N o. 1, N o vem ber 1986
Cornell Feline Health Center
InformationBulletin
Feline
Reproduction
D onald H. Lein, D.V. M ., Ph.D.
T h e c a t is u n iq u e am o n g m a m m a ls in so m e
a s p e c ts of re p ro d u c tiv e physiology. U n d e r­
s ta n d in g th e c a t's b asic re p ro d u c tiv e p h y s ­
iology a n d en d o c rin o lo g y w ill a ss ist p ra c ­
t i ti o n e r s a n d c a t b r e e d e r s in a s s e s s i n g
b r e e d i n g p r o b le m s t h a t c a n o c c u r w ith
to m s a n d q u e e n s.
T h e q u e e n is se a s o n a lly p o ly e s tro u s a n d
is a reflex o v u la to r (o v u la tio n a n d th e for­
m a tio n o f c o rp o ra lu te a o c c u r o n ly a fte r
m a tin g ). A lso , th e d u r a tio n of th e lu te a l
cycle of a n o n p re g n a n t q u e e n is a b o u t o n eh a lf th e d u ra tio n of p re g n a n c y ; a n o n p re g ­
n a n t q u e e n th u s re tu r n s q u ic k ly to th e fe r­
tile sta te .
T h e r e p r o d u c tiv e life o f th e c a t is lo n g .
T om s a n d q u e e n s c a n c o n tin u e b re e d in g
for fo u rte e n or m o re y e a rs. A q u e e n c a n ef­
ficiently b e c o n tin u o u sly b re d for a p e rio d
of e ig h t to te n y ears.
W h e n b r e d c o n tin u o u sly , m o s t q u e e n s
w ill h a v e tw o litte rs of tw o to six k itte n s
e a c h a y e a r. S ia m e se o r S ia m e se c ro s s e s
h a v e slig h tly la rg e r litte rs , a v e ra g in g six
k itte n s each . T h e first litte rs re s u ltin g fro m
p u b e rta l b re e d in g s a re u s u a lly sm all, a n d
r e a r i n g is le s s s u c c e s s f u l . A ls o , a g e d
q u e e n s a re less likely to d eliv e r v iab le k it­
te n s , a n d u s u a lly th e litte r size is re d u c e d .
Feline P u berty
P u b e rty in q u e e n s u s u a lly o c c u rs b e tw e e n
se v e n a n d tw elv e m o n th s of ag e. T h e tim ­
in g c a n b e in f lu e n c e d b y th e g e n e r a l
h e a lt h , b r e e d , a n d w e a n in g a g e o f th e
q u e e n a n d b y th e n u m b e r o f h o u rs of a rti­
ficial o r n a tu r a l lig h t to w h ic h th e q u e e n is
e x p o s e d . Q u e e n s c a n h a v e th e ir firs t e str u s as e a rly a s five m o n th s of a g e if th e y
h a v e re a c h e d a m in im u m b o d y w e ig h t of
a r o u n d five p o u n d s , b u t th e firs t e s tr u s
c a n o ccu r as late as tw e n ty -o n e m o n th s of
a g e. T h e c a t is a lo n g -d ay b re e d e r, a n d its
e s tr o u s cycle is in f lu e n c e d b y in c re a s in g
d ay lig h t. C o n se q u e n tly , if th e n o rm a l p u ­
b e rta l a g e a n d w e ig h t a re re a c h e d d u rin g
th e a n e s tro u s (sh o rt-d a y ) p e rio d of O c to ­
b e r to D e c e m b e r (in th e N o r th e r n H e m i­
s p h e re ), cycling u s u a lly b e g in s th e follow ­
in g Ja n u a ry o r F eb ru ary . If p u b e rta l w e ig h t
is a t t a i n e d d u r i n g th e p e r i o d o f M a y to
S e p te m b e r, th e n a n e a rlie r p u b e rta l e s tru s
c a n occur. P u b e rty u s u a lly o c c u rs in to m s
w h e n th e y h av e a tta in e d a m in im u m b o d y
w e ig h t o f se v e n to e ig h t p o u n d s , a t a ro u n d
n in e m o n th s of ag e. If th e o ffsp rin g w ill b e
ra is e d to g e th e r, th e n th e m ale a n d fem ale
k itte n s sh o u ld b e s e p a ra te d b efo re th e y a re
five m o n th s old.
P u r e b r e d c a ts m a y re a c h p u b e r ty la te r
th a n n o n p u re b re d s . A lso , in d o o r c ats, e s­
p e c ia lly th o s e th a t a re h o u s e d a lo n e, g e n ­
e ra lly re a c h p u b e rty la te r th a n d o o u td o o r
c ats. A B ritish s tu d y of sev eral b re e d s re ­
p o rte d th a t th e av erag e a g e a t p u b e rty w a s
b e tw e e n 9 a n d 10 m o n th s, b u t th e re w ere
c o n s id e ra b le d iffe re n c e s a m o n g b re e d s .
