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Arquivo Brasileiro de Medicina Veterinária e Zootecnia

Print version ISSN 0102-0935On-line version ISSN 1678-4162

Arq. Bras. Med. Vet. Zootec. vol.52 n.1 Belo Horizonte Feb. 2000

https://doi.org/10.1590/S0102-09352000000100007 

COMMUNICATION

(Comunicação)

Testicular tumors in dogs: frequency and age distribution

(Neoplasias testiculares em cães: frequência e distribuição etária)

 

R.L. Santos, C.M. Silva, A.F.C. Ribeiro, R. Serakides

Escola de Veterinária da UFMG
Caixa Postal 567
30123-970 - Belo Horizonte, MG

 

Recebido para publicação, após modificação, em 7 de julho de 1999.
E-mail: rlima-santos@cvm.tamu.edu

 

 

Testicular tumors are common in dogs and uncommon in other domestic species. According to Nielsen & Lein (1974), the testicular tumors can be classified as follows: (1) germ cell tumors that include seminoma, embryonal carcinoma, and teratoma; (2) sex cord-stromal tumors that include Sertoli cell tumor and Leydig cell tumor; (3) multiple primary tumors; (4) mesothelioma; and (5) stromal and vascular tumors. This classification, adopted by the World Heath Organization, was recently reviewed (Kennedy et al., 1998). The most common testicular tumors in dogs are Sertoli cell tumor, Leydig cell tumor, and seminoma. Metastases are not frequent but Sertoli cell tumors and seminomas can produce metastasis in some cases (Nielsen & Kennedy, 1990).

The goal of this study was to verify the frequency, age and breed predisposition to testicular neoplasms in dogs. Data were collected at necropsy from 497 male dogs. The animals showing macroscopic lesions compatible with testicular neoplasia were submitted to sampling and histological evaluation. Gross morphological features were recorded and at least three fragments from each testis were collected. These were fixed in 10% formaldehyde or Bouin’s solution, paraffin embedded, sectioned (5µm) and stained with hematoxylin and eosin. The frequencies of testicular tumors in different age ranges was compared using the chi-square test and the differences regarding breed and side were compared by the Fisher’s exact test.

Testicular tumors were detected as nodules of variable sizes and the macroscopic criteria used for evaluation were the same as described by Nielsen & Lein (1974). Diffuse seminoma was easily identified on gross evaluation, but intratubular seminoma was not detected in most of the cases when they were only histologically observed. An underestimation of the frequency of this type of tumor (intratubular seminoma) may had happened since the criterion established for histological evaluation was the presence of a macroscopic change in the testis.

Forty-seven animals with 67 testicular tumors were found, corresponding to an overall frequency of 9.45% (47/497) animals with testicular tumors in the whole population. These dogs were in average 11.46±3.47 years old (mean ± standard deviation). The histological criteria for classification of these tumors were the same proposed by the World Health Organization (Nielsen & Lein, 1974; Kennedy et al., 1998). Twenty-nine Leydig cell tumors, 20 seminomas (6 intratubular and 14 diffuse), and 18 Sertoli cell tumors were diagnosed, corresponding to 43.28%, 29.85%, and 26.86%, respectively. There was no significant difference between the frequency of these tumors, which implies that frequencies were equivalent. This distribution was similar to that reported by Patnaik & Mostofi (1993) who studied 262 neoplasms in 225 dogs and found a frequency of 42%, 32%, and 18% for Leydig cell tumor, seminoma, and Sertoli cell tumor, respectively. It is also similar to the frequencies reported by Lipowitz et al. (1973). However, some previous reports have shown higher incidence of seminoma than Leydig cell tumor and Sertoli cell tumor (Machado et al., 1963; Nascimento et al., 1979).

