Contributors: Autumn P Davidson, David Godfrey

 Species: Feline   |   Classification: Miscellaneous

Introduction

  • There is little published about infertility in domestic male cats.
  • Much has to be gleaned from infertility in other species, eg the dog.
  • Some experimental work has been performed on cat semen to facilitate the breeding of endangered wild felidae.

Background

  • Breeding of pedigree cats usually occurs under controlled conditions.
  • Male (stud) cats usually live in an isolated pen with indoor and outdoor areas.
  • His services are used by the stud owner or are hired out to other breeders who bring their female cats to him.
  • Calling females are housed with the male for a period of time (a few days to a few weeks).

Pathophysiology

  • Infertility problems can be divided into problems of:
    • Libido.
    • Physical or mechanical factors.
    • Problems with semen.

Decreased libido

  • Libido problems may be seen because a male is too young, stressed in his environment because he has not yet established his territory, or because he feels threatened eg by a free-roaming cat outside the enclosure or a dominant tom in a nearby enclosure. A dominant visiting queen may intimidate an insecure tom which may prevent mating from occurring.
  • Failure to accurately diagnose estrus  Queen in estrus in the visiting queen is a differential diagnosis for male infertility due to lack of libido. A tom will not show sexual interest in a non-calling female.
  • Some toms may be stressed by being moved. It is standard practice to move the queen to the tom. If a tom was moved to the queen this could be a cause of inadequate libido. Moving enclosure or moving stud could cause insecurity and a drop in libido. A tom that was used to living in a large enclosure or inside a house might have a drop in libido after being moved to an outside enclosure. Decreased contact with people or a particular person might also cause insecurity and decreased libido in a sensitive tom.
  • Immediately after mating it is usual for the queen to exhibit a fury response, turning around and briefly attacking the tom. Inexperienced toms might be put off future matings if this response were exaggerated or the tom were sensitive. Experienced toms may only mate when they can see a readily available hiding place or escape route. Queens are usually stimulated to ovulate by copulation. There need to be at least four matings per day to induce ovulation in 100% of queens. Factors that decrease the number of copulations may therefore decrease fertility Failure to accept male at breeding.
  • Decreased libido often occurs in males with abnormal genotypes eg triploidy (39, XXY) although these cats usually have sperm abnormalities that are an additional cause of infertility.
  • An idiopathic, congenital lack of libido has been reported in cats.
  • A lack of attraction between individual cats is suggested to happen.
  • Any drug therapy has the potential to cause decreased libido.
  • Leydig cell failure with consequential high levels of LH, inadequate testosterone, reduced libido and spermatogenesis has not been reported in cats.
  • Hypogonadotrophic hypogonadism is a cause of infertility which has not been reported in cats. Pituitary disease   →     inadequate FSH and LH secretion and subsequent inadequate testosterone production and azoospermia   →    reduced libido.
  • General illnesses are likely to decrease libido especially if they cause fever, pain or other systemic signs.

Physical factors

  • The tom must grasp the queen firmly by the scruff for successful mating. He must be able to protrude an erect penis and place it into the vagina.
  • Dental disease  Periodontal disease or lack of teeth may exclude successful mating by preventing the male from taking a firm grip. This might be more likely if the tom is also inexperienced or the queen is inexperienced, domineering or frightened.
  • Gross size disparity between the male and female or obesity Obesity of the male could make intromission physically impossible.
  • Skeletal problems, especially of the back and hind legs may prevent or inhibit mating behavior especially if the problem is painful eg hypervitaminosis A Hypervitaminosis A.
  • Phimosis will prevent intromission. It may occur due to an abnormal prepucal opening which may be congenital or acquired but the commonest cause is a ring of fur accumulating around the penis inside the prepuce, especially in long-haired cats.
  • Persistent penile frenulum has been reported to prevent intromission due to dorsal deviation of the penis.
  • Diphallos (a congenital defect of having two glans penis) has been reported and is likely to prevent intromission. The defect is likely to be associated with additional developmental abnormalities.

