Ciência Animal 2000, 10(1):61-70 IN DOG

(Criptorquidismo no cão)

Marcos Renato Franzosi MATTOS*, Lucilene SIMÕES-MATTOS & Sheyla Farhayldes Souza DOMINGUES

College of Veterinary Science, University of Ceará, Fortaleza, CE, Brazil

ABSTRACT

The present review aims to discuss cryptorchidism in dogs, accentuating the importance, incidence, pathogenesis, pathology, macroscopic and microscopic appearance of cryptorchid , complications and disturbances, diagnosis, treatments and control. The zootechnical and ethical aspects related to this disturbance are also discussed.

KEY WORDS: cryptorchidism, dog, pathology, diagnosis, control, treatment

RESUMO

A presente revisão têm por objetivo dissertar sobre o criptorquidismo em cães, dando ênfase a importância, incidência, patogenia, patologia, aparência macroscópica e microscópica de testículos criptorquídicos, complicações e distúrbios, diagnóstico, tratamentos e controle. Os aspectos zootécnicos e éticos relacionados a este distúrbio, são discutidos. PALAVRAS-CHAVE: criptorquidismo, cão, patologia, diagnóstico, controle, tratamento

INTRODUCTION (from greek mónos = only, alone) and anorchidism (from greek anorchos = without Cryptorchidism is of major importance testis) are more correctly applied for the among the pathologies that affect reproduction congenital absence of one (monorchidism) or both in dogs, as well as other animal species. It is (anorchidism) testis in the body. These are characterized by the failure in the descent of one extremely rare anomalies among domestic (unilateral) or both (bilateral) testis from the mammals (NASCIMENTO & SANTOS, 1997). abdominal cavity to the (BURKE, 1986; Unfortunately, the term “monorchidism” is often MICKELSEN & MEMON, 1995). Besides the used erroneously, with reference to the unilateral failure in the descent of the testis, BURKE cryptorchidism (BURKE, 1986, COX, 1986, (1986) suggests that cryptorchidism may also be MIALOT, 1988, DAELS et al., 1991; NELSON the failure to maintain the normal position of the & COUTO, 1994; HAFEZ, 1995; SORRIBAS, testis in the scrotum. For PINTO (1962) and 1995; NASCIMENTO & SANTOS, 1997). FERREIRA (1986), the term “cryptorchidism” ALLEN (1995) reported a single case of is a combination of three Greek words, “kriptós” anorchidism in dogs. (hidden, occult), “orchis” () and “idion” In several species, when the testicle is (small, diminutive). The terms monorchidism not in its normal position in the scrotum, it can

* Autor para correspondência e-mail: [email protected]

