Dog ACL injuries
As Wally can attest, dog ACL injuries are all too common.

It’s a cold winter evening. My dogs go out for their last little romp before nestling snug in their beds.

Wally, the 11-year-old cocker spaniel, calmly walks up the two little steps to the deck, turns quickly to check on me, and turns his leg on the icy step.

A tiny yelp, barely audible in the quiet of the starlit night, and there goes his cruciate ligament.


Oops, there it is. A tiny yelp that could cost $3,000 to repair.

The most common orthopedic problem in our pet dogs is not broken bones or hip dysplasia. It’s the knee! Injury to the anterior cruciate ligament (ACL), also known as the cranial cruciate ligament (CCL), is all too common.

Knee injuries can be complicated to diagnose and to fix. There is controversy about when a dog needs surgery, and which surgical procedure is the best. When there’s controversy about how to solve a problem, like the best way to fix a dog knee, it usually means we don’t have all the answers, and this can frustrate owners. It frustrates me, too.

Add another factor to this mess: The cost. Surgery to repair a dog’s knee starts at expensive and can proceed to very expensive. Think anywhere from $1,500 to $4,000.

“Okay,” says the dedicated dog owner, “so I’ll cough up the bucks and then Chester’s knee will be fine, right? Oh, and what does he come home with? A cast or something? He’s good in about two weeks, right?”

Not so fast, Chester’s dad. Do you want the troublesome news or the bad news first? Chester’s knee has a good chance of being fine but it’s going to take a while. And no, the recovery is not a walk in the park, so to speak. Chester is going to be limited to very short walks in the park for several months.

And during that time, Chester’s overall activity has to be limited. He can’t do stairs or run free. You need to be willing to do some doggie physical therapy, or bring him to a canine rehab facility. After all that, any dog who blows out one cruciate has a 30 to 40 percent chance of tearing the ACL in the other knee some time down the road.

But Chester Just Tripped!

It doesn’t take much for your dog to sprain, partially tear or completely tear his cruciate ligament. He might jump off the bed and just land funny. She might walk up two front steps and trip. Maybe he jumps up for a frisbee, like he’s done 1,000 times before, but comes down wrong on the rear leg.

Or, maybe she took a walk by the stream and stumbled on a rock. Many times, the owner brings the dog in to me for what he thinks is a minor sprain, only to learn the upsetting news about dog ACL injuries.

Think of an ACL as a cable wire or a thick piece of twine. It is made up of many fibers. Sometimes the fibers are just stretched, strained or partially torn. Some dogs may improve if they have a slightly damaged cruciate ligament. Many, however, will continually limp on the leg, not be able to have a normal life and require surgery.

Risk Factors

  • Obesity. Fat dogs are more prone to knee injury. Listen to your vet and get your dog back to a normal weight.
  • Exercise. Dogs should have regular, daily exercise. If you want your dog to be more of an athlete, condition him as you would yourself. You wouldn’t run a marathon with no training. Neither should your dog.
  • The weekend warrior. Don’t let Elmo sleep on the couch all week and then let him run up Mt. Rainier on Sunday. Overdoing exercise with a dog that is not walking/running daily sets him up for injury, particularly knee injury.
  • Genetics and conformation. Even under ordinary circumstances, the dog’s knee is under more stress than the human counterpart, and is prone to injury more easily. Many ACL injuries in humans are athletic in nature, but the dog’s knee behaves like it’s on a basketball court in everyday life. In a human, it often takes a bad accident, like what Olympic skier Lindsey Vonn just endured. Now she has lots in common with Tiger Woods! Your pup doesn’t have to take to the slopes or the basketball court to sustain serious injury to his ACL.

Stifle What?

Dog ACL injury radiographThe knee is a complex joint. If you want to impress your friends, call it the stifle joint. There are two cruciate ligaments, two collateral ligaments, the lateral and the medial menisci, four bones and a knee cap (patellar).

Think of the cruciates as a crisscross of two bands holding your femur (top bone in your leg) to your tibia (lower bone). They rarely endanger the posterior cruciate ligament. When the ACL is torn, the entire leg is unstable, and the bones are rubbing, causing inflammation and degenerative joint changes.

By the way, our four-legged friends are like us with only two knees. Dogs’ front legs are built like our arms. This may sound like a no-brainer, but many dogs come in with an elbow injury and their owners think they’ve hurt “a knee.”


