CLINICAL AND ULTRASONOGRAPHIC CHARACTERISTICS OF SALIVARY MUCOCELES IN 13 DOGS

Salivary mucocele is one of the causes of submandibular swelling in dogs and is due to a collection of mucoid saliva that has leaked from a damaged salivary gland. The purpose of this case series report was to describe the clinical and ultrasonographic characteristics of confirmed salivary mucoceles in 13 dogs admitted to the Faculty of Veterinary Medicine at Cairo University. The final diagnosis of salivary mucocele was based on aspirate cytology for all dogs and additional surgical excision for seven dogs. For dogs admitted from 2 weeks to 1 month from the onset of clinical signs, the cervical mucocele appeared as a round echogenic structure with a large volume of central anechoic content. The wall was a clearly identified hyperechoic structure surrounding the gland. For dogs admitted between 1 to 2 months from the onset of clinical signs, the volume of anechoic material appeared less than that seen in the acute cases. The overall appearance of the salivary mucocele was heterogenous. For dogs admitted after 2 months from the onset of clinical signs, the salivary mucocele appeared grainy or mottled, with a heterogenous appearance and a further decrease in anechoic content. For one dog that presented after 3 months from the onset of clinical signs, the salivary mucocele was hard on palpation and appeared hyperechoic with distal acoustic shadowing. Findings from this study indicated that ultrasonographic characteristics of salivary mucoceles in dogs vary depending on the chronological stage of the disease.     

Zygomatic salivary cyst with mucocele formation in a cat

An eight-year-old neutered male domestic shorthalr cat had a zygomatlc salivary cyst with associated mucocele formation. A fluctuating swelling developed ventral to the right eye, causing bulging of the lower eyelid, and a corresponding swelling was present in the caudal vestibule of the oral cavity. Cytological examination of the fluid obtained from asplratlon of the swelling was consistent with the appearance of saliva. A tentative dlagnosls of zygomatlc salivary mucocele was made. Surgical exploration and resectlon of the swelling demonstrated the presence of a multliobular cystic zygomatlc salivary gland. The histopathological appearance of the resected tissue was Interpreted as an Inflammatory reaction to mucus derived from a muitllocular salivary cyst.     

Oncocytoma in the mandibular salivary gland of a cat

A cat was referred for investigation of a soft tissue mass caudal to the left mandible. Initial investigations suggested a malignant salivary gland tumour, and the mass was removed by extracapsular resection of the mandibular gland. Histopathology showed an oncocytoma within the salivary gland. An oncocytoma is a neoplastic transformation of oncocytes. Oncocytes are cells with a small nucleus and intense eosinophilic granular cytoplasm due to numerous mitochondria, which proliferate during ageing in exocrine and endocrine glandular tissues. Physiological proliferation occurs next to oncocytosis, oncocytoma, and oncocytic carcinoma. This is the first report of an oncocytoma in a feline mandibular salivary gland, and the first report of long-term survival after surgical removal.     

Quantitation of histochemical staining of salivary gland mucin using image analysis in cats and dogs

Two different, computer-based, image analysis methods were employed to complement subjective assessment of patterns of mucin staining (by periodic acid Schiff/alcian blue, aldehyde fuchsin/alcian blue and potassium hydroxide-alcian blue/phenylhydrazine hydrocholoride) in digitised images of sections of major and minor salivary glands from cats and dogs. Image analysis based on red, green and blue (RGB) staining was not suitable for quantitation of histochemical staining of mucin in salivary glands. Image analysis based on hue, saturation and lightness (HSL) allowed quantitative assessment of staining by different stain components and of mixed staining, and enabled comparison of staining of different glands in dogs and cats. Quantitative analysis based on HSL allowed differentiation of differences in staining patterns of major and minor cat and dog salivary glands, and between the species; such differences would have been impossible to distinguish on subjective grounds alone. Quantitative assessment of normal salivary gland histochemistry allows comparison with staining patterns in disease.     

