Osteosarcoma, part one - Dog Cancer Blog

Featuring Demian Dressler, DVM and Susan Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide.

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Osteosarcoma, part one

Osteosarcoma (OSA) is the most common bone cancer in dogs, accounting for about 85% of bone cancer cases. The bottom line on OSA is that metastasis is a problem: 90% of patients will die from the metastasis within the 1st year when amputation is the only treatment. Those are grim statistics, but it is the bone pain from the tumor itself that creates the biggest challenge to most clients I meet. In an upcoming post I will focus on the decision to amputate and the myths I hear. But first, let’s get background info out of the way.

Which bones are most common to develop osteosarcoma?

Osteosarcoma can develop in any bone in the body, but three-quarters develop in the limbs, with the front legs twice as likely to develop osteosarcoma as the hind legs. OSA tumors are usually found at the end of the bone (called the metaphysis), and this can help to distinguish them from bone tumors that have spread from other primary cancers, which are usually found in the middle of the bone (called the diaphysis). The most common locations for OSA are the top of the shoulder (top of the humerus bone), the wrist (bottom of the radius bone), and the knee (bottom of the femur bone or the top of tibia bone). Another common site is the bottom of the tibia bone at the ankle or hock joint. OSA can sometimes be found in the middle of bones and in body bones, but this is less common.

Why is osteosarcoma considered to be aggressive?

Osteosarcoma (OSA) tumors grow fast and metastasize quickly. Only 10 to 15% of dogs with osteosarcoma already have detectable lung metastasis when they are first diagnosed, but a whopping 90% have micrometastasis (undetectable spread). This incredibly high rate of micrometastasis makes systemic chemotherapy treatments just as important as tumor removal. Treating the primary bone tumor does not address the metastasis. Still, despite this aggressive behavior locally in the bone and the metastasis, OSA is a highly treatable tumor, in my opinion.

Tumors can also metastasize to other bones, but this is less common. The regional lymph nodes can also be involved, although this only occurs in 5% of dogs.

Which dogs get osteosarcoma?

Limb osteosarcoma is usually seen in middle-aged and older dogs, age seven to nine, but we also see a smaller peak incidence in dogs between the age of eighteen months and two years. Axial OSA can be seen in any breed at any time, but limb OSA is usually seen in the front limbs of large and giant breeds, including Great Danes, Saint Bernards, Irish Setters, Rottweilers, German Shepherds, Golden Retrievers, and Doberman Pinschers. Breed is not as important as height and weight; heavier and taller dogs are more likely to develop OSA.

What causes osteosarcoma?

Many different factors have been found that may influence the incidence of this disease, although the exact cause of OSA is unknown. One theory is that small “micro-fractures” occur in the long bones as they bear the weight of the dog’s body. These tiny fractures and subsequent multiple minor injuries in cells can lead to signals that increases the chances of mutant cells and developing malignancies.

There is an also association with surgical metallic implants (like those used to repair a fracture), bone infection, bone trauma, and even fractures without internal fixation has also been found. Radiation exposure — previous radiation treatment that bone was included in the radiation field — can lead to OSA later in life.  This late complication of ionizing radiation is rare and  usually happens three to five years after radiation treatments for other cancers that a bone was included in the radiation field.

Sex hormones have recently been shown to protect against OSA development. The interesting study was of Rottweilers who were spayed or neutered before one year of age: they were four times more likely to develop OSA later in life.

A number of molecular and genetic factors have been implicated in OSA development. Some genes researched include mutated p53 (a tumor suppresser gene), retinoblastoma, PTEN, and possibly c-Kit alterations. Angiogenesis, new blood vessel formation, can also play a role in OSA development and progression. Other growth factors, cytokines, and hormone signaling systems, alterations in matrix metalloproteinases,

What are the symptoms of osteosarcoma?

OSA bone tumors can cause pain, lameness or limping, weakness and even severe bone fractures in the primary site. The risk of a pathological fracture, a sudden and painful bone break, is real, which is why amputation is the most prudent immediate course to take. We will talk about treatment including amputation more in a future blog.

