Accuracy of computed tomography in determining lesion size in canine appendicular osteosarcoma

Radiographic and CT features of metallosis in a lame dog after total hip replacement: the cloud sign

A 2-year-old female American Akita was referred for CT of the pelvis and hindlimbs due to a left hindlimb lameness after a left total hip replacement. Referral radiographs and CT images demonstrated amorphous soft-tissue and mineral opacities surrounding the proximal femur and the prosthetic stem, consistent with the "cloud sign" reported as a characteristic of metallosis in humans. Dorsomedial displacement of the prosthetic head, multiple foci of geographic osteolysis alongside the "cloud sign", presumed pseudotumor lesions, and medial iliac lymphadenopathy were also identified with CT. Metallosis was confirmed based on ultrasound-guided cytology, revision surgery, and histopathology.

Novel radical pelvectomy technique to treat chondrosarcoma in a large-breed dog

Surgical management of chondrosarcoma with hemipelvectomy is well described, but there have been no reports on extensive excision involving bilateral pubis and unilateral ischium. This report describes a novel pelvectomy technique for the treatment of chondrosarcoma in a large-breed dog. A 12-year-old Labrador Retriever presented for tenesmus due to a large, intra-pelvic mass which was confirmed on computed tomography (CT). Surgery involved removal of the entire left ischium and both pubic bones with preservation of both hind limbs. Histopathology confirmed the diagnosis of a high-grade chondrosarcoma with tumour-free margins of less than 3 mm. The dog recovered well following surgery and regained ambulation within 9 days. Four months postoperatively, the dog had no ongoing pain or tenesmus and only a mild gait abnormality in the left hind limb. Pelvectomy involving the entire pubis and unilateral ischium was well tolerated in a large-breed dog. This technique may offer a novel surgical option to treat neoplasia previously considered too extensive for complete excision.

Long-term outcomes with conventional fractionated and stereotactic radiotherapy for suspected heart-base tumours in dogs

Published radiotherapy results for suspected heart-based tumours in dogs are limited. In this retrospective longitudinal study (3/2014-2019), eight dogs with either clinical signs attributable to a heart-base mass (6), or asymptomatic with a progressively larger mass on echocardiogram (2), received conventional fractionated radiotherapy (CFRT) or stereotactic body radiotherapy (SBRT). Clinical findings in symptomatic cases included one or more of the following: retching/coughing (4), exercise intolerance (2), collapse (1), pericardial effusion (2), rare ventricular premature contractions (2), abdominal effusion (1), or respiratory distress due to chylothorax (1). CFRT cases received 50 Gray (Gy) in 20 fractions and SBRT cases received 30 Gy in 5 or 24 Gy in three fractions. Two dogs received chemotherapy post-radiation. At analysis, 7/8 dogs were deceased and one was alive 684 days post-treatment. The estimated median overall survival (MOS) from first treatment was 785 days (95% CI 114-868 days, [range 114-1492 days]). Five dogs received CFRT (MOS 817 days; (95% CI 155 days-not reached [range 155-1492 days])). Three dogs received SBRT with one alive at analysis (MOS 414 days, (95% CI, 114 days-not reached [range 114-414 days])). No statistically significant difference was found between survival for CFRT and SBRT. Of the symptomatic patients, 5/6 showed improvement. Mass size reduced in 4/5 cases receiving follow-up ultrasounds. Possible complications included asymptomatic radiation pneumonitis (4), atrial tachycardia/premature beats (4) and pericardial effusion with heart failure coincident with tumour progression (1). This study provides preliminary evidence that radiotherapy may impact clinically relevant or progressively enlarging heart-base masses.

A comparison of risk factors for metastasis at diagnosis in humans and dogs with osteosarcoma

Background

Canine osteosarcoma (OS) is a relevant spontaneous model for human OS. Identifying similarities in clinical characteristics associated with metastasis at diagnosis in both species may substantiate research aimed at using canine OS as a model for identifying mechanisms driving distant spread in the human disease.

Methods

This retrospective study included dog OS cases from three academic veterinary hospitals and human OS cases from the Surveillance, Epidemiology, and End Results program. Associations between clinical factors and metastasis at diagnosis were estimated using logistic regression models.

Results

In humans, those with trunk tumors had higher odds of metastasis at diagnosis compared to those with lower limb tumors (OR = 2.38, 95% CI: 1.51, 3.69). A similar observation was seen in dogs with trunk tumors compared to dogs with forelimb tumors (OR = 3.28, 95% CI 1.36, 7.50). Other associations were observed in humans but not in dogs. Humans aged 20‐29 years had lower odds of metastasis at diagnosis compared to those aged 10‐14 years (OR = 0.67, 95% CI: 0.47, 0.96); every 1‐cm increase in tumor size was associated with a 6% increase in the odds of metastasis at diagnosis (95% CI: 1.04, 1.08); compared to those with a white, non‐Hispanic race, higher odds were observed among those with a black, non‐Hispanic race (OR: 1.51, 95% CI: 1.04, 2.16), and those with a Hispanic origin (OR 1.35, 95% CI: 1.00, 1.81).

Conclusion

A common mechanism may be driving trunk tumors to progress to detectable metastasis prior to diagnosis in both species.

Imaging in Non-neurologic Oncologic Treatment Planning of the Head and Neck

Imaging is critical for the diagnosis and staging of veterinary oncology patients. Although cytology or biopsy is generally required for diagnosis, imaging characteristics inform the likelihood of a cancer diagnosis, can result in a prioritized list of differentials that guide further staging tests, and assist in the planning of surgery, radiation, and chemotherapy options. Advanced imaging, such as CT and MRI, can better define the extent of disease for surgical and radiation planning for head and neck cancer cases in particular. Additionally, new imaging technologies are continually being translated into veterinary fields, and they may provide more options for cancer patients as they become more widely available.