61 be present in different locations, including the also report that cryptorchidism may either happen abdominal cavity, and in normal males or animals (male subcutaneous tissue. When the testis is located pseudohermaphrodites). BROWN et al. (1976) in the subcutaneous position, it can be found in describe the occurrence of male the perineal and inguinal regions, in the medial pseudohermaphrodites associated with the part of the posterior members, around or inserted unilateral or bilateral cryptorchidism and testicular in the prepuce. Many authors differentiate neoplasia (Sertoli cells) in three miniature between abdominal and inguinal positions of Schnauzers. These animals presented clinical subcutaneous location, considering as signs of hyperestrogenism, and a cystic cryptorchidism only the former two and naming endometrial hyperplasia. In cats, the Persian the subcutaneous localization as testicular ectopy breed is mentioned with a larger prevalence of (MIALOT, 1988; NIEMAND & SUTER, 1992; cryptorchidism (NELSON & COUTO, 1994). NASCIMENTO & SANTOS, 1997). As the According to NASCIMENTO & etiology, pathogenesis, symptoms, pathology and SANTOS (1997), unilateral cryptorchidism is treatment are similar for all locations, this review more frequent than bilateral. According to will not enter that description and will consider MIALOT (1988), the right testicle seems to be testicular ectopy and cryptorchidism as more frequently affected. He supposes that is synonymous. because embryologically, there is a longer migration (since they are originally located at the Incidence caudal region of the kidneys, and the right According to HAFEZ (1995), is more cranial than the left one). Similarly, cryptorchidism incidence is greater in swine and CHRISTIANSEN (1986) suggests that the lack equines than in other domestic animals. However, of descent, in dogs, is found twice as often on according NASCIMENTO & SANTOS (1997), the right side as on the left (with a relationship of while the most affected species are the equine 2.3:1, for testis retained in the inguinal region, and canine, it may occur less frequently in other and 2:1 for abdominal retention). HAFEZ (1995) species. MIALOT (1988) reports that the canine reports that, in several other animal species, the species has the highest frequency of this left unilateral cryptorchidism is more frequent. pathology (10% of adult animals) and that the According to NELSON & COUTO (1994) there tendency is increasing. MICKELSEN & is no difference between the prevalence of left MEMON (1995) and ACLAND (1998) suggest or right cryptorchids in dogs and cats. that cryptorchidism is the most common disorder of the sexual development in dogs, occurring in Embryology and fetal development 13% of the males. NELSON & COUTO (1994) In most mammals, the testis originate describe a smaller prevalence in dogs and cats from the caudal portion of the kidneys, in the that is about 1% to 2%. COX (1986) reports abdominal cavity, pass across the inguinal canal, frequencies from 0.8% to 10.9%. There is breed and descend to the scrotum during the fetal period predisposition in clinical practice as in the (SETCHELL, 1978, apud KAWAKAMI, et al. literature. COX (1986) mentions those breeds 1993). The descent of the testis is induced by that are most predisposed to cryptorchidism are the contraction of a gelatinous cord, the the , , the smaller variants gubernaculum testis (Fig. 1), which extends from being most affected (toy > miniature > standard). the caudal pole of the testis to the genital tubercle The author also mentions that the Boxer and the (COX, 1986). The exact function of the Beagle breeds are of relative risk. NELSON & gubernaculum in testicular descent is not clearly COUTO (1994) include the breeds , elucidated. With the degeneration of the German Spitz, miniature Schnauzer, Pekinese, mesonephros (transitory kidney), the Maltese, Shetland Shepherd and Cairn terrier gubernaculum is attached in the caudal portion among the most affected dogs. These authors the testis, extends through the inguinal canal and

62 The normal period for the descent of the testis to the scrotum is not strictly established in dogs or in cats. According to NASCIMENTO & SANTOS (1997), the testicles are usually present in the scrotum at birth in dogs. NELSON & COUTO (1994), NELIS (1995) and MICKELSEN & MEMON (1995) propose that in this species, the descent usually occurs at about 10 days of age. SORRIBAS (1995) mentions one month after birth, while ALLEN (1995) and MIALOT (1988) observed it within 10-12 weeks of age, and NIEMAND & SUTER (1992), at nine weeks. There is a breed variation (NELSON & COUTO, 1994; NASCIMENTO & SANTOS, 1997). In dogs, the testis are palpable in most of the cases from 4 to 5 weeks and usually within 6 to 8 weeks after birth (CHRISTIANSEN, 1986; MICKELSEN & MEMON, 1995; NASCIMENTO & SANTOS, 1997). However, Figure 1. Macroscopic appearance of testis (1), the diagnosis of cryptorchidism in dogs is not really gubernaculum (2) and gubernacular bulb (3) in certain before 6 months of age dog fetus (45 days). (CHRISTIANSEN, 1986).

Pathogenesis The causes of cryptorchidism may be genetic, anatomical or endocrine. However, these down to the scrotum (MOORE & PERSAUD, causes are still controversial and may be 1994). The distal portion of the gubernaculum is intrinsically related. The genetic origin has been called the gubernacular bulb. It is sometimes incriminated countless times, since the condition thought that the expansion of the gubernacular has been frequently observed in inbred dogs bulb out of the abdominal cavity (Fig. 2) may (MIALOT, 1988). The most often accepted contribute to the traction that moves the testis hypothesis attributes it to an autosomal sex-linked caudally (COX, 1986). (ROMAGNOLI, 1991; MICKELSEN & MEMON, 1995), recessive in all examined Descent of the testis species (BURKE, 1986, MIALOT, 1988,

Figure 2. Scheme of testicular descent showing the testis (1), gubernaculum (2), gubernacular bulb (3) and scrotum (4) (reproduced with permission from BAUMANS et al. 1981)