As I said above, despite the aggressive behavior locally in the bone and the high metastastic rates, osteosarcoma is a highly treatable tumor in my opinion. Next we will talk about getting a diagnosis and treatment.

 

About the Author: Susan Ettinger, DVM, Dip. ACVIM (Oncology)


Susan Ettinger, DVM. Dip. ACVIM (Oncology) is a veterinarian oncologist at VCA Animal Specialty & Emergency Center in New York, and the co-author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog's Life Quality and Longevity.

  • Thanks for this article. This is the type of cancer our dog Becca developed. I just wrote about her on our blog this week in response to a post about can dogs be too old for cancer treatments. http://slimdoggy.com/can-a-pet-be-too-old-for-cancer-treatment/

    While I’d read up on this cancer when Becca was first diagnosed, I never saw causation info…I think the idea of micro fracture is interesting, particularly in Becca’s case as she carried a pack as a service dog for many, many years. I can attest to its aggressiveness.

  • Shelley Wall

    Please sign me up for your newsletter. My precious 5 yr old Boxer, Roxie, is now 3 weeks post amp for osteosarcoma. I want to do everything possible to keep her healthy.

  • KP

    Thank you for this article. Thankfully, I have not yet had to deal with cancer in my dogs and hopefully I won’t in the future. However, do you suggest that dog owners be proactive and perhaps feed the Dog Cancer Diet to an otherwise healthy dog? It seems like diet and nutrition in people can assist in preventing illnesses, I assume that is also the same for pets.

  • Juliette

    Dear Susan

    One of my rescue dogs (a medium-sized lurcher) was neutered by the shelter at 8 months old. Should I be asking my vet for testosterone replacement therapy? Is such a thing available? He is 3 years old now, seems in perfect health and I need to keep it that way! I would very much appreciate your advice.

    Best wishes,

    Juliette

    • Dr. Susan Ettinger

      Juliette,
      Spay and neuter does not mean your dog will get OSA. It’s one of many contributors. So focus on good diet, maybe a supplement like EverPup, and routine veterinary visits.
      All my best, Dr Sue

    • Dr. Susan Ettinger

      Juliette,
      Spay and neuter does not mean your dog will get OSA. It’s one of many contributors. So focus on good diet, maybe a supplement like EverPup, and routine veterinary visits.
      All my best, Dr Sue

  • Jane

    Thank you so much for this article. This hits very close to home with me.

    One fourth to one third of retired racing greyhounds in North America develop osteosarcoma. This is true whether or not they raced. Spanish greyhounds have a much smaller incidence of osteosarcoma, despite being a very similar breed and running for more hours than a racer. To me this would imply that, in the US stock of racing greyhounds at least, the problem is primarily genetic. Unfortunately, not being a doctor-type, I don’t totally understand the genetics you mention. I just appreciate all that the oncologists do to treat and hopefully reduce the incidence of this disease.

    You mentioned that a study in Rottweilers implicated that early spay/neuter might be involved. Since racing greyhounds are not spayed/neutered until they retire at about 3 to 5 years of age, would this seem to negate the Rottweiler study? Female greyhounds do receive hormones to keep them out of heat during their racing career, but males do not. Both get osteo. I guess I’m wondering what your take on this might be?

    Thankfully, due to their relatively light weight and narrow body, the greyhound responds extremely well to amputation. My greyhound, Joe, survived for 20 months after amputation of his right front leg. He had IV chemo followed by a metronomic protocol for his remaining life. Ultimately he developed a second primary tumor in his left rear leg and I had to let him go. He was my heart and soul. He couldn’t have been a better companion.

    • Dr. Susan Ettinger

      Hi Jane,
      Great point about Greyhounds who are not spayed/early. This is a complicated cancer with many factors at play. I don’t want to imply that all dogs that get spayed/neutered get this cancer or that sex hormones are compositely protective.
      Sorry to hear about Joe. Years after the loss of my Paige, a huge hole remains in my heart.
      With sympathy, Dr Sue

  • Linda Vick

    Dr. Ettinger,
    Please do not leave Greyhounds out of the group of dogs that develop Osteosarcoma. Important research is being done by Dr. Guillermo Couto at Ohio State University that may someday lead to a cure not only for canines but for humans, too!
    I hope that your readers understand that “treatable” is not the same as curable. 5 years is the record survival time post diagnosis for a Greyhound in the US. Did you know that Osteosarcoma is unheard of in Greyhounds in England and Ireland?

