Reproduction in cats: most common problems
Introduction
The vast majority of feline patients seen at veterinary clinics have been gonadectomised. This means that certain diseases affecting the reproductive tract, and which may be relatively common in other species, are less so in cats. In contrast, diseases such as mammary fibroadenomatoid hyperplasia (MFH) are seen almost exclusively in female cats. It is important that the clinician is familiar with the most common reproductive disorders in cats.
Most important reproductive disorders in cats
FIBROEPITHELIAL HYPERPLASIA (FEH)
This is a non-neoplastic disease, typical in cats, which usually affects young female cats in heat, but may also present in pregnant cats, females undergoing long-term progestogen treatment and, more rarely, in males.
- The hyperplasia tends to be severe and generally affects all mammary glands, occasionally leading to necrosis, ulceration and secondary infections.
- FEH is thought to be the result of an exaggerated response to the action of progesterone, either endogenous or exogenous, although sporadic cases have been reported in males and sterilised females with no known access to progestogens. In the latter case, a possible ovarian remnant should be suspected.
- The presumed diagnosis of FEH is established based on the clinical presentation and characteristics of the patient.
- Treatment will depend on the underlying cause of the disease.
- If exogenous progestogens are being administered, they should be discontinued.
- If the animal is not sterilised, this should be performed using either a lateral approach or by midline laparotomy once the hyperplasia has subsided, with medical treatment.
- The drug of choice for this is aglepristone, 10-15 mg/kg, subcutaneously on days 1, 2 and 7. If unavailable, the use of dopamine agonists (cabergoline or bromocriptine) should be considered.1
OVARIAN REMNANT SYNDROME (ORS)
This is defined as the presence of functional ovarian tissue in an oophorectomised or ovariohysterectomised female.
- It is the result of incomplete removal of the ovary during surgery or revascularisation of ovarian tissue accidentally left in the abdomen during surgery.
- Females then present oestrus-type behaviour on an ongoing basis, which is obviously not welcomed by their owners.
- Diagnosis:
- A vaginal cytology typical of oestrus in a sterilised cat with signs of oestrus confirms the diagnosis.
- Serum oestradiol levels > 20 pg/ml in a cat ostensibly in oestrus are also diagnostic, although lower values do not mean that this possibility can be excluded.
- Other less commonly used diagnostic methods are based on demonstrating the existence of ovarian activity by administering gonadotropin-releasing hormone or one of its analogues.
- More recently, the relevance of determining anti-Müllerian hormone (AMH) levels in the diagnosis of ORS has been reported.2
- The treatment of ORS involves locating and removing the ovarian remnant, which is typically found in the ovarian pedicle or, less frequently, in the omentum or abdominal wall. Keep in mind that the remnant may be bilateral and that it is easier to locate the tissue in diestrus or after inducing ovulation.
Quite often the clinician needs to determine whether a cat whose sterilisation status is unknown has actually been sterilised. In such cases, the cat’s reproductive status can be confirmed by measuring the luteinising hormone levels or determining the AMH concentration.1,4
PYOMETRA
Traditionally, it was thought that pyometra in cats was much less common in female cats than in female dogs given the induced nature of ovulation in cats. However, it has been demonstrated that spontaneous ovulation in cats is not as rare as initially thought, especially in oriental breeds which coincidentally present the highest incidence of pyometra. Now pyometra is considered to be a common disease in this breed.
- The clinical presentation tends to be milder than in female dogs, which may make diagnosis more difficult.
- Pyometra is usually diagnosed on the basis of ultrasound findings and the presence of leukocytosis with left shift, although totally normal blood counts may be found in some cases.
- Treatment may be medical (prostaglandin F2α, dopamine agonists or progesterone receptor antagonists), surgical or a combination of these two options. The decision regarding which option to use will mainly depend on the reproductive interest, the animal’s general condition and the surgical risk.3
CRYPTORCHIDISM
The prevalence of cryptorchidism in cats is considered to be lower than in dogs, although it appears that ragdolls are more susceptible than other breeds.
- Feline cryptorchidism is usually unilateral and affects both testicles equally. In this condition the most common location is inguinal, although if cryptorchidism is bilateral, the testicles are usually located in the abdominal cavity.
- The diagnosis can be confirmed by evaluating the presence of penile spicules (these disappear 6 weeks after complete castration), by demonstrating a marked elevation of testosterone concentration after administrating gonadotropin or by measuring AMH levels.4
- Although the potentially adverse consequences of cryptorchidism (increased risk of neoplasm or testicular torsion) are considered to be very rare in cats, these animals should be removed from breeding programmes and bilateral castration should always be performed to avoid the persistence of non-castrated male behaviour.1
Conclusions
The fact that many feline patients are gonadectomised as a preventive measure should not mean that we overlook reproductive diseases in cats. Although some of these diseases are also seen in dogs, the unique characteristics of each species should always be taken into consideration. We need to remember that “a cat is not a small dog”.
