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172 – Veterinary Voice: Cruciate Ligaments| Pure Dog Talk

Dr. Marty Greer, DVM, JD. Co-owner of Veterinary Village in Lomira, WI and board member of NAIA.


Early spay/neuter is one of the primary indicators of a potential for a “blown knee” in our dogs, according to Dr. Marty Greer, DVM. The cruciate ligaments in the stifle joint of the dog serve as a hinge when working properly. When these ligaments are stretched, frayed or torn, the dog will be painful, limping, or “off” on a rear leg. Environmental factors such as overweight and lack of condition also can contribute as causal factors, Greer adds.


Veterinary Voice with Dr. Marty Greer, DVM



Anterior Cruciate Ligament (ACL) Rupture

Rupture of the anterior or cranial cruciate ligament is more common after gonadectomy than in intact dogs (Whitehair et al. 1993; Duval et al. 1999; Slauterbeck et al. 2004). Breeds at risk for rupture of the ACL include the Akita, American Staffordshire terrier, Chesapeake Bay retriever, German shepherd dog, golden retriever, Labrador retriever, mastiff, Neopolitan mastiff, Newfoundland, poodle, rottweiler and St. Bernard (Duval et al. 1999; Harasen 2003). Other risk factors include obesity and abnormal angulation of the stifle (Ragetly et al. 2011). One could argue that increased risk of ACL injury after gonadectomy is because of decreased athleticism and obesity in gonadectomized animals but the trend stands even in studies that statistically compensated for these effects in dogs. Joint laxity may differ under varying hormonal stimuli, suggesting one possible cause‐and‐effect mechanism. Another hypothesis is increasing stifle angulation with asymmetry of growth plate closure in the femur and tibia.

Tick borne diseases that can cause joint inflammation are another area Greer notes that may cause complications. Often times, a dog will not have a fully ruptured ligament, but these important sort of elastic bands in the joint will have frayed or “stretched.” Treating these dogs with crate rest, testing for tick borne diseases and treating with a prophylactic course of Doxycycline that both treats tick borne diseases and confers some anti-inflammatory process in the joint is Greer’s recommendation.

Patellar luxation is a genetic disorder that serves as complicating factor for potential injury to the knee joint as well, according to Greer.

Surgery to repair a torn cruciate ligament is expensive and requires the best orthopedic surgeon you can find, Greer said. But it isn’t an emergency situation. If you suspect a cruciate injury,

  • Keep the dog quiet and crated.
  • Take it to your veterinarian for diagnosis.
  • Research the best surgeons available in your area.
  • Be diligent about maintaining *strict* crate rest during recovery.

We hope you enjoy today’s podcast with Dr. Greer. For more information on this topic, visit:


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Veterinary Voice – Marty Greer, DVM on Cruciate Ligament Ruptures Transcript

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LAURA REEVES: Welcome to pure dog talk. I’m your host Laura Reeves and we are back with Dr. Marty Greer for the Veterinary Voice episode. Today we are talking about something that I think a lot of our listeners are going to be very interested in because we’ve all probably run into this or at least heard of somebody who has, and that is cruciate ligament tears. And so we’re going to talk about some prevention, some possible treatment options, and Marty thank you for joining us – I appreciate your input on it.

MARTY GREER: Thank you. I’m happy to be here.

LR: Excellent. So cruciates. I’ve lived it. I know an awful lot of people who have. Let’s talk about why those cruciate ligaments are so important and so fragile.

MG: OK where do you want to start?

LR: Well I think let’s talk about exactly what the cruciate ligament is, where it is, and why it is so functionally important for the dog.

