Reproduction
The
Bitch
From around 6 months of age the anterior pituitary gland begins
to release higher levels of the gonadotropic hormones, follicular
stimulating hormone (FSH) and luteal hormone (LH). The rise
in levels of these hormones initiates the sexual cycle in
the bitch anytime from 6 to 16 months. In larger breeds such
as the Bracco sexual maturity will usually occur later than
in smaller breeds. The cyclical increase and decrease in FSH
& LH in turn will continue to control the cycle of ovarian
changes and the normal reproductive cycle of the bitch.
The Estrous Cycle is usually around 6 months
in length, although this will vary from bitch to bitch and
consists of four stages.
Proestrus – Usually lasts for around
6 -11 days with an average of 9. The swelling of the vulva
and bloody discharge mark the beginning of proestrus. During
this stage the FSH and LH hormones stimulate growth and development
of follicles, each containing ova, within the ovaries. The
follicles secrete estrogen causing changes in the cells of
the vaginal walls called cornification.
Estrus – Can last 3 -21 days with an
average of 9. This phase begins when the bitch is receptive
to the dog. Outward signs include the discharge changing from
bloody to light pink or straw coloured and tail flicking.
A surge of LH occurs and 1 – 3 days later ovulation,
the release of eggs from the follicles, takes place. During
this phase estrogen levels fall and progesterone levels rise.
The eggs become mature in 2-3 days and remain viable for up
to 72 hours.
Diestrus – This phase lasts around
2 months. The bitch becomes unattractive to the male and if
the bitch has been succesfully mated this is the beginning
of pregnancy. The ruptured follicles, corpus luteum, continue
to produce progesterone, which is necessary to maintain pregnancy,
whether the bitch has been mated or not. This stage ends just
prior to whelping or after approximately 2 months when the
progesterone level falls.
Anestrus – This stage lasts 3 –
5 months. The quiet time between seasons, the bitch is uninterested
in and uninteresting to the male. The length of this period
is affected by the breed, age, size and physical condition
of the bitch.
The
Dog
Like the bitch dogs mature at varying ages depending on size,
breed and the individual, most are capable of producing sperm
at around 10 months. At the onset of puberty the hormones
FSH and LH are secreted by the pituitary gland and stimulate
the production of testosterone by the testes and in turn the
maturation of the spermatozoa. Testosterone is also responsible
for the male sex characteristics, male sexual behaviour and
ensuring the prostate gland remains active. Sperm continue
to be produced in the testes usually uninterrupted from puberty
to old age.
The ejaculation in dogs can take as much as half an hour and
consists of three phases.
The Urethral – Semen is translucent
in this first phase acting as a lubricant.
The Spermatic – Semen is milky in appearance
and sperm rich.
The Prostatic – Semen fluid is clear,
produced by the prostate to flush the sperm up into the bitch.
The number of sperm produced varies depending on the size
and age of the dog the hormonal balance and frequency of mating.
The supply of sperm is replaced approximately every four days
and consists of around 10 million per pound weight of the
dog so for a Bracco male around 1 billion per ejaculation.
A lengthy abstinence will also affect the concentration of
viable sperm especially if the bitch in season arrives suddenly;
a second mating under these circumstances is, if possible,
advisable.
Once within the vaginal tract sperm can survive for up to
5 days but most only remain fertile for about 48 hours.
Mating
Before thinking of breeding from your dogs they should be
in good condition both in fitness and health they should also
be physically mature. The male although able to sire at a
younger age is probably more sexually mature at around 18
months. The bitch will be in her second or third season and
normally 2 + years of age. The bitch needs to be not only
physically mature but also mentally mature enough to cope
with the strains of birth and raising pups.
Determining when to mate is probably the
most worrying part for the bitch owner especially if your
chosen male is hundreds of miles away and invariably the bitch
will change her normal routine/cycle just to keep you guessing.