The best way to diagnose an injured knee is the good old fashioned way: the physical exam by your vet. A vet cannot always diagnose the exact nature or extent of the knee injury, but can give you guidance on how to proceed. If an ACL is completely torn, it is quite clear when your vet palpates the knee. There will be a back and forth movement in the knee called a “drawer” sign.

But to get more detailed info about the exact details of the injury, i.e., how many other structures are involved, etc., you need advanced imaging like MRIs or CTs. This is not usually practical for dogs, although we will probably be doing many more of these in the future as the technology becomes less expensive and more readily available.

Regular radiographs are usually taken to make sure there aren’t other significant changes in the knee or hip, but the exact damage to the ligaments in the knee do not show up on a regular radiograph.


The very first thing your vet will probably tell you is to severely limit your dog’s activity and prescribe rest. NSAIDs (non-steroidal anti-inflammatory drugs) are also usually prescribed.

If the vet did not find significant movement in the knee, swelling or pain, she or he may recommend a short period of rest to see if this is just a seriously sprained knee, with the caveat that many of these knees do not improve and will need surgery. If your dog is walking well on the knee within a week or so, clearly the ACL was not severely torn. If the limp continues without improvement, you need to follow up with your vet.

A small dog may do better with some ACL injuries without surgery, while a larger dog is most likely going to need surgical repair. I find most dogs thirty pounds or over require surgery.

Disclaimer: If the ACL is completely torn, even tiny dogs most likely need surgery, particularly if they’re active.

Surgical Repair

Here’s the part of the story I don’t like. There are at least three well-known surgeries commonly used to repair a cruciate ligament. They are all very different, and there are significant differences in cost.

Even though ACL tears are so common, and thousands upon thousands of surgeries have been done to repair dogs’ knees, there is still no clear consensus in the veterinary community as to which procedure is best for which dog.

Geometry, You Say? In a Knee?

There are three commonly used procedures to fix a knee:

  1. Lateral suture technique. This older, more common and still highly recommended repair consists of placing a synthetic suture in the knee to restore stability in place of the ACL. In the hands of a good surgeon, this surgery is recommended for many dogs, particularly dogs under fifty pounds.
  2. TPLO (tibial plateau leveling osteotomy). This is a referral orthopedic procedure. This surgery actually changes the conformation of the knee. The tibia is cut, moved and reattached. If done without complication, this surgery may result in less arthritic changes, and is often recommended for larger dogs.
  3. TTA (tibial tuberosity advancement). This surgery also requires a surgeon with specialized training. In this procedure, the tibia is cut and allowed to heal at a different angle, lessening the mechanical stresses on the knee. Both the TPLO and the TTA actually change the geometry of the knee joint. They are much more expensive than the lateral suture surgery, and require veterinary surgeons who are specially trained in the procedures.

Discussing these surgeries in detail is far beyond the scope of this article. Take-home message: Consider at least two opinions when your dog is diagnosed with an ACL injury, or ask your veterinarian if he or she is willing to talk in depth about ALL options available to you.

Beware: I think some surgeons go straight for the more involved procedures when this may not always be your best or only option. Get as much information as you can based on your particular dog, and the specific injury.


Wally, on the road to recovery
Wally, on the road to recovery

Recovery is slow, with physical therapy done by you, or with the help of a trained canine rehabilitator.

If you have some money left over after surgery, and the time to go to some rehab appointments with your dog, professional rehabilitation is great. The fact that our pets need PT after trauma or surgery seems like a no-brainer, but it is a fairly new field in veterinary medicine. We will be doing more and more of it.

There is a lot of information on the internet suggesting dogs with ACL injuries don’t need surgery. The claim is they just need physical therapy. Although dogs with incomplete tears, smaller dogs and dogs that don’t do much in life can benefit from weight loss and physical therapy, I think these claims are misleading.

Many dogs limp continuously with a knee injury, never improving with conservative treatment, or their condition worsens. If surgery should be done and is not performed, the dog can suffer arthritic changes to the knee, the hip and the other leg. This is a painful situation that also limits his life as a happy, frolicking dog.

We are seven weeks post-op Wally’s ACL surgery and he is doing great. Walking him under icy conditions this winter, and carrying him up a long flight of stairs at night, has not been easy, but it’s been worth it.