63 ROMAGNOLI, 1991; NELSON & COUTO, ACLAND, (1998) mentions testicular hypoplasia 1994, ALLEN, 1995, HAFEZ, 1995; as a predisposing factor of cryptorchidism. The MICKELSEN & MEMON, 1995), except in same author also reported parturition with the equine, in which it is due to a dominant autosomal male fetus in posterior presentation as gene (HAFEZ, 1995). Males and females carry compromising the blood supply to the testis and the gene and can transmit the pathology to their delay in the closing of the navel, causing offspring (NELSON & COUTO, 1994; retardation in the capacity for increasing the MICKELSEN & MEMON, 1995; abdominal pressure. NASCIMENTO & SANTOS, 1997). So it is The endocrine origin of cryptorchidism important to realize that normal animals can is not well-known (MIALOT, 1988) but seems transmit the pathology due to its recessive to be related to a deficiency character (MICKELSEN & MEMON, 1995). (NASCIMENTO & SANTOS, 1997) either due The monogenic theory does not explain to a malfunction by the testis or abnormal testis. the existence of right, left or bilateral Normal descent is dependent on a normal testis cryptorchidism in dogs, and neither does it explain during fetal life and removal of fetal testis results the disagreement between theoretical and clinical in no gubernaculum development. The testis frequencies of the anomaly. To remedy these removal 0-3 days post partum results in failure contradictions, a theory was proposed supposing of the gubernaculum to regress (NIEMAND et the intervention of two , one for each testicle. al., 1972). It may be a pituitary hormone The dominant allele would allow the migration, deficiency. The Müllerian inhibiting substance while the recessive allele would lead to the (MIS) hormone, a non-androgenic factor, retention of the testis. Some studies emphasize secreted by the Sertoli cells of the testis and a the existence of a simple autosomal factor, but growing abdominal pressure at the time of the do not discard the polygenic hypothesis of double development of the organs, could play an entrance. This hypothesis considers that, even if important part in testicular descent the cryptorchidism is determined by larger genes, (KAWAKAMI et al., 1993). The follicle its severity appears to be related to environmental stimulating hormone (FSH) and the luteinizing factors, as well as to the action of modifier genes. hormone (LH) probably have an important Following this hypothesis, the genetic function in the descent of the testis, because they determinism is not necessarily constant in many are important in the differentiation process and cases (MIALOT, 1988). For NASCIMENTO & function of the Leydig and Sertoli cells SANTOS (1997), three mechanisms can be (NASCIMENTO & SANTOS, 1997). However, responsible for the abnormal descent of the testis: it is believed that secreted by the fetal 1) lack of development of the gubernaculum; 2) testis are the most decisive factors to testicular abnormal development of the gubernaculum, descent (KAWAKAMI et al., 1993). which results in an alteration of its normal position; 3) excessive growth of the testicle and absence Macroscopic and microscopic appearance or retardation in the regression of the The macroscopic aspect of the gubernaculum. MIALOT (1988) reports an cryptorchid testis is normal before ; after anatomical etiology, which can be linked to the sexual maturation, the testis becomes reduction of the gubernaculum (due to as progressively smaller and fibrotic (ACLAND, abnormal insertion) and combined with the 1998). According to COX (1986), cryptorchid narrowing or closing of the inguinal canal. testicles are always small and soft, especially Furthermore, NIEMAND & SUTER (1992) when they are in abdominal position. However, propose other factors such as the occurrence of the normal size testis in abdominal bilateral adherences of the spermatic cord, hormonal cryptorchid is reported in animals at six years of alterations from the frontal lobe of the pituitary age (MATTOS et al., 2000). Histologically, and large testicular size. On the other hand, ACLAND (1998) reported interstitial deposition

