Infectious Disorders in the Female

The Cystic Endometrial Hyperplasia-Pyometra Complex

This complex is less often observed in cats than in dogs. However, its frequency might be underestimated as many cats do not clinically express the pathology. Clinical signs are few and in general no significant haematological (other than neutrophilia and left shift) nor biochemical changes are observed. The aetiology is less clear in cats than in dogs; although the relationship with progesterone is generally proposed, this hypothesis is not easily demonstrated in cats. Indeed, as queens are induced ovulators, high and prolonged plasma progesterone concentrations are only observed when ovulation occurs and not at every cycle as is the case in bitches. The recent descriptions of a high incidence of pseudopregnancies in cats might be an explanation corroborating the possible role of the repeated and prolonged progesterone influence on the endometrium. However, the observation made in dogs that uterine reactivity to local stimuli (mechanical or biological) might be the first and real inducer of cystic endometrial hyperplasia also needs to be considered in cats. Further investigation is certainly warranted before the exact aetiopathogenesis of the cystic endometrial hyperplasia-pyometra complex can be clearly understood. Hyperplastic development of the uterine tissues, whatever the origin, certainly leads to or facilitates bacterial growth and pyometra development.

Implantation Failure and Abortion

Viral agents are the most commonly reported infectious causes of abortion in queens. Implicated viruses include feline leukaemia virus (FeLV), feline immunodeficiency virus (FIV), coronavirus, feline herpesvirus and feline panleukopenia viruses.

Bacteria reported to cause fetal death and abortion include Salmonella spp., Escherichia coli and β-haemolytic Streptococcus. Toxoplasma gondii causes abortion after experimental infections but abortion after natural infections is extremely unusual.

A large variety of bacteria, mycoplasmas or viruses have been detected in infertile cats and cultured from aborted kittens. In general, these infections present similar clinical signs and the isolation of the causal agent from the placenta or the fetuses is necessary for a clear identification of the responsible agent. Among these, feline panleukopenia and leukaemia viruses as well as Chlamydophila (formerly Chlamydia) are proposed as significant pathological agents.

Feline panleukopenia infection may result in infertility due to unapparent loss of embryo, abortion of mummified or macerated fetuses or kittening of retinal, cerebellar or cerebral hypotrophied neonates. Feline leukaemia also produces this large variety of clinical signs and has been proposed to play a significant role in the pathogenesis of the 'fading kitten syndrome'.

Chlamydophila can affect the genital tract in the cat, but the exact role of Chlamydophila infections in cat colonies is not clear yet. Isolation of Chlamydophila from vaginal swabs can occur 8-25 days after the initial conjunctival challenge but infection is not usually associated with vaginal discharge. The female genital tract may become infected before the conjunctiva in the natural situation. This could lead to salpingitis and adhesion formation as demonstrated after a feline Chlamydophila strain was inoculated directly into the oviducts of cats. However, this type of lesion has not yet been demonstrated in natural ascending infections due to the presence of valve systems in the feline uterus and oviducts. The possible effect of persistent vaginal infection on both the pathology and the clinical disease in the cat is still unclear. The organism has been occasionally associated with neonatal conjunctivitis in kittens, although there has been very little success in isolating of the organism from the queen's vaginal tract. In some colonies, abortion has been noted in cats infected with Chlamydophila. However, queens that had experienced a previous conjunctival or vaginal infection produced litters of the same size as queens that had been infected conjunctivally prior to mating and during pregnancy, if they were treated adequately for a long period of time. In breeding colonies, Chlamydophila, when present, is often thought to be endemic. This is reflected in the prevalence of antibodies to Chlamydophila in 69.4% of sera obtained from feral cats. Once endemic in a cat colony, clinical signs may persist in an individual for several weeks and recurrent episodes can occur.

Infectious Disorders in the Male

The presence of bacteria is observed in more than 90% of normal intact animals and includes E. coli, Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella oxytoca, Streptococcus spp., enteroccoci, Bacillus spp. and staphylococci. The same organisms can be detected in the semen but are probably contaminants from urethral origin during sperm collection. The bacterial infections of the external genitalia in cats are most often secondary to trauma, bites or fighting wounds.