He is slowly getting back to his old routines, tolerating his physical therapy every day, and should be back to normal by spring. Hats off to his surgeon (not me), his owner (me) and to Wally!

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Leave a Comment

  • Odie’s mom

    My 8 year old cocker spaniel just had surgery. I’m glad to know yours is recovering well and hope mine does too. I’m still getting over the shock of his exposed and swollen leg. Somehow the whole post op experience is more overwhelming than what I gather from my vet and online reading before the surgery. I sure hope its all worth it in the end.

  • Michelle

    Can you please tell me where the statistic of 30-40% chance of tearing the other ACL comes from?

    • Kmix71

      Not sure that this is a statistic but I’ve had 2 dogs now with CCL tears. The first tore the second one a year (to the day) that I picked him up from his first TPLO surgery and the second tore the second CCL one week (to the day) after the first. I can testify that it’s common. :-(

  • Jes

    I agree that conservative management isn’t alway appropriate, but I don’t think it should be ruled out entirely as an option. My dog was too old to have surgery when he tore his ACL. What were my choices? Ignore it? (no) Put him to sleep? (no way) or maybe try something unconventional and see if it works. So I bought a woundwear brace. Although I was skeptical, it was the least that I could do for my friend. Even though, he’s not the dog he used to be (a status he wouldn’t have been able to achieve even with surgery), he’s way better off than he was and I hope that I’ve given him a few more years to his life :)

  • Amber C

    The vet said my basset hound puppy tore his acl, but on pain meds there is barely a limp. Is that normal or is the tear not as bad?

  • Debora lichtenberg

    Amber, It’s possible your dog suffered a severe sprain of the ACL or a minimal tear that has almost healed. In my opinion, you should bring the dog in soon for a re-check with the surgeon. If there is no movement in the knee, it may be possible to treat this conservatively. Good luck!!!

  • shelly

    My dog had acl surgery about 6 months ago, and is still not fully healed. He occasionally is still limping, or not putting any weight on it at all, and flinches in pain. I’ve brought him into the vet a few times when this happened, very worried that it was torn again. It always turned out to be okay. Everything I have read says that it shouldn’t take this long. I am concerned. I want him to heal up, not feel pain, and be able to enjoy being a puppy again. Is there anything you can suggest?

    • Benjamin Spaethe

      Hi Shelly, what kind of dog do you have? We have a pit bull puppy who just turned a year old. He’s limping, so we took him to be seen and they said he needs ACL surgery. We didnt see the surgeon yet but the vet said with his breed, he likely will need it done to both legs. If your dog is the same breed as mine, I would love to know if you have any tips or online links you can steer my way? We love our Maxie and dont know what to expect. I hear from this article that surgery can cost a lot of money and recovery can take 6-9 months and I suspect recovery visits can be pricey and numerous. Anyway, if you have the same dog breed as ours, can you offer any tips/links as to what I may expect? I would sure appreciate anything. Thank you and I hope your pup is doing well these days :)

      • Bossman

        HI Shelly i have of pit bull he is 7 year old .He just had ACL surgery a day of go & yes the cost was insane from my i went to the web and start look affordable and i found HELPING HAND VET.I CALL .best thing is i save 3gran

  • Star

    I have read alot since a vet said my 85lb bully had bi lateral acl in his back legs, a week after he was neutered. He does not limp, just walks slower and whines when getting up from laying down. He still goes to the bathroom the same just doesn’t squat down as far. I followed my instinct to rush him into see a vet and regret that I left him to be sedated and x-rayed because he seemed to be in worse shape then when I took him in. Symptons are confusing because he doesn’t walk with a limp or seems lame, just more careful. He is on pain meds and supplements with very restricted activity, this is the end of week 1 on meds but 2 weeks from start of injury. Should I continue to follow conservative management to see if he improves slightly and maybe does not need surgery?

  • Debora lichtenberg

    Most dogs are walking quite well by six months, although my little cocker was off and on limping until about seven months post-op.
    Physical therapy can be a great help in this situation. Try to find out if there is a practice in your area that does a lot of orthopedics and has a connection with a trained PT.

  • Debora lichtenberg

    Every case is different. My advice is to have him re-checked after 2 to 3 weeks of rest and meds.
    Statistically speaking, and realize I am not examining your dog, but an 85 pound dog with complete tears of both ACL’s will not do well long term.

