Testicular hypoplasia
is where the testis does not develop to its normal size. It is always
accompanied by a failure of the epididymis to acquire its normal size
also. Most cases of hypoplasia are because of cryptorchidism, but in this
section, primary hypoplasia is limited to those situations where the testis
has descended normally. Hypoplasia is almost always seen as a failure
of the prepubertal testis to enlarge, but there may be cases where even
the prepubertal testis is smaller than normal. Hypoplasia is best diagnosed
clinically by identifying that the testis has no increased in size from
puberty, but this change is seldom monitored in cats and so the presence
of a small testis could mean either hypoplasia or atrophy. Atrophy is
an acquired condition, but hypoplasia is potentially a genetic and heritable
condition, at least in other species.
Hypoplasia is variable
in its degree. In production animals, testicular volume or scrotal circumference
is measured and a certain size is deemed to be the minimum acceptible.
Smaller testes than the minimum size have some degree of hypoplasia –
in some, there are only mild changes, but in others, they are extreme.
The literature suggests that many cats with testicular hypoplasia have
chromosomal anomalies.
There are degrees of
hypoplasia. While all retained testes are hypoplastic, in some the degree
of hypoplasia is extreme. A microscopic focus of testicular tissue is
present in some (see Fig).
Axner et al (1996) report 3 cats with hypoplasia.
2 had chromosomal anomalies (XXY, XY/XXY) and one did not.
Szczerbal et al (2018) reported on 3 cats with chromosomal abnormalities. One was an XY cat with small testes, bifid scrotum, rudimentary penis and no uterus.
Figure
9
: Marked testicular hypoplasia with
only a few seminiferous tubules present. The epididymis was 'normal' for
a retained testis (YB167169).
.
Figure
10
: Extreme testicular hypoplasia (YB69029).
Figure
11
: Hypoplastic epididymis attached to
the tissue of fig 10.
I acknowledge that some
would call this testicular aplasia. I have arbitrarily chosen to reserve
testicular aplasia for those situations where absolutely no testis or
remnant or epididymis is found.
Congenital phimosis
There are several reports of cats with congenital phimosis. (Bright and Mellanby 2004, ) obstruction or partial obstruction of the preputial orifice or tip of the penis. Surgical correction is reported. It is difficult to determine if the congenital phimosis was because of the normal fusion of penis and prepuce in a prepubertal animal.
Bright SR, Mellanby RJ. Congenital phimosis in a cat. J Feline Med Surg. 2004; 6: 367-370.
Polyorchidism
Milwright and Smith (1999) report finding a cat with 3 testes.
Roca-Ferrer et al (2015) reported on a cat with 4 intraabdominal testes. They were bilateral and close to each other on each side. Each testis had its own epididymis and epilateral deferent ducts fused to form one duct.
Lohr et al (2022) reported on a cryptorchid cat with 4 testes - each with epididymides.
Lohr BR, Lieske DE, Parry NM. Polyorchidism in a cat. J Vet Diagn Invest. 2022; 34: 1020-1022.
Milwright RD, Smith KC. Polyorchidism in a cat. Vet Rec. 1999 Dec 4;145(23):679-80.
Roca-Ferrer J, Rodríguez E, Ramírez GA, Moragas C, Sala M. A rare case of polyorchidism in a cat with four intra-abdominal testes. Reprod Domest Anim 2015; 50: 172-176.
Testicular aplasia, anorchia, monorchia
Testicular aplasia is
when no testis develops. Separating testicular aplasia from extreme hypoplasia
or degeneration is arbitary. This
diagnosis, to some extent is, is one of exclusion. The total absence of
testicular tissue requires a diligent search for any tissue, and to be
thorough, necessitates examining the surgically removed tissue, trimming
all tissues and having all parts sectioned.
I have examined many cases of suspected anorchia. These are almost entirely cryptorchid tests and in most epididymis, deferent duct, and some remnant of the testis is present. Only rarely is there no evidence of any testicular structure.
McEntee (1990) reports seeing only one case.
Anorchia - No testis,
Previous surgical removal
When there has been previous
surgical removal, the end of the ductus deferens can be found, and usually
the ductus is well developed and at a size commensurate with the size of
the ductus at the age of castration or removal. No epididymal tissues or
embryonic remnants should be present.
Figure
6
: Ductus deferens from suspected retained
testis
Cryptorchidism
Retained, undescended
or ‘hidden’ testis is the most common disease of the feline
male reproductive tract. Millis et al (1992) found that of 1,345 cats
undergoing orchectomy, 23 or 1.7% were cryptorchid and 2 were monorchid.
There was no predisposition for abdominal versus inguinal, and right versus
left in unilateral cryptorchids. Yates et al (2003) castrated 3806 cats
and 50 were cryptorchids. Left and right inguinal cryptorchidism was the
most common form. Cryptorchidism is a feature of calico male cats (with
XXY or mosaics of XX/XY).It is seen in other types of chromosomal anomalies see above.
Normally, the testes
should be within the scrotum at or soon after birth. Most cases are handled
clinically, so they do not enter the domain of the surgical pathologist.
Before puberty, the retained testis is usually identical to the descended
testis in every way except for location. With the onset of puberty, there
is no spermatogenesis, so the histological appearance is identical to
that of a prepubertal testis – and to a hypoplastic testis.
Figure 12: Histology of a cryptorchid
testis.
Histologically, the
testis is composed of seminiferious tubules that are lined by sustentacular (Sertoli)
cells. Large mononuclear (germ) cells are often present in the lumen, or between
sustentacular (Sertoli) cells – these are the spermatogonia. The interstitial endocrine
cells are usually very obvious, and appear to be in greater numbers. Studies
in other species suggest that their number is not increased over normal,
but that the area taken up by the seminiferous tubules is greatly reduced.
