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from your favourite mare - to breed or not to breed?
by Liz Brown MA,VetMB, MRCVS
At this is the time
of year attention is drawn towards the stud season and preparation
of mares for breeding.
Before deciding whether
to breed from your mare there are many factors that need to be
taken into consideration. The aim of breeding should be to produce
a sound healthy foal that is suitable for the purpose for which
it will be used. Obviously there are many pitfalls that may be
encountered along the way, otherwise we would all be breeding
The first consideration
is do you actually need to breed a foal? You need to have a clear
idea of the purpose for which you are breeding the foal. If you
are unlikely to keep it yourself then do you have someone else
in mind that will want to take it on when it is older? If you
are likely to sell the foal once it is old enough then it needs
to be an attractive proposition for someone to purchase. A foal
from your favourite mare may have sentimental value for you but
this may not translate to the purchaser if there are no other
Secondly do you have
access to suitable facilities? You will need a large foaling box
and a safe paddock with post and rail fencing. Foaling can take
place outside if the weather is suitable but you should have access
to a dry and draught-free stable or barn for use at or after the
birth if necessary. Once the foal is weaned it will need a separate
turnout area away from the mare.
The next question
is, is the mare a good candidate to breed from? A common mistake
is to breed from a favourite mare that has had to be retired early
through lameness or tendon problems, this is inadvisable as the
foal may inherit a predisposition to develop these problems later
in life. Ideally you should be breeding from a sound healthy mare
that has many of the attributes you are looking for in your future
foal. Obviously not all of these will be passed on but at least
it is a good starting point. You are unlikely to breed a significantly
larger horse from a small mare so it is unwise to put a pony mare
to a much larger stallion in the hope that the children will have
something to grow into when they are older. Your mare should have
good conformation. Any conformational abnormalities present in
the mare may be passed onto the foal, despite your choice of stallion.
Mares with any serious conformational fault should not be bred
from. Inheritable conformation defects can predispose to navicular
disease, bone spavin, curb, carpal bone fracture and upward fixation
of the patella. Clean straight limbs and good foot conformation
and quality are desirable. Your veterinary surgeon will be able
to advise you about any specific faults that concern you.
of the foal may be genetic, acquired or a combination of both.
Foal behaviour tends to mimic that of the dam to a greater degree
than the stallion. Ideally your mare should be calm and easy to
handle; this will give the foal confidence from an early stage
that humans can be trusted.
Next the general health
of your mare should be considered. Increased age is associated
with a decrease in fertility, due to many factors such as anatomical
changes in vaginal and perineal conformation, endometrial fibrosis
or endocrine changes. However many older mares are still capable
of conceiving and carrying a foal to term.
Good general body
condition is important. Evidence suggests that only in mares with
extreme weight loss or obesity would reproductive potential be
markedly affected. However for general well being you should keep
your mare in normal condition, neither too thin nor too fat.
Pain and stress from
laminitis, severe navicular disease, arthritis, old fractures
and tendonitis may adversely affect cycling and reproductive efficiency.
Advanced pregnancy involves greater weight and compounds painful
effects of limb and joint disease. It is very unwise to breed
from mares with such conditions.
Conditions such as
chronic obstructive pulmonary disease with its accompanying cough
can predispose to pneumovagina. Known cardiac disease, especially
valvular insufficiencies, also may require management change or
special attention. Your vet will be able to advise you on the
significance of these conditions in your mare.
Teeth should be regularly
inspected by your veterinary surgeon. A thorough inspection prior
to breeding may highlight any early problems that might become
more significant over the coming year. Weight loss, stress and
pain can occur from problems that affect mastication. These include
sharp edges, large hooks at the back of the mouth, malocclusions,
missing teeth, wave mouth, root abscesses and occasional trauma
with fractures. Sometimes a simple rasp is all that is required
however heavy sedation is necessary to fully assess and treat
some problems, other problems may require a full general anaesthetic.
Obviously it is important to try to avoid this while the mare
is pregnant so breeding may need to be deferred until potential
problems are treated. Malocclusions such as over or undershot
jaw (sow mouth and parrot mouth) have a hereditary component so
mares or stallions with these defects should not be bred from.
Heavy burdens of parasites
are commonly associated with weight loss, poor body condition
and occasionally more severe clinical symptoms. An effective worming
regimen should be used before, during and after pregnancy.
