INCIDENCE OF EPULIDES IN THE DOG – A RETROSPECTIVE HISTOPATHOLOGICAL STUDY

The retrospective histopathological study of 468 samples of tumour material obtained from dogs, referred to the Faculty of Veterinary Medicine, Trakia University, Stara Zagora during the period 1991-2000 showed that 29 specimens (6.19%) were epulides. According to their histogenesis, the lesions were classified in two primary groups: reactive lesions – 37.94% and peripheral odontogenic tumours – 62.06%. Epulides were most commonly encountered in males (68.96%) compared to females (31.04%). The average age of affected dogs was 4 years for both genders. In 18 cases (62.06%), the lesions were mandibular whereas in 11 (37.94%) – maxillar. The highest predilection to epulides was observed in German Shepherds – 27.58%.

genic tumours are reported to be more prevalent Š3, 1, 11, 12¹.The reports by some authors show a higher incidence of epulides originating from the maxillar gingiva whereas those of others -from the mandibula Š3, 7, 12¹.The average age with the highest risk of the onset of epulides is between 6 and 8-9 years Š6, 11¹.In a study on 189 dogs with epulides, Toshida et al. (1999) observed a higher predisposition in Scotland Shepherds and Tzvetkov Š11¹ -in German Shepherds.Other authors have not observed any breed-related predisposition Š3, 9¹.Neoplasms are more commonly encountered in male dogs Š11, 12¹.
The histogenesis, the development and the prognosis of epulides could be most commonly determined using morphological criteria Š13¹.The aim of the present study was to determine the type of lesions, clinically determined as epulides via histopathological methods as well as their incidence depending on the breed, gender and age of the host with regard to the application of results as prognostic criteria in the diagnostics of tumours.
The studies were performed within the period 1991-2000 at the Faculty of Veterinary Medicine, Trakia University -Stara Zagora.A total of 468 samples from spontaneous tumour growths were obtained by excision or biopsy.Specimens for the histological study were fixed in 10% neutral formaldehyde and processed using the routine histological technique.Cross-sections were stained with haematoxylin/eosin (H/E).
From all 468 samples, 65 * (13.88%) originated from the oropharyngeal region.Twenty-nine (44.61%) of them or 6.19% of the total number of tumours were determined as epulides.In eighteen cases (62.06%) the lesions were localized to the mandibular and in eleven (37.94%) -to the maxillar gingiva.Table 1 presents the incidence of epulides depending on the breed, gender and age of hosts.The highest percentage of affected dogs was that of German Shepherds -27.58%.Then followed Collies, Irish Setters (13.8% each) and Bologneses, Boxers and mixed-breed animals (10.34% each).The incidence of epulides in Dogues (6.9%), Dachshunds and Drathaars (3.44%), that are among the commonly encountered breeds in our country, was relatively low.Epulides were more frequent among male dogs -68.96% vs 31.04% in females.The average age of affected dogs in both genders was 4 years.
Macroscopically, the lesions appeared as irregular masses with a diameter from 1-2 to 8-10 cm in all cases.The cutting surface was thick.In some cases, the surface was ulcerated.The incidence of epulides depending on the histological diagnosis is shown in Table 2. Lesions determined as peripheral odontogenic tumours were prevalent (62.06%) whereas those determined as reactive lesions were less present 37.94%.The parenchyma of the most commonly encountered tumourthe acantomatous epulis, consisted of islets and bands of epithelial cells, embedded by a connective tissue stroma.The basal cells of the parenchyma were with a pallisade-like arrangement, sometimes with a vacuolated cytoplasm.An inverse polarity was also observed (Fig. 1).
The structure of odontogenic tumours with the next frequency (in descending order) -fibromatous epulides (odontogenic fibromas) was from a primary cellular type.The parenchyma consisted of fibroblast cells and remnants of odontogenic epithelium and was characterized with a high degree of vacuolization (Fig. 2).
Reactive lesions were determined according to the respective histological features.The parenchyma of the most widespread type, that of the giant cell epulis, consisted of intensely vacuolated fibroblast tissue with multinuclear giant cells within.The parenchyma of the other lesions from this group -fibrous epulis and pyogenic granuloma, showed a focal fibrous hyperplasia in the former and a marked granulation tissue with endothelial proliferation in the latter type, respectively.
The results of our studies confirmed the high incidence of epulides among oral pathological lesions in dogs Š1, 4, 12, 8¹.Nearly half of the oral tumour growths, we observed during the period of the study, were from this neoplastic type (44.61%)Š14¹.In this respect, our results are similar to those of authors supporting the thesis that epulides are among the commonest oral neoplasms Š15, 11¹.The highest prevalence of epulides in German Shepherds, observed by us, is comparable to the incidence reported by Tzvetkov Š11¹.Probably, this frequency is due to the wide-ranging distribution of this breed in the region Š7, 12¹.
Our studies evidenced that the average age of the onset of epulides was 4 years.During the last decade, there is a tendency towards the appearance of tumour formations in a younger age compared to other periods Š1, 10, 6, 7¹.The prevalence of epulides among male individuals is similar to that, stated by others Š7, 11, 12¹.As to the localization (on the maxillar or the mandibular gingiva), we could hardly establish any predisposition because of the contradictory data Š3, 6, 7, 2, 12¹.
The results of our histopathological studies, according to the criteria of Gardner Š5¹, evidenced a dominating prevalence of peripheral odontogenic tumours (acantomatous and fibromatous epulis) -62.06% vs the reactive lesions (fibrous epulis, giant cell epulis and pyogenic granuloma) -37.94%.These data correlated with the data of Reichart et al.Š9¹, Hoffman and Gaengler, Š7¹; Yoshida et al., Š12¹ but not with those reported by Tzvetkov Š11¹ who affirmed that giant cell epulides were the commonest.
The analysis of our results confirmed the primary importance of histological investigation for the confirmation of the diagnosis and for the prognosis of lesions, determined as epulides.

Table 1 .
Incidence of epulides in the dog depending on the breed, gender and age of the host / Tabela 1. Pojava epulida kod pasa u zavisnosti od rase, roda i starosti doma}ina