History

Three of the cats were periodically allowed outdoors, and four were strictly indoor cats. Five of the seven cats had been seen by a referring veterinarian and treated with antibiotics (ampicillin, amoxicillin trihydrate-clavulanate potassium) with no improvement of clinical signs.

Physical examination findings

Except for the masses, the physical examination findings were unremarkable in all but one of the cats (case 7). The cat with a cervical mass (sublingual mucocele) exhibited ataxia consistent with diffuse cerebellar disease, which was suspected to be due to feline infectious peritonitis.

In five cats, the sublingual gland was involved, and the mucocele formed a ranula. In two of these cats, the ranula was large enough to cause respiratory stridor, but neither cat exhibited severe respiratory distress on presentation. Other clinical signs associated with the ranula included intermittent vomiting, ptyalism, and lethargy.

In one cat (case 5), the mass was an incidental finding, with no clinical signs evident.

Diagnostic test results

CBC results showed mild, normocytic, normochromic anemia and mild thrombocytopenia in one cat (case 2). Serum chemistry profiles revealed mildly elevated alanine aminotransferase activity in two cats (cases 1 & 5), an elevated glucose concentration in one cat (case 1), and elevated aspartate aminotransferase activity in one cat (case 1). Skull and thoracic radiographic examination results were unremarkable in two cats (cases 1 & 5); radiography was not done in the other five cats. Fine-needle aspiration of the mass was performed in all seven cats. In all cases, a stringy, mucoid substance consistent with saliva was aspirated from the mass, and a salivary mucocele was tentatively diagnosed.

Treatment

Surgical treatment consisted of removing the entire mandibular-sublingual salivary chain on the affected side with mucocele marsupialization (cases 1 & 2), marsupialization alone (cases 3 & 6), excising the mucocele through an oral approach and removing the sublingual gland (case 4), removing the molar gland and associated mucocele (case 5), or excising the mucocele through a cervical approach and removing the entire mandibular-sublingual salivary chain (case 7). The results of the histologic examination of excised tissues were consistent with salivary gland and associated mucocele in six of the cases (tissue from case 6 was not submitted for histology). Follow-up ranged from two months to 13 years, and no signs of recurrence were seen in any of the cats.

DISCUSSION

Salivary mucoceles are a common cause of cervical or intraoral swelling in dogs, but few cases have been reported in cats.^2-8,17 One study reported that dogs had three times the occurrence of mucoceles that cats had.¹⁷ Although the most common presentation in dogs is a swelling in the cervical region,¹² only one cat in the study described in this article presented with cervical swelling (Table 1). In cats, intraoral or sublingual swelling appears to be more common than cervical swelling is.

In cats, the mandibular and sublingual glands empty by separate duct systems, which may exit to a common papilla (sublingual caruncle) just lateral to the frenulum of the tongue. In dogs, the sublingual and the mandibular glands are intimately associated; thus, surgically removing the affected sublingual gland involves removing the associated mandibular gland as well.

Treatment

In this case series, the entire mandibular and sublingual glands on the affected side were removed in three cats, the sublingual gland alone was removed in one cat, and the entire molar gland was removed in one cat.

In all the cats, the mucocele was lanced, resected, or marsupialized into the oral cavity to provide immediate relief. In dogs, it is recommended that the salivary gland causing the mucocele be removed to decrease the possibility of local recurrence. In the two cases in this case series in which salivary glands were not removed (3 & 6), local recurrence was not noted.