Skeletal Metastasis of Canine Urothelial Carcinoma: Pathologic and Computed Tomographic Features

Invasive urothelial (transitional cell) carcinoma (UC) is the most common cancer in the canine urinary tract. Prolonged survival of dogs with UC due to better management of the primary tumor and prevention of urethral obstruction might have contributed to an apparent increase in distant metastasis. Metastasis to bone is particularly concerning because the ensuing pain often leads to euthanasia; however, little is known of the frequency, site, or nature of UC skeletal metastasis. In a retrospective analysis, 17 (9%) of 188 canine UC cases had histologically confirmed skeletal metastasis, mainly to the vertebrae. In a prospective analysis of 21 dogs with UC that underwent total body computed tomography (CT) at euthanasia followed by a standardized pathologic examination, skeletal lesions detected on CT were suspected to be metastatic in 4 dogs and were confirmed as metastatic UC histologically in 3 (14%) dogs. In all 3 cases, skeletal metastasis had been suspected based on history and physical examination; however, 1 dog had additional CT-detected skeletal metastases in a clinically unsuspected location, and 2 dogs had histologically confirmed skeletal metastases that corresponded to nonspecific osseous lesions on CT. These findings suggest that total body CT could be helpful in detecting skeletal metastasis as a cause of bone pain in dogs with UC as well as in identifying clinically “silent” sites of skeletal metastasis.

Effect of a Limited Iodine Diet on Iodine Uptake by Thyroid Glands in Hyperthyroid Cats

BACKGROUND

The effect of feeding a limited iodine diet on radioactive iodine uptake in the thyroid glands of hyperthyroid cats is unknown.

OBJECTIVES

To determine how feeding limited dietary iodine affects radioactive iodine uptake by the thyroid glands of hyperthyroid cats.

ANIMALS

Eight geriatric cats with spontaneous hyperthyroidism.

METHODS

Prospective study of eight client owned hyperthyroid cats fed a commercially available iodine limited diet for 6 months. Clinical signs were evaluated and TT4 and fT4 were measured during consumption of the diet. Uptake of (123)I was determined before and 8-16 weeks after exclusive consumption of the diet.

RESULTS

Clinical signs of hyperthyroidism resolved in all cats, but there was no significant increase in body weight. TT4 and fT4 decreased into the reference range by 8-16 weeks in all cats. Mean TT4 before consumption of the diet was 9.7 μg/dL (SD 5.2) and after consumption of the diet was 3.1 μg/dL (SD 0.9). Scintigraphy revealed unilateral uptake of isotope in 5 cats and bilateral uptake in 3 cats. Mean percentage uptake of (123)I by the thyroid gland at 8 hours after isotope administration was 16.2 (SD 11.8) before diet consumption and 34.6 (SD 11.7) 8-16 weeks after exclusive consumption of the diet. The percentage increase was variable between cats (38-639%).

CONCLUSIONS AND CLINICAL IMPORTANCE

Limited iodine diets increase iodine uptake in the autonomous thyroid glands of hyperthyroid cats. Further studies are necessary to determine if consumption of a limited iodine diet changes sensitivity of the thyroid gland to (131)I treatment.

A comparison of clinical, magnetic resonance imaging and pathological findings in dogs with gliomatosis cerebri, focusing on cases with minimal magnetic resonance imaging changes(‡)

The primary study objective was to determine whether clinical examination and magnetic resonance imaging (MRI) can underestimate canine gliomatosis cerebri (GC); we also investigated immunohistochemical features. Seven dogs with GC were studied; four recruited specifically because of minimal MRI changes. Neuroanatomic localization and the distribution of MRI, gross and sub-gross lesions were compared with the actual histological distribution of neoplastic cells. In six cases, clinical examination predicted focal disease and MRI demonstrated a single lesion or appeared normal. Neoplastic cells infiltrated many regions deemed normal by clinical examination and MRI, and were Olig2-positive and glial fibrillary acid protein-negative. Four dogs had concurrent gliomas. GC is a differential diagnosis for dogs with focal neurological deficits and a normal MRI or a focal MRI lesion. Canine GC is probably mainly oligodendrocytic. Type II GC, a solid glioma accompanying diffuse central nervous system neoplastic infiltration, occurs in dogs as in people.

