Why Is My Dog Limping On His Back Leg?

A very common injury I see in practice is an injury to a ligament in the knee. Very active dogs who like to run and chase a toy can tear the cranial cruciate ligament (ACL) in their knee. We also see this injury in older dogs where the ligament becomes weak over time or with diseases such as Cushings disease.

When the ligament is completely torn, dogs are not putting any weight on the affected leg at all. There is swelling and pain when the injury first happens but this gradually subsides over a week. Partial tears or strains can be tougher to diagnose. The lameness is more subtle and can improve with rest and anti-inflammatories.

For smaller dogs (under 15 kg) , strict cage rest for 2 weeks, then slow leash walking for the next 6 weeks can be tried. For larger dogs, surgery is recommended. For dogs over 50 lbs, the TPLO (tibial plateau leveling osteotomy) is recommended. This procedure involves making a cut in the shin bone, rotating the top part of the shin bone and then fixing that piece of bone in placed with a bone plate and screws. This changes the angle of the shin bone, eliminating the need for the cruciate ligament. The forces are now absorbed through the long bone (shin bone) instead. Dogs require physiotherapy at home after surgery and the recovery time for complete return to running form is 4 to 5 months. For dogs under 50 lbs, a different procedure can be performed called the extracapsular technique. This procedure requires placing of nylon suture around a small bone at the back of the knee joint and through a hole drilling in the shin bone. This nylon suture replaces the function of the cruciate ligament. Physiotherapy is required at home after surgery and recovery time is 4 to 5 months.

Cats with cruciate ligament injuries can be cage rested for 2 weeks, then exercise restriction for an additional 6 weeks (this is not easy!!) The extracapsular technique can be performed in cats and their recovery time is similar to dogs.

For older patients where the anesthetic risk is increased, a cruciate brace (orthotic device) can be used. These braces are custom made and support not only the knee with the damaged cruciate ligament but also the other knee which is supporting most of the dog’s body weight.

If a dog has torn its cranial cruciate ligament, there is a 30-40% chance that they will tear the other cruciate ligament in their lifetime. Pretty high!

If you are worried your pet may have a cruciate issue, give your St. Albert veterinary team at call!