Fall Deworming

Why do we wait until after the first frost to deworm in the Fall?

With the cooler temperatures setting in it’s time to start thinking about fall deworming protocols. The life cycle for most equine internal parasites involves eggs, immature larvae, and adult worms that then release more eggs into the environment through manure. Eggs or larvae shed in manure will accumulate in the environment, and if horses are turned out on these same pastures throughout the grazing season they can acquire large parasitic burdens by ingesting the eggs and larvae on the grass.  The goal of any deworming protocol is to focus treatments at times of the year that are most optimal for larval development and egg transmission, ultimately reducing the parasite load both internally and in the grazing areas. As temperatures cool down and we start to see frost, the eggs on the ground are no longer viable, and this is an ideal time to deworm because the horses won’t pick up more live parasite eggs and larvae and carry them through the winter. A few weeks after the first frost we recommend using an ivermectin or moxidectin product that also contains praziquantel to additionally target tapeworms – a serious internal parasite that is widespread and has the potential to cause disease (including colic).

Frosted Grass

 Does frosted grass cause colic?

This is a great question as I too was told that frozen grass caused colic when I was in pony club many years ago. The risk associated with eating frozen grass has nothing to do with the temperature of it. By the time it reaches the stomach, the grass has been thoroughly chewed and mixed with warm saliva, so it is no colder than any other meal.

There has been a lot of research into the sugar content of grasses as we look for safer ways to feed horses with metabolic problems such as insulin resistance. One thing we have found is that “stressed” grasses (that means drought and freezing temperatures) tend to concentrate high levels of non-structural carbohydrates (sugar). If a horse gobbles down a bellyful of this grass, the intestinal bacteria encounters a bolus of feed with a much higher sugar content than it is adapted to. Bacteria that tend to produce more gas thrive on this type of ingesta, so it is theoretically possible that a horse could get a little gassy and show mild colic signs after a frosty binge.

Don’t worry about it too much, at this time of year there is usually not much grass left and I think it would take some really dedicated pigging out to get anywhere near enough grass to get into trouble.

Melissa McKee DVM

Licking Mud

My horse is licking mud after the snow has melted. Is she deficient in something?

Although it is a common assumption that animals can sense vitamin and mineral deficiencies and will seek out substances to alleviate the problem, they are truly only able to sense a salt deficiency which is why we provide them with free choice salt licks. As winter eases into spring and the snow melts, all of the substances that accumulate on the snow surface become concentrated. Think of how snow banks on the roadside initially look beautiful and white, but as they melt away there is an ugly ridge of crud and road salt left behind. There are a lot of deer and elk killed on the road this time of year as they gravitate towards these unnatural “salt licks” on the highway shoulders. Is it possible that there are some tasty salty substances left on the muddy ground after the snow in your paddock after the snow has melted? Other than that I would not worry that she is missing a particular nutrient in her diet but she may appreciate some more roughage or other entertaining distraction.

Melissa McKee DVM

High Iron Levels in Water

Are high iron levels in drinking water safe for horses?

Iron levels are commonly quite high in well water. Fortunately, it is not considered harmful beyond the ugly stains that form around fixtures. Iron can be problematic in livestock operations however because it can taint the flavour and odour of the water, leading to inadequate intake. In addition, there is a bacteria that thrives in iron-rich water that produces a somewhat offensive slime, requiring regular scrubbing (as if you don’t have enough to do already on a farm!). Chances are, if you notice an off-taste or smell, your horses most certainly do as well, and they may not drink enough. In that case, an iron filter may be a good idea. If you are looking for more information on iron and livestock, OMAFRA is a good resource.

Melissa McKee DVM

Drought Grass- Laminitis Risk

The hot temperatures and lack of rain lately have certainly taken a toll on the pastures. If we were to get a fair amount of rain and the pastures were ‘resurrected’ would there be risks of laminitis? Like the risks with grass ‘coming back’ in the spring?

The key factor associated with the risk of pasture-associated laminitis is the amount of fructan, a type of sugar, that has accumulated in the grass. Fructan is created via photosynthesis during peak sunlight hours and subsequently consumed by the plant overnight to fuel growth and seed formation. If the overnight temperature falls below 5C, then metabolism slows and the grass accumulates fructans rather than using it up. Warm sunny days and cold nights are the high risk periods leading to peak fructan accumulation, which is why May and October are the worst months for laminitis occurrences. This is not the only risk period though. “Stressed pasture”, meaning those that are overgrazed, rapidly growing, or facing drought conditions, will also carry a high fructan level. So, your pasture may already have somewhat elevated fructan levels, but you should be especially careful and consider using a grazing muzzle if we do have enough rain to trigger lush new growth.

