Para-aural abscessation following traumatic ear canal separation in a dog

Traumatic ear canal separation is rare in animals, with only eight dogs and one cat reported with the condition in the English language literature. Para-aural abscessation occurred in six of these nine animals. Diagnosis was made on otoscopic observation of a shortened, abruptly ending external ear canal that was free from advanced disease. Radiographs in those cases which have been described showed a disruption of the normal air opacity of the affected ear canal. Drainage, by creating a separate opening for the horizontal ear canal, or total ear canal ablation and lateral bulla osteotomy (TECA/LBO), have led to resolution of the clinical signs. This report adds a further case to the literature in which TECA/LBO was employed successfully.     

BAER testing in a dog with bilateral external ear canal atresia

A 3 yr old male castrated Labrador retriever presented for evaluation and treatment of bilateral atresia of the external ear canals. The owners reported that the dog could hear only loud and high-pitched noises. Computed tomography of the head revealed intact vertical and horizontal ear canals filled with debris and a debris-filled right tympanic bulla. Air- and bone-conducted brainstem auditory evoked response (BAER) testing revealed an elevated response threshold to air-conducted stimuli and greater amplitude waveforms evoked by bone-conducted stimuli. The ear canals were surgically corrected via lateral ear canal resection. BAER testing postoperatively revealed a decrease in the air-conducted BAER threshold. This case is an example of the use of bone-conducted BAER testing to aid in the diagnosis of conductive deafness, and in determining prognosis for normal hearing after surgical treatment of external ear canal atresia.     

Total ear canal ablation and lateral bulla osteotomy in the dog

One hundred total ear canal ablation/lateral bulla osteotomy procedures were performed in 71 dogs over a four year period. The main indication for surgery was advanced disease of the aural canal or middle ear resulting from prolonged inflammatory disease of the outer ear. Complications of surgery included facial nerve injury, inner ear injury, retroglenoid vein haemorrhage and wound dehiscion. The incidence of complications (29 per cent) was, however, substantially lower than has previously been recorded following this procedure. Meticulous dissection technique and increasing familiarity with the procedure were thought to be responsible for lower complication rates than have previously been recorded. Surgery was considered to have resolved the original aural condition in 92 per cent of cases and only infrequently resulted in complete loss of hearing function.     

Cholesterol granuloma as long-term complication of total ear canal ablation in a dog

A 13-year-old cocker spaniel presented with pain on opening the mouth. History of a previous left total ear canal ablation with lateral bulla osteotomy, left intermittent facial palsy and left intermittent head tilt suggested progression of a total ear canal ablation with lateral bulla osteotomy complication. Magnetic resonance imaging revealed a large mass arising from the tympanic bulla. Cytology of aspirates revealed a chronic suppurative inflammatory reaction and numerous cholesterol crystals. The mass was removed by surgical excision and an active drainage system was placed for a few days. The head tilt, facial palsy and apparent pain were resolved by the surgery. Physical examination was unremarkable nine months postoperatively. Bacterial cultures of the collected fluid were negative and histological examination confirmed the diagnosis of a cholesterol granuloma.     

Malignant fibrous histiocytoma in a dog

A large tumour present on the proximal tibia of a Bull Mastiff dog was diagnosed on histological appearance as a Malignant Fibrous Histiocytoma. These tumours, rarely identified in domestic animals, but well recognised in humans, are typically pleomorphic sarcomas with histiocytic and fibroblastic differentiation. Less commonly, one cell type predominates. In this case there was prominent histiocytic differentiation.     

The cytology of the external ear canal in the normal dog and cat

This study was conducted on 50 normal dogs and 52 normal cats in order to characterize the normal cytological findings in specimens taken from the vertical ear canal by swabbing. Yeast were detected in 96% of the dogs and 83% of the cats. Gram-positive cocci were found in 42% of the dogs and 71% of the cats. Rods were not seen. In dogs, the median numbers per high-power microscopic field (400x magnification) for yeast, cocci and keratinocytes were 0.2, 0 and 3.9, respectively. In cats, the median numbers were 0.2, 0.3 and 8, respectively. Nucleated keratinocytes were occasionally observed in both species, and should not be mistaken for a pathological process (parakeratotic hyperkeratosis).     

