An important safeguard during your mare’s pregnancy is immunization against Equine Herpesvirus 1 (EHV-1) at the beginning of the fifth, seventh and ninth months of gestation. The EHV-1 strain of Equine Herpesvirus is the leading cause of infectious viral abortions in mares.

EHV-1 is typically associated with late-term abortions and the delivery of a well-preserved fetus and outwardly normal placenta. Most horses become infected with EHV-1 during the first year of life. In the majority of cases, the virus becomes latent, just waiting for stress-induced reactivation.

Sources of EHV-1 Infection for Pregnant Broodmares

• Clinically ill horses shedding the virus in nasal secretions
• Asymptomatic horses experiencing reactivation of latent infection and shedding virus in nasal secretions
• Virus-laden uterine secretions and placenta/fetus from mares aborting due to EHV-1

Prodigy^® EHV-1 Vaccine

To reduce the risk of EHV-1 abortion, vaccinate your mare with Prestige^® Prodigy^® at the start of months five, seven and nine of gestation. All horses in close contact with broodmares – such as barren mares, stallions and teaser stallions – should also be maintained on a rigorous EHV-1 vaccination program.

It’s also important to reduce your pregnant mare’s exposure to groups of young horses and any new arrivals that may be shedding EHV-1.

Consult your veterinarian for more information on vaccinating with Prodigy.

Before you breed, make sure your mare is current on all core vaccines. Core vaccines, as defined by the American Association of Equine Practitioners, have clearly demonstrated efficacy and safety and a high enough level of benefit and low enough level of risk to justify their use in the majority of horses.

Core Vaccines For All Horses

• Eastern Equine Encephalomyelitis (EEE)
• Western Equine Encephalomyelitis (WEE)
• West Nile Virus (WNV)
• Tetanus
• Rabies (should be administered pre-breeding or pre-foaling)

Additional Vaccines for Mares

• Equine Influenza (EIV)
• Equine Herpesvirus 1 & 4 (EHV 1&4)

Ask your Veterinarian About Vaccines based on your mare’s risk level

• Strangles (Streptococcus equi). Over-vaccination against Strangles can increase the risk of an immune mediated reaction called purpura hemorrhagica that can be debilitating and even fatal. If your mare has recently recovered from strangles infection, resides in an area with a history of strangles or has received frequent strangles vaccinations, ask your veterinarian about drawing a blood sample from your mare to measure SeM antibody levels prior to vaccination.
• Potomac Horse Fever (PHF).
• Equine Viral Arteritis (EVA) vaccine is recommended for mares being bred to EVA-positive stallions. Follow your veterinarian’s recommendations regarding use of this vaccine.

Talk to your veterinarian about which at-risk vaccines your mare should receive. Vaccination against strangles, Potomac horse fever, botulism and rotavirus is recommended only if there is a high risk of disease in your region or on your farm. If your mare will be sent to another farm for re-breeding, consider the risk of disease on that farm as well, and plan your vaccinations accordingly.

Pre-Foaling Vaccines

You should booster your pregnant mare four to eight weeks prior to foaling. This important series of pre-foaling booster vaccinations stimulates the mare to produce high levels of protective antibodies at a time during late pregnancy when she is also producing antibody-rich colostrum.

The newborn foal relies on ingestion of colostrum and absorption of these antibodies during the first 12 to 24 hours of life for protection against a wide variety of viral and bacterial diseases during the early post-natal period.

Booster your mare 4 to 8 weeks prior to foaling for

• Equine Herpesvirus (EHV-1 & 4)
• Eastern and Western Encephalomyelitis (EEE/WEE)
• Tetanus
• Influenza
• West Nile Virus
• Rabies (if not administered pre-breeding)

Keep Track of Vaccinations

Click the link to download a vaccination record for your mare. Equine Health Library Mare Vaccination Record.

The major gastrointestinal parasites of concern in the mare are large and small strongyles and, in some instances, tapeworms. Another parasite, Strongyloides westeri, can be passed from dam to foal in the milk.

Any deworming program should include dewormers that are effective against mature parasites and migrating or encysted larvae. In general, it’s wise to avoid any unnecessary drug administration, including dewormers, during the first 60 days of pregnancy since this is the time when major organ systems are developing in the fetus (organogenesis).

