Originally posted in the Greytalk forum on September 13, 2011

Hi, everyone.   This is the story of my 5 year old Greyhound, Dakota.

In the middle of October 2010, my husband and I adopted Dakota Kid. He was a 4.5 year old ex-racing Greyhound, originally from Arkansas, and had been in Canada (which is where we live) since March 2010, but had to be given back to the adoption agency because his owners were relocated overseas. About 3 days after we got Dakota, I noticed a limp on his right front leg. Initially, I thought it was because I had given him a bath, and he had jumped/fallen out of the tub. He didn't show any distress at the time of the fall, but it was the only thing I could think of that had happened to him since arriving at our house. I thought it was a soft tissue injury. Over the next week or so, the limp became progressively worse. I thought this was because Dakota had been playing in the back yard with our other 2 dogs. Finally, we confined him to an ex-pen so he could rest and heal.

On Hallowe'en, I let him into the back yard, and he slipped on the stairs on the deck. It was obvious that he'd injured the leg further. I still thought it was a soft tissue injury. The next day, however, the leg was swollen and red, so I took Dakota to the vet. X-rays revealed a pathological fracture due to an osteolytic lesion (i.e., a bone lesion caused thinning of the cortex of the bone to the degree that the bone was weakened and fractured as a result of what would normally be a minor insult). I should mention at this point that for the entirety of the time we'd had Dakota, the only symptom he'd ever shown was lameness. This will become important later.

The first thing anyone thinks when they see an x-ray like that is that it's osteosarcoma. However, osteosarcoma is rare (although not impossible) in dogs as young as Dakota, and the specific site of the lesion (proximal radius) is not typical of osteosarcoma. Needless to say, we did chest x-rays, but those appeared to be clear. So, the first thing to do was rule out some of the "weird" greyhound diseases that can cause bone lesions. 4DX snap test was negative on all accounts (this tests for common tick-borne diseases). Blood was taken for a fungal panel (another likely candidate for bone involvement). A Jamshidi needle bone biopsy was performed (to see if it was osteosarcoma, and also to culture any organisms present). A CBC (Complete Blood Count) was done.

Fungal panel came back negative. Bone biopsy was inconclusive. Because the biopsy was done with a Jamshidi needle, minimizing the chances of further fracturing the already weakened bone, we knew there was a possibility that the sample would be too small to provide a representative cellular overview, and thus would not be able to provide a diagnosis (which was exactly what happened). Cytology and bacteriological cultures didn't reveal any infectious agents. CBC showed a possibly elevated white blood cell count. Greyhounds have weird blood parameters anyway (in some ways closer to cats than other dogs), and without a baseline (we didn't have one because we'd only had Big D for 2 weeks when this all happened), it was impossible to say if WBC was actually elevated. If it was elevated, it was only slightly so.

I should also mention that, because a bone infection is another primary cause for osteolytic lesions, Clindamycin was begun immediately. The leg was stabilized with a wrapped, padded splint.

The bandage needed to be changed about every 10 days. This required tranquilizing, so x-rays were done at the same time. The second set of x-rays showed neither improvement nor degradation. The third set showed the same, and at this point, we switched antibiotics (to Clavamox). Finally, the last bandage change, Dec. 6, the vet clinic where Dakota goes had just hired a new board certified surgeon who's specialty is... bone infections. So he had a look at the x-rays (4 sets in all). He did't think it was a bone infection, but did't know what it was. The vet and the surgeon disagreed on whether the x-rays show improvement, degradation, or nothing at all. They disagreed on whether a bone infection or a tumour was the more likely diagnosis.

So, I finally contacted a top Greyhound Osteosarcoma vet. He agreed to look at the x-rays. Keep in mind that he has seen literally thousands of cases. But he had never seen one like this.

He recommended that we do a new bone biopsy, but curette the bone, which means to take a way bigger piece. So we did (we actually took 4 pieces, bone marrow aspiration, and tissue sample for bacteriological culture.)

When the clinic got the results, the surgeon immediately phoned the pathologist who had done the lab work. The surgeon gave a detailed explanation of Dakota's case. After an hour on the phone, the pathologist was unwilling to commit to any of the possible diagnoses (at that point, the list included osteosarcoma, some other bone cancer, bone infection, atypical bone cyst, and benign bone tumour). So again, the results were inconclusive. 

