Page 488 - WSAVA2018
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 25-28 September, 2018 | Singapore
instead of ovariectomy, unless there are specific health reasons. Although such data are available only for bitches, it is likely that the same situation is true also for queens. In case of specific indications for OVH, it
is advisable not to remove the cervix because of its important role in isolating the abdominal cavity from outside even in the castrated female. Hysterectomy should not be performed as bilateral development of ovarian cysts has been anecdotally reported with bitches having to undergo laparotomy again to remove the cystic ovaries. Also, if a previously hysterectomized small litter size bitch is mated during heat by a large size dog her vagino-cervical suture may rupture with a consequent coital peritonitis5.
In which stage of the reproductive cycle?
While no specific choice of time during the adult life is necessary when castrating male dogs or cats, performing gonadectomy in adult females may have has some health implications with regard to the reproductive cycle stage in which the female is at the time of surgery. This
is particularly true for bitches, as when such surgery is performed in proestrus or estrus there is an increased risk of short-term post-surgical complications (see below), while when it is performed in diestrus there
is an increased risk of false pregnancy (due to the sudden decrease in serum progesterone causing a peak in serum prolactin concentration which sets in mammary function and maternal instict). In bitches gonadectomy should best be performed during anestrus (2.5-5.5 months following onset of proestrus); serum progesterone assay may be of help in ruling out diestrus when history is not available. Although no specific study has ever looked at what is the best stage for performing gonadectomy in felines, the queen is not known to experience any such problems depending on when in her reproductive stage she is castrated due to lack of clinically evident effects of estrogens on vascularization of the reproductive tract and absence of false pregnancy in felines.
Advantages of gonadectomy
There are several health advantages due to gonadectomy in male and female dogs and cats6. The removal of the ovaries is associated in both bitches
and queens with a reduced risk of mammary and
uterine diseases (mammary neoplasia and pyometra, respectivey), as well as absence of ovarian diseases (ovarian tumors, ovarian cysts), progesterone-related diseases (false pregnancy, feline mammary hypertrophy), pregnancy-related diseases (unwanted pregnancy, pregnancy complications, abortion) or parturition-related diseases (dystocia, uterine prolapse, and in the bitch only subinvolution of placental sites) and in bitches
also estrogen-related diseases (vaginal hyperplasia/ prolapse, persistent estrus, bone marrow aplasia). Bitches gonadectomized prior to puberty have a 95%
reduction of the risk of developing mammary tumors
as opposed to bitches spayed after 1st heat (92% risk reduction), after 2nd heat (74% risk reduction) or bitches spayed after 2.5 years of age or left intact (no difference in risk)7. Incidence of pyometra in adult intact bitches vary from 15% to 25%, but the risk tends to increase with increasing age8. Libido, aggressiveness, urine marking and roaming are never displayed in male dogs and
cats neutered prior to puberty, while they may persist
at some degrees in a few cases when a male animal is neutered as an adult9. From a behavioural point of view it is commonly believed that, apart from not showing reproductive behavior, neutered animals have a more relaxed, somewhat lazy attitude. In male dogs there is
a significant reduction of all prostatic conditions6 and
in male cats the decreased (or lack of) roaming attitude certainly decreases the risk of death due to trauma. Gonadectomy may play an important role in reducing pet ovepopulation.
Changes due to pre- and post-puberal gonadectomy Physical changes
In dogs, growth plate closure is delayed when surgery is performed prior to puberty, but the delay is significantly longer when neutering is done at 7 weeks as compared to 7 months. The rate of growth is unaffected but both radius and ulna become longer regardless of the age at neutering. Food intake is not affected nor is weight gain or back-fat depth during the first 15 months or until the age of 18 months when comparing 7 week- to 7 month- neutered puppies 10,11, but weight gain later in life has been reported in non-working bitches. Although it is well known that neutering predisposes (non-working) dogs to develop a significant increase in body weight, the time
at which gonadectomy is performed in these animals probably does not affect the clinical manifestation of this problem. External genitalia do not develop fully: penile and preputial immaturity and decreased radiodensity
of the os penis are frequently observed (which rarely
if ever constitute a problem). Vulvar development may be insufficient in bitches gonadectomised at 7 weeks. However, the incidence of infolding of vulvar lips leading to perivulvar dermatitis and chronic vaginitis is not different when compared to bitches neutered at 7 months12. When penile protrusion was attempted at the age of 22 months, it could be done in all intact cats, in only 60 % of cats neutered at 7 months and in none of the cats neutered at 7 weeks13.
In cats neutered at 7 weeks or 7 months of age physeal closure is delayed 5 to 7 months resulting in a 10% longer size of long bones when comparing neutered to intact cats. Physeal (Salter-Harris) fractures have been reported in neutered dogs and cats at 12-16 months of age14. Salter-Harris fractures are a potential complication when prepubertal gonadectomy is performed, but appear to be as an extremely rare condition in both

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