H im a la y a n s a n d co lo rp o in ts w e re th e o ld ­
e s t a t p u b e rty , a v e ra g in g 13 m o n th s , a n d
B u rm e se w e re th e y o u n g e st, a v e ra g in g 7.7
m o n th s.
T he Estrous Cycle
T h e n a t u r a l b r e e d i n g s e a s o n fo r c a ts in
te m p e ra te z o n e s u s u a lly b e g in s tw e n ty to
six ty d a y s a fte r th e w in te r so lstice a n d m ay
e n d a n y tim e a fte r th e s u m m e r so lstic e .
T h e q u e e n is s e a s o n a lly p o ly e s tro u s (i.e .,
s h e is re c e p tiv e to th e m a le se v e ra l tim e s
w ith in a b re e d in g se a so n ). In c o n d itio n s of
a rtificial o r n a tu ra l lig h t, m a n y q u e e n s w ill
cycle th r o u g h o u t th e y e a r if th e y a re ex ­
p o s e d to tw elv e to fo u rte e n h o u rs of lig h t a
day. In s ta llin g a tim e r is a n efficien t w ay to
c o n tro l th e a m o u n t o f a rtific ia l lig h t in a
b re e d in g cattery .
If n o t m a te d , m o s t q u e e n s w ill hav e n o n ­
o v u l a t o r y e s t r o u s c y c le s t h r o u g h o u t a
b re e d in g s e a s o n . T h e cycle th e n c o n sists of
w av es of o v a ria n follicles p ro d u c in g e s tro ­
g e n , follow ed b y d e g e n e ra tio n of th o s e fol­
licles a n d a n in te r e s tr a l p e rio d b u t n o lu ­
te a l o r m e te s tr o u s p e rio d . T h a t s itu a tio n
re s u lts in p e rio d s o f b e h a v io ra l e s tru s in ­
te r r u p te d b y p e rio d s of se x u a l n o n re c e p ­
tivity.
T h e e s tro u s cycle a n d in te re s tra l p e rio d s
a re q u ite v ariab le. P ro e s tru s la s ts for u p to
th r e e d a y s, follow ed b y a n e s tru s o f th re e
to tw e n ty d a y s ( th e a v e ra g e is s e v e n o r
e ig h t d a y s). T h e in te r e s tr a l p e r io d la s ts
th re e to fo u rte e n d ay s; it a v erag es n in e to
th irte e n d ay s d u rin g th e b re e d in g se a s o n
b u t c a n b e a s lo n g a s th irty d ay s. T h u s, th e
le n g th of a n u n b re d q u e e n 's cycle (th e in ­
te rv a l fro m o n s e t o f o n e e s tru s to o n s e t of
th e n e x t) c a n r a n g e fr o m s e v e n to fo rty
d ay s; m o s t cycles la st tw elv e to tw e n ty -tw o
d ay s.
Vaginal Cytology
V aginal cy to lo g y c a n b e u s e d to c h a ra c te r­
ize th e q u e e n 's e s tro u s cycle. V aginal cells
fo r c y to lo g ic e v a lu a tio n c a n b e co lle c te d
w i t h a m o i s t e n e d s t e r i l e c o tt o n s w a b
(3-m m d ia m e te r) o r a cle a n g lass e y e d ro p ­
p e r. F o r c o lle c tio n , th e s w a b o r e y e d r o p ­
p e r is p a s s e d in to th e v a g in a a b o u t 1 to 1.5
c e n ti m e t e r s b y firs t i n s e r t i n g it in to th e
v e stib u le in a d o rsa lly d ire c te d m a n n e r u n ­
til re s ista n c e is m e t, th e n re d ire c tin g it h o r­
iz o n ta lly to a d v a n c e it in to th e a n te rio r v a ­
g in a . T h a t e n s u r e s t h a t th e c lito r is a n d
clito ral fo ssa a re n o t e n te re d o r irrita te d .
To c o lle c t v a g in a l c e lls th e m o i s t e n e d
s w a b is ro ta te d sev era l tim e s in th e v ag in a,
o r a b o u t 0 .2 5 m illilite rs o f ste rile p h y s io ­
logical sa lin e in a n e y e d ro p p e r is flu sh e d
tw o o r th re e tim e s in th e v ag in a. T h e sw ab
is th e n ro lled o n a clea n g lass slid e, w h ic h
is th e n im m e d ia te ly fixed in alcohol o r air
d r i e d , o r flu id fr o m t h e e y e d r o p p e r is
p la c e d o n a g la s s s lid e a n d a llo w e d to a ir
d ry. T h e slid e is th e n s ta in e d w ith e ith e r a
cytologic o r a h e m a to lo g ic sta in . T h e slides
s h o u ld b e k e p t a s a re fe re n c e o f c h a n g e s
th a t o c c u r th r o u g h o u t th e e s tr o u s cycle.
