Magnetic resonance imaging technique for the examination of canine mammary tumours

The aim of this study was to adapt the human magnetic resonance imaging (MRI) sequences for use in the routine examination of canine mammary glands. MRI was performed on 10, middle- to old-aged dogs of different breeds. It was found that T1- and T2-weighted spin echo, short T1 inversion recovery sequences and a gradient echo (GE) dynamic T1-weighted measurement made in the coronal and transversal planes were the most informative MR diagnostic methods for imaging canine mammary tumours. The static MR technique is the most detailed imaging modality for differentiating the tissue types in the substance of the mammary gland. The MRI findings were in close relationship with the histological result (five malignant mixed tumours and five cases of invasive ductal carcinoma). Using the GE dynamic contrast-enhanced sequence the morphological patterns as well as the kinetic parameters proved to be malignant. By the dynamic measurement technique initial information was obtained on the contrast enhancing properties, which are valuable factors during in vivo staging and in the prognostic work.

Histochemical and immunohistochemical characterization of canine mammary mucinous carcinoma

Mucinous carcinoma is a rare mammary tumour, characterized by intracellular and extracellular mucin. It is still uncertain whether the origin of the mucin is epithelial, myoepithelial or fibroblastic. Eleven canine cases originally classified as mucinous carcinomas were reassessed and compared with myoepithelial nests of mixed tumours. All samples were examined (1) histochemically by the periodic acid-Schiff (PAS) and PAS-diastase methods, and with alcian blue (pH 2.5 and pH 1.0), mucicarmine and Grimelius silver stain, and (2) immunohistochemically for cytokeratin 19, vimentin, alpha-actin and chromogranin A. This examination revealed that only five of the 11 tumours were genuine mucinous carcinomas. In these five tumours the mucus-secreting cells showed cytoplasmic cytokeratin 19 positivity; the mucus showed PAS-diastase and mucicarmine positivity, and alcianophilia which was stronger at pH 2.5 than at 1.0. The remaining six cases were re-classified as mixed tumours because both mucus and mucus-producing cells shared the following similarities with myoepithelial nests of mixed tumours: vimentin and alpha-actin cytoplasmic positivity, PAS negativity, alcianophilia both at pH 2.5 and 1.0, and mucicarmine positivity.

Primary malignant mixed mesenchymal tumour of the heart in a dog

A case of primary malignant mixed mesenchymal tumour of the heart in an 8-year-old golden retriever is described. The cardiac tumour, measuring 2.5 x 3 x 5 cm, was located in the posterior part of the atrial septum, extending into the surrounding region. Histologically, the tumour was composed of multiple mesenchymal elements of fibrosarcoma, rhabdomyosarcoma, liposarcoma and chondrosarcoma. No previous reports of such a tumour occurring in the heart of the dog were found in the literature.

In vitro efficacy of chemotherapeutics as determined by 50% inhibitory concentrations in cell cultures of mammary gland tumors obtained from dogs

OBJECTIVE

To determine the 50% inhibitory concentration (IC-50) of carboplatin, cisplatin, and doxorubicin in cell cultures of mammary gland tumors obtained from dogs and to assess whether in vitro efficacy was within the range of clinically relevant concentrations,

SAMPLE POPULATION

30 mammary gland tumors excised from dogs.

PROCEDURE

Cell cultures were established from the 30 tumors. Cultures then were treated with carboplatin, cisplatin, or doxorubicin. Growth inhibition of cultures was assessed via DNA measurement 24, 48, and 72 hours after treatment. The IC-50 values were calculated by use of linear interpolation.

RESULTS

Cultures varied in their pattern of susceptibility. Doxorubicin induced significantly lower IC-50 values than the platinum derivatives. Cisplatin and carboplatin had comparable effects. The IC-50 values for carboplatin and doxorubicin were in the range of clinically relevant concentrations, but only part of the cisplatin cultures had IC-50 values within clinically relevant concentrations. We did not detect differences in the in vitro susceptibility among subtypes of tumors (ie, adenocarcinoma, solid carcinoma, malignant mixed tumor).

CONCLUSION AND CLINICAL RELEVANCE

The IC-50 values determined in this study allowed assessment of in vitro drug efficacy of chemotherapeutics in cultures of mammary gland tumors obtained from dogs. Variations in susceptibility were evident and emphasize the importance of assessing susceptibility and resistance patterns for each tumor. Prospective studies to assess direct correlations between in vitro and in vivo efficacy must be performed to determine the clinical predictive value of this in vitro chemosensitivity assay for treatment of dogs with mammary gland tumors.

Apocrine gland tumor of the eyelid in a dog

A 13-year-old male Shetland Sheepdog with progressive exophthalmos had a neoplastic mass in the ocular adnexa. Histologically, this neoplasm was composed of duct-forming epithelial cells with decapitation secretion. Tumor cells invaded the globe through the tunica conjunctiva and replaced the vitreous body. The cornea, iris, ciliary body, and retina were extensively destroyed. Both the epithelial and spindle-shaped myoepithelial cells showed nuclear atypia and mitotic activity in the globe. The primary tumor was diagnosed as adenocarcinoma, probably originating from apocrine sweat glands of the eyelid, and the infiltrating intraocular neoplasm was diagnosed as a malignant mixed tumor.

Ceruminous gland tumors in dogs and cats: a review of 124 cases

The histological features of 124 ceruminous gland tumors from canine and feline biopsy submissions were reviewed. The tissues, which represented submissions from private veterinary practices and a veterinary college, included ceruminous gland adenocarcinomas and adenomas as well as a single, mixed ceruminous gland adenocarcinoma. A majority of the masses from both dogs and cats were identified as malignant processes.