Reproductive Physiology of Cats

Reproductive Cycle in the Queen

• Queen is seasonally polyestrus

  • Increases in daylight length decrease melatonin release

  • Less melatonin allows more hypothalamic GnRH release

• Queens are also induced ovulators

  • Ovulation is triggered by coitus

Puberty in the Queen

• Avg. 6-9 months

• Influenced by:

  • Body weight: 2.3-2.5 kg

  • Time of year she is born

    • If queen reaches body weight in fall or winter, won’t cycle till daylight length increases in the spring

  • Breed

    • Siamese and Burmese at lower weights

Reproductive Cycle

• Proestrus

  • Follicles are starting to grow, estrogen levels still low

  • Queen does not spot so hard to detect

  • Usually considered first 1-4 days of the cycle when Queen is calling

  • Calling = vocalizations to attract Toms

• But won’t allow them to mate

Estrus behavior

• Follicles are mature, maximum level of estrogen day 3 – 7

• Rolling, rubbing, very affectionate

• Lordosis = crouches with forelimbs, raises hind end, paddling with hindlimbs, deflects the tail to present vulva

• Allows male to mount

• High estrogen levels stimulate LH surge from pituitary

If NOT MATED. . .

• Follicles regress

  • NO ovulation

• Estrogen falls

• Estrus behavior stops

She enters Interestrus

• Period between one estrus and the next

• Queen comes into heat again in about 2 weeks

• Whole cycle is about 21 days

  • 7d of proestrus and estrus, 14 days of interestrus

Anestrus

• During winter when there is no ovarian activity

• Increase secretion of melatonin from pineal gland

  • Suppresses release of GnRH

  • No FSH or LH to stimulate growth of follicles in ovary

Back to the spring. . .

• Proestrus: Calling attracts several Toms

• They stalk until she is receptive

• Estrus: She may allow several matings in quick succession if more than one Tom present

Mating

• During lordosis Tom grabs Queen’s scruff with his mouth and mounts

• Intromission and ejaculation are quick

  • When he withdraws Queen often yowls

  • Due to barbs on the Tom’s penis

  • Queen will often turn around, swipe at him, then lick her vulva

When mating occurs. . .Ovulation

• Vaginal stimulation causes a reflex release of GnRH and then LH

  • LH has been going up due to rises in estrogen

  • Each mating causes higher and higher LH peaks

  • Need successive matings & coitus over a short period of time otherwise LH levels drop and no ovulation

  • Average four matings in a 2-4 hr period

  • Some breeds need fewer, some Queens need only one

Ovulation without fertilization

• Queen goes out of estrus 24-48 hrs after ovulation

• Corpora lutea develop from each follicle

• If fertilization does not take place

  • No implantation of embryo

  • Corpora lutea produce progesterone then naturally regress over 30-40 days

  • Shorter than the Dog

  • Diestrus period

    • No pseudopregnancy behaviors like dam

Interestrus period

• After regression of corpora lutea

• Basal levels of hormones

• FSH starts to rise again if it’s spring and summer

• Queen comes into heat again

• If fall or winter queen goes into anestrus with no ovarian activity

Ovulation with fertilization – pregnancy

• Fertilization in oviducts

• Day 4-5 embryos pass into uterine horns

• Day 12-16 implantation occurs

• Gestation = 64 days from first mating

Relaxin

• From placenta

• Helps stimulate prolactin release at end of pregnancy

  • Milk production

Pregnancy diagnosis

• Same as dog

• Easier to tell a cat is pregnant via abdominal palpation at 3-4 weeks

Parturition

• First stage labor:

  • Lasts 6-12 hrs, as long as 36 hrs

  • Fetal stress, cortisol levels rise

  • Stimulates enzymes that convert progesterone to estrogen

  • Fall in progesterone

  • Increased uterine contractions

  • Restless, uncomfortable, pacing, panting

  • Nesting

  • No decrease in temp like the dam

  • Rise in estrogen = PGF_2⍺ (luteolytic) and oxytocin

  • Relaxation of cervix and vagina

  • Uterine contractions become more frequent and more intense

Stage 2 labor

• Abdominal straining

• Fetus engages pelvic canal, membranes may rupture

  • Fluid in queen has reddish brown color

• Expelled fetus remains in amniotic sac

• Queen breaks it, vigorously licks neonate

  • Bites umbilical cord

• First kitten usually expelled within 1-2 hours of stage 2 labor

Stage 3 labor

• Fetal membranes / placenta

  • Can pass with each kitten

  • Can pass 15 min. later

  • Can pass 2-3 kittens then placentas

  • Queen usually eats the placentas

• Parturition usually complete in 6 hrs of the start of second stage labor

• If 24 hrs have passed and not all kittens delivered call vet = Dystocia

Tom

Sexually active all year

• Puberty at 8-12 months, older than females

  • Breed variations

• With puberty penis develops ‘barbs’

  • Cornified papillae

  • Testosterone

Testes

• Descend into scrotum at birth

• Slide back and form between scrotum and inguinal canal

• Permanently in scrotum by 4-6 months old

  • If not by 6 months cryptorchid

  • Persians might be predisposed

• Puberty: spermatogenesis like the dog

Other male characteristics

• Accessory sex glands = 2

  • Prostate

  • Bulbourethral glands

• Secondary sex characteristics

  • Thick skin

  • Thick cheeks and neck

  • More muscular

  • Tom cat ‘odor’, tom cat urine