S m e a r s o f v a g in a l c e lls s h o u ld b e d o n e
d aily o r e v e ry o th e r d a y w h e n lo o k in g for
c h a n g in g c e ll ty p e s to d if f e r e n t ia t e th e
sta g e s of th e e s tro u s cycle (see table 1). T he
v a g in al sw a b b in g o r flu sh in g m ay in d u c e
o v u la tio n in so m e q u e e n s in e s tru s . If th e
q u e e n d o e s n o t o v u la te , th e cy to lo g y w ill
n o rm a lly re g re s s to a n a n e s tro u s ty p e , a n d
n o n c o rn ifie d e p ith e lia l cells w ill a p p e a r.
R ed b lo o d cells n o rm a lly sh o u ld n o t b e
p re s e n t in th e q u e e n 's v a g in a d u rin g a n y
sta g e of th e e s tro u s cycle. If th e y a re , th e
m o s t-c o m m o n c a u s e s a re th a t tr a u m a to
th e v a g in a l c a v ity o c c u rr e d w h e n ta k in g
t h e c y to lo g ic s a m p le , t h e q u e e n h a s a
g e n ita l-tra c t in fe ctio n , o r th e sam p le w as
ta k e n in th e e a rly p o s tp a r tu m p e rio d .
2
Inducing Estrus
In d u c tio n o f e s tr u s in a q u e e n c a n b e ac­
c o m p lish e d b y le n g th e n in g th e d a ily lig h t
cycle to w h ic h sh e is e x p o s e d , so cializin g
th e q u e e n w ith o th e r cyclin g q u e e n s , e x ­
p o s in g h e r to a to m , o r g iv in g h e r h o r ­
m o n a l th erap y .
V ario u s h o rm o n a l r e g im e n s h a v e s u c ­
c e s s f u ll y i n d u c e d q u e e n s in t o e s t r u s .
C olby re p o rts a n 80 p e rc e n t efficiency ra te
w h e n u s i n g g o n a d o tr o p h in s . H o w e v e r,
t h a t m e t h o d w o rk s b e s t o n q u e e n s b e ­
tw e e n th e a g e s o f o n e a n d five y e a rs . C ol­
b y 's tr e a tm e n t c o n sists of a n in itia l d o se of
100 in te r n a tio n a l u n its (IU s) o f p r e g n a n t
m a r e 's s e r u m g o n a d o t r o p h i n (P M S G )
g iv e n in t r a m u s c u la r ly (IM ). T h a t is fo l­
lo w e d b y a lo w e r d a ily d o s a g e , g iv e n o n
se v e n co n se c u tiv e d a y s, of e ith e r 25 IU s or
50 IU s, d e p e n d in g o n th e s e a s o n (C o lb y
a d m in is te r e d th e lo w e r d o s e w h e n tr e a t­
m e n t o c c u rre d b e tw e e n F e b ru a ry a n d A u ­
g u st). W h e n e s tro u s b e h a v io r b e c o m e s a p ­
p a r e n t , th e d o s e is r e d u c e d to 25 IU s to
p re v e n t o v erd o sag e.
A n o th e r m e th o d , w h ic h p r o d u c e s r e ­
su lts c o m p arab le to th o s e of n a tu ra l b re e d ­
in g , u s e s a s in g le in je c tio n o f 100 IU s o f
PM SG , follow ed in sev en d ay s b y a n in je c­
tio n of 50 IU s of h u m a n ch o rio n ic g o n a d o ­
tro p h in (H C G ). A th ird m e th o d u s e s folli­
c le s t im u la t in g h o r m o n e fro m p i t u i t a r y
e x tra c ts (F SH -P) to in d u c e e s tr u s . A d o s ­
a g e o f 2 m illig ra m s o f FS H -P is a d m in is ­
te r e d IM d a ily fo r five d a y s o r u n ti l th e
q u e e n sh o w s s ig n s o f e s tru s . O n d a y s o n e
a n d tw o o f e s t r u s , 250 IU s o f H C G a re
g iv en IM to e n h a n c e o v u la tio n . T h e q u e e n
sh o u ld th e n b e b re d a t le a st fo u r tim e s o n
e a ch d ay o f e s tru s fo r a p e rio d of u p to fo u r
d a y s. T h a t re g im e n su ccessfu lly p ro d u c e d
litte rs e v e n w h e n u sin g fro z e n c at se m e n .
