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common k9 injury patellas
Common Canine Injury
The primary cause of the joint disease may be difficult to identify as, after a period of degeneration, the process become self-perpetuating. It is also possible that the initial process – say a mild injury to a collateral ligament – recovers fully, but the associated cartilage damage results in clinical disease of the joint years later. This highlights the fact that, although direct injury to cartilage can be the cause of damage, in most cases, the joint degenerates due to continuing insult from the inflammatory process. Molecules of any type that are not supposed to be in the joint space are removed by the synoviocytes lining the joint space. This includes proteoglycans and Type II collagen released from damaged cartilage. If there is a continuous load of this debris, these cells are stimulated, release pro-inflammatory cytokines, and recruit a wider array of inflammatory cells into the synovial membrane, and, thus, into the joint space. Release of enzymes from these activated cells causes more breakdown of exposed cartilage collagen and proteoglycans. The process feeds upon itself. Patellar luxation, defined as the displacement of the patella out of the trochlear groove of the femur, is a common problem in both small and large dogs. The condition may be congenital, developmental, traumatic, or iatrogenic in origin. The pathology can vary from mild instability of the patella within the trochlear groove to severe permanent luxation of the patella, either medially or laterally, with skeletal deformities. Medial patellar luxation (MPL) is more common in all sizes and breeds of dogs
Medial patellar luxation is more common in all sizes and breeds of dogs than is lateral patellar luxation (LPL). In a study of 124 dogs that were referred for patellar luxation, the majority of dogs had a congenital form (82%), as opposed to acquired patellar luxation (15%), and the majority (89%) had MPL, as opposed to lateral luxation MPL accounted for 98% in small breeds (<9.1 kg), 81% in medium breeds (9.1-18.2 kg), 83% in large breeds (18.2-36.4 kg), and 67% in giant breeds (>36.4 kg). In one study of 70 referred large breed dogs, MPL accounted for 97% and LPL accounted for 2.8% . That study also suggested that in large breed dogs MPL occurs more frequently in males (male:female sex ratio of 1.8:1). In contrast, other studies have shown that in small breed dogs females are more frequently affected (male:female sex ratio of 1:1.5) . Although females are more likely to be affected than males, prevalence is similar among spayed females, neutered males, and intact females, with intact males being at a lower risk. Bilateral luxations are significantly more common (65%) than unilateral luxations (35%) The cause of MPL remains unclear. Because toy and miniature breeds are affected with MPL approximately 12 times more than large breeds, a hereditary basis and genetic predisposition of this condition is likely but NOT DETERMINED . In addition, because many affected dogs are presented at 3 to 6 months of age, in absence of trauma, often with a bilateral condition, a congenital or developmental disorder rather than an acquired disorder is likely. It is also possible that congenital patellar instability predisposes an animal to traumatic luxation.If onset is after 3 -6 months then it is far more likely a possibility that it has been a traumatic onset, ie running and tripping, being held back on a restrictive leash , doing exercises that are unsuitable for age in both time and extent. It is generally accepted that MPL is a multifactorial anatomic anomaly, not only of the stifle but of the entire pelvic limb. Although the sequence of structural remodeling and variety of deformities of the pelvic limb have been well described, information regarding cause and effect relationships in MPL is limited in the veterinary literature. Specific musculoskeletal abnormalities such as coxofemoral anomalies, malalignment of the extensor mechanism, muscular pathology in the quadriceps, and shallow trochlear groove have been proposed as underlying causes of MPL.
Coxofemoral abnormality may cause MPL and related limb deformities, however no correlation has been found between hip dysplasia and MPL.
