Occurrence of tumours metastatic to bones and multicentric tumours with skeletal involvement in dogs

A retrospective study on bone metastasis in dogs with advanced-stage solid cancer

OBJECTIVES

To review clinical characteristics, treatment, outcome and prognostic factors in dogs with solid cancer-bearing bone metastases.

MATERIALS AND METHODS

Records were reviewed from dogs with histologically-proven solid cancer and bone metastases. Clinicopathologic variables, bone metastases characteristics and skeletal-related events were recorded. Endpoints were time to bone metastases and survival.

RESULTS

Fifty dogs were included, 20 of them with synchronous and 30 of them with metachronous bone metastases. In the latter group, median time to diagnosis of bone metastases was 210 days (range, 30 to 1835). Most common primary cancer locations included mammary gland (n=6), spleen (n=5) and tonsil (n=5). Most common histotypes were carcinoma (n=32) and hemangiosarcoma (n=10). Nineteen dogs had multiple bones involvement, with humeri and vertebrae more commonly affected. Twenty-four dogs received antitumoural therapy, five symptomatic treatment and 21 were not treated. Overall median survival after bone metastases diagnosis was 30 days (range, 11 to 49); 83% of dogs died because of skeletal-related events. Lack of antitumoural therapy was significantly associated with shorter survival (hazard ratio: 2.7; 95% confidence interval: 1.3 to 5.6) and with increased risk of skeletal-related death (hazard ratio: 3.3; 95% confidence interval: 1.4 to 7.4). Dogs with endocrine/neuroendocrine tumours (odds ratio: 8.8; 95% confidence interval: 1.2 to 63.9), without appendicular metastases (odds ratio: 5.1; 95% confidence interval: 1.0 to 25.8), without extra-skeletal metastases (odds ratio: 5.2; 95% confidence interval: 1.1 to 24.5) and receiving antitumoural therapy (odds ratio: 14.8; 95% confidence interval: 1.7 to 131.4) had an increased chance of surviving more than 100 days.

CLINICAL SIGNIFICANCE

Bone metastases in dogs with solid cancers are associated with poor prognosis and a high risk of skeletal-related events. Treatment appears to have an impact on survival.

Sternal Abnormalities on Thoracic Radiographs of Dogs and Cats

Evaluation of the sternum is part of the routine examination of small animal thoracic radiographs. However, descriptions on frequency and type of abnormalities are lacking. This retrospective observational study aimed to describe abnormal radiographic findings of the sternum in a cross-section of client-owned dogs and cats undergoing thoracic radiography between 1 January 2019 and 1 January 2021 for reasons unrelated to diseases of the sternum. The study population consisted of 777 dogs (mean age, 7.3 ± 3.9 years) and 183 cats (mean age, 7.3 ± 5.1 years). Sternal abnormalities were observed in 189/777 (24%) dogs and 53/183 (29%) cats, mostly around the intersternebral cartilages, accounting for 32/80 (40%) dogs and 20/35 (57%) cats. This was followed by an abnormal number of sternal segments (8% dogs, range 3–9 sternebrae; 15% cats, range 7–9 sternebra). Pectus excavatum was observed in 6/777 (0.8%) dogs and 6/183 (3%) cats, and pectus carinatum in 18/777 (2%) dogs and 2/183 (1%) cats. Post-traumatic changes, such as subluxation, were observed in nine dogs (1.1%) and three cats (1.6%). Presumed prostatic carcinoma metastasis and malignant lymphoma were observed in two dogs (0.2%). Incidental radiographic sternal abnormalities are common in cats and dogs but mostly of unknown clinical relevance.

Surgical management of a metastatic vertebral tumour originating from a mammary adenocarcinoma in a dog

An 11-year-old spayed female Toy Poodle presented with acute tetraparesis. A small subcutaneous mass was found in the right trunk region, and the magnetic resonance revealed a compressive spinal cord lesion due to an irregular bone proliferation at the third cervical vertebra. After surgical resection of the vertebral lesion, the neurological symptoms improved, and the patient could walk on her own. The excised vertebral and subcutaneous masses were diagnosed as a mammary adenocarcinoma on the histopathological examination, with Ki-67 and HER-2 immunohistochemistry staining. This case report highlights the importance of defining the primary tumours of metastatic vertebral tumours and the necessity of palliative surgery to improve the patient's quality of life.

Low-field magnetic resonance imaging characteristics of multifocal vertebral lesions in dogs

BACKGROUND

There is a lack of information regarding magnetic resonance imaging (MRI) features of polyostotic vertebral lesions in dogs. The aim of this retrospective study was to identify and differenciate low-field MRI features of aggressive versus benign multifocal vertebral diseases in dogs.

METHODS

MRI examinations from 49 dogs with polyostotic vertebral lesions were reviewed. Images were evaluated for vertebral intensity changes, expansile lesions, new bone formation, cortical bone interruption, paravertebral musculature changes, lymphadenomegaly, spinal cord compression and spinal cord signal changes.