MG: So humans, dogs, horses, cows, everybody has a cruciate -a pair of cruciate ligaments – there’s the cranial and caudal cruciate ligament if you’re human; There is anterior and posterior or cranial and caudal if you’re a dog. So the cranial cruciate ligament is the one that usually gives us trouble. But there are actually two cruciate ligaments inside each knee joint, the knee being the one with the knee cap the joint that is your knee is the joint that goes forward in the dog and some people confuse which joint we’re talking about. So the two cruciate ligaments cross inside the joint – that’s where the word cruciate or the term cruciate comes from – cruciate means cross like crucifix – that’s all the same word root. And so there are two ligaments that cross inside the joint and when they’re working correctly that allows the knee joint to act as a hinge joint. So it just moves forward and back it – doesn’t have any other rotation. And then there’s some ligaments on the sides – collateral ligaments – that hold it so that it doesn’t wobble back and forth. But it takes both cruciate ligaments – both the cranial and caudal cruciate ligaments – functioning correctly make the joints healthy and stable.

MG: If one of the ligaments tears is almost always the cranial ligament that tears and what happens when that happens is a couple of things. One is it’s painful. So the dogs start to limp not or use the leg – carry it – and the other is that it leads to instability in the joint. So instead of the joint just acting as a hinge it also ends up with shearing motion back and forth so that the tibia and the femur shear across each other and there’s not stability, and then that starts to damage the meniscal cartilages inside the joints and then you end up with meniscal damage a meniscal tears. So it’s compounded – it’s not just painful but it’s also unstable and then a secondary damage starts to develop and then that leads to arthritis.

LR: Right. And so what types of things will cause the cruciate ligament to tear or to strain or to be injured at some level.

MG: There’s a lot about that that we still don’t fully understand. When we were in school – I graduated 36 years ago – we were taught that it was primarily trauma that caused the cruciate to rupture … that a dog would be running and catch its foot in a hole and as they were moving forward their momentum would then tear the ligament. But since that time cruciate ruptures have escalated in incidents just astronomically. You know we used to see, oh, an occasional cruciate here and there, but now almost any dog that comes into our practice that’s limping on a back leg is suspect to being cruciate ruptures. Sometimes it’s hip dysplasia – most of the time it’s a cruciate ligament and our clients already know that. They’ve already gone online, they’ve already googled it, and they already know that we’re going to come in the room and tell them that their dogs torn their cruciate ligament. One of the contributing factors, and we don’t understand completely what the incidence is goinb to be, but there’s a huge increase in incidents of cruciate ruptures in dogs that are spayed and neutered when they’re young. And because there’s been a big movement to early spay and neuter from the rescue organizations and the Humane Societies, for reasons of population control, they’ve put our dogs at increased risk inadvertently – they didn’t set out to do that – but inadvertently they set our dogs up for failure in the development of their joints.

MG: So when a dog is spayed or neutered when they’re really young their growth plates stay open longer. We know that from Llama’s, we know that from human eunuchs, you know – the young boys that were castrated when they were really young back in the European countries so that they could continue to sing in the choirs – the eunuchs grew tall, longer body, longer legs, longer limbs, and the same thing happens with our dogs. So if you walk down the aisle in a humane society and you see a long legged, skinny, straight kneed black 60 pound dog, odds are pretty good that it’s a male that was neutered when he was 3/4/5 weeks old – maybe two or three months old. But we do know that the incidence is much, much increased in dogs that are spayed and neutered really early. So that’s one factor that really needs to be taken into account. Now that doesn’t mean that every dog with a cruciate rupture is spayed or neutered. We certainly do see some athletic dogs, some of the field trial dogs and so forth, that come into the practice that have had true trauma to their joint and has caused that ligament damage and rupture. But we know that spaying and neutering has a big impact. There’s going to be an article that’s coming out fairly soon that shows in Golden Retrievers the incidence of cruciate rupture is four times what it is if they’re spayed and neuter young, than if they’re not. So four-fold – the incidence – it’s huge and I don’t think it’s just going to be Golden Retrievers. I think that’s just the first study that’s going to be coming to the literature. But I’m sure over the next few years we’re going to see a huge number of supporting documents that suggest that that happens in more breeds than we know, and it’s almost always the larger breed dogs of 40/50/60 pound dogs and up that have cruciate ruptures. It’s usually not the smaller dogs.