Eighteen out of the 47 dogs (38.29%) showed more than one type of testicular tumor. The combination of seminoma and Leydig cell tumor was the most frequent in this study corresponding to 10 cases, followed by the combination of Leydig cell tumor and Sertoli cell tumor (4 cases), seminoma and Sertoli cell tumor (2 cases), and seminoma, Leydig cell tumor and Sertoli cell tumor (2 cases). Nielsen & Lein (1974) reported as the most common combination the seminoma and either a Leydig cell tumor or a Sertoli cell tumor. Any of the tumors showed predisposition to the right or left side, which is in agreement with a previous report (Nielsen & Kennedy, 1990).

Although Lipowitz et al. (1973) reported a high incidence of testicular tumors in Boxer dogs, no breed predisposition was detected in the present study. Among the 10 Boxers in the whole population (497), none of them had testicular neoplasms.

There was a significant increase in the frequency of testicular neoplasms in elderly dogs. The frequency of testicular tumors according to the age varied from 0.0% to 71.4% (Fig. 1). Differences in the frequency of testicular tumors among the age ranges were significant (P<0.001). This finding is in agreement with a previous report (Nascimento et al., 1979).

 

 

Three of the testes with testicular tumors were cryptorchid. One of them had a seminoma and the other two had Sertoli cell tumor. The only animal under 5-year-old with testicular tumor was a 3.5-year-old cryptorchid dog with Sertoli cell tumor. Cryptorchidism is recognized as an important predisposing factor for testicular neoplasms in dogs, particularly for seminomas and Sertoli cell tumors (Nielsen & Kennedy, 1990).

Two animals with Sertoli cell tumor developed metastasis. One of these animals was cryptorchid. In one case internal iliac lymph nodes were involved and in the other beyond this site there was also metastasis in the mesenteric lymph nodes with extension to retroperitoneum. Sertoli cell tumor in dog is the most prone to produce metastases occuring in 10 to 14% of the cases. In contrast, seminoma produces metastasis in 6 to 11%, and metastasis from a Leydig cell tumor is extremely rare (Nielsen & Kennedy, 1990). On the other hand, Nielsen & Lein (1974) reported metastasis of 3 Sertoli cell tumor and 7 seminomas in a study made of 344 testicular tumors.

Keywords: Dog, testis, neoplasia

 

RESUMO

Estudaram-se a ocorrência e a predisposição etária de neoplasias testiculares em cães. Em 497 cães necropsiados, 47 apresentaram tumores testiculares, correspondendo à frequência de 9,45% (47/497). Houve aumento significativo na freqüência de tumores testiculares em animais velhos.

Palavras-chave: Cão, testículo, neoplasia

 

 

REFERENCES

KENNEDY, P.C., CULLEN, J.M., EDWARDS, J.F. et al. Histological classification of tumors of the genital system of domestic animals. Washington: Armed Forces Institute of Pathology, 1998.        [ Links ]

LIPOWITZ, A.J., SCHWARTZ, A., WILSON, G.P. et al. Testicular neoplasms and concomitant clinical changes in the dog. J. Am. Vet. Med. Assoc., v.163, p.1364-1368, 1973.        [ Links ]

MACHADO, A.V., LAMAS DA SILVA, J.M., CURIAL, O. et al. Incidência de blastomas em animais no Brasil. Arq. Esc. Vet. UFMG, v.15, p.327, 1963.        [ Links ]

NASCIMENTO, E.F., SILVA, J.M.L., NOGUEIRA, R.H.G., et al. Alterações testiculares em cães: V. neoplasias, hiperplasia de células intersticiais e adenomiose. Arq. Esc. Vet. UFMG, v.31, p.113-118, 1979.        [ Links ]

NIELSEN, S.W., KENNEDY, P.C. Tumors of the genital systems. In: MOULTON, J.E. (ed) Tumors in domestic animals. Berkeley: University of California Press, 1990, p.479-517.        [ Links ]

NIELSEN, S.W., LEIN, D.H. Tumours of the testis. Bull. Wld. Hlth. Org., v.50, p.71-78, 1974.        [ Links ]

PATNAIK, A.K., MOSTOFI, F.K. A clinicopatologic, histologic, and immunohistochemical study of mixed germ cell-stromal tumors of the testis in 16 dogs. Vet. Pathol., v. 30, p.287-295, 1993.        [ Links ]

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