64 of collagen, hyaline thickening of the basal position of the testis, outside the abdominal cavity membranes and of the germinative and inside the scrotum, allows maintenance at a epithelium and only some spermatogonia temperature lower than body temperature remained together with the Sertoli cells (Figure (JUNQUEIRA & CARNEIRO, 1990). 3). COX (1986) described only one single layer NELSON & COUTO (1994) explained that the of spermatogonia, primary spermatocytes and of a cryptorchid testis, especially Sertoli cells. The same author mentioned that the when abdominal, is totally absent, because the Sertoli cells are characterized by increased temperature is too high for this function, but, if Golgi’s complex and smooth endoplasmic the testicle is inside the scrotum, the reticulum (site of steroidal synthesis) and spermatogenesis is generally normal, in line with decreased number of lysosomes. ACLAND other authors (BURKE, 1986; (1998) reported that the interstitial cells seem CHRISTIANSEN, 1986; COX, 1986; MIALOT relatively more numerous than in the descended 1988; JUNQUEIRA & CARNEIRO, 1990; testis, and that the differentiation of the ROMAGNOLI, 1991; NELSON & COUTO, epididymides were coordinated by the testicular 1994; NIEMAND & SUTER, 1992; ALLEN, descent. An epididymidal differentiation could be, 1995; HAFEZ, 1995; SORRIBAS, 1995; consequently, late in some cases of ACLAND, 1998). PINART et al. (1997) report cryptorchidism. that unilateral abdominal cryptorchidism in male goats can cause disturbances at the end of Complications spermatazoa maturation during spermiogenesis According to MIALOT (1988), of the normal testis, but not in the epididymal cryptorchidism can cause various complications maturation process. In experimental unilateral in relation to the individual’s age and the type of cryptorchidism, no spermatogenesis was testicular ectopy, such as: sterility, behaviour observed in the cryptorchid testis and the number disturbances, neoplasia, local pain and skin of germ cells in the contralateral testis had diseases. He also mentions that abnormalities decreased 52 weeks later (KAWAKAMI et al., have been seen in the eutopic testis, as well as 1999). They suggest that a large quantity of gland atrophy and hyposexualism (reduction of estradiol-17-beta secreted by the cryptorchid size of the prepuce and penis). The normal testis inhibits the endocrine and spermatogenic

Figure 03. Histological appearance of normal (left side) and cryptorchid (right side) testis in dog. Observe the germinative epithelium atrophy in cryptorchid testis (arrow).

65 functions of the contralateral testis in the dog. Neoplasia in the ectopic testis are more BADINAND et al. (1972) observe that less than frequent than in the eutopic, being 50% of unilaterally cryptorchid dogs were able tumors and mainly, and they generally to ejaculate, and that 69% of these animals which appear in animals of six to ten years of age can ejaculate, do not have spermatozoa in their (ROMAGNOLI, 1991; NIEMAND & SUTER, semen. The same authors mention that the 1992). NASCIMENTO & SANTOS (1997) fructose and citric acid concentrations of the mentioned a risk ten times greater for a retained seminal plasma are increased, while the lactic testicle to develop neoplasia compared to a normal acid concentration is reduced. The acid one. This is similar to 9.2 to 13.6 reported by phosphatase level is higher than in the normal COX (1986). ACLAND (1998) added that there animals. is a tendency for an increase in tumor incidence Despite the finding of and with the severity of the retention. The same decrease in the ejaculate volume in the unilateral author reports that in dogs, Sertoli cell tumors cryptorchid dogs, we feel that on the contrary, occur with a greater probability in testis retained the unilateral cryptorchid animal is generally able in the abdomen, while inguinal testis tend to to mate and produce offspring, despite their lower develop seminomas. REIF et al. (1979) reported sperm concentration. Regarding the reduction of the double incidence of testicular neoplasia in the secundary sexual characteristics and libido, inguinal retention compared to the abdominal a high number of animals it is commonly observed situation. According to HAYES & that, although being unilaterally or bilaterally PENDERGRASS (1976), seminomas and Sertoli cryptorchid, normal sexual behaviour and libido cell tumors occur at the same frequency in are mentioned. According to JUNQUEIRA & cryptorchid as normal dogs, but for REIF & CARNEIRO (1990), NELSON & COUTO BRODEY (1969), the apparition of these (1994), NIEMAND & SUTER (1992) and neoplasias is more precocious in the retained ALLEN (1994), the interstitial cells continue to testis. The Sertoli cells tumors are more common produce testosterone, thus inducing the secondary in , German Spitz, Yorkshire Terriers, sexual characteristics and normal libido, which Pekineses, English , miniature can even be increased, according to NELSON Schnauzers, and Old English Sheepdogs & COUTO (1994), due to a disarray in the (MICKELSEN & MEMON, 1995). Some of the negative feedback. MATTOS et al. (2000) report testicular neoplasias are hormonally active, a natural case of a bilaterally cryptorchid dog causing alopecia and feminization syndrome in that presented high libido. They observed the the males. This occurs in 40 % of the cases of absence of libido after six months of Sertoli cells tumors in dogs (COX, 1986). cryptorchiectomy. According to the author, this fact may be In humans where the testicle is surgically associated with an increased smooth moved and placed in the scrotum at a young age, endoplasmatic reticulum of the Sertoli cells in the the spermatogenesis returns to normal, because retained testis, which are the site of steroidal the spermatogonia are still normal (JUNQUEIRA synthesis, and more precisely for oestradiol & CARNEIRO, 1990). However, in animals, this production. The skin disorders, according to procedure is not recommended. MIALOT (1988), are caused by hormonal When cryptorchidism is bilateral, the imbalance due to the degeneration of the testicle. animal is sterile (BURKE, 1986; MIALOT, 1988; KAWAKAMI et al. (1999) report low levels of DAELS et al., 1991; ROMAGNOLI, 1991; testosterone and high levels of estradiol-17-beta NELSON & COUTO, 1994; ALLEN, 1995; in experimentally unilaterally cryptorchid testis. HAFEZ, 1995; MICKELSEN & MEMON, MATTOS et al. (2000) report high levels of 1995; NASCIMENTO & SANTOS, 1997). estradiol in the serum of a natural case of a There is a certain tendency to obesity, sudden bilaterally cryptorchid dog. This hormonal and transitory aggressiveness, nervousness or imbalance may be the reason of skin and prostatic apathy in these animals (MIALOT, 1988). disorders verified in old cryptorchid dogs. 66 Table 1. Protocol treatments of cryptorchidism in dogs.