LR: Okay, so early spay/neuter – this can be a problem. Trauma – this can be a problem. <Mm-hmm> When I was speaking to Dr. Gerold Bell (Click HERE), that episode was released before this one, he made some reference to a genetic basis for cruciate problems. <Mm-hmm> Can we expand on that at all – are we talking about just genetically the dogs are not structurally sound or are we talking about actual ligament development problems?

MG: Well I’m not sure we really have a great handle on that yet. I know UW Wisconson was looking at Labradors to try and get normal dogs over the age of eight and dogs with cruciate ruptures and compare them genetically looking for if there’s a genetic basis for it. Some of our breeds, we have inadvertently bred them to be really straight through the stifle. So, you know, if you look at most breed standards they should have good angulation – front and back – you know those are kind of the words that you see and breed standards. But if you look at the dogs, if you look at Chows, Rottweilers, all sizes of Poodles – it doesn’t matter if you’re talking standard/miniature/toy – if you look at how they stand when they’re in a stack they tend to be pretty straight through the stifle. Their hip is straight above their knee, is right about their hock, is right above their foot. You don’t see that nice angulation that would be ideal in a lot of breeds. So I think that we have structurally developed dogs that look like we want them to look and inadvertently, by doing so, have created dogs that are more straight genetically. So there is certainly a genetic basis to it when we have that and when we see any kind of disease that we can say has a breed predisposition, then that certainly has a genetic component. Now that’s not to say that all breeds can’t potentially rupture their cruciates because they all can. There’s also an increased risk of cruciate rupture if there are dogs with patellar luxation, and certainly patellar luxations are one of the things that OFA allows us to register our dogs to be normal or abnormal in their patellar configuration. But if the dogs have patellar luxation and again those are the toy breeds, the Poodles, the straight-legged dogs.

MG: But we can see it in any breed. I saw it in a German Short Haired Pointer that’s a very athletic dog a couple of weeks ago. So any dog that has a predisposition to have patellar luxation will also be predisposed to cruciate rupture. Beyond that we don’t really know if there’s something else going on or not, but about 50% of dogs that rupture one cruciate within a 12 month period of time will rupture the other one as well. So that leads you to believe that there is either an environmental or genetic cause for that. And what could be environmental? Well it could be that they’re overweight. It could be the age that they were spayed or neutered. It could be a lot of different things. So I don’t think we have a great handle on it. We certainly don’t have a DNA test yet that can say, “Oh yes, this dog is likely to have a crucial rupture.” I would encourage people, that when they’re looking for a dog to breed to, if I have to hold a stud dog up to collect his semen so we can do an AI, because he just had cruciate surgery – maybe he’s not the dog you should have in your gene pool. Maybe that’s not something <laughter> that you want to introduce into your line of dogs if you haven’t had problems before. And I do actually have people come in that. “Well he just had his knee done so, could you help him breed her? Because I don’t want him to hurt him–,” I’m like, “Oh, sure but maybe we should step outside the room for a moment and have a conversation about– <LR: Maybe we should think about this> –is this the ideal dog. Yeah. <LR: Oh my gosh> Because I don’t want to diss your stud dog, but on the other hand I’m worried that this might be a genetic problem.

MG: We don’t have a DNA test at this point. Will we ever? Probably but I think there’s a lot of environmental pieces that we need to work on first. We also don’t see all cruciate ruptures being equal. Some dogs will start to stretch their cruciate ligament or it’ll start to fray a little bit. The cruciate ligament is actually kind of two ligaments all in one. One is a very tight band that runs down the center and then the other part of it kind of fans out on both ends where it attaches to the bone, so we can see some dogs that fray it, that start to tear it, some of those dogs with rest and with anti-inflammatories we can get things quieted back down and they may be OK. But many of them go on to have a full rupture, so it can either snap just walking down the street with your dog on a leash – you can hear it – and actually I have had clients come in and say I heard rupture. You can sometimes hear it just snap and sometimes it’ll slowly, over the course of time, fray and deteriorate and then tear all the way through. So I don’t think there’s only one kind of cruciate disease and I think we kind of lump them all together because we don’t have the resources at this point to really sort out what the different types are. Obesity, being out of condition … those kinds of things are certainly contributing factors to any kind of joint injury. And it’s questionable – I mean could something like Lyme disease that sets up inflammation of the joints – is there some other inflammatory disease process going on in these dogs’ joints that predispose them to cruciate ruptures? And at this point we don’t have all the answers for it. It’ll be a while I think before we do. But people are certainly looking, and the surgeons are very happy because they get to do lots of expensive surgeries on our dogs. So unfortunately when a dog does have a cruciate rupture, unless they’re pretty elderly, they are going to be subject to a fairly expensive surgery or potentially two surgeries, if they’re that 50% of the dogs that rupture the second side.