Venous air embolism detected on computed tomography of small animals

OBJECTIVE

To describe the prevalence, location and clinical significance of abnormal gas accumulations in dogs and cats detected on computerised tomography images.

METHODS

Retrospective evaluation of all canine and feline computed tomography examinations (292 pre-contrast and 219 post-contrast) performed in a 12-month time period. All studies were evaluated for the presence of venous air emboli. The location of intravenous gas was noted and the volume of intravenous air emboli was estimated visually. The medical records of animals with venous air embolism were reviewed for signs of cardiopulmonary complications.

RESULTS

The overall prevalence of air embolism on pre- and incidence on post-contrast images was 4 · 5 and 2 · 3%, respectively. The prevalence of air embolism on pre-contrast and incidence on post-contrast thoracic images was 35 · 7 and 14 · 2%, respectively. The volume of venous air was generally small and the most common was in an axillary vein. None of the animals had any cardiopulmonary complications.

CLINICAL SIGNIFICANCE

The presence of small volume venous air embolism on routine computed tomography examinations is a frequent incidental finding that does not appear to cause cardiopulmonary complications.

Pulmonary abnormalities in dogs with renal azotemia

BACKGROUND

Clinical signs associated with respiratory tract disease are regularly encountered in people with kidney failure, and have been anecdotally reported in dogs.

OBJECTIVES

To compare clinical signs indicative of pulmonary disease, clinicopathologic findings, radiographic abnormalities, and histologic findings in dogs with acute kidney injury (AKI) or International Renal Interest Society Stage 3 or 4 chronic kidney disease (CKD) to nonazotemic dogs. To determine associations between abnormalities indicative of pulmonary disease and outcome in azotemic dogs.

ANIMALS

One hundred sixty-seven pet dogs (54 AKI dogs, 50 CKD dogs, 63 nonazotemic control dogs diagnosed with intracranial disease).

METHODS

Retrospective cohort study comparing signalment, clinical signs, clinicopathologic variables, prevalence, and severity of pulmonary radiographic patterns, histopathologic findings, and survival times in AKI, CKD, and control dogs.

RESULTS

Clinical signs of pulmonary disease were significantly more common in AKI dogs. Prevalence of an alveolar lung pattern was greater in AKI and CKD dogs. Alveolar mineralization was the most common pulmonary histologic lesion in AKI dogs (6 of 8 dogs), with concurrent alveolar concretions or mineralization of pulmonary vessels or bronchioles noted in 1 dog each; mineralization of lung tissues was not noted in control dogs. Neither clinical signs nor presence of an alveolar pattern were associated with likelihood of survival to discharge or median number of days from discharge until death.

CONCLUSIONS AND CLINICAL IMPORTANCE

Abnormalities indicative of pulmonary disease are more common in azotemic dogs than in control dogs; however, prognosis is not associated with presence of clinical or radiographic pulmonary dysfunction.

Gastric submucosal fat in cats

A previous study showed that a gastric intramural radiolucent band seen on radiographs and a gastric intramural hypoattenuating layer seen on computed tomography were due to the presence of gastric submucosal fat in a cat. There is no known prevalence and distribution pattern of this gastric submucosal fat in cats. This study was carried out to determine the prevalence and distribution pattern of submucosal fat in cat stomachs. Histologic examination of 41 cat stomachs was performed after scheduled killing of cats, obtained from animal shelters. The results revealed that submucosal fat was present in all stomachs. However, thickness and distribution pattern of the submucosal fat varied.

Mandibular Ossifying Fibroma in a Dog

An aged mongrel dog was admitted for hemimandibulectomy as treatment for a mandibular mass that had been diagnosed as osteosarcoma. The fibro-osseous mass that surrounded the first molar tooth and replaced alveolar and cortical bone was reclassified as ossifying fibroma on the basis of anatomic location and histologic features. The tumor was composed of isomorphic fusiform cells with few mitotic figures. Tumoral stroma contained trabeculae of woven bone that were bordered by a single layer of osteoblasts. Excision was deemed complete with no evidence of extension or metastasis by computed tomography of the skull or thoracic and abdominal radiography. The dog was reportedly healthy 6 months after initial presentation. Though far less common than osteosarcoma as a primary canine bone tumor, ossifying fibroma should be included in the differential diagnosis for fibro-osseous proliferations, especially those of the jaw. Although benign, en bloc excision may be necessary for surgical cure.