In the average bitch if day one is defined as the first day
the bloody discharge is seen the LH surge will occur on day
ten and ovulation on day 12. As the ova take 48 -72 hours
to mature optimal conception occurs on day 14. It is not unusual
for owners to have a double service on days 12 & 14 or
a triple service on days 11, 13 and 15 as the sperm and the
ova remain viable for up to 5/6 and 2/3 days respectively.
The signs the owner can look for in the bitch that show readiness
to mate are – the discharge becoming light pink or straw
coloured, ‘tail flicking’ or lateral deviation
of the tail whilst raising the vulva. The swollen flesh of
the vulva also softens.
There are also several clinical methods for determining ovulation
such as vaginal smears and blood testing which require assistance
from your Vet.
Pregnancy
The pregnancy or gestation period for a bitch lasts between
56 and 66 days with an average of 63 days. After conception
the fertilized eggs (Zygotes) begin cell division growth and
become embryos. The developing embryos then move from the
oviducts into the uterus at 6 – 10 days after conception.
They implant or attach to the uterine walls 17 - 21 days after
fertilization. The placenta develops, the embryos become foetuses
and are, usually, evenly spaced along the uterine horns. By
the 21st day there is a rudimentary heart beat.
During the first 35 days or so there is very little increase
in size of the embryo but after the 35th day growth is much
more rapid and by 40 - 45 days the foetal skeleton is dense
enough to show up on an x-ray.
Care
of the bitch
Care of your bitch will have begun even before the breeding
phase; she will be in excellent physical shape, well nourished,
up to date with vaccinations and have been wormed.
Once she is pregnant she should be fed a high quality well
balanced diet at the normal maintenance level, an increase
in quantities is not necessary until the 4th week. Recommended
guidelines state the diet should consist of 29% protein and
17% fat. High amounts of soluble carbohydrates and low fibre
content will ensure adequate energy intake and avoid hypoglycaemia
in late pregnancy. Amounts should increase 10% by the 5th/6th
week and up to 30% by the time of whelping. Common sense should
of course be used; your bitch should not be under or very
overweight.
If a high quality diet is fed the increase in amounts will
ensure an increase in the vitamin and mineral content. Feeding
dietary supplements is now thought to be unnecessary and can
in fact be detrimental. For example excess vitamin A is associated
with congenital defects such as cleft palate and vitamin D
may affect the mobilization of calcium within the bitch. Vitamin
C may interfere with normal processes of bone development.
Many breeders give calcium supplements but high levels of
calcium within the body interferes with the normal process
of storage and metabolism by suppressing parathyroid hormone
production. Calcium supplementation can have the opposite
of the intended effect and puts the bitch at greater risk
of developing hypocalcemia. As the pups grow and there is
less room available your bitch will appreciate being fed smaller
meals several times over the day rather than her normal 1
or 2.
Outward signs that the bitch is pregnant may include the vulva
remaining more swollen than is normal also the nipples can
be slightly more prominent and rosy but not always. Some bitches
suffer from morning sickness around the third / fourth week
due to hormonal changes and through the physical changes of
the uterus. Feeding smaller meals more frequently may help
to alleviate this. By the fifth week of pregnancy the mammary
glands and nipples swell and become darker in colour and the
coat thins around that area. Between 5 and 6 weeks the abdomen
will become enlarged and by 8 weeks the mammary glands will
have become considerably enlarged and the nipples may show
signs of milk.
In addition to a good diet exercise is also important to maintain
fitness; a fit strong healthy bitch is less likely to have
complications during whelping. The more physically demanding
exercises such as hunting should be avoided and obviously
as the pregnancy advances exercise should be reduced as she
will tire more easily.
It is also important to avoid stress during the pregnancy.
Studies have shown that puppies born to bitches that who have
suffered even mild stress demonstrate a permanent condition
of hypersensitivity to stress due to the effects on the hypothalamic-pituitary-adrenal
gland axis of the foetuses.
Kim
Parris