MR anatomy of salivary glands in the dog

This retrospective analysis documented the magnetic resonance imaging (MRI) appearance of normal salivary glands based on 101 studies in dogs with no detectable disease in the splanchnocranium. Surface, signal intensity, homogeneity, structure, symmetry and the relationship of glands to surrounding tissues were noted, and gland topography was assessed with E12 plastinated embedded sections. Signal intensity of salivary glands was isointense (7-40%) to hyperintense (60-90%) to muscle tissue on T1- and hyperintense on T2-weighted images. Salivary glands had an increased T1 signal after contrast medium was applied. Salivary gland structure appeared homogeneous in mandibular and major sublingual glands and heterogeneous in zygomatic and parotid glands. Consistent landmarks were the external auditory canal for parotid glands, the digastric muscle for mandibular and major sublingual glands, and the pterygopalatine fossa for zygomatic glands. The minor sublingual and ventral buccal glands could not be localized with low-field MRI.     

Cystic Dilatation of the Parotid Duct of a Goat

Cystic dilatation of the parotid duct of a goat was diagnosed by exploratory surgery and analysis of cyst contents. The cyst and its associated salivary gland were surgically removed. This case is compared with the more common salivary mucocele.     

Zygomatic salivary gland mucocele in a ferret

A zygomatic salivary gland mucocele was diagnosed in a 1-year-old female domestic ferret with exophthalmos. A T-shaped incision from near the lateral canthus to the base of the ear and continuing ventrally to the level of the commissure of the mouth was made to expose the mucocele. Surgical removal was complicated by the large open orbit of the ferret, adjacent cellulitis, extension ventromedial to the globe, and difficulty in identifying important motor nerves. Vision was maintained, but slight postoperative enophthalmos and mild upper eyelid paresis developed.     

Pharyngeal mucoceles in dogs: 14 cases

This report describes the clinical features of a series of dogs with pharyngeal salivary mucoceles. A retrospective study of 14 dogs with pharyngeal mucocele was performed. Medical records from 1983 to 2003 were reviewed for information regarding signalment, clinical signs, diagnosis, surgical procedures, and short-term and long-term outcome. Miniature and toy poodles were common breeds in the study population, and 79% of the dogs were male. The most common presenting sign was dyspnea (50%). Diagnosis was by fine-needle aspirate, which revealed a mucoid substance in 93% of dogs. Histopathology of the excised salivary glands revealed lymphoplasmacytic inflammation in all dogs that had histopathology performed. Forty-three percent of the dogs had a cervical mucocele on the same side as the pharyngeal mucocele. Surgical therapy was performed in 13 dogs, which consisted of excision of the mandibular and sublingual salivary glands, excision of the mucocele, or marsupulization of the mucocele. Only two dogs had recurrence of the pharyngeal mucocele. In this study, pharyngeal mucoceles occurred in predominantly small dogs that frequently presented with respiratory signs. Surgical treatment was successful in most dogs.     

Carcinoma of the submandibular salivary glands with multiple metastases in a cat

A 9-year-old neutered male domestic shorthair cat was presented because of coughing, dysphagia, and prostration. Examination revealed firm bilateral anterocervical swellings extensively adhered to the surrounding tissues. Anisocoria with left-side miosis was also evident. X-ray and ultrasound examinations along with a fine-needle aspiration biopsy were performed. Slides were stained with May-Grünwald Giemsa, and a diagnosis of salivary gland carcinoma was made. At surgery, the tumor was found to involve both submandibular salivary glands as well as adjacent lymph nodes and surrounding tissues. The cat was euthanized and necropsy was performed. The majority of tissues and organs examined histologically, including mandibular and retropharyngeal lymph nodes, soft palate, laryngopharynx and lungs, contained neoplastic cells whose appearance was consistent with adenocarcinoma. Bilateral salivary adenocarcinoma has not previously been reported in cats, and extensive metastases are rare.     

Partial ligation of the transposed parotid duct at the level of the parotid gland for excessive salivary secretions