    • Dr. Susan Ettinger

      Hi Linda,
      You are the 2nd comment about Greyhounds. Yes they are a breed that we see too many OSA! And Dr Couto and his research at OSU is great.
      Your distinction of treatable vs curable is correct, but dogs with treatment live statistically longer (and with better quality to life) than without treatment. Still OSA is touch and more treatment options are needed!
      All my best, Dr Sue

  • theresa

    I have heard of something called Hoxey Boneset that is often used as a treatment in osteosarcoma cases. What is it and has it been used with success?

    • Dr. Susan Ettinger

      Therese,
      It’s a mixture of herbs created by an insurance salesman in the 1920s and promoted as a cure to cancer. It has not been shown to be effective. In the Guide, my co-author Dr D does not recommend it. I have never used it.
      All my best, Dr Sue

  • Sandra Owens

    My racing greyhound died at 13 from bone cancer probably due to the stress on her bones on the racetract. She may have had small fractures that no one knew about and this could have attributed to this. I have another greyhound now who is 11 years old but nothing so far. Hope he does not get bone cancer due to him also being a race dog.

    • Dr. Susan Ettinger

      Sandra,
      Knowing you have a breed at risk, be vigilant with monitoring including watching for lameness, limping. While it could simply be arthritis, you can be proactive and get into your vet promptly.
      All my best, Dr Sue

  • Debra

    My Louie a great Pyrenees is 6 months post amp. I take him to a holistic doctor and give him everything I can to boost his immune system. We opted to not do chemo. Chemo, in my opinion, wrecks an already weak immune system. We give him artemisinin as well as many other herbs. In my opinion much of the cancers our dogs are suffering from is caused by weakened immune systems because the dog food we feed them is full of awful stuff.

    • Dr. Susan Ettinger

      Debra,
      Chemo is not for every pet Guardian, but for OSA, chemo does statistically and significantly increase how dogs live after amputation. And I think chemo is tolerated very well by most dogs. Still each person must weigh the pros and cons and decide what is right for them. I am trying to help pet owners make educated decisions. Thanks for sharing and good health to Louie!
      All my best, Dr Sue

  • Judy

    I just read an article in the Penn Veterinary “Penn Vet Extra” regarding a vaccine for osteosarcoma in dogs.

    Maybe some readers as well as Dr. Dressler and Dr. Susan Ettinger will find some helpful and interesting information.
    judy

    • Dr. Susan Ettinger

      Judy
      Yes this is an exciting study. As the article points out, it is too early to know if the vaccine will increased survival, but it would be great to have more treatment options for OSA.
      Thanks for sharing with us and our readers.
      All my best, Dr Sue

  • Steph

    My 6 year old rottie passed at the end of October from Osteosarcoma. We did the amputation but within 3 months she had 2 huge masses in her lungs. I was working with a holistic vet and she was on the cancer diet as described in the book. She had trouble recouperating after the amputation and I decided against the chemo. (I was also dealing with my ailing mother at the time. She passed in September.) Towards the end her remaining legs swelled. The vet said her body was putting down new bone over her leg bones, something they see sometimes with osteosarcoma. She was a stray, I adopted her when she was 3 (we’re guessing). She had just been spayed and tested positive for heartworms when I adopted her. She went through the heartworm treatment. I can’t help but think that her life before I found her could have had an effect. What kind of nutrition did she get as a pup? What kind of stressors was she subjected to? I think the micro-fractures theory is interesting.

    I also find it interesting that Greyhounds in England rarely get osteosarcoma. I wonder if it’s food/nutrition related. There is so much garbage on the market in the US (just like US human food).