Hormone Protocol HCG 35 IU/Kg in six applications, with a two days interval* GnRH 50 to 100mg/animal for four days and after continue with a series of six applications of 25 to 50mg/animal with a two days interval* ECG 30IU/Kg once a week for two months**

hCG - human chorionic .eCG - equine chorionic gonadotrophin. GnRH - gonadotrophin releasing hormone. *MIALOT, 1988. ** NIEMAND & SUTER, 1992

According to MIALOT (1988), local pain the non-palpable testis represents 20% of cases symptoms are rare, but can occur, taking the form of cryptorchidism. He mentioned that several of difficulties or limping due to a torsion methods are used for diagnosis of the cryptorchid of the spermatic cord, generally associated with testicle including ultrasonography, hormonal a testicular neoplasia. NIEMAND & SUTER evaluation, pneumoperitoneography, (1992) and ROMAGNOLI (1991) reported that herniography, venography, arteriography, is relatively frequent when there is a torsion of computerized tomography, magnetic resonance the cord and strangulation of the intestinal loop. imaging, laparotomy and laparoscopy, indicating COX (1986) also mentioned a blood dyscrasia that the ideal method of diagnosis and localization as a complication of the cryptorchid condition. does not really exist. MADRAZO, et al. (1979) cited by Diagnosis MALONE & GUINEY (1985) mentioned that Clinical diagnosis is generally easy, by in humans, the ultrasound is a difficult method of inspection and palpation. By inspection, the diagnosis for abdominal testis because of the great absence of one or two testis in the scrotum is amount of gas in the intestines associated to the diagnostic. By palpation, the testicle can be felt small size of the retained testicle. MALONE & between the scrotum and the inguinal canal, in GUINEY (1985) recommended diagnosis by the subcutaneous tissue or can be non-palpable. ultrasound for non-palpable testis, only when they By this procedure, the small size of the ectopic are in the inguinal canal, thus avoiding invasive testicle may be assessed (MIALOT, 1988). procedures such as laparoscopy. WEISS & However, especially in the first months, the testis SEASHORE (1987) cite that in man, a careful can have a normal size. According to MIALOT physical exam has been more efficient than (1988), palpation is sometimes difficult; a ultrasonography. Laparoscopy in humans has pressure exercised on the abdomen may allow been recommended as a simple and more the testicle to appear, if it is in the inguinal canal. efficient technique for localizing non-palpable He also cites as characteristic of a retained testis, testis (MALONE & GUINEY, 1985; WEISS & the mobility, the presence of the epididymides, SEASHORE, 1987). the smooth surface and firm consistency. In obese animals, palpation and even the ultrasound Treatment examination are difficult and do not allow the There are two forms of treatment for localization of the retained testicle. The diagnosis cryptorchidism in dogs: hormonal and surgical. can only be accomplished after ten weeks of age (MIALOT, 1988) or even six months (COX, Hormonal 1986). The hormonal treatment of CASTILHO (1990) reported that in man cryptorchidism in dogs (table 01) is based on

