Patellar Luxation in the
Cavalier King Charles Spaniel

Cavalier King Charles spaniels may suffer 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.

Grades of Patellar Luxation



-- medications

Dogs with milder grades of luxation often are prescribed non-steroidal anti-inflammatory drugs (NSAIDs), such as such as carprofen* (Rimadyl, Quellin), meloxicam (Metacam), firocoxib (Previcox), mavacoxib (Trocoxil), deramaxx (Deracoxib), and aspirin** to relieve the pain but not any but not the deterioration.

*Carprofen (Rimadyl, Quellin) may have serious side effects and should not be given without a veterinarian's close guidance and monitoring.
**Aspirin may also have serious side effects and should not be given without a veterinarian's close guidance and monitoring.

-- surgery

Veterinary orthopedic surgery usually is required to correct more severe stages of the condition, such as Patella SurgeryGrade 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.

Water Therapy-- alternative therapies

In some cases, non-traditional therapies such as holistic healing or homeopathy, including acupuncture, and joint supplements such as Glyco-Flex II by VetriScience, may be useful alternatives to conventional medicine and surgery. Some physical therapy, such as hydrotherapy (swimming) (right), may also be prescribed. Dogs with patellar luxation should not be over-weight.


Canine Patella DiagramBreeders' 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

Patellar luxation in the dog and cat. John Ferguson. In Practice. April 1997;19(4):174-184. Quote: "Patellar luxation is a commonly seen orthopaedic problem in veterinary practice. Diagnosis of the condition is usually straightforward. However, a knowledge of the normal anatomy, function and interrelationship between the hip and stifle joints, femur, tibia and soft tissues is necessary if the surgeon is to choose the most appropriate method of treatment. This article describes medial and lateral patellar luxation, the clinical signs, diagnosis and treatment options available in the dog and cat. ... . Cavalier King Charles spaniel: a breed with a high incidence of patellar luxation."

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."

The prevalence of canine patellar luxation in three centres. Clinical features and radiographic evidence of limb deviation. N. Bound; D Zakai; S. J. Butterworth; M. Pead. Vet.Comp.Orthop.Traumatol. Jan. 2009. Quote: "The medical records of 155 dogs with patellar luxation (PL) from three different centres were analysed. [Cavalier King Charles spaniels were the second most common. See Figure 3 of the article.] Each case was classified according to the nature of its luxation and any concurrent orthopaedic conditions plus the age at diagnosis were also noted. Measurements relating to angle of inclination (AOI) of the femoral neck and medio-lateral bowing of the femur and tibia at the stifle were also recorded. The femoral and tibial data were compared to dogs with another orthopaedic condition in a case-control assessment. Labradors were most commonly affected (21%). Most luxations were medial (92%) and 54% of affected dogs were female. The mean AOI of the hip was 148.95°. There was a statistically significant difference between the stifles of dogs with PL compared to a control population. This study concluded that PL in large breeds is increasing. Lateral luxation was uncommon and was not associated exclusively with large breeds. Females were more likely to have PL than males and being female was a risk factor associated with coxa valga. There are significant differences in medio-lateral stifle conformation between dogs with PL and control dogs."

Breed Predispositions to Disease in Dogs & Cats (2d Ed.). Alex Gough, Alison Thomas. 2010; Blackwell Publ. 52.

Surgical treatment of medial patellar luxation without femoral trochlear groove deepening procedures in dogs: 91 cases (1998–2009). William R. Linney,Douglas L. Hammer, Susan Shott. J Am Vet Med Assoc. 2011;238:1168–117. Quote: "Objective: To assess signalment, outcomes, and complications for dogs surgically treated for medial patellar luxation (MPL) with a combination of lateral retinacular imbrication and tibial crest transposition procedures without femoral trochlear groove deepening techniques, and to determine whether osteoarthritis progressed in these patients during the 8-week period following surgery. Design: Retrospective case series. Animals: 91 dogs. ... The most commonly represented breed was mixed, followed by Cavalier King Charles Spaniel ... Procedures: Medical records were reviewed for information on signalment, clinical history, unilateral versus bilateral disease, preoperative and postoperative MPL grades, duration of follow-up, and perioperative and postoperative complications. Radiographs obtained preoperatively and during 8-week follow-up examinations were reviewed and assigned degenerative joint disease (DJD) scores (range, 0 to 3). Data were analyzed to determine factors influencing outcomes. Kaplan-Meier curves were constructed for recurrence of MPL. Results: Minor postoperative complications were reported for 31 of 91 (34.1%) dogs. Patellar reluxation occurred in 18 of 91 (19.8%) dogs. Reluxation or complications for which additional surgery was recommended developed in 6 of 91 (6.6%) dogs. At last clinical follow-up, 10 of 91 (11.0%) dogs had at least occasional lameness. No difference was revealed between preoperative and postoperative (8-week follow-up) radiographic DJD scores. Conclusions and Clinical Relevance: Results of surgical treatment of MPL without femoral trochlear groove deepening procedures were comparable to those in studies of surgical treatment that included groove deepening procedures. Radiographic indices of DJD did not increase during the 8 weeks following surgery. These results suggest that trochlear groove deepening procedures are not always necessary, and patients that undergo these techniques should be carefully selected."