LR: Right. So that is the segue I was headed for. So, prevention … I don’t know that we have much prevention except for don’t spay them when they’re babies and don’t let them get fat and sloppy. <laughter>

MG: Yeah and I would really talk hard about the spay and neuter piece because a lot of veterinarians are still fighting us on that and they’re still very convinced that everything should be spayed and neutered and spayed and neutered young. And for a lot of reasons, I think early spay and neuter is really hazardous to our dog – individual dog – health for a population control situation. I understand that if I ran a humane society I would feel the same, but I don’t. I’m in private practice. I get to treat individual dogs and individual dogs – the owners need to be counseled on what the appropriate age to spay and neuter would be. And this is only one of the reasons – but a very important reason – because we’re talking sometimes three and four thousand dollars per knee to fix them. So pretty quickly a dog you spayed young or neutered young can end up to be an eight thousand dollar dog.

LR: Right. And we have talked on other episodes about cancer risks that come with early spay neuter and all of that. So definitely part of the process. So in the treatment category you talked about surgery. You also spoke a little bit, and I think we could go back to this just for a little bit, about the dogs who have had partial tears or a stretched or a frayed and so can we talk about a treatment protocol for those dogs? Because I’ve personally encountered those and that’s something that I think is a lot for a new owner to understand, “No, I mean it really can’t go run around.”

MG: Yeah you really do need to keep them rested. Not fat and out of shape, but rested. Try to come up with some activities that are safe or maybe go see someone that specializes in physical therapy for dogs. Do some underwater work, do some non-weight-bearing kinds of work so that you can keep the dog fit. Increasingly there’s numbers of places with underwater treadmills and swimming pools for dogs. In fact in the small town that I live in we’re only 15 minutes away from one and we’re an hour away from four pools. So there’s opportunities there, when the weather is nice of course, you can do swimming in the outdoor world. But here in Wisconsin when you have to break through the ice to go swimming it’s not much fun for the dog or for us. So we tend to avoid that – we tend to go inside. So underwater treadmills, working in the pool, good physical therapy. Braces – I don’t think can – splints have not really been proven to be highly effective in preventing the ongoing damage to the joint. I would certainly use an appropriate diet and there are several really good prescription diets on the market that are meant to reduce inflammation and joints. Hills makes one called J.D. There’s a mobility made by Purina … Royal Canin makes one. So there’s a couple of really good prescription diets that have high fatty acid contents and anti-inflammatory components to them that reduce inflammation in the joint. They tend to have a little glucosamine in them but they don’t have adequate levels of glucosamine and condroitin protect the joint, so I would be looking at a supplement and our favorite one is Dasuquin – one of those made by Cosamine, made by the Nutra Max company. They’re one of the few companies that actually has supporting evidence that says that their product has in it what it says it has in it. Because they’re nutraceuticals and not drugs, the FDA doesn’t oversee them. So we do see a lot of variability in efficacy and product quality. If you’re looking for an inexpensive version of it you’re probably not going to successfully find a good quality inexpensive version. So plan on spending a little bit of money and getting a good one but getting one that has some research behind it. But those are the things that you can do to <inaudible> inflamation. There’s also been some discussion about Doxycycline being anti-inflammatory in the joint. So not only does it treat Lyme disease, Anaplasmosis and Erlichia which all can contribute to joint inflammation – all three of those are tick borne diseases that are checked for on a lot of the tick panels that we do in practice – especially if you’re in Minnesota, Wisconsin, the Northeast where Lyme- you know, Connecticut and those areas are. So a lot of dogs being tested for those. So I would look at having the dog tested for those diseases – the tick borne diseases – and if there’s any question at all, a three week course of Doxycycline is generally pretty safe. Now I don’t do it on every dog, but if there’s any question about the dog carrying a tick borne disease I would try the dog on a course of Doxycycline to try and reduce inflammation in the joint. So those are the things that we can really do – just to protect the dog from over-exertion and to try and keep the dog in good physical condition and protect that joint until it could have a chance to heal.