Here's a brief summary of why this was such a strange case at this point:

They didn't know what it is because, the most likely thing is osteosarcoma and:

1) osteosarcoma is rare in a dog as young as Dakota (4.5)
2) osteosarcoma almost never happens in the proximal radius (in fact, the osteosarcoma vet had NEVER seen it in that location)
3) osteosarcoma usually gets worse really fast, and this was so slow that the vets didn't even know if it WAS getting worse
4) osteosarcoma usually metastasizes to the lungs, and that hadn't visibly happened in the 2 months since the initial vet visit (but lung metastases start off very small and are impossible to see on x-rays)
5) with the bone biopsy, cancer cells should be (but are not always) evident. None had been found.

If it wasn't some type of cancer, it could have been a fungal or bacterial infection, an atypical bone cyst, or a benign tumour. Here were the issues with those options:

Infection:
1) generally, there are other symptoms, like loss of appetite, lethargy, etc (normal things you'd expect to see with any kind of infection). There had been no symptoms other than lameness.
2) a fungal culture came back negative (ruling out most types of fungal infections)
3) infections also generally drain out the skin somewhere -- that wasn't happening
4) with a bone biopsy, it is possible to culture infectious organisms from the sample. None had grown.
5) a bacterial infection should respond to antibiotics -- it was unclear if that was happening or not
6) infections should change things like white blood cell counts -- greyhounds have weird blood cell count parameters anyway, but it didn't look like they were changed too much, if at all, from normal

Bone cyst or benign tumour:

1) EXCEEDINGLY rare (like only about 7 reported cases of cysts in the literature, and a handful of benign tumours)
2) usually occur in the same spots as osteosarcoma (again, not the proximal radius)
3) unfortunately, hard to identify with histopathology

After the second inconclusive bone biopsy, a sample was sent from the lab here to the osteosarcoma specialist's pathologist. They couldn't make a definitive diagnosis either. At this point, my husband and I were definitely feeling the financial burden. So that, in addition to not wanting to subject Big D to further veterinary torture, made us decide to simply take him home and let him be a dog. And so we did.

As time wore on, Dakota's pathological fracture, against all odds, actually healed (verified by x-ray later). He got to a point at which he hardly limped at all. In March, we decided to take him for a new set of x-rays to see if anything had changed. Indeed, as I just mentioned, the fracture was healed. Unfortunately, the lesion had grown in size. My husband and I were torn as far as what we should do. The vet and surgeon were recommending yet another biopsy. The osteosarcoma specialist had recently had a very similar case that had unexpectedly turned out to be osteosarcoma, so he also was recommending a biopsy, but this time a trephine biopsy (an even bigger sample than the previous two). Finally, we reluctantly agreed. Unsurprisingly, the result again came back inconclusive (it had even been sent to an entirely different lab in hopes that there was something wrong with the first one). So once again, we decided to resume our regime of doing nothing.

Within a few weeks of the last biopsy, Dakota was again using the leg almost normally. He was happy to come on long walks with our other 2 dogs. All was as well as could be expected.

Dakota enjoyed a nice summer -- until late August, that is. While playing, he suddenly began to cry out, and was obviously in extreme pain. So, back to the vet he went. Upon x-ray, a new pathological fracture was evident. But what was most striking was the lesion, which had expanded considerably since the previous March x-ray. My husband and I decided that this wasn't going to get better (and even if the lesion were not cancerous, its location precluded any sort of limb-sparing). So we decided to amputate. On August 29, Dakota went in to surgery to have his right front leg removed. After some initial complications with bleeding, requiring a blood transfusion (Greyhounds are notorious bleeders), Dakota has since been making a great recovery. He is adapting well, and today had most of his sutures and staple removed.

But the best thing was tha we finally got a definitive diagnosis from the pathologist today (we had the whole leg sent off when it was removed). It wasn't cancer... it was an aneurysmal bone cyst. This is a diagnosis so rare that I can only find about 5 case reports in the literature (I am in science, and so have access to all the journal databases). It was the best possible news. We knew we couldn't have saved the leg, and anuerysmal cysts can apparently turn cancerous if left unchecked (although given the paucity of canine cases, who really knows what would have happened).

Now, am I happy I made all the decisions that I did? Not at all. I feel horrible for having put Dakota through all of those procedures. But at the same time, there was always some hope that the lesion was the result of an infection or something that might resolve itself -- although looking back on it, and having a fairly decent understanding of probability, it would have been smarter to simply assume that it was osteosarcoma. And it was so tempting to hope when he actually recovered from the first fracture. And he did get to enjoy a summer of 4-legged fun. But now it is evident that having 3 legs isn't really an issue for him. Part of me wishes we would have gone straight to amputation.. or at least done it much earlier. However, it is what it is, and all I can do now is help Dakota to have the best possible life, which, as a result of today's information, should be a long one [Image Can Not Be Found] 

Below this post, I will post a series of x-rays of the leg, and some videos of Dakota as he is now...