by Cindy Reich | AHW
Once your foals have been weaned and have accepted their new circumstances, the expectation is that they will require nothing more than maintenance over the next year or so as they grow up. However, just as children have diseases and problems that are common to them, so do horses. Developmental problems, nutritional challenges, and diseases that can be more serious in young horses than in adults may occur. How you manage these foals might have a significant effect on how they weather these developmental bumps in the road.
Pneumonia is the most common disease in weanling foals. It can be caused by several different organisms, and we will examine several further along in this article. The more stressful the weaning, the weaker the immune system will be. The combination of increased stress and lowered immunity makes the weanling extremely susceptible to respiratory disease. Additionally, foals at 5 to 6 months of age are transitioning from the immunity to many diseases they received from the mare’s colostrum at birth. They are in the process of developing their own immune system. However, often when foals are weaned, they are also vaccinated — which stresses their new emerging immune status even more. Therefore, management practices that are aimed at reducing the stress of weaning while boosting the immune system may spell the difference between managing a barn full of sick babies or a pasture full of healthy weanlings.
In the northern hemisphere, weaning usually coincides with late summer or early autumn. Keeping weanlings in a barn when winter comes early, or bringing them to the barn for weaning may in fact be setting youngsters up for respiratory problems. Confinement in a small space with a limited flow of air can concentrate bacteria in the air the weanling breathes. Combine that with a low-functioning immune system and you have a perfect scenario for pneumonia. If you are going to wean your foals in a barn (and I recommend leaving the foals in pasture and removing the mares over time or separating the mare and foal in adjoining stalls at night and separating the pair gradually), take a good look at the environment in which the foal will be living.
Most Arabian weanlings are not that tall. If the stall has solid sides and a door with only a half-grill, there will be virtually no air circulation in it. If you want a taste of what that weanling will experience, go into a stall in the morning, before cleaning the stall. Crouch down so that your head is below the level of the grill. Walk around and kick up the bedding while crouched down. How much dust and debris are you kicking up? How much ammonia can you smell? Humans walk around in an aisleway with good air flow if the doors are open and without shavings, straw, or dust several inches thick. Meanwhile, the weanling in the “box” is breathing everything that is in the stall, with no air exchange. To compound the problem, since weaning usually occurs in fall/winter — if the weather is bad, the barn is usually shut up, decreasing the air circulation even more. Therefore, give some serious thought to what that weanling’s living environment will be BEFORE you wean, to prevent problems after. Stalls with screens between stalls, full screen doors, fans that draw air through the stall, screened windows — all are designs in barns that can go a long way toward improving the health of all the horses in the barn, both mentally and physically.
However, sometimes, despite the best-designed facility and good management practices, foals become ill. There is no way to have a readout of a foal’s daily stress level or the state of its immune system. Some foals are stoic and don’t seem to react badly to weaning, but internalize everything and become sick. Other foals bounce off the walls and are frantic for a day or two, then never have a problem. But there is no way that I’ve found to predict which foals will do well and which ones won’t. What I can do is plan ahead and do everything possible to minimize the risk of illness.
Horses were designed to live outside. Even in the Rocky Mountains in late fall and early winter, the weaned foals grow great winter coats and thrive in the cold weather and fresh air — outside. The show horses, confined inside a barn that is often heated, are frequently body-clipped, and are consistently coming down with one “bug” or another. In the south, it can be the opposite problem — especially with early foals (January/February) that are weaned in July or August. It may be sweltering outside and very humid — while inside the barn, with fans and good air circulation, it is much more pleasant. My base position is always to have the weanling in the least stressful environment and with the best possible air circulation. Your decision as to where to house the weanlings will be dictated by your facility and its location.
Nutrition is another key element in the weaning process. The gut is the “mission control” of the immune system. Therefore, any serious changes in the bacterial flora of the gut and the function of the gut will affect the immune system. So let’s get one thing straight: horses are herbivores. They evolved to eat small amounts of food constantly throughout the day. Their stomachs have two different types of mucosa that constantly secrete acid (since, theoretically, there is usually food in the stomach). Foals that are confined and fed a concentrated amount of food twice a day are candidates for ulcers at the very least and intestinal problems in the worst-case scenario. I am not a fan of feeding weanlings a lot of concentrates or grain. Their stomachs are not designed for it and they will often eat too much of all foods, but especially grains when newly weaned. You have taken away their milk bar and they look for oral comfort somewhere else — usually the grain bucket. If foals have been eating at a creep feeder while with the dam, they will be a bit more accustomed to eating grains and concentrates, but remember — under stress, the immune system is highly challenged. Where is the control center for the immune system? The gut. If you stress that gut by overfeeding, or feeding concentrates and grains, or the foal has ulcers, you are setting up the weanling for an exceedingly weak immune system. Which is when the pneumonia steps in.
Streptococcus zooepidemicus is one of the more common bacteria involved in pneumonia of older foals and weanlings. Signs include depression, lethargy, nasal discharge, labored breathing, and cough. Chronic cases may also show signs such as weight loss, colic, edema along the midline, and swollen legs. While bacterial pneumonia can usually readily be treated with antibiotics, it always seems to take a greater toll on these already stressed weanlings. If it becomes chronic, the weanling will usually fall far behind in terms of weight gain and condition. Weanlings with chronic pneumonia are then also at risk for other infections due to their debilitated condition.