Hakala (1984) reported on a cryptorchid cat.
Hakala JE. Reproductive tract anomalies in 2 male cats. Mod Vet Pract. 1984; 65: 629.
Memon M, Tibary A. Canine
and feline cryptorchidism. In: Recent advances in small animal reproduction.
PW Concannon, G England and J Verstegen (Eds) International Veterinary
Information Service (www.ivis.org) 2001
Millis DL, Hauptman
JG, Johnson CA.(1992) Cryptorchidism and monorchism in cats: 25 cases (1980-1989). J Am Vet Med Assoc 200(8):1128-1130.
Yates D, Hayes G, Heffernan
M, Beynon R. Incidence of cryptorchidism in dogs and cats. Vet Rec. 2003; 152: 502-504.
Persistent paramesonephric
(Mullerian) ducts (Uterus masculinus) - deficiency in Antimullerian hormone or receptor
This is a common anomaly
in male cats. The paramesonephric ducts, those ducts that, in the female,
would give rise to the uterine tube and uterus, are retained. In dogs this
is called the persistent mullerian duct syndrome (PMDS). Affected cats are
gonad and phenotypic males, but have a persistent paramesonephric duct. This
can be found parrallel to the ductus deferens and also beside the epididymis.
Persistent paramesonephric
duct (uterus masculinis) in a male cat. The inner two ducts have a uterine
appearance, whereas the outer ducts are ducti deferentes.
Persistent paramesonephric
duct in a male cat. The tube on the left resembles a uterine horn and the
tube on the left is the ductus deferens. (YB135279).
Schulman and Levine (1989)
reported a 10 month old castrated male cat with pyometra of a cystic uterus masculinus. It was a cryptorchid
as the gonads were inguinally retained.
Vallefuoco et al (2013) reported on a 3 month old kitten with an anovaginal fistula, cloaca with vaginal but testes and an XY genotype.
Schulman J, Levine SH (1989) Pyometera involving uterus masculinus in a cat. J Amer Vet Med Assoc 194: 690-691.
Vallefuoco R, Alleaume C, Jardel N, Maenhoudt C, Cordonnier N. (2013) Type II atresia ani associated with rectovaginal fistula in a male pseudohermaphrodite kitten. Canadian Vet J 2013; 54: 475-478.
No scrotal contents, ambiguous genitalia including hypospadias
King and Johnson (1983) reported on one cat with hypospadias. It was XY with testes.
Hakada (1984) reported on 2 cats with external genital lesions. One had hypospadias.
Nowacka-Woszuk et al (2014) reported on 4 cats that were 38XY and normal SRY and ZFY and they had abnormalities of the external genitalia - 3 had hypospadias and one had a normal penis and a blind vulva. The molecular background for this is unknown.
Dzimira S, Nizanski W, Madej JA. Morphological analysis of testicles in cats with disorders of sex development. Pol J Vet Sci. 2017; 20: 123-131.
Hakala JE. Reproductive tract anomalies in 2 male cats. Mod Vet Pract. 1984 Aug;65(8):629. PMID: 6149456.
King GJ, Johnson EH. Hypospadias in a Himalayan cat. J Small Anim Pract. 2000; 41: 508-510.
Nowacka-Woszuk J, Szczerbal I, Salamon S, Kociucka B, Jackowiak H, Prozorowska E, Slaska B, Rozanska D, Orzelski M, Ochota M, Dzimira S, Lipiec M, Nizanski W, Switonski M. Testicular disorder of sex development in four cats with a male karyotype (38,XY; SRY-positive). Anim Reprod Sci. 2014; 151: 42-48.
No scrotal contents, phenotypic female
Disorders of androgen synthesis or action
There are many reports
of male feminisaton in cats.
Meyers-Wallen et al (1989) examined one such individual in detail and determined that there
was a testosterone receptor problem and that this was an X linked heritable
disease.
Hakala (1984) reported male pseudohermaphroditism in a 3 year old cat. The owner reported
that the cat had been castrated, but it had a vulva
and a penis that could not be extruded and was 3 mm long. No gonads were found
and the karyotype was unknown.
Meyers-Wallen et al (1989) reported on a phenotypically female
cat with gonads in the location of the ovaries, but no tubular genitalia.
The gonad was testis and the karyotype was 38 XY.
Based on fibroblast cultures, there was no testosterone binding to receptors.
Bredal WP, Thoresen SI, Kvellestad A, Lindblad K. (1997) Male pseudohermaphroditism in a cat. J Small Anim Pract.
38(1):21-4.
Hakala JE. (1984) Reproductive tract anomalies in 2 male cats. Modern Vet 65: 629.
Meyers-Wallen, VN, Wilson JD, Griffin JE, Fisher S, Moorhead PH, Goldschmidt MH, Haskins ME, Patterson DF. Testicular feminization in a cat. Vet Med Assoc 1989; 195: 1456-1458.
XY ovarian DSD
XY ovotesticular DSD
Schlafer et al (2011) reported on a cat that was phenotypically male with penis and scrotum, but had ovotestes in the location of the ovaries. It had both male and female tubular genitalia. It was typed as an 38XY, SRY positive.
Schlafer DH, Valentine B, Fahnestock G, Froenicke L, Grahn RA, Lyons LA, Meyers-Wallen VN. (2011) A case of SRY-positive 38, XY true hermaphroditism (XY sex reversal) in a cat. Vet Pathol 2011, 48: 817-822
XY gonadal dysgenesis