Orchitis

Orchitis is rare in the cat but has been described following testicular infection (due to tuberculosis, feline infectious peritonitis (FIP, caused by feline coronavirus) or aerobic bacteria). Orchitis can be secondary to ascending infections from the urinary tract but is most often due to injuries, wounds or bite wounds. One or both testes can be involved. Brucellosis is rare in cats, which seem to be resistant to natural infection with Brucella spp. In cases of FIP, scrotal distension due to the extension of the peritoneal infectious process through the inguinal ring to the testes has been reported.

Orchitis due to bacterial infection is associated, as in other species, with bilateral swelling, fever, lethargy, pain, redness and anorexia. Furthermore, licking of the lesion is generally observed and may lead to an aggravation of the condition, sometimes with self-mutilation. Appropriate antibiotic therapy must be administered for at least 2 weeks, and, if not successful, must be followed by castration.

Anatomical and Congenital Abnormalities in the Female

Congenital defects and intersexuality have been reported but are uncommon in the queen. Clinical abnormalities described include:

 Cystic rete ovarii tubules: dilated ovarian tubules occurring in queens of any age and often observed in case of remnant ovaries.

 Unicornis uterus (lack of one uterine horn) or segmental aplasia (lack of development of portion(s) of the genital tract). They are in general of no clinical significance and are usually detected postmortem or during surgery.

 Bartholin's gland abnormalities: mainly cysts. The Bartholin's gland in queens appears to be clearly dependent on ovarian steroid hormones, particularly oestrogen.

Anatomical and Congenital Abnormalities in the Male

The causes of congenital defects are generally related to gene mutation. However, some congenital defects might not be related to gene mutation or abnormalities. Breeding of cats with heritable defects is not recommended and breeding of cats with defects whose heritability is not proven should also be discouraged. The main congenital or genetic defects are related to abnormal chromosome numbers (XXY, XO, chimeras and mosaics), abnormalities of gonadal sex (XX sex reversal, XX true hermaphrodite) or abnormalities of phenotypic sex.

Hermaphroditism and Pseudohermaphroditism

True hermaphroditism and abnormalities of gonadal differentiation are very rare conditions in cats. Herron and Boehringer reported abnormal testes at the tip of the uterine horns of a 1-year-old phenotypic female blue tabby (male pseudohermaphroditism). The testes contained seminiferous tubules lined with Sertoli cells but no spermatogonia.

Cryptorchidism

The absence of one or both testes in the scrotum is called cryptorchidism and has to be distinguished from monorchidism or anorchidism, which represents the agenesis of one or both testes and which are exceptional conditions in cats. The normal feline testis descends into the scrotum before birth. However, testes may move freely up and down the inguinal canal prior to puberty. Therefore, the definitive diagnosis of cryptorchidism should not be made in cats of < 7-8 months of age. Indeed, most cats presented for cryptorchidism at 4 months have normal testes at 5 or 6 months. The prevalence of cryptorchidism in adult cats ranges from 0.07-1.7%, which is much less common than in dogs. Hereditary evidence in this species has not yet been found but some authors ascertain a hereditary origin based on the observation that certain breeds like Persian cats or certain families seem to be predisposed to this pathology. However, no consensus exists and the mode of possible inheritance is not yet clear. A simple autosomal recessive sex-linked model has been proposed.

Cryptorchidism is more commonly unilateral than bilateral (ratio 3:1). In unilateral cryptorchid animals, either testicle can be equally involved.

Cryptorchid cats are most often normal and fertile when the process is unilateral. Complications (general, behavioural or pathological) are rarely observed in cats, contrary to other species, including dogs. The presence or absence of testes in a male without testes in the scrotum can be assessed by the presence of the penile spines, which totally disappear if the male has been castrated. A hormonal evaluation can also be proposed by measuring testosterone concentrations before and after a human chorionic gonadotrophin (HCG) or gonadotrophin-releasing hormone (GnRH) injection. This stimulation test is required because the testosterone concentration is often basal or close to the minimum detectable value in many normal male cats, therefore low basal values are not indicative of the absence of testis. This stimulation test is the only tool to conclude the status of the animal.

