Should You Rebreed Your Mare on Foal Heat?

About this time every year, as mares foal, mare owners begin to consider rebreeding on foal heat (estrous), rather than waiting for the 30-day estrous.  Wanting to move the birth-date of next year’s foal up a couple of weeks is an option that horsemen have considered for decades. When weanling and yearling halter futurities were popular, early foals were highly desired.  Thoroughbred breeders, especially those breeding for the sales ring, seek early foals as well while racing soundness and success, is less affected by an early birthdate.  If you are considering breeding your mare on foal heat, ask yourself two questions:  1. What do you actually gain by moving the breeding date and resulting foaling date up approximately 3- weeks?  2.  Is there anything to be gained by waiting until the 30-day foal heat?

 

Let’s look at the first question, what do you actually gain by moving the breeding date and resulting foaling date up approximately 3 weeks?  The first answer to this question is actually found in the question itself, by breeding your mare on the foal heat, the foal is born approximately 3 weeks earlier the next year, than it would have been had you waited to breed the mare during the 30-day heat.  Of course, this assumes the mare conceives on either of those heat cycles. 

 

The second advantage to breeding mares on foal heat is that the mare is less likely to return to anestrus (period of reproductive inactivity) following the foal heat.  If the mare does return to anestrus post foaling, it may be 2-3 months before she is physiologically ready to be bred.  So, these are the primary advantages of breeding on foal heat, what are the disadvantages? 

First, comparing mares bred for the first-time, postpartum, on either foal heat or on a 30-day or later heat, mares bred on foal heat have a lower pregnancy rate.  Second, postpartum mares bred on foal heat, lose a greater number of the resulting pregnancies than mares bred on or after the 30-day heat.  This information alone, suggests that waiting to breed mares on the 30-day postpartum estrous, may result in greater reproductive efficiency (pregnancy and then carrying the foal to term).

 

In the week or two after parturition (foaling) occurs, the reproductive tract goes through a period of cleansing and recovery.  The length of time required for post-foaling recovery may be determined by the ease of the foaling process, the level of trauma to the uterus during foaling, and the timely passage of the placenta, among other things.  Therefore, not every mare is a good candidate to be bred on foal heat and even if the mare becomes pregnant off of that breeding, chances of carrying the foal to term are generally less than if the mare were bred on the 30-day or later heat. 

 

If the mare undergoes a normal foaling, the placenta is passed in a timely manner, the mare carries good body weight, and a breeding exam by a veterinarian indicates the reproductive tract has recovered sufficiently, then breeding on foal heat may be a reasonable option.  If the breeding soundness exam indicates the mare could use a week or two of further recovery before breeding, you have little to lose by waiting.  In this situation, if you breed the mare on foal heat and she later loses the pregnancy, you may lose the entire year, only to start over the following breeding season.

                                                                                            Mike Yoder, Ph.D., PAS

 

Will fresh grass make my horse colic or founder?

After a solid week of sunshine and temperatures reaching mid 70's, it certainly feels like spring is just around the corner!  This also means many of us are eagerly anticipating our pastures greening up again.  However, would my horse suffer any negative side effects - such as founder, colic, diarrhea - from grazing pastures full of lush, spring grass?

Well, like so many times when it comes to horses, it depends.

Lush spring growth, for both grasses and legumes, not only has a higher moisture content (75-85%), but is also higher in protein, vitamins, and minerals on a dry matter (DM) basis as opposed to any other time of the year.  Horses have a very delicate microbiome (think probiotics in yogurt) in their cecum that plays a crucial role in their digestion.  If suddenly introduced to fresh pasture, the higher nutrient content can wreak havoc on the microbiome, causing cases of colic and diarrhea.

In addition, early spring pastures are higher in simple sugars and starch.  These are an excellent source of energy, but in large quantities can cause horses with any metabolic disorders, such as Equine Metabolic Syndrome or insulin resistance, to founder.