E stro g e n s (50 m eg of estra d io l b e n z o a te
o r 0.25 m g of estra d io l c y p io n a te , g iv e n IM
a n d re p e a te d in fo rty -eig h t h o u rs ) w ill in ­
d u c e false e s tru s in m o s t q u e e n s . To avoid
c a u sin g toxicity o r e x tre m e b o n e -m a rro w
s u p p r e s s io n in a q u e e n , n o m o re th a n 8
m illig ram s o f e s tro g e n sh o u ld b e a d m in is ­
te r e d w ith in a n y c o n tin u o u s fo u r -m o n th
p e rio d . T e sto s te ro n e (20 m g /d a y IM ) h a s
a ls o b e e n r e p o r t e d to in d u c e e s t r u s in
q u een s.
H o w e v e r, u s in g g o n a d o tr o p h in s to in ­
d u c e e s tr u s in q u e e n s m ay in a d v e r te n tly
le a d to t h e q u e e n 's p r o d u c i n g w a v e s o f
o v a ria n follicles th a t m ay c o n ta in im m a ­
tu r e ova a n d c a u se cystic fo llicular d e g e n ­
e ra tio n . A lso, ex cessively lo n g e s tro u s p e ­
rio d s, la s tin g tw o to fo u r w e e k s, m a y o c cu r
follow ing a d m in is tra tio n of e ith e r g o n a d o ­
tr o p h in s o r se x -s te ro id h o rm o n e s u n le s s
n a tu r a l o r artificial m a tin g is p ro v id e d .
T h e e s tro u s b eh av io r of q u e e n s receiv ­
in g h o rm o n a l th e ra p y sh o u ld b e e v a lu a te d
d a ily b y a h a n d le r o r b y o b s e r v in g th e
q u e e n 's re s p o n s e in th e p re s e n c e of a n ex ­
p e r i e n c e d to m . S t u d i e s i n d i c a t e t h a t
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Figure 1
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Figure2
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Figure 4
Figure 3
Table 1. Vaginal C ytology
A n e s tru s
N u m e ro u s sm all ro u n d e p ith e lia l cells w ith a h ig h nuclear: cy­
t o p l a s m i c r a t i o a r e p r e s e n t ( s e e f i g u r e 1 ). O c c a s i o n a l l y
p o ly m o rp h o n u c le a r le u k o c y te s a re v isible. T h e re is in c re a se d
d eb ris.
P ro e s tru s
A n in c re a se d n u m b e r o f in te rm e d ia te e p ith e lia l cells a re p re s ­
e n t. C o rn ifie d e p ith e lia l cells b e g in to a p p e a r m o re fre q u e n tly
b e fo re e s tru s o c c u rs. T h e re is a d e c re a s e in n u c le u s size a n d a n
in c re a se in cy to p la sm . T h e re is also in c re a se d d e b ris. (See fig u re
E stru s
T h e sm e a r is d o m in a te d b y p o ly h e d ra l c o rn ifie d e p ith e lia l cells
w ith cu rle d e d g e s (see fig u re 3; th e b lo o d cells a re p re s e n t b e ­
c a u se of tra u m a in flicted o n th e v ag in a l m u c o sa w h ile o b ta in in g
th e sp e c im e n ). B ecau se th e v a g in a l flu id is w ate ry , th e re is less
d e b r is c o m p a r e d w ith th e o t h e r s t a g e s o f th e e s t r o u s cy c le .
P o ly m o rp h o n u c le a r le u k o c y te s a re a b se n t.
M e te stru s
A fte r o v u la tio n , c o rn ifie d e p ith e lia l cells a re still p re s e n t, b u t
th e m a rg in s a re le ss d e fin e d (see fig u re 4, left). O ccasio n ally n u ­
m e ro u s b a c te ria a n d p o ly m o rp h o n u c le a r le u k o cy tes a re p re s e n t.
D u rin g la te m e te s tru s th e re is a n in c re a se in sm a lle r b aso p h ilic
e p ith e lia l cells (see fig u re 4, rig h t).
2 .)
q u e e n s in w h ic h e s tru s h a s b e e n in d u c e d
c a n p ro d u c e litte rs o f n o rm a l size.
Sexual Behavior and M ating
P h e ro m o n e s a re involved in th e se x u a l b e ­
h a v io r a n d m a tin g of c a ts . D u r in g a
q u e e n 's e s tr u s , v a le ric acid is p r e s e n t in
v a g in a l se c re tio n s th a t act a s a se x u a l p h e ro m o n e to to m s . O n ly s e x u a l ly m a t u r e
q u e e n s re s p o n d to o d o r fro m a to m 's u rin e
sp ra y in g b y e x h ib itin g e s tro u s b eh av io r. It
is th o u g h t th a t c a ts' s e n s o ry re c e p to rs for
p h e r o m o n e d e te c tio n a r e lo c a te d in th e
v o m e ro n a sa l o rg a n , a b lin d p o u c h s itu a te d
d o rs a l to th e h a r d p a la te , w h ic h c o m m u ­
n ic a te s w ith th e n a s a l a n d o ral cavities via
th e n a so p a la tin e d u c t.