RESULTS

Twenty-nine dogs with non-aggressive bone lesions and 20 dogs with aggressive vertebral lesions were included. Non-aggressive lesions had variable T2-weighted fast spin-echo (T2W) signal intensity and the majority displayed low signal intensity on short tau inversion recovery (STIR). Aggressive lesions predominantly had high T2W and STIR signal intensity, with variable signal intensity on T1-weighted spin-echo and contrast enhancement. Aggressive lesions were associated with spinal pain (p < 0.01), new bone formation (p = 0.02), spinal cord compression (p < 0.01) and lymphadenomegaly (p < 0.01). Cortical interruption (p < 0.01) and paravertebral musculature changes (p < 0.01) were the strongest indicative imaging features for aggressive lesions.

CONCLUSION

Spinal pain, spinal cord compression, new bone formation, lymphadenomegaly and especially cortical interruption and paravertebral musculature signal intensity changes were the best discriminators for differentiating malignant from benign vertebral lesions.

CT characteristics of uterine and vaginal mesenchymal tumours in dogs

OBJECTIVES

To describe the CT characteristics of uterine and vaginal mesenchymal tumours in dogs and to discuss imaging findings of the tumour types encountered.

MATERIALS AND METHODS

Retrospective study on female dogs with confirmed histological diagnosis of uterine and vaginal mesenchymal tumours and available CT images.

RESULTS

120 records obtained through a medical record search were manually evaluated for eligibility, and 11 dogs presenting masses associated with the genital tract were identified. Of these 11 dogs, 7 dogs met the inclusion criteria and were included in the study. A clear degree of overlap was present between measurements of maximal diameter of benign and malignant tumours; however, malignant neoplasms tended to occupy a larger portion of the pelvic canal. Objective measurements of length suggest that malignant tumours were longer than benign forms. Bone involvement was only observed with malignancy.

CLINICAL SIGNIFICANCE

Although CT is likely to play a limited role in the advanced workup of uterine and vaginal mesenchymal neoplasms, CT may represent a more accessible diagnostic tool than MRI and results of this study may help imagers familiarise themselves with their appearances.

Review of oncological emergencies in small animal patients

Oncological emergencies can occur at any time during the course of a malignancy and need to be recognized promptly to maximize successful outcomes. Emergencies are characterized as chemotherapy-induced, paraneoplastic syndromes, or directly related to the neoplasm. Prompt identification with treatment of these emergencies can prolong survival and improve quality of life, even in the setting of terminal illness. This review aims to educate the reader on the pathophysiology, clinical presentation and treatment of some of these emergencies, and to review the current veterinary literature to help educate veterinarians in primary and tertiary facilities to know how to diagnose and treat these serious conditions.

Malignant pilomatricoma in a dog with local and distant metastases treated with chemotherapy and bisphosphonates

A ten-year-old male neutered cross breed dog presented for evaluation of a mass associated with the left scapular bone, identified as a carcinoma. The dog had a malignant pilomatricoma removed from the left lateral thigh 6 months earlier. Histopathology review of the cutaneous and scapular mass identified the same tumour type, confirming metastatic disease; additional metastases to the inguinal lymph node, liver and lungs were identified. Chemotherapy resulted in partial responses/stable disease of very short duration. Bisphosphonates were administered due to lack of a measurable response and worsening of the associated lameness. The patient ultimately developed a symptomatic vertebral metastasis and was euthanased. The dog survived 255 days since medical treatment was started and 455 days since surgical removal of the primary tumour. This case report suggests that medical treatment with the addition of analgesia may be able to palliate clinical signs and possibly extend survival in dogs with metastatic epithelial cancer.

Animal Models of Bone Metastasis

Bone is one of the most common sites of cancer metastasis in humans and is a significant source of morbidity and mortality. Bone metastases are considered incurable and result in pain, pathologic fracture, and decreased quality of life. Animal models of skeletal metastases are essential to improve the understanding of the molecular pathways of cancer metastasis and growth in bone and to develop new therapies to inhibit and prevent bone metastases. The ideal animal model should be clinically relevant, reproducible, and representative of human disease. Currently, an ideal model does not exist; however, understanding the strengths and weaknesses of the available models will lead to proper study design and successful cancer research. This review provides an overview of the current in vivo animal models used in the study of skeletal metastases or local tumor invasion into bone and focuses on mammary and prostate cancer, lymphoma, multiple myeloma, head and neck squamous cell carcinoma, and miscellaneous tumors that metastasize to bone.

Pain management in veterinary patients with cancer

Pain is a widespread clinical symptom in companion animals with cancer, and its aggressive management should be a priority. Education and skills can be acquired by health care professionals and caregivers to better understand, recognize, and treat cancer-associated pain. The early and rational institution of multimodality analgesic protocols can be highly effective and maximize the chances of improving quality of life in dogs and cats with cancer. This article describes the pathophysiology of pain in companion animals diagnosed with cancer. The foundational causes of cancer-associated pain and treatment strategies for alleviating discomfort in companion animals with cancer are discussed.