lameness and cannot straighten knee. They may have bow-legged appearance.
Diagnosis
MPL can be easily diagnosed on routine orthopedic examination. Radiographs or other imaging modalities may be needed to determine the extent of abnormalities (structural deformities, depth of femoral groove, etc).
Treatment
Those pets with Grade I or II luxation that rarely or never show any clinical signs are unlikely to need surgical treatment. For those with Grade II or greater that show more persistent lameness, surgery can help to correct the underlying abnormalities. If both legs are equally affected, most surgeons recommend correcting one leg at a time and allowing time for the first to heal prior to correcting the second (at least 8 weeks). The exception to this may be a dog that is still growing as correcting one at a time may lead to conformation changes if the bones are still growing.
Trochlear Modification – this surgical correction is meant for those small breed dogs with a shallow groove. The goal is to deepen the groove by removing some of the bone below the cartilage, then replacing the cartilage to keep the smooth surface.
Tibial Tuberosity Transposition – this is a more complicated surgery which is meant to
change the alignment of where the patellar tendon attaches to the top of the tibia (shin bone) to prevent the patella from being pulled to the side. The tibial tuberosity (crest where the ligament attaches) is removed and pinned in a different location to adjust the pull on the patella. In some severe cases, the entire bone must be cut and realigned.
Post- operative care
In simple cases of trochlear modification, 3-4 weeks of rest is sufficient for recovery. With more complicated surgery, a longer period of confinement, possibly up to 8 weeks or more, may be recommended. Some of these dogs also benefit from physical therapy.
Need More Information?
If you suspect your dog may have patellar luxation or another orthopedic problem please contact one of our veterinarians or schedule an examination.
Jenna Koenigstein DVM
o be artificially supplemented with special UV light bulbs. Improper levels of this kind of light can lead to bone disease and other illnesses. It is also important to know that UV bulbs lose their strength over time. I have personally measured UV output on new and used bulbs and have found drastic differences. I recommend changing UV bulbs every 4 months in order to make sure your reptilian friend is getting the healthy amount of rays it needs.
Lizards tend to shed in small sheets and over time will rub off pieces of their outer skin. Snakes will often shed their skin in one piece; however, they may shed in sections if the humidity is not right. Difficulty shedding or “dysecdysis” is a problem we veterinarians see very frequently. Retained shed over the eyes, nostrils, toes, and tails is common. If old shed is left on, over time it can cause serious eye damage and can kill tissues by strangulating the blood supply. This is a major concern during the shedding period. In general, DO NOT pull shed if it is not ready to come off easily. This can lead to serious damage to the underlying tissues. Consult our exotic veterinarians when in doubt. Learning what’s normal and what’s not normal for your species of pet is essential. 
In our area of New Jersey ticks are a concern, both for humans as well as animals. Of the many diseases that ticks carry, several are transmissible to both species. Although very small and seemingly fragile, ticks are actually tremendously hardy parasites, capable of surviving through a wide range of climate conditions. This is one of the reasons that OCVH, FVH & NPVH advocate treating our pets with a flea/tick preventative all year round in our area.
bacteria called spirochetes, which ticks ingest when feeding on wildlife or other dogs that are infected with the spirochete. The tick then spreads the infection to another animal when it bites them looking for its next blood meal. The species of tick that transmits Lyme Disease is Ixodes Scapularis (Deer Tick).
xposed to Lyme Disease can exhibit a variety of clinical signs, ranging from no signs at all to an irreparable kidney failure and death. The most common clinical signs are joint inflammation leading to lameness, fever, and lethargy or depression. Many dogs test positive for Lyme Disease and never develop clinical signs of the disease. Kidney disease secondary to Lyme Disease seems to be more prevalent in Labrador Retrievers, Golden Retrievers and Burmese Mountain Dogs.