E s tr o u s b e h a v io r b y a q u e e n in th e a b ­
se n c e o f a to m u s u a lly in c lu d e s p e rs is te n t
vo calizatio n , rollin g , ru b b in g , ex tre m e a f­
fe c tio n , a n d — a t v a ria b le fr e q u e n c y a n d
in te n s ity — tre a d in g of th e h in d leg s, lor­
d o sis, a n d tail d e v ia tio n . A slig h t a n te rio r
a n d la te ra l p o sitio n in g of th e e a rs is co m ­
m o n , a s is a n i n t e n s e fa c ia l e x p r e s s io n ,
sim ila r to th a t s e e n in a g g re s sio n o r frig ht.
A r e p e a te d m o n o to n ic c ry in g o r h o w lin g
for a s lo n g a s th r e e m in u te s a t a tim e m ay
o c c u r, p e r h a p s a c c o m p a n ie d b y tr e a d in g
a n d ro llin g . T h e e s tr o u s h o w l is g iv e n by
/
3
th e q u e e n w h e n sh e is in e s tr u s a n d in th e
p re s e n c e of a to m . T h e q u e e n 's “ a p p e a s e ­
m e n t" h o w l stim u la te s th e to m to m o u n t.
R estle ssn e ss, g e n e ra l u n e a s in e s s , a n d p a c ­
in g b ack a n d fo rth m ay a c c o m p a n y a n y of
th e b e h a v io r p a tte r n s d e sc rib e d ab o v e. A
g e n e ra l lo ss o f a p p e tite in b o th th e q u e e n
a n d th e to m o fte n o c c u rs d u rin g th e b re e d ­
in g se a so n .
S o m e e s tro u s q u e e n s m ay e x h ib it m o s t
of th e b e h av io ral s ig n s o f e s tru s o n ly w h e n
e x p o se d to a to m o r w h e n c h e c k e d for e s­
tr u s by h a n d lin g . T read in g , lo rd o sis, a n d
th e ty p ica l m a tin g sta n c e w ith late ra l d e ­
v ia tio n of th e tail ca n b e ev o k ed b y stro k in g
th e f la n k s , th e b a c k , th e t h i g h s , o r th e
p e rin e u m . R u b b in g o r sc ra tc h in g th e b ack
o f th e n e c k o r th e sh o u ld e rs in d u c e s tr e a d ­
in g b u t u s u a lly n o t th e m a tin g sta n c e . T h e
e a rs ' p o sitio n in g a n d th e facial e x p re ssio n
m ay b e in d u c e d by all of th o s e m a n ip u la ­
tio n s . In a d d itio n , h a n d lin g a n d s tro k in g
a n e s t r o u s q u e e n m a y p r o v id e e n o u g h
n e u ra l stim u la tio n to c a u se o v u la tio n .
T h e m a tin g s e q u e n c e u s u a lly in v o lv e s
th e b itin g of th e q u e e n 's n e c k b y th e m ale,
follow ed by m o u n tin g a n d p elv ic th r u s tin g
u n til p e n ile in tro m iss io n o c c u rs. T h e m a t­
in g sc re a m , o r cry, w h ic h is e m itte d b y th e
q u e e n a t th e tim e of p e n ile in tro m is s io n ,
w a s on ce th o u g h t to b e p a in c a u s e d b y th e
p e n ile s p in e s. H ow ever, th a t re a c tio n c an
b e elicited in e s tro u s o r a n e s tro u s q u e e n s ,
in ta c t o r sp a y e d , w ith a n y in s tru m e n t th a t
in v ad es th e v a g in a l a n d cerv ical are a . In ­
tr o m is s io n is b rie f, la s tin g tw o to tw e n ty
se c o n d s. Im m e d ia te ly follo w in g in tro m is­
sio n , th e q u e e n fre e s h e rs e lf fro m th e m ale
a n d in te rru p ts b o u ts of rollin g a n d ru b b in g
w ith lick ing of th e e x te rn a l g e n ita lia . T h e
to m u s u a l ly s ta y s n e a rb y , w a tc h in g th e
q u e e n a n d p r e v e n t in g h e r fr o m m a tin g
w ith o th e r to m s. If th e q u e e n m a te s w ith a
fre e -ro a m in g to m , o th e r to m s m a y s u b s e ­
q u e n tly c h a llen g e h im a n d a lso m a te w ith
th e q u e e n , r e s u lti n g in a li tt e r s ir e d b y
m o re th a n o n e to m (s u p e rfe c u n d a tio n ).
