This factsheet is not intended to be a comprehensive guide to the care of the pregnant brood mare but it will highlight the areas that need particular attention or are sometimes forgotten about.Pregnancy checks - when should they be done?
Pregnancy loss without any overt signs is not at all uncommon and therefore failure to return to heat after covering cannot be taken as confirmation that the mare is in foal or has maintained her pregnancy. It is essential that mares receive one or more veterinary examinations for pregnancy, usually by ultrasound scanning
How do we test for pregnancy?
a) Ultrasound scanning: This is by far the commonest and most preferred method of determining pregnancy. Scanning is generally very accurate, causes no more than minor discomfort to the mare, and allows the identification of twin pregnancies.
Your mare will normally have been scanned at least twice (at 16 days and again at 25-30 days) at the stud. A third examination at 6 weeks is advisable, as early foal loss up to this date is not uncommon. Checking the mare again on or around the 1st October is important for two reasons
- Many stud fees are due at this time and are paid if the mare is confirmed in foal by 1st October
- It is as well to know whether your mare is still pregnant so that you can plan her winter feeding regime
If you mare has been returned from the stud without any veterinary confirmation of pregnancy it is essential that she is checked at least once by us to confirm that she is definitely in foal.
b) Blood testing: Blood tests are occasionally used instead of scanning but in general are less accurate (false positives can occur), do not allow the identification of twin pregnancies, must be carried out over a narrower time frame, are more expensive and do not produce an instant result.
When should brood mares be wormed?
It is both safe and important to worm pregnant mares. In late pregnancy the mare's natural resistance to worms is lowered. At this time the number of worm eggs in the mare's droppings tends to rise and when these develop on the pasture they are an important source of redworm infection for the foal. In addition the threadworm Strongloides westeri is passed through the mare's milk and is an occasional cause of diarrhoea in young foals.
Follow your normal worming regime. Further information on choosing wormers and how to use them can be found in our factsheet entitled Worms and Worming.
What about vaccinations?Keep up the mare's normal vaccination course against tetanus and 'flu. If the mare receives a booster vaccination 4 weeks prior to foaling the concentration of antibodies to these infections in the colostrum (first milk) will be significantly increased and the newborn foal will obtain immediate protection as soon as it suckles.
In addition we recommend that all pregnant mares be vaccinated against Equine Herpesvirus (EHV or virus abortion) at the 5th, 7th and 9th months of pregnancy. EHV is becoming an increasing problem in the U.K. Affected mares abort in late pregnancy or give birth to weak foals that die in the first few days of life. Vaccinating against EHV is money well spent.
Some studs require that pregnant mares are vaccinated against Rotavirus at the 8th, 9th and 10th month of pregnancy. This virus causes diarrhoea in young foals on large public studs. Protection for the foal is provided via the colostrum.
Routine foot and dental care
These are sadly neglected in many brood mares. Although most brood mares are unshod, regular trimming at 6-8 week intervals is important to prevent foot abscesses (gravel), which are all too common in mares with overgrown feet. Dental care is important too. Mares live on a largely forage-based diet, and each kilogram of hay requires 5000 chews before it is swallowed. To ensure that this feed is utilised with maximum efficiency and without discomfort to the mare it is essential the teeth are rasped annually, usually at the time of the 1st. October pregnancy check
What should I feed?
First eight months: Mares are commonly overfed during this period. Although forage (grass or hay/haylage) will meet the mare's energy (calorie) requirements at this stage she is likely to be deficient in good quality protein and some vitamins and minerals. A modest amount of stud cubes/stud mix should be therefore be fed but avoid allowing the mare to become overfat. In-foal mares with a foal at foot will need to be fed to meet their lactation requirements until weaning. We recommend you follow the feed company's advice.
Last three months: The foetus gains 65% of its bodyweight during this period. It is important therefore that a balanced ration is fed. A purpose-made brood mare diet (stud mix or stud cubes) will provide all of the necessary calories, protein, vitamins and minerals a mare needs to supply to her developing foetus. This should be fed in conjunction with good grass or hay/haylage. The amount to be fed will depend on the manufacturer's recommendations and the quality of the grass/hay available. The temptation to feed a home-mixed ration should be avoided, as it is very likely to be unbalanced and inappropriate for the mare and her foal.
Exercise
Mares in early pregnancy can be ridden lightly for the first 4-5 months. In late pregnancy mares should spend as much time out of doors as possible as exercise is important at this stage.
For information on foaling mares see Factsheet No.8 'Foaling: what you need to know'
DISCLAIMER
This factsheet is intended for use by registered clients of EqWest only. The advice offered is general advice only. EqWest clients who wish to discuss the individual circumstances of their horse should contact the Clinic.
To speak to a vet please phone between 8.30 - 9.30 am on weekday mornings.
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