Broodmare Reacts Badly to Vaccines

My mare reacts badly to vaccines and has not received any for maybe 5 years because of it. What is the best way to deal with immunization for her upcoming foal?

Foals are born with no natural immunity to disease, so they obtain protection by ingesting colostrum immediately after birth from their dam. The maternal antibodies in colostrum are absorbed through the gut via a process called “passive transfer”. Failure of this will result in a foal that is very prone to overwhelming infections (sepsis) and other health complications. The quality and level of antibodies in colostrum is directly dependent on the mare’s immune status, so the colostrum from unvaccinated mares won’t provide coverage for tetanus, rabies, and most of the disease that we try to protect horses from with vaccination. Since you can’t vaccinate a very young foal, there is a several month period where they are quite vulnerable to these infections. The old habit of giving tetanus antitoxin to a newborn has fallen out of favor because the antitoxin (which provides immediate protection, not like a vaccine) can cause devastating serum sickness and liver damage. To ensure maximum colostrum quality, we give mares their booster shots about a month before foaling so their antibody levels are peaking near birth. If your mare reacts badly to vaccines, I would find out which ones are problematic and decide on a schedule that allows you to either prepare her for that shot with some banamine, or decide if you can safely skip it. Many horses are given the more economical “5-way” vaccine which combines multiple vaccinations in one shot. While this is more convenient, I have found the adverse reaction rate to be much higher than when vaccines are split into individual doses and administered over a couple of visits. That way you can also identify if your horse is sensitive to a particular vaccine, and gives you the opportunity to plan for the next shot or try a different brand of vaccine. I suggest that you discuss this with your vet well in advance of her due date so you can come up with an appropriate strategy to protect the health of her baby.

Melissa McKee DVM

Swayback Broodmare

A friend got this mare that she would like to breed to our stallion buts he has a swayback. Just wondering if there is a way you can tell if it is genetic or from being ridden too young. She is a TB and I am checking to see if she raced. Do you know how well a swayback mare handles carrying a foal and foaling? That is a lot of weight to carry below the back area for along time. I am thinking, I would like to stay clear of this mare.

It is difficult to tell in a mature horse if a swayback is congenital or if it resulted from a back injury. While there is no evidence that swayback is a specific genetic condition that can be passed on, conformation in general is heritable and hers is not desirable. If born this way, she could pass the tendency on to her offspring, and if acquired, then she likely had weak back conformation in the first place. As for carrying a foal, I am surprised at how comfortably a swaybacked horse can carry a rider, but a fetus and amniotic fluids are an awful lot of weight centered directly under the weakest part of the back even in the most sturdily built broodmare. I believe that this mare could be more prone to complications such as rupture of the prepubic tendon (runs under the belly and supports the abdomen) since this will be under considerable strain. I think you instincts are totally correct here. Why breed a horse with flawed conformation and increase the risk of producing poor quality offspring when there are already so many unwanted and starving horses? Not to mention that it is not great publicity for your stallion if the foal is not up to his usual standards.

Melissa McKee DVM

Alleviating Signs of Heat

With spring just around the corner I was wondering if there were any suggestions for a 17 year old mare that goes into heat. She can become quite unmanageable. I do not want to suppress her heat but is there something that I can do to alleviate her symptoms.

Behavioural signs of estrus are related to changing hormone levels in the bloodstream. Estrogen levels peak and progesterone drops away, leading to the (often annoying) behaviour of a mare who is more interested in finding a date than paying attention to the work at hand. It is actually the higher levels of progesterone in between cycles that suppress these inappropriate moods, so the most successful treatments involve artificially elevating circulating progesterone. This is achieved by administering oral Regumate or a comparable injectable progesterone throughout the months that a mare is actively cycling. If your mare seems to have particularly difficult estrous periods, I recommend that you ask your vet to perform a rectal ultrasound to evaluate the cervix, ovaries, and uterus. Conditions such as uterine infection and retained follicles can really complicate things and make a mare seem like she is always in heat if they are left untreated. Older mares also can develop a tipped vulva, leading to urine pooling in the vagina and similar problems with irritation and infection. A simple surgery called a caslick’s operation can alleviate this. Remember too that mares undergo a transitional period at the beginning and end of each breeding season where they tend to have strong and irregular heats as their reproductive tracts come online. These usually settle down after a few cycles so it may be worth just waiting it out or using one of those progesterone replacements for a brief period.