E a rly in th e e s tr o u s p e rio d , m o s t q u e e n s
w ill c o p u la te a g a in in te n to fifte e n m in ­
u te s . In o n e stu d y , c o p u la tio n o c c u rre d
tw e n ty to th irty -six tim e s d u rin g a th irty s ix -h o u r o b s e rv a tio n p e rio d ; it w a s m o re
fre q u e n t d u rin g th e first tw o h o u rs (th re e
to six co p u la tio n s) th a n in a n y s u b s e q u e n t
tw o -h o u r p e rio d .
T h e relativ e b o d y size o f th e to m a n d th e
q u e e n m a y in flu e n c e th e s u c c e s s o f m a t­
in g . Q u e e n s th a t a re to o larg e o r to o sm all
m ay m ak e it d ifficu lt to ach iev e a su c c e ss­
fu l r a p id m a tin g a n d c a n r e s u lt in a fr u s ­
t r a t e d , u n s u c c e s s f u l to m . T h a t is e s p e ­
cially a p ro b le m w ith y o u n g o r tim id to m s
th a t a re p lace d in a m a tin g s itu a tio n b y a
b re e d e r. T h e activ ity of th e to m 's a tte m p t­
in g to b r e e d a q u e e n , h o w e v e r, m a y b e
e n o u g h to in d u c e o v u la tio n e v e n in th e a b ­
s e n c e of in tro m iss io n a n d e ja c u la tio n a n d ,
c o n se q u e n tly , s e m e n for fertiliz a tio n .
Table 2. R eproductive E ndocrinology
L u te in iz in g h o rm o n e R elease d d u rin g m a tin g . O v u la tin g c a ts hav e levels of 17 ± 2 n g /
m l, w h e re a s n o n o v u la tin g ca ts h av e levels o f 8 ± 2 m g /m l.
P ro g e s te ro n e
A t b a s e lin e lev el ( ln g /m l o r lo w e r) d u r in g firs t 2 o r 3 d a y s of
p re g n a n c y b u t d e te c ta b le th e re a fte r. T h e level c o n tin u e s to in ­
cre a se u n til d a y 21, w h e n th e a v erag e level is 10 n g /m l. A fte r d ay
21 it d e c re a s e s, to 4 - 5 n g /m l b efo re p a rtu ritio n . A fte r p a r tu r i­
tio n th e h o rm o n e level d ro p s to 1 n g /m l o r low er. P s e u d o p re g ­
n a n t q u e e n s h a v e a sim ila r in c re a se ; h o w ev er, b y d a y 30 th e level
b e g in s to d eclin e.
E strad io l
O n t h e d a y o f m a t in g th e le v e lis a b o u t6 0 p g /m l. D u rin g th e n e x t
5 d a y s it d e c re a s e s rap id ly , to 8 - 1 2 p g /m l. T h a t level is m a in ­
ta in e d u n til p a rtu ritio n , w h e n a slig h t in c re a se o c c u rs. P s e u d o ­
p re g n a n t c a ts follow a sim ila r c o u rs e , b u t a m o re -ra p id d e c re a s e
follow s m a tin g .
P ro lactin
L evels a re e le v a te d in th e la s t trim e s te r of p re g n a n c y . T h e av er­
a g e is 31.2 ± 5.1 n g /m l th r o u g h th e la s t w e e k o f p re g n a n c y ; th e n
it in c re a se s to 43.5 ± 5.4 n g /m l d u rin g th e la s t 3 d a y s b efo re p a r ­
tu ritio n . A b o u t 2 w e e k s a fte r w e a n in g , p ro lac tin d e clin es to p r e ­
la cta tio n levels.
O vulation
O v u la tio n in th e q u e e n d e p e n d s o n th e re ­
le a s e of s u ffic ie n t a m o u n ts o f lu te in iz in g
h o rm o n e (LH ) fro m th e a n te rio r p itu ita ry
g la n d . S in c e th e q u e e n is a n in d u c e d , o r
reflex, o v u la to r, L H is re le a se d in a n e u ra l
reflex in itia te d b y v ag in al-c e rv ic a l s tim u ­
la tio n d u rin g m a tin g . P ro b a b ly lu te in iz in g
h o r m o n e - r e le a s in g h o rm o n e (L H -R H ) is
first re le a se d fro m th e h y p o th a la m u s fol­
lo w in g in tro m is s io n , w h ic h r e s u lts in r e ­
le a s e o f L H fro m th e a n te r io r p i t u i t a r y
g la n d . L H levels in th e q u e e n flu c tu a te e p ­
iso d ically ; in c re a se s o c cu r e v e ry tw e n ty to
th i r t y m i n u t e s a n d a r e p r o b a b ly u n d e r
t h e in f lu e n c e o f th e e p is o d ic r e le a s e o f
L H -R H .