Invasive epithelial mesothelioma in a dog

This report describes the gross, microscopic, and immunohistochemical features of an invasive epithelial mesothelioma in an 11-year-old neutered male Golden Retriever. The tumor involved the pericardium, pleura, mediastinum, and peritoneum and invaded into submesothelial tissues. Neoplastic cells in the thoracic fluid showed prominent features of malignancy in a background of mixed inflammatory cells and scattered erythrocytes. Histologically, the tumor consisted of nests of epithelioid cells with frequent mitotic figures and multinucleation that infiltrated submesothelial tissues. Neoplastic cells strongly coexpressed vimentin and cytokeratin intermediate filaments, which assisted in the differentiation from other epithelial tumors of nonmesothelial origin.     

Multiple, resolving, cutaneous histiocytoma in a dog

Mycosis fungoides was initially diagnosed in a 7.5-year-old German Shepherd Dog with generalized canine cutaneous histiocytoma. Lesions resolved without treatment over approximately 16 weeks. The final diagnosis of histiocytoma with 2 histopathologic patterns was obtained by use of a special staining technique for the detection of lysozyme found in histiocytes.     

Tumors of the ear canal

This discussion will focus on the clinical presentation, diagnostic evaluation, expected biologic behavior, and therapeutic options for tumours of the ear canal in the dog and cat. Particular emphasis will be placed on neoplasia of the ceruminous glands, squamous cell carcinoma, and non-neoplastic mass lesions.     

Orbitotomy for retrobulbar malignant fibrous histiocytoma in a dog

A retrobulbar malignant fibrous histiocytoma was diagnosed in a 12-year-old castrated male Keeshond dog. The mass was excised with a lateral orbitotomy and zygomatic arch resection. Vision was preserved in the affected eye, and no recurrence was noted up to 10 months postoperatively. Malignant fibrous histiocytoma originates from primitive mesenchymal stem cells. The malignant fibrous histiocytoma seen in our patient was most consistent with the storiform-pleomorphic variant, given the storiform arrangement of spindle cells, the presence of histiocytoid cells, and a mixed inflammatory infiltrate, without giant cells. The metastatic potential of malignant fibrous histiocytoma in general, and the storiform variant in particular, is unknown. Seventeen months later the dog was presented to the referring veterinarian with anorexia, diarrhea, weight loss and bilateral purulent nasal exudates. The dog was euthanized without necropsy.     

Space-occupying leiomyoma in the pelvic canal of a dog

A large space-occupying mass was found in the pelvic canal of an 11-year-old, entire female shih tzu with rectal tenesmus and dyschezia. Computed tomography revealed an extraluminal mass located on the dorsal aspect of the rectum, causing complete rectal obstruction. Histopathological examination of biopsy tissue identified it as a leiomyoma. The tumour was successfully removed by blunt dissection, via a dorsal approach to the rectum, and there were no complications after surgery.     

Invasive multiple lymphangiomas in a young dog

An unusual case of multiple lymphangiomas with lymph node involvement is described. A seven-month-old, spayed female golden retriever was presented with a myriad of cystic masses in the inguinal and caudal mammary regions. She was diagnosed with congenital lymphangiomas (i.e., lymphatic hamartomas). As in human lymphangiomas, lymphatic endothelial cells expressing factor VIII-related antigen and smooth muscle were present in this case. A literature search did not identify similar characteristics in other reported canine lymphangiomas. The dog was treated surgically and had a recurrence. Following a second surgical intervention, she is now disease-free.     

Partial atrioventricular canal defect in a dog

A case of a partial atrial canal defect is described in a nine-month-old female English setter. The patient had a large ostium primum atrial septal defect and a concurrent malformation of the mitral valve. Electrocardiographic and radiographic findings were suggestive of marked enlargement of the right heart and pulmonary overcirculation. Definitive diagnosis and assessment of the haemodynamic consequences were made using echocardiography. The magnitude of the left-to-right intracardiac shunt was estimated by measuring the pulmonary to systemic flow ratio (Qp/Qs) from Doppler-derived pulmonary and aortic blood flow. The results of this report suggest that dogs with a partial atrioventricular canal defect and concurrent mild mitral regurgitation may exhibit no clinical signs during the first years of life, even in cases with a Qp/Qs ratio of greater than 2.