Melissa McKee DVM

Shipping Pregnant Mares

Do you think it is safe to ship a mare to Canada from Germany that has been bred March 30/09? She will not be ready to fly till after Oct. 26.

Many mares are shipped long distances while pregnant. It is very typical for race mares to travel across several states to the breeding farm in late preganacy to foal out and be rebred. Most horses travel very comfortably on airplanes as they are in fairly roomy pallets and are able to eat and drink throughout. If you take normal precautions including checking that her vaccines are up to date and not shipping if she appears unwell or has a temperature at the last minute, you should be fine. Remember that she probably won’t have certain vaccines such as rabies, so make sure she is fully updated for North American diseases before she foals so her baby gets protected through her colostrum.

Melissa McKee DVM

Bleeding from Vulva

I have noticed this winter my mare seems to bleed a bit from her vulva at certain times of the month. I understand mare do not menstruate, so what could this be from? If I had to guess I would say it is less than half an ounce at a time and by the time I find it is always dried. She is a healthy 10 year old mare who had 2 foals before I bought her as a saddle horse. I have no intentions on breeding her in the future.

The small amount of blood you have noticed likely is a result of a common condition in broodmares (even retired ones) called “vaginal varicose veins”. In this situation, small blood vessels in the vaginal wall develop weak spots and bulge into the vaginal vault. Occasionally, these vessels will break open and bleed, resulting in some bloody discharge. This condition is not life threatening and is easily managed by tying off or cauterizing the offending vessel if the bleeding is persistent. There are other less common causes for rusty/blood tinged discharge including low-grade vaginal and uterine infections, and some mares do have a little normal discharge throughout their cycle that does not indicate any particular problem. Diagnosis is made by vaginal exam with a speculum, preferably when some bleeding is evident. The veins usually look like clusters of grapes on the sides of the vaginal vault.

Melissa McKee DVM

How Young to Geld?

What is the youngest age you can geld a colt? I have a 7 month old appy colt that I would like to geld before he starts showing stallion behavior as he lives with 2 mares, neither is his dam.

I have gelded colts as young as four months without any complications, but the general recommendation is to perform the operation any time after they are about a year old. If you are concerned about him developing stallion behaviours, then why don’t you arrange to have him castrated in mid-spring? This would place him near a year of age, and gets the job done before the mares start showing serious signs of estrus, and the flies have not have come out yet.

Melissa McKee DVM

Abdominal Hernia

I was hoping you could tell me what can causes a Hernia in a foal? Our orphan foal has developed a hernia, and he is just
2 months old. He is going to have to go for surgery to repair it. When he was born we were told that he had no hernia, and it seemed to open quickly. It’s about 2 fingers now. What if anything can we do to prevent this from happening to another foal?
An abdominal hernia is a weakness in the layers of muscle and fascia that surround the abdominal cavity. They typically occur along the midline just in front of the belly button, and the visible swelling occurs when the internal organs “pooch out” through the opening. Hernias in foals are usually congenital (present at birth), although they can appear or become enlarged in the following days if the foal is ill, has an umbilical infection or strains excessively during urination/defecation. Older horses can develop an abdominal hernia if they have incisional problems after a colic surgery. It is likely that some tiny defect or
weakness was present initially on his midline that subsequently became sufficiently enlarged to be palpable. A small hernia may be considered merely a blemish and left alone, but those larger than two fingers are best treated either medically or surgically. Medium sized hernias are actually a greater health risk than very large ones, since intestine is more likely to be trapped
and strangulated through a small opening then through a large permissive one, where the gut can move in and out freely. Medical treatment involves clamping or banding the pouch with elastic bands, causing the sac to scar closed and drop off. This approach is cheap, but somewhat risky if you accidentally trap some intestine in t he clamp. If that happens, you are going to quickly end up on the surgery table anyways. I used to give foals a short general anesthetic and roll them on their back to reduce the chance of introducing gut into the area I was banding, but a small risk still exists. I also think that the foals experience more prolonged discomfort after this approach than after a surgical repair. Nobody is sure why abdominal hernias occur, but it is
not a bad idea to avoid that particular mare/stallion combination in the future, and treat any neonatal health problems aggressively.
Melissa McKee DVM

