So mammary tumors. Obviously, we have a big one there. They are hormone dependent tumors. This is a very wide classification. So so they can be a whole bunch of different things. Epithelial is the most common. The benign ones are adenomas or sometimes mixed tumors. And the aggressive meta, or malignant ones are carcinomas. Okay. But there's a whole bunch of variety here. We get, again, a little bit of older range of 7 to 11, so not maybe quite as old, but they are very rare in animals or dogs under five. And then we all know this at this point, the predisposition is the unspayed females. We have had that absolutely drilled in at this point unspayed females or late spayed females are much, much more likely to have mammary cancer. There is a predisposition to purebreds and smaller dogs are a little bit more predisposed than larger dogs. But all of that goes back to being a late spayed or unspayed female. Not that males can't have it really, really rarely. But this is, you know a female dog disease for the most part. There's actually interestingly a little bit of predisposition in a couple of studies for young age obesity and for red meat consumption. So if their diet is based on red meat rather than poultry, there is a little bit of increased risk there. Clinical signs is often an incidental finding on your exam. The times it's not as when it's metastasized. So if it's gone to the lungs, you're going to get dyspnea. It can go into bones where you get lameness or just in general tumor burden causing malaise. I have seen them where they've gotten so big, they've outgrown their blood supply, they've gotten necrotic or they're ulcerated and bleeding. So you can get local signs. But in general, it's tumor burden and metastasis. The inflammatory carcinomas can be painful, but in general, these tumors are not. 

So diagnostically, again, I put a little circle on this one, but I think it's pretty obvious where that is, cytology can rule out non mammary masses, but it's not going to tell you the difference between the metastatic or a malignant or not. Histopathology is the one that's going to do that for you. Again, the staging, we get those regional lymph nodes. And staging we take from the human world where they are looking at mammary cancer in people and they stage with a T N M stage, which is tumor size, regional lymph node and distant Mets. So that gives you your staging. And depending on what you have of those and your tumor size grade. We definitely want thoracic rads on these. I do like to metastasize the chest and then obviously full bloodwork and this is another one, you want a clotting profile. As far as the grading with the histopath, you know, the more poorly differentiated, similar to mast cell tumor, the higher the grade and the more aggressively they're going to behave. 

Treatment wise. Primary treatment again, is surgical removal. Sometimes that is a lumpectomy. Remembering that in mammary cancer, if you have one, there is a 70% chance you have more than one in one of those chains. That does not mean it's metastatic. It just means you're going to have more than one. They can all be benign, but you're going to surgically remove either lumpectomy. You can do a regional mastectomy or sometimes a radical mastectomy. And there's some evidence everybody agrees with spaying at the time of surgery, but there's conflicting evidence whether taking those hormones away improves survival time or decreases the chances of reoccurrence even with the benign ones. But the general rule is to spay. Radiation and chemo again are used, but the benefits are unclear. So if we have incomplete excision with malignant tumors, we might think about some chemotherapy. Those are still unclear how much help that is. NSAIDs are often used because they do have cox II overexpression on these tumors. And so sometimes that can have some anti-tumor effect, which is super handy. 

And then just some pearls. Prognosis is extremely variable. The benign ones can be completely removed. They can be gone forever or they may come back in that chain, but that doesn't mean they're going to go anywhere else. Obviously, the more aggressive metastatic ones are not as good. In this population, so intact female dogs and intact female dogs in that age range of seven plus, it is the most common tumor. So a very select population. But in that population it's the most common tumor. 50 to 70% the neoplasia we see in that population. OVH, again, we all know this early spay before the first heat cycle reduces the risk of mammary cancer to less than 1% in that dog's lifetime. After two plus heat cycles, that dog will carry a 25% risk. Again, there is some conflicting opinions. If spaying later than that conveys some improvement in the risk of developing later on. There are some that say yes, so it is worth it. I will note as an emergency clinician that that population continues to have an increasing chance of pyometra every year. So I still think it's worth it to spay them. Dogs over ten years old have a 50% chance of having a pyometra if they are intact at ten years old and it only gets higher than that. So 50% chance in that year at ten years old. So a little plug for spaying for that reason. And so this is no longer common in the United States because we've adopted early spay practices. So it really decreased incidence. But in other geographic locations there are still high rates. So important tumor to know about. All right.