Cystinuria is a genetic defect in the kidney tubules. Normal kidneys filter the amino acid cystine and do not allow it to go into the urine. In dogs with cystinuria, this filtering action fails, and cystine passes into the urine, where it can form crystals and/or stones (uroliths). If stones form, they can block the urethra and obstruct urinary flow, especially in males.

Congenital heart diseases in dogs are malformations of the heart or great vessels. The lesions characterizing congenital heart defects are present at birth and may develop more fully during perinatal and growth periods. Many congenital heart defects are thought to be genetically transmitted from parents to offspring; however, the exact modes of inheritance have not been precisely determined for all cardiovascular malformations.

Hip dysplasia is an abnormal formation of the hip socket that, in its more severe form, can eventually cause crippling lameness and painful arthritis of the joints. It is a polygenic trait, that is affected by enviromental factors in the production of the final phenotype. It can be found in many animals and occasionally in humans, but is most commonly associated with dogs, and is common in many dog breeds, particularly the larger breeds.

Patellar Luxation: The patella, or knee cap, is a small bone buried in the tendon of the extensor muscles (the quadriceps muscles) of the thigh.  The patella normally rides in a femoral groove within the stifle (Figure 1).  The patellar tendon attaches on the tibial crest, a bony prominence located on the tibia, just below the knee.  The quadriceps muscle, the patella and its tendon form the “extensor mechanism” and are normally well-aligned with each other.  Patellar luxation is a condition where the knee cap rides outside the femoral groove when the stifle is flexed (Figure 1).  It can be further characterized as medial or lateral, depending on whether the knee cap rides on the inner or on the outer aspect of the stifle.

Elbow Dysplasia

  • Elbow dysplasia can cause lameness in young large-breed dogs and is commonly found in both elbows.
  • Elbow dysplasia is a generic term meaning arthritis in the elbow joint.
  • There are four developmental causes of elbow arthritis in dogs:
    • osteochondritis dessicans, ununited anconeal process, fragmented coronoid process, and elbow incongruency.
  • The photo below of a dog's elbow shows the three bones that make up the joint:  radius, ulna and humerus.  The humerus bone has been separated from the radius and the ulna bone in this photo to reveal the three problems within the joint.  The red painted regions on the specimen denote the location of osteochondritis dessicans of the lower part of the humerus bone (labeled OCD), fragmented coronoid process (labeled FCP) and an ununited anconeal process (UAP).