Hi Tripawds!

Firstly, we can't thank you all enough for this incredible resource. I'd love to fill you in a little on our pup and would greatly appreciate any feedback. I apologize for the length of this post, I just felt the actual remarks would be helpful. We're hoping someone has been through this as well and had insight. We also know there's a wealth of knowledge on this site. We're scared for our pup and the super challenging road ahead.

Our little man, Holden, a 2.5 year-old Aussie Mix rescue, collided with a dog at the dog park at the beginning of December. He immediately sat, looking a little dazed, and did not want to put his left paw down. We kept an eye on him, and it resolved itself over the course of two weeks. He had a minor limp, but was otherwise his normal, bubbly self. Mel and I both travelled home for Christmas and boarded Holden at his favorite play place. When I picked him up, I noticed the limp was back, and there was swelling. We gave him three days, and then when I took him to the vet for some vaccines, the vet offered to X-ray. The X-ray showed some cloudiness in his leg at the bone and she referred us to a surgeon in the area for a closer look.

Our surgeon's initial thought was that we were dealing with osteosarcoma. It's in the number one place this presents, and since Holden is still young, he felt he was in the young age range for when this disease presents.

That's when we started on a very long journey for answers. Chest X-ray (early January) was negative for masses. We also did an aspirate. This came back inconclusive, but was positive for "active cells" and negative for infection. So, we went back again and did a bone biopsy. This biopsy was very, very confusing. Here's the summary from the pathologist:

The intimate intermingling of the spindle cells and collagenous stroma with irregular lakes of osteoid is suggestive of a

fibroblastic variant of osteosarcoma and given the location and the radiographic findings this is the favored differential diagnosis.

However, these kinds of changes can also occur at fracture sites and secondary to inflammation and trauma. Other differential

diagnoses such as fibrous dysplasia and ossifying fibroma cannot be entirely ruled-out but are less likely.

Immunohistochemistry for an osteoblasts marker (osteocalcin) may be useful although this marker is associated with relatively

low sensitivity (70%) and therefore false negative results are common. If a cellular aspirate is available, ALP staining could also

be considered. This test can be useful for identifying osteoblasts if atypical cells are present on cytology.

We've also done a stain that came back inconclusive, and we also had the bone sample sent to the leading pathologist on osteosarcoma in the country. Everyone seems to think this certainly LOOKS like osteosarcoma, but no one really wants to definitively say it.

We met with an oncologist yesterday to discuss our options. He was willing to offer palliative radiation to the area. He works very closely with our surgical vet at the same clinic, and they discussed. We originally were going to do a biopsy again on Friday, but now are thinking we should amputate and send the entire limb to the leading specialist so that she might take samples as she pleased to try and get a definitive answer. We also re-Xrayed yesterday and the degeneration has very mildly advanced, but stayed in the same place, which our vet believes is also indicative of osteosarcoma.

We are willing to amputate because he IS in pain and has a consistent limp. We also want to start getting some definitive answers. Our vet said young pups average 9 months to a year after diagnosis. We don't want to lose out on time.

However, we feel as if we might be taking a drastic measure with not enough information. Our write up from yesterday says:

Diagnostics & Treatments:

Two-view left carpal radiographs:

Image Findings:

Compared to rdvm films dated 1/7/2017:

There is moth eaten lysis and stippling of distal metaphysis of the radius with an ill-defined zone of transition. There is mild

cortical expansion and there is thinning of the cranial cortex at this level. Minimal ill-defined new bone formation is noted

along the cranial cortex. These findings are relative unchanged from the prior study. The remaining skeletal structures are

unremarkable.

Diagnostic Interpretation:

Left distal radius aggressive lesion. The primary differential is a primary bone tumor. Fungal osteomyelitis cannot be

completely excluded. A benign lesion (e.g. bone cyst or osteoblastoma) cannot be completely excluded given the slow rate of

change. Bone biopsy is recommended. Thoracic radiographs are recommended.

Visit Summary:

The lack of a definitive diagnosis coupled with the somewhat atypical presentation of the lytic bony lesion makes

Holden's case challenging. Radiation therapy typically plays a role in the palliation or alleviation of pain/discomfort in

bony neoplastic processes when aggressive surgical intervention is not possible or declined by the owners. While

Holden is uncomfortable from his mass at this time, his young age and possible detrimental short and long term side

effects from radiation therapy (particularly if the lesion turns out to not represent osteosarcoma), as well as the

possibility of Holden being a good, reasonable candidate for amputation (and chemotherapy if needed) leads us to

not recommend radiation therapy as the treatment of his condition at this time.

We discussed additional sampling of the mass with resubmission of biopsy to attempt to gain a diagnosis. While a

somewhat drastic procedure, a limb amputation would potentially gain the best chance of diagnosis (by submitting

the entirety of the lesion) as well as likely be well tolerated by Holden considering his lack of additional comorbidity.

The possibility of a non-diagnostic biopsy, even despite an amputation, was discussed. We would also recommend

obtaining an additional cytologic sample of the lesion even is amputation is pursued to hold for potential future ALKP

ICC in the future. If amputation is elected, we strongly recommend repeating thoracic radiographs for restaging to

ensure there is no evidence of pulmonary metastatic disease which would drastically alter Holden's prognosis.

If amputation is elected and the diagnosis confirms osteosarcoma, we recommend following surgery with adjuvant

chemotherapy to attempt to slow the metastatic progress of the tumor.

The thought of doing this and it isn't cancer is devastating. We are feeling very lost, and need to tell our vet tomorrow morning what to do.

Any and all advice is welcome. Thank you in advance!

Mel, Katie, & Holden