Objective To determine the outcome and effect of a partial ligation of the transposed parotid duct at the level of the parotid gland in four dogs with excessive salivation and ocular irritation. Methods Four dogs were previously diagnosed with absolute keratoconjunctivitis sicca. After a parotid duct transposition (PDT) surgery, these dogs experienced excessive saliva production and abundant salivary precipitates, which resulted in epiphora, moist dermatitis, blepharospasm, and keratitis. In an effort to decrease saliva production, a partial ligation of the transposed duct at the level of the parotid gland was performed. Two or three accessory branches to the primary parotid duct were ligated at the level of the salivary gland. Results The four cases were three Yorkshire terriers and a Chihuahua. The average age of the four patients was 2.5 years. Partial ligation of accessory branches of the parotid duct at the level of the parotid gland after a PDT in this study demonstrated improved ocular comfort, decreased salivary precipitates, and adequate Schirmer tear test results without marked epiphora in three of the four animals. The male Yorkshire had epiphora after the initial partial ligations of two accessory branches were placed at the level of the parotid gland. To correct the excessive salivary flow, two additional ligatures were placed at a later date, which resolved the epiphora. Conclusion Partial ligation of the parotid duct at the level of the parotid gland proved to be an effective technique in moderating the salivation in these four patients with excessive salivary secretions after PDT.     

A salivary malignant myoepithelioma in a dog

Salivary tumours are uncommon in domestic animals and there are no known previous confirmed reports of salivary tumours of myoepithelial origin in dogs. A 12-year-old female mixed breed dog was presented with a lobulated mass, composed of white-yellowish tissues, extending from soft palate to epiglottis. Histological examination revealed a neoplastic lesion consisting of a dense population of cells showing moderate pleomorphism, with pale cytoplasm and large oval nuclei, arranged in solid lobules. Mitotic activity was very high. Tumoral cells were negative for both periodic acid-Schiff reaction and Alcian blue stain and displayed strong immunohistochemical reactivity for pan-cytokeratin, muscle specific actin and myosin and focal positivity for cytokeratin 14. On the basis of the morphological, histochemical and immunohistochemical findings a diagnosis of malignant tumour of myoepithelial origin (malignant myoepithelioma) was made.     

Zygomatic sialocele secondary to infarction treated with sialoadenectomy in a dog

Zygomatic salivary gland disease is not commonly reported in dogs and there is a paucity of literature reporting salivary gland disease secondary to infarction in dogs. A 9-year-old German wirehaired pointer presented with left eye exophthalmos, 3rd eyelid elevation, negative retropulsion, and pain upon opening of the mouth. Computed tomography revealed a mass extending from the left zygomatic salivary gland, consistent with a sialocele. A left-sided zygomatic sialoadenectomy was performed successfully. Histopathologic diagnosis concluded zygomatic salivary gland infarction. The dog had no signs of recurrence 20 mo after surgery.Key clinical message:To the authors’ knowledge, this is the first case report with long-term outcome of a zygomatic sialocele secondary to salivary gland infarction in a dog treated by zygomatic sialoadenectomy via zygomatic osteotomy.     

Putative salivary allergens of the cat flea, Ctenocephalides felis felis.

The cat flea, Ctenocephalides felis felis, is the major initiator of flea bite hypersensitivity in dogs. Previous analyses of whole extracts of the flea and flea salivary secretions have failed to identify the allergens responsible. We dissected >2000 salivary glands from adult female fleas, extracted them into buffered saline containing protease inhibitors and fractionated the extract using gel permeation HPLC. Dogs were classified as hypersensitive to fleas (flea-feeding positive, FF+) or insensitive (flea-feeding negative, FF-) using a provocative test with live fleas. The allergenicity of the components of the salivary gland extract was tested by intradermal injection of samples of the column eluates. Dogs were also injected intradermally with a sample of whole salivary gland extract, and with histamine as a positive control. Negative control injections consisted of eluate from the column collected prior to fractions containing any protein. The skin of FF- dogs either did not respond or had a minimal response (a bleb approximately 2 mm larger than the injection blebs at the negative control injection sites) to all fractions and to the whole extract; histamine control injections produced positive responses (defined as wheals 5 mm greater than the blebs at the negative control injection sites) in all dogs. The skin of three of the nine FF+ dogs reacted positively to injection of a fraction containing protein/s with apparent MW 40k. Five other FF+ dogs reacted positively to the fractions containing proteins with apparent MW 12-8k. A single dog responded with very large, red wheals to injection of both the approximately MW 40k and MW12-8k fractions. These findings suggest that proteins with apparent MW 40k and MW 12k-8k are important in flea bite hypersensitivity. This work also supports a previous finding that mice which had been exposed to flea bites had antibodies to proteins with approximately MW 40k that were detected in salivary secretions of the flea.     

