Arthritis is very common in dogs and cats. There are many different forms of arthritis but the most common by far in dogs and cats is ‘osteoarthritis’. Other forms of arthritis occur from time to time and it is important to differentiate between the different types because treatment may be very different.
Below is a diagram showing the different form of arthritis. You can read more on our site about osteoarthritis and immune-mediated polyarthritis.

Publications from Movement Vets surgeons
Alves, J. C., and J. F. Innes. 2023. ‘Minimal clinically-important differences for the “Liverpool Osteoarthritis in Dogs” (LOAD) and the “Canine Orthopedic Index” (COI) in dogs with osteoarthritis’, Plos One, 18.
Innes JF 2018. Chapter 68 “Arthritis” in Veterinary Surgery (2nd edition), Johnston S and Tobias K, Elsevier, St Louis