At present, it appears that medical therapies (using GnRH or exogenous gonadotrophins) are not successful in preventing or correcting abnormal testicular descent. In addition, since this condition may be inherited, a cryptorchid testis should not be corrected and the animal should be excluded from reproduction.

Since in the cat neoplasia is really uncommon (described once in a cryptorchid cat), testicular cord torsion has not been documented, the heritability of the process is still not demonstrated, and since no behavioral changes are noticed, from a clinical point of view doing nothing about cryptorchism is a reasonable option. Castration of course remains an option, and addresses the desire to modify urination or reproductive behaviour and the problem of male-related odour. If surgery is performed, as monorchidism is very rare in this species, the assumption that the absent testicle is somewhere in the animal is always true. If not detected in the abdomen, the missing testis can often be found in the inguinal ring or under the skin close to the inguinal ring.

An incision in the midline is the author's preferred method since the testes may be anywhere in the abdomen from caudal to the kidney up to the inguinal ring, and the observation of the ductus deferens at the bladder neck is probably the easiest way to find the testis. When the ductus deferens is located, gentle traction on it allows the withdrawal of the testis from its position and its surgical removal.

Testicular Hypoplasia

This condition is rarely reported in cats since the vast majority are castrated, but it can observed following infection with panleukopenia virus in the prepubertal cat, in cases of cryptorchidism and in some conditions associated with chromosomal abnormalities. It may also be observed as a complication of general acute diseases associated with persistent hyperthermia and causing the destruction of the germinal layer. This condition is often bilateral. The testes appear small and soft. Poor libido and variable testicular degeneration leading to azoospermia have been associated with malnutrition, obesity, hypothyroidism and hypervitaminosis A.

Penile Hypoplasia and Persistent Penile Frenulum

Penile hypoplasia and failure of separation between the surface of the penis and the preputial mucosa, resulting in persistence of penile frenulum, have been described and associated with early castration or genetic conditions. As animals are neutered more and more and at an earlier age, the incidence of these abnormalities as well as the relation with urethral obstruction often observed in male cats may increase in the future. No specific treatment exists but urethrostomy has to be performed when penile hypoplasia is associated with urethral obstruction. The persistence of a penile frenulum is often not clinically detectable, except if complications of balanoposthitis occur. It might be advisable to check that penile-preputial separation has occurred before castration particularly when this is performed in animals of less than 5 months of age.

Phimosis and Paraphimosis

The inability to extrude or to re-enter the penis into the prepuce may be congenital or acquired following infection or trauma. The preputial hairs of longhaired cats may entangle the orifice, causing clinical signs similar to phimosis or paraphimosis. Clipping the hair should resolve the problem. This condition is rare in cats.

Acknowledgement

BSAVA thanks John Verstegen DVM MSc PhD DipECAR for his assistance with these notes.

References

1.  Christiansen IJ. Reproduction in the dog and cat. London: Baillière Tindall, 1984.

2.  Feldman E, Nelson R. Diagnosis and treatment alternatives for pyometra in dogs and cats. In: Kirk R. ed. Current Veterinary Therapy X. Philadelphia:WB Saunders, 1989.

3.  Schille VM, Sojka NJ. Feline Reproduction. In: Ettinger, SJ; Feldman, EC. eds. Textbook of Veterinary Internal Medicine. Philadelphia: WB Saunders Co, 1995; 1690.

4.  Ström Holst B, Bergström A, et al. Characterization of the bacterial population of the genital tract of adult cats. American Journal of Veterinary Research 2003; 64: 963-968.

5.  Verstegen JA, Russel HA. eds. Fertility and infertility in dogs cats and other carnivores. Journal of Reproduction and Fertility 1993, suppl 47.