Causes and types:
Arthritis is a degenerative disease affecting one or more joints. This disease is most common in dogs with inherited orthopedic diseases such as osteochondrosis or hip dysplasia; joint injury is also one of the main causes. Some cases are associated to the joint diseases and infections induced by the immune system. There are few types of arthritis, with several different causes and outcomes: rheumatoid arthritis; non-erosive arthritis; infectious arthritis; osteoarthritis ( degenerative joint disease).
Immune system disorders and arthritis. There is a rare group of diseases when antibodies directed against the own body's connective tissue, which results in erosive and non-erosive arthritis. In case of erosive arthritis joint destruction of articular surfaces occurs; while in non-erosive arthritis there is only inflammation, no tissue destruction present.
Non-erosive arthritis tends to affect the medium and larger dogs in their fifth and sixth years of life. The reasons causing this type of arthritis are not fully known.
Rheumatoid arthritis include erosion, which occurs primarily in small breeds and mostly in the fourth year of life. It is an immune-mediated disease, the body mistakes some of its own protein for foreign protein and makes antibodies to attack its own tissue. Due to constant inflammation cartilage and bone inside the joint are gradually worn out.
Infectious arthritis is caused by various infectious diseases, such as canine ehrlichiosis, Lyme disease , fungal infections, and etc. usually after injury, wounds of all kinds, surgery, also when infection comes from other parts of the body.
Degenerative arthritis is a progressive disease (it means that an affected dog may exhibit increasing irritability and his behavior may change due to increasing pain), it is also known as osteoarthritis. This is a relatively common disease, which affects old and young dog alike. Large breeds of dog are more prone than small, mainly because larger dog's have higher load on their joints. It is thought that osteoarthritis might affect as much as one of the five dogs during their life time. In most cases it is associated with inherited orthopedic diseases and in some cases with immune-mediated diseases. Hip dysplasia , ligament rupture, dislocation of the kneecap , joint injuries and other joint diseases may also become a cause of degenerative arthritis .
Symptoms of various arthritis forms
Rheumatoid arthritis symptoms: joint stiffness, lameness , reduced joint swelling , fever, loss of appetite, lymphadenopathy .
Non-erosive arthritis symptoms: fever, loss of appetite , joint swelling, lameness.
Osteoarthritis (degenerative joint disease): dogs suffering from degenerative arthritis may experience varying degrees of lameness , limb rigidity , pain in the joints , which are more pronounced in the morning and when getting up. Cold and damp surroundings tends increase pain and stiffness. As mentioned above it is a progressive disease, pain and irritation increases with time, causing changes in dog behavior and inevitable suffering to affected dog.
Infectious arthritis symptoms: it can affect all joints but usually one joint is affected. Swelling, fever, pain, loss of appetite, depression, limping, lameness, inability to move affected joint (reluctance to walk or climb stairs, difficulty getting up after rest and difficulty to lie down), whining or squealing with no reason, affected joint is hot to touch.
Diagnosis of arthritis is made depending on clinical signs, X-rays, routine laboratory tests (including complete blood count, biochemistry, urinalysis). While results differ depending on the type of the arthritis in most cases on X-rays inflammation maybe seen. Also look out for bone/cartilage destruction signs. Synovial fluid samples are also important when determining arthritis. It may show changes in fluid quantity, color, inflammatory cell presence, fluid consistence. If infectious arthritis is suspected synovial fluid culture sample is advised. In some cases biopsy of joint tissues may be taken.