Dear Daisy Dog
Sam, my 6-year-old Labrador retriever, tore the anterior cruciate ligament (ACL) in his knee. Coincidentally, Sam’s father tore both ACLs when he was about the same age. Is this condition inherited? How likely is Sam to tear the ACL in his other knee?
The anterior cruciate ligament, also called the cranial cruciate ligament, stabilizes the knee and prevents the lower part of the back leg from flopping forward as we walk.
Torn ACLs are the most common knee problem we dogs suffer. Active large-breed dogs are predisposed, especially if they are overweight.
An additional risk factor is an abnormally shaped hind leg. Bow-legged dogs and dogs with overly straight knees have an increased risk of tearing the ACL.
The ligament may tear during a traumatic injury — or simply from gradual degeneration.
ACL disease has been shown to be inherited in Newfoundlands, and it’s thought to be inherited in other breeds as well.
One in two or three dogs with a torn ACL eventually will tear the ACL in the other knee. To minimize the risk, keep Sam’s weight at the low end of the normal range.