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."

Genome-wide survey indicates involvement of loci on canine chromosomes 7 and 31 in patellar luxation in flat-coated retrievers. Ineke C Lavrijsen, Peter A Leegwater, Chalika Wangdee, Frank G. van Steenbeek, Monique Schwencke, Gert J. Breur, Freek J. Meutstege, Isaac J. Nijman, Edwin Cuppen, Henri C. Heuven, Herman A. Hazewinkel. BMC Genetics. May 2014. Quote: "Background: Patellar luxation is an orthopedic disorder in which the patella moves out of its normal location within the femoral trochlea of the knee and it can lead to osteoarthritis, lameness, and pain. In dogs it is a heritable trait, with both environmental and genetic factors contributing to the phenotype. The prevalence of patellar luxation in the Dutch Flat-Coated Retriever population is 24%. In this study, we investigated the molecular genetics of the disorder in this population. Results: Genome-wide association analysis of 15,823 single nucleotide polymorphisms (SNPs) in 45 cases and 40 controls revealed that patellar luxation was significantly associated with a region on chromosome CFA07, and possibly with regions on CFA03, CFA31, and CFA36. The exons of the genes in these regions, 0,5 Mb combined, were analyzed further. These exons from 15 cases and a pooled sample from 15 controls were enriched using custom genomic hybridization arrays and analyzed by massive parallel DNA sequencing. In total 7257 variations were detected. Subsequently, a selection of 144 of these SNPs were genotyped in 95 Flat-Coated Retrievers. Nine SNPs, in eight genes on CFA07 and CFA31, were associated with patellar luxation (P <10-4). Genotyping of these SNPs in samples from a variety of breeds revealed that the disease-associated allele of one synonymous SNP in a pseudogene of FMO6 was unique to Flat-Coated Retrievers. Conclusion: Genome-wide association analysis followed by targeted DNA sequencing identified loci on chromosomes 7 and 31 as being involved in patellar luxation in the Flat-Coated Retriever breed."

Corrective surgery for canine patellar luxation in 75 cases (107 limbs): landmark for block recession. Mitsuhiro Isaka, Masahiko Befu, Nami Matsubara, Mayuko Ishikawa, Yurie Arase, Toshiyuki Tsuyama, Akiko Doi, Shinichi Namba. Vet.Sci.Development. May 2014;4(1). Quote: "Canine medial patellar luxation (MPL) is a very common orthopedic disease in small animals. Because the pathophysiology of this disease involves various pathways, the surgical techniques and results vary according to the veterinarian. Further, the landmark for block recession is not completely clear. We retrospectively evaluated 75 dogs (107 limbs) with MPL in whom our landmark for block recession was used from July 2008 to May 2013. Information regarding the breed, age, sex, body weight, body condition score (BCS), lateral vs. bilateral, pre-operative grading, surgical techniques, removal of implants, concomitance with anterior cruciciate ligament (ACL) rupture, re-luxation, re-operation, and rehabilitation was obtained from the medical records. The breeds were as follows: Chihuahua (n=23), Pomeranian (n=12), Yorkshire Terrier (n=9), and so on [2 cavalier King Charles spaniels with 3 limbs]. The study group consisted of 33 males (castrated n=13) and 42 females (spayed n=21). The median age was 53.3±35.9 months old (32-146 months); 13 cases were less than 12 months of age (17.3%). The pre-surgical BCSs were as follows: 1(n=0), 2(n=20), 3(n=24), 4(n=24) and 5(n=7). The body weight was 4.51±3.48kg (1.34-23.0kg); 71 cases (94.7%) were less than 10 kg. The MPL grades (each limb) were G1 (n=1), G2 (n=18), G3 (n=78), and G4 (n=10); 32 cases were bilateral and 43 cases were unilateral (right n=27; left n=16). The specific surgical procedure (distal femoral osteotomy) was 3 stifles in Chihuahuas. Concurrent with ACL rupture was 16/107 stifles (15.0%) corrected with the over-the-top method or the extracapsular method in Papillons (5/6), Chihuahuas (5/23), and so on. The occurrences of re-luxation and re-operation were 3 out of 107 stifles (2.8%) and 0%, respectively. In this retrospective study, we present a potentially good surgical landmark for block recession of MPL in dogs."