Hip and Elbow Dysplasia: What the Grades Actually Mean

Hip and Elbow Dysplasia: What the Grades Actually Mean

Dysplasia is one of those words that gets repeated in breed descriptions until it stops meaning anything. It is worth slowing down on, because the screening behind it is genuinely precise, and the difference between a dog with a real clearance and a dog with a vague reassurance from a breeder is large.

Dysplasia means abnormal development. That is the whole word. A dysplastic joint is one that did not grow into the right shape, so its two halves do not fit together as they should.

What the Hip Joint Is Supposed to Do

A hip is a ball-and-socket joint. The ball is the femoral head, the rounded top of the thigh bone. The socket is the acetabulum, a cup in the pelvis. In a sound hip the ball sits deeply and tightly in a well-formed cup, and the two surfaces glide against each other on a layer of cartilage.

In canine hip dysplasia the joint is abnormally developed, and over time cartilage deteriorates until movement itself becomes painful. That last part is the bit owners often miss: the looseness is the cause, but the arthritis it produces is what actually hurts.

The OFA Hip Grades

The Orthopedic Foundation for Animals, almost always written OFA, is the registry most American breeders screen through. It sorts hips into seven grades in two groups.

Only the first three receive an OFA number. Dysplastic results are closed to the public unless the owner chooses otherwise, which is worth knowing when you are reading a pedigree: absence of a result is not the same as a passing result.

The Elbow Is Three Problems, Not One

Elbow dysplasia is described by the OFA as an inherited polygenic disease, meaning many genes contribute rather than a single one. It is really an umbrella term for three developmental abnormalities that can appear alone or together, and research indicates their inherited traits are separate:

• Fragmented medial coronoid process (FCP), where a small piece of the ulna, one of the two forearm bones, breaks away inside the joint.
• Osteochondritis of the medial humeral condyle, where cartilage on the end of the upper arm bone fails to develop into bone properly.
• Ununited anconeal process (UAP), where a projection of the ulna that should fuse to the rest of the bone never does.

Grading is simpler because the OFA only grades abnormal elbows, in three grades, measured by bone change along the anconeal process: Grade I is under 2mm, Grade II is 2 to 5mm with sclerosis, and Grade III is well developed degenerative joint disease with more than 5mm of bone proliferation.

When Screening Happens

The OFA will not certify a normal elbow until the dog is two years of age. Preliminary radiographs are accepted earlier, and preliminary hip screening is available between 4 and 23 months.

That distinction matters when you are talking to a breeder. A preliminary result at 8 months is a useful early signal and a legitimate breeding tool, but it is not certification, and it should not be presented as one.

What Owners Actually See

Lameness, which may be mild, moderate or severe, and which is worse after exercise. Alongside it: a distinctive bunny-hopping gait where both hind legs move together, reduced range of motion in the joint, stiffness, and pain on movement.

None of these are subtle once you know to look, but they come on gradually enough that owners often attribute them to age.

What Influences Severity

Excessive growth, exercise, nutrition and hereditary factors all affect whether hip dysplasia occurs. The OFA is explicit that severity can be affected by environmental factors, specifically caloric intake and level of exercise.

This is the single most actionable fact in this article. A genetically predisposed puppy that is grown slowly and kept lean will generally do better than the same puppy grown fast and kept heavy. It is also why large breed puppies need large breed puppy food rather than standard puppy formula, a point covered in our large and giant breed dog guide.

Treatment

Medical management for mild cases: weight reduction, restriction of exercise on hard surfaces, physical therapy, anti-inflammatory drugs, and possibly joint fluid modifiers.

Surgical options range across several procedures aimed at reducing pain and arthritis, up to total hip replacement. Outcomes are generally good when the procedure is properly performed.

Prognosis varies considerably and depends on the animal's overall health, the degree of dysplasia and joint damage, and its environment. Because dogs pass hip dysplasia to their puppies, at-risk breeds should be evaluated before being bred.

It Is Not Only Dogs

Hip dysplasia is routinely described as unusual in cats. In the Maine Coon that is simply not true, and the numbers are not close. Of 2,548 Maine Coons in the OFA registry, 24.9 percent were affected, bilateral in 56 percent of cases, with the youngest affected cat picked up at 4 months. A Swedish screening programme covering 5,038 pedigree-registered Maine Coons over 2000 to 2019 found radiographic signs in 37.4 percent, with a heritability of 0.36.

The mechanics are the same as in a dog: a joint that did not form correctly, wearing itself out. What is different is that almost no pet cat is ever radiographed, so the disease is largely invisible rather than largely absent. Stiffness or a reluctance to jump in a young Maine Coon deserves investigation rather than being written off as size.

For the breeds where this matters most, see our Labrador Retriever guide, German Shepherd guide and Golden Retriever guide, each of which lists the clearances worth asking a breeder for.

Sources & Further Reading