  • Karen

    My golden retriever had her front leg amputated 17 feb 2011 due to bone cancer but she sadly died 6 days later , the results from her lymph nodes showed that her cancer had spread every where

    • Dr. Susan Ettinger

      Karen,
      I am so sorry for your loss. Years after losing my Paige, I still miss her. I know the pain can be overwhelming.
      With sympathy, Dr Sue

  • Tammy von Langen

    My dog (lab mix) age approximately 11 was diagnosed today with bone-cancer. I have been trying to study my options and I understand amputation is best but he already has severe arthritis in his hips (recently had the stem cell procedure to help his arthritis) so I am concerned his arthritic remaining hip would not be strong enough. What are my options? Will radiation help the pain if I don’t amputate? He has an appointment with an oncologist on Tuesday but I am trying to learn everything I can in advance. Thank you.

  • Jolli

    My Pyr was diagnosed w/OSA one week ago. He is 120# good health male 6 yrs old. Left rear leg affected, lungs appear clean. My question is how do these large breeds recuperate after amputation and get around? They are so big and mine can be tempermental at times when made to something he doesn’t want to do. I need to make a decision quick. Amputation vs pain, amputation and chemo, or let it be and use pain meds. Anyone with a large Pyr??

    • Hello Jolli, I’m sorry to hear that you are battling a cancer diagnosis with your wonderful dog. You are good to consider all the possible options to both help him and give him the best quality of life. It is understandable to resist the recommendation for amputation… to our human minds it is an incredibly drastic option. But here are some thing to consider: Statistically, if you have a confirmed diagnosis of osteosarcoma, amputation of the affected limb is one of the best options you have, because you stand a good chance of literally cutting the cancer out of the body if it has not spread. The keys to knowing whether your large breed will cope is… (a) when a dog is in pain he begins to limp and not use the affected leg. In effect he is already rehabilitating himself to rely on the other three legs. Remember they have four altogether, and we only have two, so it’s harder for us to adjust to losing half of our resources! (b) Your vet will want to really examine his other joints, particularly the other, healthy leg and hip to determine whether everything is sound and his joints and body can carry the adjusted weight well. There is a wonderful resource, http://www.tripawds.com which will give you more information and examples of dog who cope very, very well after losing one leg. If your vet specialist recommends chemo after amputation, discuss it with him or her so you know what to expect. Dog can also cope very well with most chemo protocols. There is an extensive section in The Dog Cancer Survival Guide book which discusses osteosarcoma and most of the chemo protocols. I hope you have the book, and do you have your dog on the Dog Cancer Diet? Good nutrition is vital in this fight. IF you haven’t changed his diet, you can get all the info again from the book, and the main point of the diet are at http://www.dogcancerdiet.com. Also, Apocaps can help in so many ways to support your dog in this fight. If you have not started with any of these portions of his care, please go to http://www.dogcancerkit.com. Regarding your dog’s temperament, talk to him Jolli. Explain what’s going on, with your thoughts and fears, and with your love. He needs you as a champion now, and I can tell that you are have already taken on that role. Remember that if he is in discomfort with that leg, he will be irritable. I hope this helps. Please let us know how you get on. Susan from the Dog Cancer Support Team

  • Mike

    My greatdane girl, Angel was diagnosed with Osteosarcoma 4 years ago and an amazing vet at Mililani Mauka Vetinary Clinic did surgery and chemo. Prognosis had been poor but this tx gave her 4 years. No other vet was willing to do this and I am not sure why. Anyways recently it has come back and is sprerading quickly. She looks miserable and I am giving her Tramadol. She is going to the vets today. My greatest concern is pain. She is almost 9 years old. I do not want her to suffer. I want to know if chemo or radiation would be advised. I also want a good pain management plan. I think paliative or Hospice for dogs would be compassionate for dogs and owners alike. I have had other dogs die from Cancer and basically there was no good pain management available. Vets always prescribed anti inflamatories which were useless. Help.