Consult your veterinarian for the most effective deworming schedule for your horses and region. 

• Equine Health Library Mare Deworming Record

Recommended mare deworming

After you determine the shedding status of your mare through a fecal egg count examination, deworm her prior to breeding with a drug appropriate for the time of year, her parasite susceptibility and risk of exposure. Large strongyles and small strongyles, as well as tapeworms, are typically acquired from pasture and any environment contaminated by horse manure. Since broodmares spend most of their time on pasture, they are at constant risk for parasite infection.

If you have a large breeding operation with many mares grazing limited pastures, you’ll have an increased threat of heavy worm burdens accumulating during the grazing season. Remember, if your mares are shipped off to be re-bred, they will be exposed to other parasites on other farms. All incoming or returning mares should have fecals performed and may benefit from deworming prior to exposing them to your pastures and resident mares. Soon after foaling, deworm your mare with a broad-spectrum dewormer that’s effective against Strongyloides westeri. Periodically monitor fecal egg counts (FEC) to evaluate efficacy of drugs used.

Prebreeding (late winter/early spring)

• Low shedders: Ivermectin, pyrantel or fenbendazole
• High shedders: Larvicidal fenbendazole or moxidectin
• Spring/post foaling: Ivermectin

End of First Trimester/Second Trimester (late spring – early summer)

• High shedders: Broad-spectrum dewormer such as pyrantel, ivermectin or fenbendazole. If tapeworms are a problem, consider a double dose of Pyrantel or an ivermectin/praziquantel combo.
• Avoid administering dewormers during peak hot, dry summer months since risk of strongyle transmission is greatly reduced. Late spring/early summer or early fall are more optimal times to deworm in most regions. Excessive drought conditions will also reduce the risk of strongyle (and possibly tapeworm) transmission and should be taken into consideration.
• High shedders may require a second treatment in early fall.

Third Trimester (late fall/early winter)

• Treat for bots, tapeworms, large and small strongyles and encysted small strongyle larvae (if indicated as in the case of high shedders).

Ideally, your broodmare should maintain a body score around 5 to 6.5. Body scores less than 4.5 to 5 have been linked to reduced fertility and lower pregnancy rates. Likewise, maternal obesity has been associated with decreased breeding efficiency and milk production (especially in mares age 15 years and older at body condition scores 8 to 9) as well as potential metabolic problems.

If your mare is obese, avoid implementing a weight-reduction program during the first 60 days and last 90 days of gestation due to potential negative effects on embryonic and/or fetal growth and development. In the event a pregnant mare is significantly obese and weight loss is necessary for her health, it is critical that adequate protein, vitamins and minerals be provided during calorie restriction. Be sure to check with your veterinarian if you have concerns regarding your mare’s body weight and condition throughout pregnancy.

If your broodmare is not maintaining condition, contact your veterinarian. There may be an underlying health problem.

Click the link below for a downloadable nutrition record.

Nutrition – 1st and 2nd Trimesters

During the first and second trimesters, you should feed your pregnant mare at a maintenance rate with her total daily feed intake at 1.5 to 3 percent of body weight.

Provide access to good quality pasture and/or hay, fresh water and an additional source of nutrients including adequate amino acids, vitamins and minerals. Your pasture may provide adequate crude protein and calories to support pregnant mares during early gestation, but it could be deficient in essential minerals. Hays are often deficient in amino acids, vitamins and minerals. Additional supplementation is recommended to support optimal fetal growth and development.

At this stage, your mare’s ideal body condition score is 5 to 6.5. Underweight mares may require concentrate supplementation to gain weight. If your mare is overweight, weight reduction feeding programs should be delayed until after the first 60 days of pregnancy.

Nutrition – Last Trimester

During the last trimester, you should focus on a slowly rising plane of nutrition. Fetal growth increases significantly during the last trimester of pregnancy, an estimated one pound per day during the last 90 days.

Your mare’s increasing caloric needs most likely require a change in feeding program to supply calories in a more concentrated form, such as a change from a vitamin/mineral supplement to a concentrate feed, or an increase in feed provided.