Semen problems

  • Genetic abnormalities, triploidy (38,XXY) or mosaicism/chimerism (XX/YY, XXY/XY) are associated with the absence of sperm in the ejaculate. They should be suspected in calico or tortoiseshell cats with male genitalia.
  • Testicular hypoplasia Testicular hypoplasia is a reported cause of infertility in male cats. It may be congenital, associated with abnormal genotype. It has been reported to be associated with a perinatal panleukopenia infection.
  • Testicular degeneration Testicular degeneration suggests an acquired pathology that had led to decreased sperm quality.
  • Retrograde ejaculation has been reported to occur in an infertile male cat although this cat had an additional possible cause of his infertility (arrested spermatogenesis). Retrograde ejaculation occurs when there is failure of the internal urethral sphincter to contract fully during ejaculation leading to more than normal amounts of semen entering the bladder during ejaculation.
  • Oligozoospermia occurs when an external or internal disturbance affects spermatogenesis leading to an ejaculate with normal volume but low numbers of spermatozoa. Azoospermia is when there are no spermatozoa. Temporary oligospermia and infertility has been reported in a cat. It was of unknown cause. Potential causes are:
      • Endocrinopathies.
      • Metabolic diseases eg liver or kidney failure.
      • Fever.
      • Infectious diseases.
    • Any drug is a potential cause but the following have a high potentiality:
    • Stress is a possible cause. Overuse is a possible cause. Immune-mediated orchitis is seen in dogs and is a potential but is so far an unrecorded condition in the cat. The potential for reversibility depends on the cause and severity. The longer the disturbance and the more fibrosis in the testicle, the lower the chance of recovery. Blockage of the ducts is a potential cause of azoospermia which is unrecorded in the cat.
  • Sperm production probably reduces with age. Stud cats are generally retired and castrated at about 7 years old, although they are probably fertile for considerably longer than this.
  • Teratozoospermia is when the ejaculate contains a higher than normal number of abnormal spermatozoa. Potential causes are listed above for oligospermia. Either or both can occur with testicular hypoplasia and degeneration.

Diagnosis

  • Male infertility is suspected if more than one female fails to become pregnant to a particular stud cat.
  • Observation of the male's mating behavior is necessary and is ideally performed by someone experienced in observing normal behavior. Observation may inhibit mating in some cats as they often prefer to mate unobserved Copulation . Hearing the female's cry as the penis is withdrawn after intromission is evidence that mating has occurred. After mating there is the fury response and both cats will usually lick their perineums. The female will usually roll repeatedly on the ground Post-mating behavior .
  • The male's reproductive and medical history need to be reviewed. Is he mature? Has he a suitable diet and environment? Have suitable females been presented to him? An ideal female for an inexperienced male is one who is proven to be fertile and without a domineering personality. If the tom was previously fertile, have there been management changes or evidence of illness since the last pregnancy?
  • The cat should have a thorough physical examination. Are there any signs of systemic illness?
  • The coat color of the cat should be assessed. Calico or tortoiseshell cats cannot be normal male cats (38,XY) and most will be infertile. However a fertile male tortoiseshell cat has been reported, this was a chimera (38,XY/38,XY). Although nearly all cats reported to have abnormal genotypes have been calicos or tortoiseshells this is probably because of case bias and they can be any color.
  • The external genitalia should be examined Penis and sheath: clinical examination. Some toms will not allow an examination of the penis unless sedated. Penile frenulum, phimosis, diphallos and other anatomical abnormalities should be ruled out. The scrotum should be examined for wounds. The testes should be palpated to assess size and consistency Testis: clinical examination. Testes that are small or flaccid may have hypoplasia or degeneration. Swelling of the scrotum can occur with ascites and is particularly associated with FIP Feline infectious peritonitis.
  • Screening test for systemic illness should be performed and any findings form the history or physical examination that suggest systemic or significant local disease should be followed up with diagnostic tests. Routine hematology, biochemistry, urinalysis, serological tests for feline immunodeficiency virus and feline leukemia virus, radiography of the chest Radiology: chest (excl heart and lungs), abdomen Radiography: abdomen, spine Radiography: spine and hip and ultrasonography of the abdomen might be appropriate.
  • Semen may be collected Semen collection from the vagina after normal mating or from centrifuging urine collected via cystocentesis form the tom after mating as it is normal for many sperm to enter the bladder. These techniques only allow evaluation of the spermatozoa motility and morphology.
  • It is also possible to collect semen under anesthetic by electroejaculation. Semen evaluation is performed as for other species. This technique allows measurement of ejaculate volume in addition to motility and morphology.
  • Ejaculate obtained from toms trained to use an artificial vagina is reported to contain 150,000-13,000,000 total sperm, a volume of 0.02-0.12ml with mobility of 60-90% of the sperm and less than 10% abnormal sperm. However toms with apparently normal fertility have been reported with 40-50% abnormal sperm. The ejaculate obtained with electroejaculation is usually a larger volume (0.05-0.14ml) but is otherwise identical.
  • Testicular examination by ultrasound has not been reported but a skilled operator should be able to observe some abnormalities using this technique.
  • Testicular biopsy or histopathology after castration Castration is necessary to diagnose hypoplasia Testicular hypoplasia or degeneration Testicular degeneration but these conditions may be indistinguishable. These techniques would be necessary to diagnose Leydig cell failure or immune-mediated orchitis. In order to obtain diagnostic results testicular tissue should be preserved in Boulin's or Zenker's solutions rather than formalin.
  • Karyotyping is available from some commercial laboratories and is necessary to show sex chromosome abnormalities. Samples for karyotyping may be obtained from blood or skin biopsy.
  • Hypogonadotrophic hypogonadism would be diagnosed by finding low levels of serum LH, FSH, testosterone and inactive seminiferous tubules without inflammation on testicular biopsy. If this condition were suspected a MRI and/or CT scan of the pituitary area should be performed.
  • Testosterone levels can be measured Testosterone assay. Low levels would be expected to be associated with poor libido and testicular function but this condition does not seem to have been reported in cats. There is therefore no indication to blindly treat a possible infertile tom with testosterone. Basal testosterone levels are likely to be less useful than a hCG stimulation test:
    • Take basal serum sample.
    • Inject 600 iu hCG IV (Chorulon, Intervet UK Ltd).
    • Collect post-stimulation serum sample ½-2 hours later.