However, these problems mostly occur if horses have been stalled overwinter without any access to pasture.  Horses are incredibly adaptable and can adjust to changes in pasture quality (i.e. its nutritive value - how much protein, sugar, and minerals it has) over long periods of time.  If your horse was stalled overwinter, or if you know you are concerned your horse has a metabolic disorder, here are a few management practices you can do to help them slowly adjust to fresh pastures:

1. Restrict grazing time: Allow horses 20 minutes of grazing time the first day out on fresh pasture, then increase grazing time by 5 minutes each day over a 2 week period, or until they have fully adapted to fresh pastures.
2. Supplement with hay: Before turning horses out, feed hay to help fill their stomachs and prevent overeating.
3. Avoid grazing early spring pastures altogether: You can avoid problems associated with grazing early spring growth by waiting 4 to 6 weeks - or when the grass is 6 inches tall - before introducing horses to pasture.  It is good practice to still restrict grazing time and supplement with hay if you do this.
4. Use a grazing muzzle: If your horse is susceptible to founder, but must be turned out on pasture, use a grazing muzzle to limit pasture consumption.

For more information on spring pastures and founder, see our previous article: Spring Pasture, Fructans, and Founder

For more information on how to make sure your pasture is ready for spring, see: Spring Pasture Checklist

Soil Sampling: The Key to Growing More Forage

Equine Protozoal Myeloencephalitis (EPM)

Equine Protozoal Myeloencephalitis, or EPM, is a serious disease that can be difficult to dignose because its signs and symptoms can mimic other health problems in horses and the signs can range in severity. More than 50 percent of all horses in the country may have been exposed to the causative organism so it is important to be aware of the signs and symptoms of this disease. 

The causative organism is a protozoa called Sarcocystis neurona, and is spread by opossums. Opossums are the definitive host which is an organism that supports the adult or reproductive form of a parasite. Opossums aquires the causative organism from cats, raccoons, skunks, and armadillos. The infective stage of the protozoa, the sporocysts) is passed in the opossum's feces and horses can come into contact with it while grazing or eating contaminated feed or drinking contaminated water. Once the sporocysts are ingested by the horse, the sporocysts will migrate from the intestinal tract into the bloodstream and will then cross the blood/brain barrier. Once this barrier is crossed, the horse's central nervous system begins to be attacked. Disease onset may be slow or sudden and if left undiagnosed and untreated, EPM can cause devastating and lasting neurological damage. 

The clinical signs and symptoms of EPM will vary and can be different in different horses. Clinical signs are usually asymmetrical, meaning not the same on both sides of the horse. Signs may include:

Ataxia (incoordination)

Spasticity (stiff movements)

Abnormal gait or lameness

Incoordination and weakness which worsens when going up or down slopes or when head is elevated

Muscle atrophy mostly along the topline or in large muscle groups like the hindquarters but can sometimes involved the muscles of the face or front limbs

Paralysis of muscles of the eyes, face, or mouth evident by drooping eyes, ears, or lips

Difficulty swallowing

Seizures or collapse

Abnormal sweating

Loss of sensation along the face, neck, or body

Head tilt with poor balance - horse may assume a splay-footed stance or lean against something for support

There are several factors that can influence the progression of the disease but these four things seem to play an important role:

The extent of the infection (number of organisms ingested)

How long the horse harbors the parasite prior to treatment

The point(s) in the brain or spinal cord where the organism localizes and damage occurs

Stressful events following infection or stressful events while infected

Almost every part of the country has reported cases of EPM, however there is a lower incidence of the disease in the western United States because of the smaller opossum population. About one percent of horses exposed to EPM will show clinical signs of the disease and due to the transport of horses and feedstuffs across the country, almost all horses are at risk to being exposed.

Diagnosing EPM can be difficult because there is no specific assay for this disease and it's clinical signs mimic other neurological diseases. A veterinarian will fist conduct a thorough physical exam to asses the horse's general health and identify any suspicious signs. One clue that can help lead to the correct diagnosis is that EMP tends to affect one side or part of the horse more than another. 