The conformation of
the perineum and vulva of the mare is important for fertility
and conception. This is the area you can see just by lifting up
the tail, but does include deeper structures which can be assessed
by your vet. For optimal perineal conformation the right and left
vulval lips should meet evenly and appear full and firm, functioning
as a seal and forming the first protective barrier between the
external environment and the uterus. The vulval lips should be
in a vertical position with a slope of no more than 10 degrees
from vertical. Variations in perineal conformation include lengthening
and sloping of the vulva forwards and sinking of the anus. Abnormal
perineal conformation can lead to sucking of air into the vagina
(pneumovagina) and problems such as cervicitis, endometritis,
and subfertility. This can have many causes and is inherent in
some mares. A flat croup, elevated tail set, underdeveloped vulval
lips, and sunken anus all contribute to faulty perineal conformation.
Poor physical condition
intensifies the problem and can lead to abnormal structure even
in mares with normal conformation; as the muscles deteriorate
the anus sinks farther forward and the vulva shifts from its vertical
position to a more horizontal orientation. As mares age the effective
length of the vulva increases. Trauma from previous foalings or
from external factors can result in damage to the vulval seal.
A Caslick's operation
is a simple surgical procedure whereby the edges of the vulva
are cut and sewn together at the top to create a better seal and
prevent air being sucked into the vagina. This can enhance the
fertility of some mares with poor conformation. The use of the
Caslick operation may perpetuate conformational faults by enabling
mares to become pregnant that otherwise would be unable to conceive.
A normal healthy udder
is necessary for the mare to lactate and feed the foal. Any hard
lumps or abnormal swellings should be checked by your vet. These
may indicate a previous episode of mastitis, which may have left
scarring, rendering the gland non-functional for milk production.
records, if they are available, are useful as an indicator of
problems that may recur. Factors such as previous reproductive
surgery, previous history of uterine infection or treatment, early
embryonic death or abortion may affect conception or pregnancy
The following conditions
should also be considered.
also known as pituitary adenoma or cushings can affect reproductive
potential. This condition usually occurs in older mares over
13 years, symptoms can include a long hair coat, often curly,
that persists into the summer months, weight loss, excessive
sweating, laminitis or excessive drinking.
Melanomas are tumours
seen in some older grey horses, frequently observed round the
anus, tail and perineal region as well as the head, neck and
skin. They are unlikely to affect fertility unless they are
extensive in the perineal region, however trauma during mating
or foaling may precipitate growth and metastasis to internal
lymph nodes or organs. Therefore it would be unwise to breed
from a horse significantly affected by these tumours especially
in the perineal region.
While there is no
evidence to suggest that the tendency to develop sarcoids is
heritable, sarcoids should still be carefully assessed before
breeding from the mare. Sarcoids round the groin and udder region
may confuse the foal and affect its ability to suckle. Many
of the drugs or ointments used to treat sarcoids are unsuitable
for use in pregnant mares, therefore treatment should be carried
out prior to breeding.
The presence of
any defects in the ventral abdominal wall or history of previous
abdominal surgery such as for colic may pose a potential hazard
to the pregnant mare.
Last but not least
the cost of breeding a foal should be considered. The stallion
fee is probably only a small percentage of the cost unless you
are aiming to breed a derby winner. It is possible to breed
a foal on the cheap without much veterinary input, however if
you run into difficulties the bills can soon start to add up.
Routine veterinary care would include a pre-breeding examination
by your veterinary surgeon and the taking and testing of the
necessary swabs and blood tests prior to going to stud. These
will include swabs for contagious equine metritis (CEM), klebsiella
and pseudomonas and may include a blood test for Equine Viral
Arteritis (EVA). You should check directly with the stud as
to their particular requirements and consult with your veterinary
surgeon for advice on the appropriate times for these tests.
Once at stud or the AI centre further veterinary costs include
more swabs, scans and routine examinations. Further scans to
confirm pregnancy and that the foal is developing normally will
be carried out either at stud or by your veterinary surgeon.
These routine costs will run into several hundred pounds.
If there are any minor
hiccups along the way such as treatment for endometritis, caslick's
operations or extra scans these will add to the cost. Vaccinations
against Equine Herpes Virus need to be carried out in the 5th,
7th,and 9th months of pregnancy, revaccination for tetanus should
be carried out 6 weeks prior to foaling. The foal and mare will
need to be checked after the birth. As you will see breeding a
foal is not a moneymaking exercise! If you have taken all the
factors into consideration and decide to go ahead then good luck,
but remember that your veterinary surgeon will be a very good
source of advice especially if you are a first timer!
Anvil Equine Veterinary Clinic, Tuckmans Farm,
Copsale, Horsham, West Sussex RH13 7DL
Tel: 01403 731 213 Fax: 01403 733992
ANVIL EQUINE VETERINARY CLINIC'S HOMEPAGE