Introduction

The diagnostic and treatment of cancer represent the hardest challenge that the small animal physician face nowadays. The increase noticed in the diagnostic of neoplasms is related to the advance accomplished in diagnostic techniques. This advances brought along with then an increase in life expectation of dogs and cats and an increase in the diseases associated with advanced ages (Venturini, 2006). The oral neoplasias represent 5% of the neoformation found in dogs and cats (Venturini, 2006) and the oral cavity is the fourth more common site of the occurrence of neoplasia in dogs and cats (Harvey & Emily, 1993, Dhaliwal et al., 1998). Oral neoplasias can be classified as oropharyngeal, including those whose origin are gingiva, oral mucosa, tongue, mandible, maxilla and tonsils, and odontogenic whose origin are the epithelial and mesenchymal structures of the teeth (Dhaliwal et al., 1998). The purpose of this study is to document the prevalence of oral neoplasias in dogs attended at Centro Veterinário do Gama--CVG in the year of 2008.

Materials and Methods

Fourteen (N = 14) dogs attended at CVG in 2008, with oral neoplasia, were categorized in species, race, gender, age, localization of the neoplasia in the oral cavity and kind of tumor diagnostic. For diagnosis procedure, the animals were anesthetized with midazolam 0.2 mg/kg (IM) + morphine 0.5 mg/kg (IM) in premedication + propofol 6 mg/kg (EV) for induction and + isoflurane 2.0% for maintenance and the tumors were punched in three dimensions. The collected materials were putted in a 10% formol solution and sent for anatomopathology and immunohistochemistry analysis.

Results

The oral neoplasias represent 5% of the neoformation found in dogs and cats (Venturini, 2006). The animals attended at CVG 64.3% were diagnosed with malignant tumors and 35.7% were diagnosed with benign tumors. In dogs with benign neoplasia, epulides are most frequent and our study has shown that the prevalence of this neoformation was 35.7% and acanthomatous and ossifying were the most found, each corresponding 13.9% of the neoplasms we diagnosed. As malignant neoplasia, squamous cell carcinoma were the most found corresponding 42.8% of the diagnosis in dogs followed by melanoma, histiocytoma and hemangiosarcoma each corresponding 7.1% of the cases. Gender was not significant as the risk to develop neoplasia as both gender were affected equally. Dogs with more than 7.3 years were considerate senile and they represent 57.14% of dogs with oral neoplasia in our sample. Gingiva was the site of more prevalence as developing malignant and benign neoplasias corresponding 40% of the cases. Mandible came in second as the site most committed with neoplasias representing 20% of the cases attended in the year of 2008 at CVG, the other 30% correspond to tumors in oral mucosa, tongue and frontal bone.

Discussion

The animals attended at CVG 64.28% were diagnosed with malignant tumors and 35.71% were diagnosed with benign tumors. A prevalence of malignant tumors over benign tumors was described by Felizzola (1999) in his study. Epulides were the benign neoplasia most found in dogs and acanthomatous and ossifying were the most common type of this neoplasia we have found. Acanthomatous, usually behaves locally as a bone-invasive malignancy (Harvey & Emily, 1993), and ossifying epulides, a firm non-painful mass covered by intact normal colored epithelium (Harvey & Emily, 1993), were most frequent benign tumors in our findings. Yoshida et al. (1999) describe epulides as being the most frequent benign neoplasia but in his article fibromatous epulides were prevalent over the other types. Squamous cell carcinoma were the most common malignant neoplasia found in dogs in this recent study, this same result were described by Lacerda et al. (1999) showing a prevalence of squamous cell carcinoma over melanoma in dogs attended at Uberlândia from 1976 to 1997 meanwhile, Tyler et al. (1999) explain that whether squamous cell carcinoma or malignant melanoma is more common in dogs has not been well established. Gender was not a significant parameter in this study as we noticed that both gender was affect equally in both types of neoplasia, benign and malignant. Harvey & Emily (1993) affirm that male dogs are at greater risk to develop malignant oral tumors then are females. Lacerda et al. (1999) in his studies found that females were more affected by neoformation. Older animals were more affected by oral neoplasias in accordance to Harvey & Emily (1993) therefore a significant increase in neoplasia cases in younger dogs are not to be neglected, in this present study 40% of our cases were diagnosed in dogs under 7.3 years old. Gingiva was the site of more prevalence as developing malignant and benign neoplasias corresponding 40% of the cases, Harvey & Emily (1993) described that this site is the most frequent site of involvement by malignant tumors. Mandible came in second as the site most committed with neoplasias representing 20% of the cases attended at that year at CVG, the other correspond, 10% oral mucosa, 10% tongue and 10% frontal bone.

Hemangiosarcoma localized in the tongue was the diagnosis we have in a 12 year old male dog. Harvey & Emily (1993) mentioned that the tongue is a less common site for oral tumors in dogs, they also describe that the squamous cell carcinoma is the most common type of neoplasia in this region. The neoplasia found in the frontal bone was a malignant fibrous histiocytoma diagnosed in a young male (11 months) dog, although the frontal bone in not a part of the oropharynx, it is part of the veterinary dentistry study as it involves the face of the animals. Malignant fibrous histiocytoma is a common tumor of soft tissues such as skeletal muscles and abdominal or retroperitoneal cavity (Siqueira et al., 2004) but is rare tumor of the bone (Picci et al., 1997) and it usually affects young patients (Siqueira et al. 2004). Although is a rare condition our findings fits the data found in bibliographical references.

Conclusion

The data presented in this study represent the cases of oral neoplasias diagnosed in dogs attended at CVG in the year of 2008. The increase in small animals' life expectation, the better use of diagnostic exams represents an elevation in diagnosis of cancer in these animals. As the mouth is the fourth more common site for development of neoplasias and oral neoplasias represent 5% of neoformation found in dogs and cats more papers from this nature are necessary for we know the real frequency of this neoplasms and identify the more commons neoplasias are found in this species.

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