O v u la tio n u s u a lly o c c u rs w ith in
tw en ty -fiv e to th irty h o u rs a fte r m a tin g if
su fficien t L H h a s b e e n re le a se d ; so m e in ­
v e s tig a to rs h a v e r e p o r te d th e o c c u rre n c e
of o v u la tio n u p to fifty h o u rs a fte r m a tin g .
T h e v a ria n c e s m ay b e d u e to th e q u e e n 's
in d iv id u a l th re s h o ld levels o f L H -R H a n d
L H , th e n u m b e r o f d a y s th e q u e e n h a s
b e e n in e s tru s w h e n m a te d , im m a tu rity of
th e o v a ria n follicles, o r th e n u m b e r o f in ­
tr o m is s io n s r e q u ir e d b y a q u e e n fo r a d e ­
q u a te re le a se of L H . It a p p e a rs th a t so m e
q u e e n s w il l n o t r e l e a s e a n o v u l a t o r y
a m o u n t o f L H u n til th e s e c o n d , th ir d , o r
e v e n f o u r th d a y of e s tr u s . T h e re fo re , th e
b e s t tim e to b re e d q u e e n s is o n th e se c o n d
o r th ird d a y o f e s tru s , a n d a t le a st fo u r m a t­
in g s sh o u ld o c cu r to e n s u r e th a t th e q u e e n
re le a se s a d e q u a te L H a n d ach ie v es m ax i­
m a l o v u la tio n .
O v u la ti o n c a n b e i n d u c e d in e s t r o u s
q u e e n s b y artificially s tim u la tin g th e v ag i­
n a l w a lls o r c e rv ix w ith a p r o b e ; j u s t a s
m u ltip le in tro m iss io n s d o , m u ltip le p ro b ­
in g s re p e a te d a t five- to fifte e n -m in u te in ­
te r v a ls w ill e n h a n c e th e r e l e a s e o f a d e ­
q u a te L H . In je c tin g b o th a n e s tr o u s a n d
e s tr o u s q u e e n s w ith e x o g e n o u s L H -R H
(25 m eg) c a u s e s L H re le a se a n d re s u lts in
o v u la tio n d u r in g e s tr u s . O v u la tio n w ill
a l s o o c c u r in e s t r o u s q u e e n s w i t h i n
tw en ty -six o r tw e n ty -se v e n h o u rs a fte r a d ­
m in is te rin g 25 to 50 IU s of H C G . F ertiliza­
tio n ra te s fo r n a tu r a l m a tin g s a re a lm o s t
100 p e rc e n t for u p to tw e n ty -se v e n h o u rs
a fte r a d m in is te rin g th e H C G b u t d eclin e to
b e tw e e n 35 a n d 80 p e rc e n t d u rin g th e p e ­
rio d o f t h i r t y h o u r s to f o r ty - n i n e h o u r s
a f t e r t r e a t m e n t . C o n c e p tio n s c a n o c c u r
fifty -tw o o r m o re h o u rs a fte r H C G a d m in ­
is tra tio n , in d ic a tin g th a t th e fe rtile life of
th e q u e e n 's o v a a fte r o v u la tio n is a b o u t
tw e n ty - f o u r h o u r s . S o m e in v e s tig a to r s
h av e d e m o n s tra te d th a t a sin g le in jectio n
of 500 IU s of H C G , o r a n in jectio n of 250 o r
500 IU s o f H C G o n tw o co n se c u tiv e d ay s of
e s tru s , p ro d u c e d a sig n ific an t in c re a se in
th e p e rc e n ta g e o f o v u la tio n ra te s in co m ­
p a ris o n to th e p e rc e n ta g e a c h ie v e d by a
sin g le in jectio n of 50 o r 100 IU s of H C G .
Pregnancy
G e s ta t io n la s ts s ix ty - f o u r to s ix ty - n in e
d a y s (th e a v erag e is six ty -six d ay s). B reed ­
e rs o fte n d e p e n d o n th e p h y sical c h a n g e of
th e q u e e n 's n ip p le s fro m lig h t p in k to ro sy
p in k in th e se c o n d a n d th ird w e e k s follow ­
in g m a tin g as a n in d ic a tio n of p reg n an cy .
P re g n a n c y d ia g n o s is is b e s t a cco m p lish ed ,
h o w ev er, b y carefu l a b d o m in a l p a lp a tio n
o f t h e u t e r u s fr o m d a y s s e v e n t e e n to
tw en ty -fiv e , w h e n th e c o n c e p tu s is ro u n d
a n d s e g m e n te d fro m o th e r c o n c e p tu s e s .
A fte r th ir ty to th irty -fiv e d a y s th e e lo n ­
g a te d fe tu s a n d fetal m e m b ra n e s b eco m e
c o n flu e n t, a n d it is d iffic u lt to d is tin g u ish
p r e g n a n c y fro m a n e n la r g e d u te r u s
c a u s e d by p se u d o p re g n a n c y o r p y o m etria.
