All right. Everybody kind of knows this one. It's maybe not as common as some of the others classically, but it's definitely a very, very common bony tumor and especially in our big guys. And we see these very classic lesions that we're going to get into. I'll show you a couple more x rays. But this, this very moth eaten, bony appearance. The loss of the cortice, the bony tissue extending into the soft tissue area, new bone being put down outside of the bone. And then it's not crossing the joint and I'll show you that again. But very classic x rays with this. 

So this is a tumor of mesenchymal tissue that has malignant osteoblasts. We have actually a bimodal age in this. Now, the small peak with the younger dogs is really small compared to the older dogs, but it is actually a bimodal age. The majority are the 7 to 9 year old, but we're talking about a 7 to 9 year old giant breed dog, which is actually quite elderly for a lot of these breeds. The biggest thing, the biggest predisposition for this type of cancer is dogs height and weight. So this is a giant breed disease. So these dogs over 30kg have a 60 times higher risk of getting osteosarcoma versus our cute little Chihuahua here who is leading the great dane around and is obviously in charge of the situation. But even even in our 20 to 30 kg dogs, which aren't that big, there is still an eight times higher risk than our smaller dogs. But we definitely think about our giant breeds. So that's the Great Danes, Dobermans, Irish Wolfhound, Irish setters. The tall ones in particular. But all of our big heavy dogs. And then there is some association with old fracture sites and the metallic implants that often go along with fixing them bone infarcts, radiation, chronic osteomyelitis, they do all increase the chances that we're going to have an osteosarc at those sites. 

The classic presentation here is about 75% of these tumors are going to be appendicular, meaning they're going to be on the limbs, are going to be on long bones. And then the classic away from the elbow towards the knee works most of the time. Remember, it doesn't have to work. You can still get osteosarcs in other areas, but away from the elbow being distal radius and then proximal humerus and towards the knee be distal femur, proximal tibia. Do you keep in mind, though, because this will trick some people up, distal tibia is equally likely when we look at the hind limbs, we see about 30% in that distal femur, 30% in the proximal tibia so arch towards knee and another 30% in the distal tibia. So the the rhyme works. But just keep in mind, it doesn't have to be the reason for the, the way it's going to present. And then we do get 25% in the axial skeleton. And that primarily we're going to see on one of the two jawbones, but we can see it on the vertebra, on the pelvis and on ribs. Clinical sign wise, they often present with a progressive lameness. We might see limb swelling and pain. And we've got this picture here of this dog with this obviously very, very swollen limb. But I also want everybody appreciate how painful this dog looks. If we're going to pain score this dog, this gets at least a four out of five for me. His eyes are squinted. He's pulling his whole body away from that site. And you know, his whole posture says pain. And these guys are incredibly painful. On the axial sites the signs develop a little bit on the locations. So if it's in the mouth, we might have dysphagia, we might have weight loss because they are having trouble with eating. If it's in a vertebra we might have neurologic deficit. So it does depend where those axials are. And these guys also can present with a pathologic fracture. So if you think about that x ray, you know that that bone is really compromised and it is not uncommon to get a pathologic fracture. I will say I see these maybe a little bit more frequently than on average for those pathologic fractures. And the story that comes along with it is often, "well he was getting older, he's arthritic, he was limping and boy, he stood up today and screamed and wouldn't put weight on it again". And that's because those bones break and that that gets you to these really, really high pain scores. 

So diagnostically, again, very dependent on the x rays. The x rays themselves will create a very strong suspicion. Can you diagnose 100% of them? No. But really strong suspicion. So you have some of these classic changes. You can see, this really dramatic soft tissue swelling here. You can see the loss of cortical bone. You can also appreciate in both of these that it is not crossing the joint. The other bone on the side of that joint looks entirely normal. And that is really important. We go through our deferential diagnosis list. It's usually in this metaphysial region which again, like proximal or distal end of the bones. And it has just this moth eaten appearance. If you look down here, it's just the bone is being lost. So pretty classic x ray appearances. We also want to do x rays of the chest to check for metastasis. That's a very common metastasis. So cytology is diagnostic in these guys a lot of the time, 75 to 80% if you can get the cytology out of there. So you can try. Histopathology is going to be a more definitive diagnosis. You can try an incisional biopsy. And when we say incisional biopsy to these guys, we mean a very specialized biopsy needle. There's jam shooting needles, other bone biopsy tools that actually need to go in the center of this lesion to get good cells that can be diagnostic. One thing I would caution you with is I mean, if you look at these bones that are already very compromised and we push a big needle in the middle of that, we can fracture it. So something to remember, if we're considering doing histiopath. And then that C.T. can be especially for like the jaw tumors, other locations for planning, we don't necessarily need it for these limb ones. All right, let's see. There is a new CT out, and again, touching on this. Do not expect it to be on your NAVLE® , but it's called a PETCT, P E T slash C T, and that's positron emission tomography. And it's actually starting to look at increased glucose use in various areas of the body. And it can identify primary but also metastatic sites. So that is that is up and coming. Just kind of some fun new technology. 