67 human treatment presenting various results. Surgical These treatments are recommended in the two Surgical treatment should not be or three first months of life of the animal. Their undertaken in dogs under six months old because goal is to aid the descent of the testis, especially of the possibility of a late descent (COX, 1986). when they are in the inguinal or inguinal-scrotal In the surgical treatment, the traction on the position. testicle through the scrotum and its fixation Testicular hypertrophy may be observed () is not recommended for with the use of GnRH, followed by a definitive zootechnical reasons (NIEMAND & SUTER, migration. According to NIEMAND & SUTER 1992). BURKE (1986) commented that (1992), some authors still mention the use of orchiopexy is a contravention of veterinary ethics. testosterone, however they do not recommend In addition this procedure may harm the blood due to an excessive response of the supply to the tissues by stretching of vessels negative feedback for gonadotrophin liberation, (MIALOT, 1988). The recommended surgical and due to the premature closing of the growth treatment consists of cryptorchiectomy (COX, cartilage in young animals. The same authors also 1986; MIALOT, 1988; NELSON & COUTO, reported a good prognosis for this therapy in the 1992; ALLEN, 1995; SORRIBAS, 1995). Two case of inguinal cryptorchidism, but a more reports were found on the use of laparoscopic uncertain prognosis in abdominal cases. for cryptorchiectomy in dogs (GIMBO et al., 1993 The indication for hormonal treatment is and PENA et al., 1998). These authors affirmed controversial, and some authors reported an that laparoscopy allows the orchiectomy in a less efficacy, which tends to be small or nil (BURKE, traumatic manner for the animal than a classic 1986; ROMAGNOLI, 1991). It is maybe because laparotomy. The retreat of the testicle in a normal the hormonal treatment only speeds up the position (eutopic) is recommended to prevent the descent of the testis, which was already crossing and dissemination of the undesirable descending to the scrotum any way, and, thus character (ALLEN, 1995). It is realized by only accelerates a late descent. Moreover, many ablation of the normal testicle or by the section authors do not recommend the hormonal of the canal (vasectomy). treatment because of the risk of hereditary Vasectomy is reserved for young animals, and transmission (COX, 1986; MIALOT, 1988; the intervention can be made by inguinal or ROMAGNOLI, 1991; NELSON & COUTO, abdominal ways, adapted to the position of the 1994; ALLEN, 1995 and MICKELSEN & ectopic testicle (MIALOT, 1988). The MEMON, 1995). The use of hormonal treatment vasectomy of the normal testicle associated with for the descent of inguinal, inguinal-scrotal or the orchiectomy of the ectopic testis, is valuable abdominal cryptorchid testicles can be or choice alternative for preventing the recommended with great restrictions and only if dissemination of the characteristic without necessary. This procedure can facilitate a displeasing the animal owners, since there is great posterior orchiectomy, to avoid much more opposition by owners to a radical orchiectomy. complex surgical procedures, such as laparotomy Complete presents some benefits to mainly in animals, in which surgery presents a the animal’s health that the vasectomy does not, risk. such as prevention of prostatic and skin disorders, It should be clear that this hormonal anal dysplasia and carcinomas, because the treatment may be carried out only by veterinarians source of the sex steroid hormone was removed. who understand the seriousness of the case, and It is important to notice that the testis, the customers’ honesty, avoiding the dissemination which suffered orchiopexy and/or hormonal of this anomaly. treatment, may present a greater risk for

