Pathological Conditions of the Reproductive Organs of Male Stray Dogs in the Tropics: Prevalence, Risk Factors, Morphological Findings and Testosterone Concentrations

Abstract

The objective of this study was to estimate the prevalence of and risk factors for pathological conditions of the reproductive organs in stray dogs under tropical conditions. Three hundred and eighteen dogs were examined post-mortem in the period from 1 July 2002 to 30 June 2003. Before killing, a blood sample (from the cephalic vein) for testosterone assay was taken. Pathological conditions of the reproductive organs were found in 135 of the dogs (42.5%) and in 175 of the testes (64.8%). The most frequent pathologies found were testicular degeneration, cryptorchidism, testicular hypoplasia and testicular tumours (in 15.1%, 6.6%, 6.6% and 5.4% of the dogs and 15.1, 4.6, 6.0 and 3.5 of the testes, respectively). Transmissible venereal tumour (TVT) was seen in 5.4% of the dogs. Testicular degeneration was more common in old dogs and underweight dogs (p < 0.05). Testicular tumours were 14.3 times more common in cryptorchid dogs. Age was another important factor for the development of testicular tumours (p < 0.05). Lower levels of testosterone concentration (p < 0.05) were observed in dogs with advanced testicular degeneration (0.7 +/- 0.8 nM), dogs with hypoplastic testicles (0.8 +/- 0.9 nM) and dogs with one degenerated and one retained testis or with bilateral cryptorchidism (1.2 +/- 0.9 nM) compared to dogs with one or two normal testes (7.0 +/- 5.5 nM). Testicular volume and weight were significantly lower in degenerated, hypoplastic and retained testes compared with the contralateral normal testis. Some spermatogenic activity was found in three of the retained testes, producing oligozoospermic smears with a high percentage of sperm abnormalities. No comparable epidemiological data about male pathological conditions of the reproductive organs in the dog is available. The prevalence found in this study, yet, appears high.

A 12-Year Retrospective Study of Canine Testicular Tumors

“…Cryptorchid testes were approximately 13.6 times more likely to develop a tumor than scrotal testes [6]. Thirty years later, a similar result at 14.3 times the previous rate was reported from a study of 308 stray dogs [11]. The occurrence rate of SCTs and SEMs in the cryptorchid testis of dogs was much higher than in scrotal testis [16].…”

Fibrolipoma of a Cryptorchid Testis in a Young Bull

“…Incidence of cryptorchidism is relatively high in dogs and it is well documented that cryptorchidism and advanced age are major risk factors associated with testicular tumours in dogs [12,16,19]. In addition to the present case, where the tumour was diagnosed at nine months of age (the mass was initially palpated per rectum at six months of age), tumours in other newborn and young cattle have been reported [2,6,17].…”

Testicular Neoplasia in the Retained Testicles of an Intersex Male Dog

“…The relative risk factors published are 14.3, 13.6, and 9.2. 15–17 The data are mixed regarding the most common tumor type encountered. There is similar contradiction regarding the prevalence of tumor types in the retained versus the descended testicle.…”

“…Overall frequency of tumor types in feral dogs in Mexico and client-owned dogs in Italy were found to be similar to those identified in Taiwan. 15,20 However, neither of those studies reported data regarding incidence of tumor types in relation to retained versus descended testes. These reports are in stark contradiction to an earlier study of dogs in the United States that reported Sertoli cell tumors to be the more common tumor of retained testes.…”