Surgery wise our treatment, I should say, is really surgery. That is the, you know, treatment of choice for these guys. So amputation with these appendicular ones is your standard. And believe it or not, this is one of those times where we will consider amputation prior to having a definitive diagnosis. So that's why I'm really harping on those x ray appearance being super specific. So if you have a large breed dog, it's older and you have that lytic lesion that is not crossing joints. It is okay in that dog to talk about amputation before you have the biopsy because you might fracture it, taking the biopsy and even and we're going to be lucky if we're wrong. Right? We would love to be wrong, But that bone is so compromised already that some of these other things that can cause that compromise, that bone is not going to heal anyway. And that's why it's okay to consider amputation prior to full diagnosis. There are also some limb sparing techniques, and that's for owners that really don't want to consider amputation or when we have a dog that is not going to do well on three legs. So limb sparing is equal to amputation when we look at survival times, but it does have increased complication risk. We get infection more off to the side. So increased complications certainly increase cost. But as far as survival times, it is equal to surgery. And they go in and they'll either cut out that piece of bone and use prosthetics. There's a new technique and we'll go into it with radiation. Couple of different ways that they can do that. They fuze the joint that's closest to that site. But again, a higher complication rate. Radiation can be used in two different ways with these guys, it's actually palliative. You can radiate that area. And in 75% of the cases, you're going to reduce pain. So it can be a palliative method and then it can also be post surgical for those axial locations that you can't get all of or sometimes you can't even get to it all surgically. We can talk about radiation. And then there again, there's this new type of radiation, radiation, radiation, goodness, which is SRT, and that's stereotactic radiation therapy. And that is a very focal large dose of radiation that spares the surrounding tissue and just gets at the tumor. So, again, it's using the limb sparing techniques and it's it's coming up in some others, too. But this is pretty promising new therapy. Chemotherapy is often used with these guys as well. Less success rates sometimes, but they absolutely, we'll, we'll put it out there. And those are usually platinum agents. So Carboplatinum, cisplatinum, palladia, again, has shown to slow pulmonary Mets. And then there are some palliative treatment options with these guys because remember, you know, that that first slide where we have all of that pain. So you have an owner with a 10 or 11 year old, you know, large breed dog that really doesn't want to put their dog through all this. And that's that's obviously not wrong. But we don't want that dog to look as painful as the dog in that picture. And so multi modal multi-drug therapy for pain. So you want to use combination therapy so you have an additive pain effect. So often using anti-inflammatories in combination with gabapentin, codeine, amantadine, maybe some tramadol seeing what works for that dog and what can handle. But aggressive, aggressive pain control bisphosphonates are used with these guys. They actually reduce pain and they will decrease bone reabsorption. So bisphosphonates decrease bone reabsorption and that can slow the tumor down a little bit and decrease the risk of those pathologic fractures. If you have thoracic Mets with these guys, then we actually consider glucocorticoids instead of NSAIDs, obviously not together. And then with these guys, we do the chest x rays and only 10% are going to present with metastasis at the time of diagnosis, but they all have them and we will have micromatast, micromets in those chests about 90% of the time at diagnosis. So again, we're not talking here with this one either, but that's where some of these other treatments come in. There's new therapies. Again, there's an anti tumor vaccine in the works and there are some autologous activated t cell therapy, which is using the patient's own OSA essentially in a vaccine to target that. When we talk about palliative, we look at this guy here, he's got this nasty bone tumor. He's probably not eating well. So sometimes we need to deal with the nutrition, secondary bacterial infections again, depending on location. That's pretty specific to, to that mouth problem will come with another couple of tumors that give us problems there. 

And then again, prognosis wise, we're not looking for cure with an appendicular with palliative alone, so that's just pain medication we get 4 to 5 months. Amputation without additional therapy is essentially palliative because we talked about 90% of these guys already have Mets in their chest when you find it. So those are going to continue to cause a problem but we've taken away the pain of that bone with amputation. And when we add multiple drug chemotherapy, we can get them up to almost a year. But if we have visible thoracic Mets at the time of presentation, no matter what we do, they're going to be a very low survival time. Axial really depends on where it's located and how well you can get at it. The mandibular OSA's actually have a better prognosis even just with surgery alone. So that's actually a little bit better. But obviously if you have a vertebral one, that's not a good location. So it really depends locationally with those guys. And then other differentials to consider when we look at those x rays. Basically there's other tumors that can do that. There is a list of other types of tumors, either other primary bone tumors, metastatic. You could have soft tissue and tumors that invade the bone locally. You can have blood tumors, hematopoetic tumors that get in there, but basically other tumor. So still cancer. And then you have these cases of bacterial or fungal infection, and that's always there when we tell the owner, well, I can't completely rule out that it isn't a fungal infection. But there's a couple of ways we can look at that. First, where you live in the country, you know, these are blastomycosis, coccidiomycosis, so travel history becomes important. And even just where this dog lives. Does it go out and dig in the desert or does it live by me in Virginia in somebody's house most of the time? And then we're really not seeing fungus. And even for the osteomyelitis, do we have a source? Has this dog been sick? Is it immunocompromised? Why is there bacteria there? And is it crossing the joints? So so both the both types of infection, bacterial and fungal, like to cross those joints. So again, we using our investigator skills to kind of come up with the most likely solution, talking to those owners and considering amputation and then knowing also that OSA accounts for 85% of all bone tumors we see and 95% in those in those really big breeds. So it's a nasty one.