If clinical signs are present and the animal is
at skeletal maturity (nine to 10 months of age), there is no reason to delay the surgery while the arthritis worsens.
The fundamental flaw with such tests is that, because children grow at widely different rates,
skeletal maturity shown on X-rays — which is used to gauge age — doesn't necessarily match chronological age.
Recommended timing may depend on factors such as expected age
of skeletal maturity, the presence of developmental problems such as recessed vulva in females, and behavioral concerns.
Small and medium breed dogs may reach close to their adult size well before a year, whereas large breed dogs may continue to grow beyond a year of age and reach
skeletal maturity around 15 - 18 months of age.
Total hip replacement can be performed successfully on dogs (and cats) of any size between 3.5 to 180 pounds and any age
once skeletal maturity is reached (usually at about 9 - 10 months of age), although total hip replacement has been performed in dogs 6 months of age in some circumstances.
While small dogs may reach
skeletal maturity faster, or be close to their ultimate size earlier than large dogs, they are not as good candidates because their bones are too small to accommodate present synthetic parts.
Because the growth plates at the end of the major bones in a child's arms and legs are open, their muscles and bones are still developing, and because their hormone levels aren't the same as adults, an intense strength and conditioning program is inappropriate
before skeletal maturity.
The American Academy of Pediatrics recommends avoiding competitive Olympic - style weightlifting and powerlifting until the athlete reaches physical and
skeletal maturity (typically after puberty).
Most dogs with mild HD are free of outward signs after they reach
skeletal maturity (when the physes are ossified and no further growth changes take place in the joints and bone ends) and before they reach an age when the effects of arthritis build to a noticeable level.
These include tight extensor and adductor muscles and ligaments, poor muscle tone or development, atrophy or dystrophy, transitional vertebrae, high - calorie diet and rapid growth rate, excessive activity before
skeletal maturity, anteversion or valgus deformity, poor positioning on the radiography table, narrow pelvis, and possibly (though not likely) estrus.