Use of a sclerosing agent (1% polidocanol) to treat an orbital mucocele in a dog

A case of a salivary gland mucocele in a dog causing nonpainful exopthalmos with dorsolateral deviation of the globe and protrusion of the third eyelid. Diagnosis was made via ultrasound and confirmed with computed tomography. Aspiration of the cystic material along with injection of a sclerosing agent, 1% polidocanol (Aethoxysklerol), was used to destroy the mucocele. Follow-up monthly examination post injection confirmed resolution of clinical signs to date, namely abnormal globe position, with no complications observed.     

Idiopathic salivary gland enlargement (sialadenosis) in dogs: a microscopic study

A histological, histochemical and morphometric study was performed on submandibular salivary glands from 13 dogs which had presented with a submandibular mass or swelling that proved to be a portion of non-inflammatory and non-neoplastic submandibular salivary gland. There were no consistent changes in lectin-binding histochemistry or immunohistochemical expression of various cell markers, and, in most cases, there was no measurable difference in acinar size in the affected gland. The possible explanation for the clinical salivary gland enlargement is therefore unclear.     

Carcinoma ex pleomorphic adenoma with sebaceous differentiation in the mandibular salivary gland of a dog

A carcinoma ex pleomorphic adenoma was diagnosed in the left mandibular salivary gland of an 8-year-old female spayed dog. The animal presented with a large nonpainful swelling in the left submandibular region. A computed tomography scan detected an irregularly enhancing soft tissue mass that was closely associated with the left external ear canal and extended to the left wing of the atlas. On surgical exploration, the mass was intimately associated with the left mandibular salivary gland. Both the mass and the adjacent gland were removed, and the diagnosis was determined by histopathology. The tumor was comprised of basaloid and low columnar epithelial cells, many glandular units formed by well-differentiated sebocytes, and multifocal regions of necrosis, mineralization, and hemorrhage. Salivary gland tumors with sebaceous differentiation are very rare in animals, with one previously reported case in a cat.     

Histology of salivary gland infarction in the dog.

Salivary gland infarction was found in two adult dogs. The main changes were ischaemic necrosis, capsular fibrosis and regenerative hyperplasia of surviving ductal epithelium. Necrosis of arterial tunica media and thrombosis were found only in the infarcted parts of the salivary glands. The lesions appeared to be confined to the salivary glands; no cause of the infarction was found.     

A pathological study of the salivary glands of rabid dogs in the Philippines

Rabies is a zoonotic disease caused by the rabies virus. While the salivary glands are important as exit and propagation sites for the rabies virus, the mechanisms of rabies excretion remain unclear. Here, we investigated the histopathology of the salivary glands of rabid dogs and analyzed the mechanism of excretion into the oral cavity. Mandibular and parotid glands of 22 rabid dogs and three control dogs were used. Mild to moderate non-suppurative sialadenitis was observed in the mandibular glands of 19 of the 22 dogs, characterized by loss of acinar epithelium and infiltration by lymphoplasmacytic cells. Viral antigens were detected in the mucous acinar epithelium, ganglion neurons and myoepithelium. Acinar epithelium and lymphocytes were positive for anti-caspase-3 antibodies and TUNEL staining. In contrast, no notable findings were observed in the ductal epithelial cells and serous demilune. In the parotid gland, the acinar cells, myoepithelium and ductal epithelium all tested negative. These findings confirmed the path through which the rabies virus descends along the facial nerve after proliferation in the brain to reach the ganglion neurons of the mandibular gland, subsequently traveling to the acinar epithelium via the salivary gland myoepithelium. Furthermore, the observation that nerve endings passing through the myoepithelium were absent from the ductal system suggested that viral proliferation and cytotoxicity could not occur there, ensuring that secretions containing the virus are efficiently excreted into the oral cavity.     

Otitis media in five cats associated with soft palate abnormalities

The medical records of five cats that were diagnosed with otitis media and soft palate abnormalities, three of which had concurrent otitis interna, were reviewed retrospectively. The animals presented with unilateral or bilateral otitis media or otitis interna associated with soft palate hypoplasia (four cases) or unilateral soft palate cleft (one case). Otitis media was confirmed by radiography, CT or MRI. The soft palate abnormalities present were discovered on oropharyngeal examination at induction of anaesthesia. These five cases provide additional support of a link between otitis media and soft palate abnormalities in cats, as reported in humans and dogs.