68 developing a neoplasia. CHRISTIANSEN, I. B. J. 1986. Reprodução no Cão e no Gato. Manole. São Paulo. 362p. Control COX, V. S.1986. Cryptorchidism in the dog. In: Morrow, In agreement with what has been D.A. Current therapy in Theriogenology. ed2. WB previously discussed, it becomes clear that the Saunders. Philadelphia. p. 541-544. DAELS, P. F., HUGHES, J. P. & STABENFELDT, G. H. best control of cryptorchidism is surgical. The 1991. Reproduction in horses. In: CUPPS, P.T. complete castration of these animals is the best Reproduction in domestic animals, ed4, Academic choice because of the health benefits quoted Press. San Diego. 670p. previously. The veterinarians have to know about FERREIRA, A. B. H. 1986. Novo Dicionário Aurélio da the importance of this anomaly, motivating the língua portuguesa. Ed2. Nova Fronteira S/A. Rio retreat of the reproduction of unilateral and de Janeiro. 1294p. bilateral cryptorchidic animals, due to the GIMBO, A., CATONE, G., CRISTARELLA, S. & possibility of hereditary transmission of this illness. SCIRPO, A. 1993 A new, less invasive, laparoscopic- MICKELSEN & MEMON (1995) firmly laparotomic technique for the cryptorchidectomy recommend not to use in breeding, relatives of in the dog. Arch. Ital. Urol. Androl., 65:277-81. HAFEZ, E. S. E.1995. Distúrbios reprodutivos nos the cryptorchid animal, which may transmit this machos. Reprodução animal. 6ed. Manole. São character, even if it is with decreased frequency. Paulo. p.291-293. ROMAGNOLI (1991) affirmed that the control HAYES, H. M. & PENDERGRASS, T. W. 1976. Canine of animals used in reproduction is highly efficient testicular tumours: epidemiologic features of 410 to decrease the incidence and to control this dogs. Int J. Cancer., 18:482-487. pathology. JUNQUEIRA, L. C. & CARNEIRO, J. 1990. Aparelho reprodutor masculino In: Histologia básica. ed7. REFERENCES Guanabara. Rio de Janeiro. p.323-334. KAWAKAMI, E., YAMADA, Y., TSUTSUI, T., ACLAND, M. H. 1998. Sistema reprodutor do macho. OGASA, A. & YAMAUCHI, M. 1993. Changes in In: Carlton, W. W. & McGAVIN, M. D. Patologia plasma androgen levels and testicular histology veterinária especial de Thompson. 2ed. Artmed. with descent of the testis in dog. J. Vet. Med. Sci., Porto Alegre. p. 575-576. 55:931-935. ALLEN,W. E. 1994. Fertilidade e obstetrícia eqüina. KAWAKAMI, E., HORI,T. & TSUTSUI,T. 1999. 1ed. Varella. São Paulo. p. 174,180-182. Function of contralateral testis after artificial ALLEN,W. E. 1995. Anormalidades anatômicas no unilateral cryptorchidism in dogs. J. Vet. Med. Sci., macho. In: Fertilidade e obstetrícia no cão. 1ed. 61:1107-11. Varella. São Paulo. p. 92-93. LADDS, P. W. 1993. Congenital abnormalities of the BADINAND, F., SZUMOWSKI, P. & BRETON, A. genitalia of cattle, sheep, goats and pigs. Vet. Clin. 1972. Étude morphobiologique et biochimique de North. Am. Food. Anim. Pract., 9:127-144 sperme de chien cryptorchide. Rec. Méd. Vét., MALONE, P. S. & GUINEY, E. J. 1985. A comparison 148:655-689. between ultrasonography and laparoscopy in BAUMANS, V., DIJKSTRA, G. & WENSING, C. J. 1981. localizing the impalpable undescended testis. Br. Testicular descent in the dog. Anat. Histol. J. Urol., 57:185-186. Embryol., 10:97-110. MATTOS, M. R. F., PEREIRA, B. S., DOMINGUES, S. BROWN, T. T., BUREK, J. D. & MCENTEE, K. 1976. F. S., COSTA, M. A. L. & LIMA, P. R. B. 2000. Male , cryptorchidism, Criptorquidismo em um cão: relato de caso. Ci. and Sertoli cell neoplasia in three miniature Anim. supl. 10:128-129. Schnauzers. JAVMA. 169:821-825. MIALOT, J.P. 1988. Patologia do aparelho genital BURKE, T. J. 1986. Causes of infertility. In: Small animal masculino. In: Patologia da Reprodução dos reproduction and infertility. ed1. Lea & Febiger. carnívoros domésticos. ed1. Metrópole. Porto Philadelphia. p. 233-235. Alegre. p.69-71. CASTILHO, L. N. 1990. Laparoscopy for the non- MICKELSEN, D. W. & MEMON, M. A. 1995. In: palpable testis: how to interpret the endoscopic STEPHEN J. ETTINGUER, EDWARD FELDMAN. findings. J Urol, 144: 1215-1218. Textbook of veterinary internal medicine. ed4. WB

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