Streptococcus equi (strangles) can cause some respiratory signs as well as nasal discharge, but does not cause pneumonia. It usually causes abscesses within the lymph system associated with the upper respiratory tract. A weanling with strangles may have difficulty in swallowing or may drool. The lymph nodes on either side of the throat (submandibular lymph nodes) may become swollen, impairing swallowing. Stretching of the neck to relieve pain and pressure is another symptom. The weanling will usually spike a fever for a short time prior to the development of the abscesses. Your earliest warning of many of these diseases is presence of a fever.
If strangles is suspected, the weanling should be removed from the population and quarantined, because strangles is highly contagious. Contact your veterinarian regarding treatment, as treatment with antibiotics is controversial and may result in “bastard strangles” in which the abscesses retreat internally, forming throughout the body (most commonly in the lungs, liver, spleen, kidney, and brain).
Rhodococcusequi is another common cause of pneumonia in young horses, occurring primarily in foals younger than five months of age. Having said that, if you have a weanling with pneumonia it would be good to rule this out — or in — as a causative factor. This organism lives in soil, and dusty conditions where the weanling is housed or fed can be a likely cause of infection. While some signs are similar to those of strangles — depression, lethargy, cough — the weanling usually does not have a discharge from the nostrils. Affected foals can develop lesions within the lungs, and crackles and wheezes can be heard when listening to the lungs with a stethoscope. This organism may also cause micro-abscesses in the colon, leading to diarrhea, which also differentiates it from the Streptococcus zooepidemicus.
From a management standpoint, it is hard to distinguish a lethargic, depressed foal that has just undergone a traumatic weaning from a lethargic, depressed foal that is incubating pneumonia. Therefore, it is a good idea to take temperatures daily on foals that have been weaned, especially if the process has been stressful, in order to detect oncoming problems early. Obviously, if the farm practice is not to handle or halter-break the foals until after weaning, this will not be possible. The danger of stress and the possibility for injury involved in trying to corner, restrain and “temp” a foal that has not been handled far outweighs the value of the information gained. Needless to say, that is another good reason why I halter-break all foals within their first month of birth. They are not overhandled or made into pets, but they can be haltered, led, and handled.
Equine herpesvirus (rhinopneumonitis) type I (EHV-1) and equine herpesvirus type 4 (EHV-4) can each infect the weanling’s respiratory tract. **Note—EHV-1 responsible for epidemic abortion in mares, can also cause the neurologic form of herpesvirus infection. However, in some cases, EHV-1 can also occasionally cause respiratory infections.
One of the early signs of an EHV infection is a high fever, so having the ability to take temperatures on the weanlings may prove to be useful. Cough, nasal discharge, and lethargy are all possible signs of this disease. Most horses carry this virus, which lies dormant until stress or a weakened immune system cause the virus to proliferate, resulting in infection. As it is a virus, there is no treatment other than supportive nursing care.
It is more or less impossible to tell the difference between EHV and equine influenza infections by the signs alone. Weanlings with equine influenza develop a high fever, are lethargic, have a nasal discharge, and cough. A blood test will reveal whether the culprit is influenza or not; therefore, it is important to call your veterinarian when symptoms become apparent, as influenza is treatable with antibiotics.
Any parent that has sent a young child to day care knows full well what happens when a naïve immune system, often under stress, confronts a lot of new organisms. Similarly, when foals leave their dams at weaning, with an immune system in transition and are exposed to new environments and organisms, disease can result. However, like human children, if the weanling’s immune system is healthy and strong, it will likely not succumb to these organisms that live in and around the horse on a daily basis.
Some emerging research suggests that it might be useful to give weanlings a probiotic to support their immune system throughout the weaning process. Consult your veterinarian as to whether this is a good management practice for your case. I would recommend feeding the probiotic in a creep situation to the weanlings along with other feed (if applicable) for several weeks prior to weaning, continuing the routine after weaning. Weaning is not the time to change a foal’s feeding program abruptly. Ideally, the weanlings will still be on pasture with creep feeding during the day or stall feeding at night. Maintaining the same routine lessens the stress level that the foal will experience when weaned.
The subject of feeding weanlings could easily fill another article, but the greatest mistake farm managers make is feeding weanlings too much grain or concentrates. Often, the owners want to push weanlings to gain condition for show or sale. While a fat, sleek weanling may look good in the short term, there may well be long-term damage occurring to both the gastric system and the musculoskeletal system. I prefer weanlings to be slightly light and not carry too much weight as yearlings. Arabians are a light breed by genetic design and growing joints are subjected to a lot of stress and strain if the weanling is carrying excess weight. When visiting farms full of late weanlings and yearlings, I can usually tell that their nutrition program is defective by simply checking the legs on the young horses, looking for any sign of epiphysitis.
Among the causes of epiphysitis (compression of the growth plate [physis] between the long bones of the developing horse), is an imbalanced diet, carrying too much weight, or a rapid growth rate. Contrary to popular thinking, protein is not the culprit. Calcium, phosphorus, copper, and zinc must be fed in the proper ratio to avoid physitis. Weanlings subjected to a high calorie, high-energy feeding program are also at risk. Generally, when you look at the legs of weanlings/yearlings with epiphysitis, the fetlock joints will look larger than normal, causing the leg from the cannon to the hoof to look like an “hourglass.” I devoted a column to developmental changes in young horses several years ago, but it may be time to revisit the subject.
With good management practices, weaning will have been relatively nontraumatic, and the “class of 2012” will spend the rest of the autumn and winter growing into happy, healthy yearlings that bear the promise of the breeder’s dreams and goals into the new year. Just remember, all of the older horses you will see in Tulsa, if you attend the Nationals, were once weanlings. And look how they turned out. Best of luck to everyone competing at the U.S. National show