    • DrSueCancerVet

      Mike,
      I am sorry about Angel. If the cancer is spread, you could consider oral chemo like Palladia or low dose oral/metronomic chemo. Radiation is a good palliative option for one are like a met/spread to another bone, but not the lungs. As for pain, there are lots of good options and often dogs need more than one from different categories – such as an NSAID, Tramadol, gabapentin, amantadine, fentabyl skin patches. And what works for one dog may not work for another, so work closely with your vet to find a safe combo for pain meds.
      All my best, Dr Sue

  • mary

    I have a very large labradoodle (weighs over 100lbs), he will be 9 in two months. My dog has an extremely high pain threshold, and he never shows pain until its almost too late. I work at a vet clinic and I brought him in for limping, we thought was from potentially injuring himself the previous day. My doctors couldn’t feel anything nor did he show any discomfort or pain aside from limping. After taking x-rays, I was told that it looks just like osteosarcoma but that he was not reacting painfully to them pressing/touching his leg like they would normally see in cases of bone cancer. We decided to send the views out to get further answers because they weren’t sure what to make of it since the only pain my dog has been showing is by limping. The past few weeks my dog has been really lethargic and has not been wanting to eat very much and I thought he was just showing signs of old age until I read about cancer signs/symptoms in dogs. The results from our outside radiologist will not be in for another day or two, and I am just wondering could it be possible that my dog has osteosarcoma even if he doesn’t show that he is in extreme pain?? Any opinion would be helpful

    • Susan Kazara Harper

      Hello Mary, Every dog is different, just as every human is, so yes, it could be osteosarcoma. But before you put too much energy into worry, get those results back. You’re fortunate to have access to diagnostics and I’m glad you got him checked immediately. The thing with osteosarcoma, sometimes the discomfort may only be shown when weight is put on the leg, rather than on palpating or pressing the area. If he’s been off his food and lethargic lately, something is bothering him. Here’s another link that might help you: http://www.dogcancerblog.com/dr-sues-recommended-tests-for-osteosarcoma-diagnosis-and-work-up-pre-surgical-biopsy-optional/#.U0KY6q1dUnI If it is a confirmed diagnosis for your boy, there is a lot you can do, so please stay positive. If your vet has an oncologist to refer with, that will really help. Nutrition is also key (at any stage, of course but particularly if he’s got a chronic situation to deal with) so you may want to download the Dog Cancer Diet at the top of the blog page. The full diet plus loads of other information is in the Dog Cancer Survival Guide book. Good luck. Give him a big cuddle from us. Let us know if we can help in any way going forward. We’re with you.

  • Lori Barrett

    I just found out my 10yr old dog Midnight has osteosarcoma. She also has an old injury which is torn acl from when she was 4 yrs old that never got fixed. She has lived with that really well. But I would like advice if amputation would be a good option especially with a bum back leg and the weight bearing issue

    • Susan Kazara Harper

      Hi Lori,
      So sorry to hear about the diagnosis. Give mIdnight a big cuddle from all of us, and one for you. The decisions about amputation surgery is hard, as all of these decisions are in a cancer journey. You are right that weight and the condition of the other legs both play a big part in making this decision. Whether the surgery is right for Midnight is really down to you with the advice from your vet. If the osteosarcoma is localised and hasn’t metastacized, it also plays a part. Dr Dressler and Dr Ettinger devoted and entire chapter (chapter 12) to osteosarcoma in their book The Dog Cancer Survival Guide. It really goes into all the considerations, options for treatment etc. that would be very hard to cover here. Nutrition will play a huge part in Midnight’s ability to respond to whatever options you choose and of course the chapter in the Dog Cancer Diet gets into the food to feed, and those to avoid, during a cancer fight. There is also a terrific website, http://www.tripawds,com which is devoted to all the options of a three legged lifestyle. I have seen many dogs bound around three days after surgery; it’s not as debilitating for them as we humans believe. But just like us, each dog is an individual. I urge you to check the resources I’ve mentioned, read that chapter so you have some good information to work with your vet, and talk with Midnight. When you know what is in her heart and what her wishes are, combined with the medical information, you will be able to make a decision that you will feel content with. Good luck to you both. There is so much you can do, and the biggest first step is to get informed as you take the panic away from your heart. Hold that girl close and she’ll know you’re in this together.