  • Gherkin Merkin

    My (on the larger side) pom/maltese x had an on and off limp for a long time. It would usually happen following a fight with one of the other dogs and i thought she was putting it on since she was usually the one starting the fight. The limp would stop as soon as she walked away. One day though, I came home and she wasn’t putting any weight on it at all and she looked particularly uncomfortable. Off to the vet. Torn ACL. Likely it had minor damage and then she has completely torn it. She was 11.

    AU$2000 later, she had the lateral suture technique. I kept her completely confined for a good 10 days. After that she seemed to look after herself and took it relatively easy without my interference. She walked on 3 legs for a while and would use the sore leg to balance when she stopped or walked slowly. She slowly used it more and more herself, over time. We didn’t take her for any big walks for a good six months.

    It has been a year now and from her general demeanor following the procedure and recovery (trauma), i’d say it probably took a lot out of her. She definitely seems slower and quieter but she was already old, and now she’s 12, so it could just be old age mixed with the trauma of such an event.

    She does everything she used to do before, jumps on and off furniture, and she seems happy enough and doesn’t limp at all anymore.

  • Jocelyn Wilson


    I’m just wondering if you could share some of the physical therapy techniques you used? My dog is going in for the traditional operation today.


    • Pets Adviser

      You might find this post-operative care guide to be helpful reading:

      Of course you should speak with your vet/surgeon about specific care for your dog. Consider this care guide to be for information purposes only.

      Good luck on the road to recovery!

  • Julie Parton

    I understand that this is a very old post, but I am seeking any advice that I can find. In March of this year my year old English Mastiff slipped on the snow and tore her right cruciate. We immediately had surgery. I was working through her rehab and at week 3, she tore the left cruciate. Again, we had surgery. Now we find ourselves in June….my baby girl is STILL not walking. The vets have been amazing and taking her every day for rehab. Her legs are stronger but she is still not extending her hind legs at all. She can’t walk. I don’t know what to do and the vets feel as though they have exhausted their ideas. Do you have any suggestions on what to do for my girl? Have you ever seen something like this happen before? I never imagined that she would never walk again. Thanks in advance.

  • Joan Peterson

    My 100 pound shepherd cross had knee surgery almost 4 years ago. And sadly, today I think he blew out the same knee. He is only 6 so I think I will try surgery again. He is such a sweet boy and I don’t want to euthanize him. If they can fix him up, that will be great. But if this were to occur for a third time and at 8 or 9, I would likely make the decision to euthanize him.

  • Kelly

    My dog Lucy is steal healing from an ACL tear but she never had injury…I was too scared to do it!! I was trying to find non-surgical ways to help her and I came across Woundware. I got her a brace and it has been working wonders! Although she is not healed fully yet :( she is not wobbling anymore and can go on short walks with me again.

  • Olivia

    My 5 year old Cavachon has this surgery yesterday. It seems like she is having trouble chewing and her eyes appear to be bugged out. Could these side effects be from the medication or is there a bigger concern

  • Kmix71

    HELP! My dog tore (complete tear) both CCL’s. I’ve been to three surgeons; one that wants to do the lateral suture – one knee at a time and two that want to do the TPLO – one wants to do both knees at one and the other wants to do them one at a time. My 6 year old pit mix is almost 80 lbs and, from what I seem to be finding, is not a good candidate for the lateral suture. However, the vet claims “that it will work just fine.” I don’t know what to do!

  • Kelly

    Thank you for sharing your story about Wally :) My dog, Button, is a little Yorkie and she tore her acl about a month ago. She is so tiny I was too scared to put her through surgery. I ended up getting her a a-trac brace from Woundwear and it has been wonderful! She had to get used to it but after she did I could tell she was happy to walk around again. Thanks for sharing your story!!

  • Cheryl

    This just happened to my 5 year yorkie terrier mix today. She jumped off our driveway retaining wall about a foot high off the level ground. We took her to the vet as soon as she yelped and started limping with no weight on the leg. I thought I was going to pass out when the vet said surgery probable if it doesn’t get better within a week. Anyway, thank you for this article. We have a good pet therapy place near us and I’m hopeful our active little dog will get back to herself eventually, surgery or not.