Patellar Luxation in the
Cavalier King Charles Spaniel
- Symptoms & Diagnosis
- Grades of Severity
- Treatment
- Breeders' Responsibilities
- Related Links
- Veterinary Resources
The cavalier King Charles spaniel as a breed suffers from a recurring hereditary condition which causes luxating patellas. The disorder is believed to affect as many as 20% of cavaliers. The patella is the dog's knee cap. It should be located in its groove in the center of the stifle (knee joint) of the femur (upper leg bone). A luxating patella is a knee cap that moves out of its groove. Genetic conditions which cause patellar luxation are a shallow groove, weak ligaments, and misalignment of the muscles and ligaments between the femur, patella, and tibia (lower leg bone).
If the condition is not corrected, it will degenerate: the patella's ridges will wear, its groove will become shallower, and the cavalier will become progressively more lame. Arthritis will prematurely affect the joint, causing a permanently swollen knee with poor mobility.
Symptoms & Diagnosis
Veterinarians can check for patellar luxation by manipulating it. The dog is examined awake and the veterinarian classifies its degree of luxation. Adult cavaliers should be evaluated annually, and puppies should be examined at 6-8 weeks of age prior to their release to the new owners.
The Orthopedic Foundation for Animals (OFA) has a diagnosis protocol and registration for examining dogs for patellar luxation.
There are four grades of severity of patellar luxation, and they usually progress
Grade 1: The patella is nearly normal and can be only dislocated if the stifle (knee joint) is expanded and digital pressure is applied.
Grade 2: The patella can be dislocated in extension and remains out of place when the stifle is flexed (Cavaliers with this condition may suffer from joint cartilage and secondary osteoarthritis due to the patella constantly dislocating). Luxation occurs when there is occasional spontaneous lameness, but the patella returns to normal positioning easily, and the dog usually does not indicate pain. This dog typically occasionally carries a rear leg for two or three steps but then puts it back down as if nothing was wrong.
Grade 3: The patella is dislocated most of the time; it can be manually repositioned, but it slips out easily again (Cavaliers with this degree can also be a high risk for rupture of the anterior cruciate ligament in the knee joint). Luxation is to the extent that the dog begins to have a loss of function. It has more frequent "skipping" episodes and may not want to jump up; it may have pain, and the patella does not always return to normal positioning when it is pushed out of its groove during a physical exam.
Grade 4: The patella is dislocated all of the time. The dog's legs are painful enough that it tries not to use them, when the leg can not be fully straightened manually, and the dog shows evidence of chronic pain or disability, including poor or no ability to jump up.
Treatment
Dogs with milder grades of luxation often are prescribed non-steroidal anti-inflammatory drugs (NSAIDs), such as such as carprofen (Rimadyl), meloxicam (Metacam), firocoxib (Previcox), mavacoxib (Trocoxil), and aspirin to relieve the pain but not any but not the deterioration. Some physical therapy, such as hydrotherapy (swimming), may also be prescribed. Dogs with patellar luxation should not be over-weight.
Veterinary orthopedic surgery usually is required to correct more severe stages of the condition, such as Grade 3 or 4. The groove may be surgically deepened to better contain the patella. The patella itself may be tied down laterally (on its outside), to prevent it from deviating medially (toward the inside). The bony protuberance at the point the quadriceps tendon attaches to the tibia may be cut off and then re-attached in a more lateral position.
Recovery from patella surgery includes a lot of downtime, resting in a crate, with very limited physical activity, for as long as the surgeon recommends.
Breeders' Responsibilities
The Canine Inherited Disorders Database
recommends that any dogs with patellar luxation not be bred, nor should their
parents or littermates. Because of the strong hereditary relationship, all
cavalier King Charles spaniel breeding stock should be examined by qualified
veterinarians at least annually and cleared for patellar luxation, the closer
the examination to the breeding the better.
The Cavalier King Charles Spaniel Club, USA (CKCSC,USA) recommends that, prior to breeding any cavalier, the dog have no evidence of patellar luxation from an evaluation by a licensed veterinarian. The American Cavalier King Charles Spaniel Club (ACKCSC) states that "Cavaliers used for breeding should have within normal limits patellas as determined by an OFA examination at age one. The patellas should be reevaluated as the Cavalier ages."
The Canine Health Information Center (CHIC) is a centralized canine health database sponsored by the AKC/Canine Health Foundation (AKC/CHF) and OFA. The CHIC, working with participating parent clubs, provides a resource for breeders and owners of purebred dogs to research and maintain information on the health issues prevalent in specific breeds.
AKC's national breed clubs establish the breed specific testing protocols. Dogs complying with the breed specific testing requirements are issued CHIC numbers. The ACKCSC requires that, to qualify for CHIC certification, cavaliers must be screened for patellar luxation (OFA).
Related Links
Veterinary Resources
Control of Canine Genetic Diseases. Padgett, G.A., Howell Book House 1998, pp. 198-199, 246.
Guide to Congenital and Heritable Disorders in Dogs. Dodds WJ, Hall S, Inks K, A.V.A.R., Jan 2004, Section II(235).
Complications Associated with Corrective Surgery for Patellar Luxation in 109 Dogs. Gareth I. Arthurs and Sorrel J. Langley-Hobbs. Vet. Surg. Aug 2006; 35:559.
Patellar luxation. Greg Harasen. Can Vet J. 2006 August; 47(8): 817–818. Quote: "Congenital luxation of the patella represents one of the most common orthopedic conditions in small animal practice. Medial luxations account for 75% to 80% of cases in all breeds. The majority of patients are small breed dogs including ... cavalier King Charles spaniels. ... The overwhelming majority of patellar luxation are congenital and certainly hereditary, although a mode of inheritance has not been described."
Breed Predispositions to Disease in Dogs & Cats (2d Ed.). Alex Gough, Alison Thomas. 2010; Blackwell Publ. 52.
Genetic Connection: A Guide to Health Problems in Purebred Dogs, Second Edition. Lowell Ackerman. July 2011; AAHA Press; pg 134. Quote: "Table 9.10 -- Breeds at Risk for Patellar Luxation on the Basis of a Large-Scale Epidemiologic Study: ... 8. Cavalier King Charles spaniel -- odds ratio 9.1."