Prognosis and treatment

  • There is little information about this but most cases are likely to be untreatable.
  • Behavioral problems seem likely to have the best prognosis. Housing changes, trying different females or allowing longer periods of socialization are possible treatments.
  • Phimosis is easily treated if caused by a coil of fur. The fur is removed using fingers or forceps, this may require sedation. Phimosis due to trauma to the prepuce may be treated successfully by circumcision.
  • Persistent frenulum is potentially treatable but other developmental abnormalities may be present and the cat is probably not an ideal candidate for a breeding program.
  • Some physical problems such as dental or skeletal pain may be curable. Some toms with these problems might be able to mate with more tractible or experienced queens.
  • Physical infirmities or tom/queen size disparities are potentially treatable with artificial insemination Artificial insemination. Semen collected by electroejactulation can be diluted with saline to make up 1ml. 0.1ml of the mixture is then inserted into the proximal vagina of the conscious queen using a lubricated tomcat urethral catheter. The queen's hindquarters should be raised for 10 minutes after insemination. 250 iu hCG are given i/m. The insemination and hCG are repeated after 24 and 48 hours.
  • Abnormal karyotypes are untreatable.
  • Testicular hypoplasia is untreatable.
  • Testicular degeneration is potentially reversible. Unfortunately many cases will have no obvious cause and no treatment. The best option may be to repeat semen evaluation after a few months to see if there has been any improvement or deterioration and base future management of the tom on this. The case reported that recovered from idiopathic testicular degeneration had reduced libido as well as oligospermia and took about a year to recover. Any local or systemic disease found in the infertile cat could be the underlying cause for the testicular degeneration and should be treated if possible. Elimination of the underlying cause would not guarantee a successful return to fertility but there would likely be more success in cats with a shorter period of testicular dysfunction.
  • Retrograde ejaculation is diagnosed by finding, after ejaculation, all the spermatozoa in the bladder and none in the ejaculate. It has been treated in dogs using sympathomimetic agents eg ephedrine or phenylpropanolamine Phenylpropanolamine / diphenylpyraline but this has not been reported in cats.
  • If a cat with poor libido had low levels of testosterone then testosterone could be used therapeutically; however, this tom might not be a suitable candidate for a breeding program. If there was hypogonadotrophic hypogonadism, treatment with FSH and LH would be necessary but the pituitary dysfunction could be causing additional disease.