If pets could talk, many would probably ask for K-Laser therapy and to have those treatments done at OCVH, of course! Class 4 (the most advanced) therapy Lasers are used to treat arthritis, fractures, ear infections and many other conditions that affect our pets. Laser treatments have been used in human medicine in Europe for over 20 years and were approved for use in the United States about 10 years ago. Medical doctors, chiropractors and physical therapists all use the K-Laser to help their patients. Professional sports teams have also started using this healing modality.
its joint fluid for lubrication and some of the cartilage has been replaced by bone. 
need to have treatments several times each week for the first 2-3 weeks, and then the frequency of visits decreases. Some pets continue to have treatments on an as needed basis to maintain their comfort. During therapy you will be with your pet and you get to wear fancy, protective safety goggles. Pets very quickly learn that the Laser does not hurt and actually helps them feel better. My own dogs love the extra TLC. It feels good!
This is very important as cats may not show any signs of heart disease until it is very advanced and then are at risk of sudden death. We will palpate her abdomen to assess organ size and any pain. Lower urinary tract (bladder) disease is more prevalent in cats age 1 through 10, whereas upper urinary tract (kidney) disease is more prevalent in cats over 8 years old. We will check her weight and address any signs of obesity or weight loss. Overweight cats are more prone to diseases such as arthritis, diabetes mellitus, heart disease, constipation, and more. Weight loss may indicate metabolic disease, over active thyroid disease, or cancer. We will also assess her body condition, skin, coat, eyes, ears, lungs and neurologic health. Surprisingly 90% of cats over age 12 have some degree of arthritis! Most owners simply chalk it up to “slowing down” or “getting older” when actually these cats are experiencing pain. Many conditions are treatable with timely diagnosis and medical management.
During the physical examination the doctor will make recommendations for vaccines based on your cat’s lifestyle. The doctor may make recommendations for blood tests in senior cats or those that show changes from their previous visit. These tests allow us to address problems before they become too advanced or reduce your cat’s quality of life. It gives us a chance to be proactive in preventing the complications frequently associated with medical problems. By investing twice yearly in exams, you may dramatically extend your cat’s lifespan and comfort.
For more information on the test go to 
Ocean County Veterinary Hospital veterinarians want to know… Do your dogs go outside? If they do they may be at risk for Leptospirosis. This disease is caused by one of the many strains of the Leptospira bacteria. Wild animals that walk through your yard, day or night, can leave the bacteria behind wherever they urinate. Remember, there is not a yard or park in New Jersey that does not have a squirrel or mouse run through it! Dogs most often become infected with Leptospirosis through contact with the bacteria that live and multipl
y in contaminated puddles or moist areas. Any dog that goes outside is at risk. Even when I walk my own dogs on a leash they sometimes reach down before I can stop them from investigating a puddle. We used to think that only dogs that swam in lakes or rivers, such as hunting dogs, were at risk. The fact is that many dogs diagnosed with Leptospirosis are medium to small dogs that are mostly indoors. People are at risk as well because Leptospirosis is a zoonotic disease which means it can spread from animals to people.
e signs can be nonspecific such as: lethargy, loss of appetite, fever, increased thirst and urination, vomiting, diarrhea and yellowing or bruising of the skin. There are different strains of the Leptospira bacteria and different strains target different organs. Kidney and liver failure may occur. The treatment will vary depending on the extent of the illness. Some dogs are treated with oral antibiotics alone, while others need to be hospitalized for intensive care.
The good news is that there is a vaccination that can help prevent Leptospirosis. We recommend it for all dogs living in New Jersey. Discuss your dog’s risk of exposure and the vaccination with your veterinarian. All of my dogs are vaccinated for Leptospirosis every year. Even though they are not outside often, I want them to be protected. Remember “Lepto” and remember there is a way to prevent this deadly disease.
ount of food to your dog or cat, pick one up next time you come to visit!
food can up-regulate the gene for metabolism, which in turn “burns more calories”. Hills Prescription Diet R/D and W/D are both calorie-restricted and can be used to promote weight loss while inducing satiety. Hills Prescription Metabolic Diet is a relatively new food that up-regulates the gene for metabolism. Higher metabolism means weight is accomplished by burning more calories. Please contact your veterinarian for more information about these diets and which one would be best for your pet.
Heat Stroke occurs when a warm blooded animal is no longer able to self-regulate their body temperature due to environmental conditions. For our furry pets that are not able to sweat, this means the outside world is too hot for them to cool themselves down by panting. It cause hyperthermia (their body temperature gets too hot like a super fever!). What quickly follows is internal organ damage and that can lead to death or long term health problems if not immediately and aggressively treated.