Early diagnosis and treatment are key to increase the horse's chance at a full recovery. Sixty to 70 percent of EPM cases that are treated aggressively show significant or complete reversal of symptoms with many horses being able to return to normal activity. Although there are drug combinations available to treat EPM, there are propriety anti-protozoal drugs specifically labeled to treat the disease. Anti-inflammatory drugs may be prescribed to alleviate symptoms. Vitamin E, an antioxidant, supplementation aids in healing the nervous system tissue. Treatment duration generally lasts one month when using the proprietary products, but can be longer (up to six months) depending on which medication is used. Treatments for this disease can be expensive and may affect stallion fertility and may pose health risks for unborn foals. Despite the high success rates, not all horses respond positively to treatment, with approximately 10 to 20 percent of horses experiencing relapse. During treatment taking blood samples may be needed to monitor potential side effects sushc as anemia, low platelet count, and low white blood cell count. Horses undergoing treatment should be closely monitored for sings of improvement or decline and any changes should be reported to your veterinarian immediately. 

The best way to prevent this disease is good horse keeping practices that discourage opossums and other rodents from getting into and contaminating hay, grain, bedding, and water sources. Here are a few suggestions for how to do that.

Keep feed rooms and containers closed and sealed

Use feeders that minimize spillage and are difficult for wild animals to access

Clean up any dropped grain immediately to discourage scavengers

Feed heat-treated cereal grains and pelleted feeds sind these processes seem to kill the infective sporosysts

Keep water tanks clean and filled with fresh, clean water

Maximize your horse's health and fitness through proper nutrition, regular exercise, and routine vaccinations and vet visits

If you have more questions on the topic, please contact your local livestock Extension agent and your veterinarian. 

 

Signs and Stages of Labor in the Mare

 

Is your mare in foal this spring?  Are you ready for the big day and the new arrival?  I recently had a friend adopt a mare and has been surprised to find out she is expecting, and asked for help.  One tool for her, and anyone in this situation is to understand the stages of labor.  Mares may display some or all of the signs below. 

 

Signs that the time is near:

•  Filling of the udder (2-4 weeks)
•  Distention of the teats (4-6 days)
•  Waxing of the teats (1-4 days)
•  Obvious dripping of milk
•  Sagging muscles around tailhead
•  Sagging of vulva (up to twice normal length)

STAGE 1:  Contractions started  (1-4 hours)

• May act colicky and paw the ground
• Sweat around neck and flank
•  Frequently passing small amounts of urine or manure
•  Pacing or circling stall or paddock
•  Up and down; nervous
•  Dilation of birth canal; water bag may become visible
•  Rush of fluid when bag breaks.  Do not break the water bag

Breaking of the water bag is the transition from Stage 1-2

 

STAGE 2: Delivery of the Foal (15-20 minutes)

·      If this stage goes past 30 minutes or you see a red, velvety sack, call your vet immediately!

• Usually, the mare will lie down for delivery.  If not, be close to catch the foal.  The mare may get up and lie down again to reposition. 
•  Normal delivery is front feet first with the nose tucked level with the knees, Soles of the hooves should be pointed down. One foot may be slightly in front of the other. If soles are up, call the vet immediately!
•  The foal will be encased in a thin, transparent to whitish membrane (amniotic sac).  If it does not rupture during delivery, tear it open and pull back from the foal’s face.  
•  The mare and foal may rest with the foal half out, but if stage 3 goes longer than 30 minutes, call the vet.

 

STAGE 3: Expulsion of the placenta (1-3 hours)

·      If the placenta has not passed in 3 hours, call your vet!

 

•  A retained placenta is toxic to the mare in less than six hours. 
•  The mare will usually stand up after delivery and the umbilical cord should break naturally

·      Do not cut the umbilical cord!  If needed, the cord can be broken manually by a twist/pull method or tied with twine, but best to follow your veterinarian’s guidance

 

 

After foaling, the foal and mare should be monitored closely for at least 24 hours.  The foal should be breathing normally, bright and alert, and should stand within 30-60 minutes after delivery.  Nursing should happen within 2 hours,  If not, call your vet.  The first 8-12 hours are critical to absorb enough antibodies through the colostrum.  The foal should also pass the meconium within 12 hours.  It is recommended for the mare and foal to be seen by the vet within 24-36 hours after birth to examine them and the placenta/afterbirth.

 

Information in this article was compiled from The Equine Reproduction Lab at Colorodo State University, along with a Vocational Services, Inc. (VSI) foal kit and an article from the University of Illinois CVM.