AI vs. Live Cover

I was wondering what the different in cost and prep for live cover vs. AI. We own the stallion and I co-own a few mares. A couple of the mares have had foals before but 4-5 of them are maidens. I have done live cover years ago, but have never done AI.

The simplest, cheapest, but least controlled and most likely to result in health problems, is turning the stallion out with a band of mares and hope everybody has a baby in the spring. This approach will result in some successful conceptions but also makes it impossible to predict foaling dates, manage the health of the mare and fetus, detect twins in time to pinch one, increased likelihood of unmonitored foalings, and is not an efficient use of the stallion. Managed live cover is widely used and is a requirement for some breeds such as thoroughbreds. In general, the mare is kept at the stallion farm and is presented for breeding based on palpation of a follicle on the ovary and signs of estrus. Drugs can be given to stimulate ovulation, minimizing the number of breedings a stallion has to do. Controlling the situation increases the management expenses but you will probably recoup the costs in more efficient use of your breeding stock and increased production of viable foals. Live cover is still more risky for the health and safety of the horses and the handlers. Artificial insemination has several advantages. The stallion does not have to be at the same facility as the mares, as cooled live semen can be viable for overnight transport. Mixing the semen with extenders enables multiple breedings from one collection depending on the sperm count of the stud. A mare can be monitored to detect when she are ready to breed and the semen can be delivered when she is most fertile, and the collection/insemination procedure is generally safer and cleaner this way. This method also reduces the spread of venereal diseases. With either method of insemination it is important to check the mare with an ultrasound 2-3 weeks after breeding to confirm pregnancy and detect any twins. This enables you to deal with problems early on and gives you a better idea of when to intensively monitor her for foaling. Every veterinarian has a different way of packaging their breeding services and charging for them so I suggest you contact your local repro vet for an estimate.

Melissa McKee DVM

AI Syringes

I recently read that the rubber plunger in some syringes can act as a spermicide. Is this correct?

It is true that the rubber stopper at the end of some syringe plungers can kill sperm, which is why artificial insemination syringes usually do not have any cap on the plunger. Having said that, some veterinarians have successfully inseminated several mares from cooled semen that arrived in rubber-plunger syringes, so the effect is likely minimal.

Melissa McKee DVM

Depo vs. Regumate

I have a mare that has a problem shutting off her brain, she anticipates every move and does not wait for rider cues. It has been recommended that she might be a good candidate for depo or regumate. Is one better than the other. Do you need to keep them on it 12 months or can you just look at the show season.

I am not sure if this behaviour is really a reproductive issue, especially if you are not noticing that it comes and goes with her estrous cycles. If you do want to try these medications, there is little chance that you will hurt the horse but you may not notice any difference. Both of these medications work essentially by hormonally mimicking the conditions of pregnancy by elevating progesterone levels. You may be surprised to find out that many mares actually continue to cycle on these programs, but the progesterone has significant effects on “behavioural estrous”. In general, I like to try an appropriate dose of injectable Depo-Medrol first because this eliminates the risk of people handling Regumate and the inconvenience of having to give it daily. While many mares respond well to the injectable form, I do find that there is a population that will only have an improvement in behaviour on the oral product, so I will move to this if the injectable does not seem to help. The cost of each treatment is about the same if you are giving an adequate dose of the injectable (2-3x5ml bottles for a large mare).

For economic reasons alone I suggest just keeping them on the medication during show season. Mares in this part of the northern hemisphere usually stop cycling around October and start up again in March/April unless they are kept under lights starting in November. Only about around 10% of the ladies will show estrous year-round. I also like to take them off it once in a while because you may be surprised to discover they don’t really need it any more.

Melissa McKee DVM