T h e m in e ra liz e d o p a q u e fe ta l sk e le to n
4
w ill sh o w on abdom inal radiographs from
the fortieth to forty-fifth day of gestation to
term . The approxim ate gestation age can
be estim ated by the radiographic appear­
ance of m ineralized bone in the fetu s— at
forty-one days the radius and uln a are v is­
ible; at forty-three days the tibia, fibula, il­
iu m , isch iu m , an d occipital b o n e s o f the
skull can be seen; at fifty-five days the e n ­
tire sk eleton is visible.
A p h en o m en o n k n ow n as p seu d o p reg ­
n ancy can occur in q u een s. In fact, a q u een
can have as m any as five p seu d o p reg n a n ­
cies in a breeding season . Elevated p roges­
te r o n e le v e ls o cc u r in p se u d o p r e g n a n t
q u een s at the sam e tim e in the estrou s cy­
c le— days ten to tw elve— that im planta­
tion of the fertilized ova occurs in a preg­
nant q u een . W ithin about forty days o f its
o n se t, the p seu d o p reg n a n c y w ill term i­
nate as progesterone levels return to pre­
b r e e d in g le v e ls . O v a ria n a c tiv ity is r e ­
estab lish ed w ith in seven to ten days after
the en d of a pseudopregnancy.
Parturition
The endocrin ology (see table 2) and p h y si­
o logy of parturition in the q u een have not
b een fully stu d ied . A few days before par­
turition, the q u een exp erien ces a decrease
in c ir c u la tin g p r o g e s te r o n e to prepreg^
n ancy levels and an increase in estradiol178 lev els. T h en the estrad iol level d ro p s
on the day of parturition as circulating pro­
lactin levels increase. T he e n d o g en o u s ef­
fects and levels of p rostaglan d in s, relaxin,
cortisol, and oxytocin are u n k n o w n . C lin­
ically, adm inistration of oxytocin is very e f­
fective in ca u sin g u terin e con traction s to
en d uterine inertia, exp el retained kittens
or p lacen tas, and in itiate m ilk let-d o w n .
Probably en d o g en o u s oxytocin is present.
The q u een w ill also react to “ feathering"
the vagina during parturition, resulting in
uterine contractions.
The rectal tem perature falls in the first
stage of labor. The second stage of labor is
u su ally qu ite rapid; there are a few abdom ­
inal strain s, sim ilar to d efeca tio n , before
th e first k itte n is d e liv e r e d . T h e th ird
sta g e— placenta ex p u lsio n — clo sely fol­
lo w s the fetal delivery.
Summary
The cat is u niq u e am on g m am m als in som e
a sp ects of reproductive p h y sio lo g y and e n ­
docrinology. T his article d isc u sse s the g e n ­
eralities of feline puberty, estro u s cycles,
sex u a l b eh avior and m atin g, p regn an cy,
and p artu rition . M o re-d etailed in fo rm a ­
tion can be o b ta in ed from th e referen ces
listed below.
Selected General References
B u rk e, T. J. F e lin e r e p r o d u c tio n . F elin e
P ractice 5 (6 ):1 6 -1 9 ,1975.
Colby, E. D . T he e stro u s cycle an d p reg ­
nancy. In T herapy in theriogenology, ed . D.
A . M orrow, pp. 8 3 2 -3 9 . P hiladelphia:
W. B. Saunders, 1980.
C olby, E. D . In d u c e d e s tr u s a n d tim ed
p r e g n a n cies in cats. L aboratory A n im al
C are 20:1075-80, 1970.
C on can n on , P. W., and D . H . Lein. Feline
reproduction. In C urrent Veterinary Ther­
a p y V III, e d . R. W. Kirk, p p . 9 3 2 -3 5 .
Philadelphia: W. B. Saunders, 1983.
H erron, M . A . Feline reproduction. Veteri­
nary C linics o f N orth A m erica 7(4):715-22,
1977.
H erron, M. A . Feline vaginal cytologic ex­
am ination. Feline P ractice 7:36 -3 9 ,1 9 7 7 .
Paape, S. R. Luteal activity in the p se u d o ­
p r e g n a n t ca t. B io lo g y o f R ep r o d u c tio n
1 3:470-74,1975.
R ichkind, M. T he rep ro d u ctiv e en d o cri­
n o lo g y o f the d om estic cat. Feline P ractice
8(5):28—31, 1978.
Roberts, S. J. Infertility and reproductive
d isea se s in b itch es and q u een s. In Veter­
inary obstetrics and gen ital diseases therio­
gen ology, third e d itio n , p p . 6 7 8 -7 0 9 .
A n n Arbor: Edward Brothers, 1986.
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