Nutritional Changes

• Gradually increase caloric intake 10 to 20 percent above maintenance.
• Provide a concentrate designed for broodmares containing high-quality protein (an average of 14 to 16 percent crude protein and appropriate amino acids such as lysine), adequate caloric density (high fat provides a dense source of calories), and containing the proper balance of important vitamins and minerals, including: calcium, phosphorus, copper, zinc, selenium and vitamin E.
• Offer an average of ½ – ¾ pounds of concentrate per 100 pounds of body weight divided into two to three feedings per day.
• Mares grazing endophyte-infected fescue grass should be removed from pasture and offered an alternate source of hay during the last 60 to 90 days of gestation to prevent a host of late-pregnancy complications, including lack of milk production, prolonged gestation, difficult delivery, abnormal placenta and the birth of weak, severely compromised foals.

The importance of balanced nutrition

Choose a concentrate with balanced minerals and vitamins, and don’t dilute it.

• Copper deficiency is associated with skeletal lesions in foals. Copper provided to gestating mares has been shown to be stored in the liver of the fetus for the foal to utilize following birth until the foal consumes adequate creep feed to supply mineral needs.
• Selenium/vitamin E deficiency is associated with White Muscle Disease in foals.

After foaling

Once the mare foals, she will produce, on average, up to 3 percent of her body weight in milk per day during early lactation and consume 2 to 3 percent of her body weight in total feed (concentrate plus hay) daily. Underfeeding during early lactation can lead to weight loss that can negatively affect reproductive efficiency, conception rates, and growth and development of the suckling foal.

Nutrition needs post foaling

• Peak lactation occurs around four to six weeks post-foaling
• Mares require ≥ 35,000 kcal/day to support optimum milk production
• The mare’s energy, protein, vitamin A, calcium and phosphorus requirements may more than double from early gestation to early lactation

By the fourth month of lactation, your mare’s milk provides less than 30 percent of the total energy needed by her foal. Offering a concentrate rich in fats or oils and high-quality protein may help slow the downward curve in milk production and nutrient content.

Consult your veterinarian for specific information regarding your mare’s nutritional needs.

As your horse ages, incisors, premolars and molars continue to erupt from the jaw, gradually being worn down by grazing and chewing. The average adult horse has about 1/8-inch of tooth erupt annually.

Problems can occur when the teeth wear unevenly, either because of the horse’s anatomy or because of a missing opposing tooth. This uneven wear can cause sharp points on the edges of the teeth that are painful when chewing or wearing a bit, or even a wave mouth where the surface of the tooth forms a wave-like pattern rather than a straight line. The best course of action is prevention and attending to your horse’s teeth before sharp points ever form.

Breeding stock should have a dental exam performed annually by a licensed veterinary dental provider.

Signs it’s time to call the dentist

• Resistance to the bit, excessively mouthing the bit or sudden training problems
• Dropping grain or hay while chewing
• Abnormal movement and positioning of head and mouth while eating
• Unusual or foul odor to breath

Click the link to download the Equine Health Library Mare Dental Record.

Most horses benefit from trimming and/or shoeing every six to 10 weeks depending on the individual horse and specific hoof care needs such as corrective shoeing, hoof growth and hoof condition. If your horse has trouble holding shoes or has hooves that crack and chip easily, look to nutrition first. Your horse may not be getting all of the nutrients needed to grow a strong foot.

If you start having problems such as sole abscesses, laminitis or navicular disease, you may need to coordinate treatment with both your veterinarian and farrier for the best results.

If you’ve ever seen thrush, you won’t forget it. Thrush is a bacterial infection of the frog caused by gram-negative, anaerobic (not requiring oxygen to grow) bacteria. Wet, moist conditions favor development of thrush.

Signs of thrush include black, bad-smelling, greasy discharge around the frog and adjacent tissues. Severe cases can even cause lameness if the infection invades deeper tissues of the sole and frog. Call your veterinarian if you think thrush has progressed to this state.

Treatment

• Provide more air to the site of infection
• Clean dirt and mud away from the frog daily
• Treat topically with a povidine-iodine solution or other over-the-counter medications
• Keep the feet dry and clean to reduce the risk of thrush