LR: Right. And how long typically is it going to take them to heal that type of an injury where they haven’t actually ruptured the ligament, but they’ve injured it.

MG: It can take several months. <LR: Ok> So if you’ve got an active dog that’s involved in hunting, of course it’s always going to be at the wrong time of the year, it’s going to be during hunting season. If you’ve got a dog you’re competing with, of course it’s going to be right after you sent your entries in. You know I understand those things but you have to look at the long term benefits for the dog and that’s reduced risk of really significant arthritis if the dog goes on to have a full cruciate tear you’re unable to completely manage it surgically.

MG: And even with surgery, the best surgery – whether it’s a TTA or a TPLO – depending on the surgeon that you talk to, those are both very, very good surgeries for the <inaudible> back to about 90 percent of their full capacity.

LR: OK. OK, so TPLO was the one I’ve heard – say the other one again because I have – I’m not as familiar with that one.

MG: So the other one is the TTA. It’s similar to a TPLO – they’re both procedures that they go in and take a section of the tibia, cut that off, reposition it, and then change the angles in the joint with some hardware. So it’s similar to TPLO – just depending on the surgeon preference. Some do TTA, some do TPLO. The procedures that are considered to be the most effective for the athletic dog or the dog over 50 pounds. The smaller dogs – they still do a fair number of what are called tightrope or secureos or fishing line. There’s a couple of other terms for those, and those they just go in, clean up the joint and tighten it up but they don’t try to reposition some of the bone and change the angle so the joint, like they do in the TTA and the TPLO. So it depends on your dog, it depends on your budget, it depends on your surgeon and it depends on what your activity levels are expected to be when you’re trying to plan for what the procedure that’s best for your dog. And it’s not an emergency surgery. So if it happens on Saturday night you don’t have to have the emergency clinic do the procedure on Sunday.

MG: This is something that you should take your dog home, put them on anti-inflammatory medications, and do some research on who the best surgeons in your community are. And I really encourage people to go to a board certified surgeon for their knees to be done. It’s a big deal especially in a performance dog. So what we recommend in our practice is that the board certified surgeon does the surgical procedure on the dog. This should be somebody that does multiple cruciates a day, a week. Not somebody that does a couple of them a month. I like to have board certified surgeons doing these procedures. The outcome is much better. There’s a couple of different procedures. I had a surgeon that recently came in and we had a dog that had just a real mess in her knee. She spent three hours cleaning up the knee. And that’s something that’s beyond the scope of what many local veterinarians are going to do. So <inaudible>, talk to people and find out how you find the best surgeon. Spending a little extra money on the front end and getting a good surgery done the first time is really valuable. If the procedure goes badly it’s very difficult for that dog to make a full recovery with even a second and third surgery. Select your surgeon carefully and do use somebody that’s a really good surgeon when it comes.

LR: I think these are some excellent tips Marty and I really appreciate focusing on getting a good surgeon if you do have treatment, focusing on not early spay and neuter, and good fitness and weight levels to help prevent it. And just the awareness that this is something that may have some level of a genetic component for our breeders.

MG: Right. So select your genetics carefully. Even though we don’t know everything there is to know yet, think hard about how you put genetics together in your gene pool.

LR: Right. Very good. Thank you so very much Marty we appreciate it and we’ll look forward to talking to you on our next Veterinary Voice episode.

MG: Thank you.

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LR: That’s all for today. Thank you for joining us on Pure Dog talk.



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