Lateral patellar luxation occurs infrequently in dogs. Although LPL can occur in any size breed, it is proportionally seen more frequently in large breed dogs. The reported incidence of LPL varies widely between studies from 3%  to 8.9% of patellar luxations in large breed dogs  to 38.7% of patellar luxations when all small and large dogs are included. The male to female ratio of patellar luxation is 1.5:1, with intact males being at lowest risk
Muscular imbalance among the quadriceps may be a primary cause of malalignment of the extensor mechanism and MPL. A clinical study reported grossly evident atrophy and fibrosis of vastus medialis (tight band-like appearance) in puppies with severe MPL . As puppies grow, medial displacement of the patella and the quadriceps muscle group, and underdevelopment of the patella and trochlear groove occur. Abnormal tension from the pathologic vastus medialis and medially displaced extensor mechanism may produce a "bowstring effect", causing lateral bowing of femur and internal rotation of tibia. Clinical observation that skeletal deformities can be completely reversed in young puppies (less than 2 months of age) by the release of tight vastus medialis suggests that muscular pathology is the primary cause of MPL and related deformities of the pelvic limb.
Clinical signs associated with MPL vary with degree of the pathology of the pelvic limb. A classification of MPL was designed by Putnam and adapted by Singleton. Grades l and 2 represent reducible luxations, whereas grades 3 and 4 represent the permanent luxations.
Grade l: Patella can be manually luxated on full extension, with spontaneous reduction on release. Minimal skeletal deformity.
Grade 2: Patella luxates on stifle flexion or manual manipulation, and remains luxated until stifle extension or manual reduction. As much as 30° of medial tibial rotation.
Grade 3: Patella remains luxated continuously but can be reduced manually; 30° to 60° of medial tibial rotation.
Grade 4: Patella luxated permanently and cannot be reduced; 60° to 90° of medial tibial rotation.

Various surgical procedures have been proposed to treat patellar luxations with the common objective of restoring the alignment of the extensor mechanism through a combination of corrective osteotomies and soft-tissue procedures. Until the pathophysiology of patellar luxation is more completely understood, surgeons must be content to repair the apparent structural abnormalities of their patients. Glucosamine and chondoritin sulphate products are popular in the US. Studies vary in the strength of their support for these products. There is debate regarding their real mode of action. It is likely that there are some situations in which they will help the patient, but we don’t know enough about them, or may not be able to be specific enough in our diagnosis to separate out those with appropriate disease, to really select the right time to use them. The broader approach is to perform an n-of-1 trial on each patient, ideally with no other management changes and, after a 3 to 4 month period, critically evaluate the response. If the response is equivocal, discontinuing and assess for deterioration would confirm the lack of response. Pentosan polysulfate is used extensively outside of the US in a similar manner. Modification of dietary levels of various fatty acids is also used to modulate the inflammatory response. Commercial diets are now available with various ratios of the different components, and further work is needed to see if there is an ideal combination. Oral supplements can also be used to add these fatty acids to the diet.
Vets do not know enough to state that this is caused by any genetic fault and many case studies show that by using supplements similar to those used in human medicine to repair knee injuries and restore loss of cartilage many dogs will stop signs of lameness and some will remodel their own joints to work effectively, there is no link with this and osteo arthritis onset later or hip dysplasia.
It is important when playing with puppies under 12months not to encourage a disturbance in any of the hinged joints ie knees, hips, shoulders elbows , be mindful a pup should RUN for more than the recommended age per month in time , it shouldn’t jump more than the height of its wrist (between 2-8 inches) a task that appears almost impossible, but it can cause displacement and trauma that could go unnoticed for many months. The pup shouldn’t slip on laminated floors, jump off stairs, knock these joints that can easily be moved out of correct angulation. We all want a pup because it is fun to watch them develop but we don’t want them to become injured through our negligence or our ignorance. It is not recommended for any young dog under 12 months of age to perform stunts, do agility, jog alongside owners, swim in extreme cold water dance on their hind legs, Perform tricks standing or walking on hind legs for long periods. If you are wanting to do this then ask a breeder for an older dog.
 recommended for all small breeds after they reach 12 months is
vitamin c
diet rich in fatty acids and omegas
salmon oil ,

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