Melissa McKee DVM

Feeding Senior Horses

This is a common problem that many older horses face. Despite the fact that their appetites are good and they appear to be eating well, many horses will suffer weight loss as they age. This can occur for various reasons, perhaps the most common of which are poor nutrient absorption in the GI tract and poor dentition.

For proper digestion to occur, horses must chew hay to an appropriate (small) size before swallowing. These small pieces are required for the bacteria in the GI tract to properly digest the hay and extract all of the nutritional components. As horses age or develop poor dentition, they lose the ability to chew hay into the appropriate size needed for digestion. Despite eating large amounts, the system is unable to utilize the hay appropriately and therefore it provides little nutritional support.  Additionally, some aged horses have a harder time absorbing nutrients from the GI tract.

That being said, the goal with feeding senior horses is to maintain a well balanced diet in a form that is easily digestible. There are many viable nutritional options available ranging from hay cubes/roughage chunks to complete pelleted feeds.   Hay cubes are often a good place to start, as they are pre processed into small pieces and therefore do not need to be broken down, or chewed, into smaller pieces. In an older horse, especially one with poor dentition, it is a good idea to soak hay cubes prior to feeding to avoid any choking hazards.

Many feed companies also produce a senior feed, or a complete pelleted feed. These feeds are labeled ‘complete’ as they contain complete balanced nutrition including forage, vitamins, minerals etc. These products can be used in combination with a hay/hay cube diet or can be used as the sole source of nutrition.  Most horses tend to do very well on these feeds, but it is important to remember that many of these feeds are high in sugar. If your horse has had metabolic problems such as Cushing’s disease or laminitis, these products may not be appropriate.

Another excellent, safe source of fat and fiber is non molasses beet pulp. Non molasses beet pulp is especially good if your horse has had metabolic or laminitis issues, as it is very low in sugar but very high in fat.   High fat/high fiber pelleted products are also suitable in some situations, but again care must be taken to assess the energy and sugar content before feeding.

There are various supplements available containing flax seed and omega oils that can also help with weight gain.  On the topic of supplements, we can never forget the importance of a well balanced vitamin and mineral mix – every horse, especially geriatric ones, should be supplemented in some manner with vitamins and minerals as a straight hay diet is often not sufficient to meet these needs.

As pointed out, there are many products available for senior horses, but each product is not necessarily appropriate for every horse. You should always speak to your veterinarian about your individual horse’s situation so that he/she can help you formulate an appropriate diet.

Finally, diet alone may not be responsible for such a dramatic weight loss in a short period of time. There can be many other causes for weight loss in aged horses, and so it may be worth having a veterinarian do a physical exam +/- bloodwork to ensure there are no underlying health issues that need to be addressed.



Electrolyte Supplementation

In this kind of weather with the heat and humidity, what are the guidelines for giving or not giving oral electrolytes?

As long as they have constant access to fresh water, most horses that are in light or no work will meet their needs adequately without electrolyte supplementation. Once a horse starts to work hard enough to sweat, they lose salts and minerals (electrolytes) generally equivalent to the rate that they are sweating, which must be replaced through the diet. There are a couple of ways to offer electrolytes, one is to hang a water pail with electrolytes added for the horse to consume free-choice. A more consistent method is to add the electrolytes directly to the diet to ensure the horse is actually getting them every day. There are many commercial electrolyte supplements available at the tack shops that are flavoured for improved palatability, but you can easily make your own by combining equal parts salt (sodium chloride) and lite salt (potassium chloride) and feeding a couple of tablespoons of it per day. Fortunately, horses do not suffer from dietary induced hypertension from excess salt like humans do, so this is a safe way to supplement the electrolytes they lose through sweating. This will also stimulate thirst encourage them to drink more, which is also desirable to guard against dehydration.

Melissa McKee DVM

Chewing Trees and Ground

My 4 year old mare is constantly trying to dig through the snow to get to the grass and is chewing on the tree bark and her run in shed.

Do you think she is lacking something in her diet???

She eats high/fat&fiber, beet pulp, equalizer, salt and flax and lots of good hay. As well she has a mineral block in her stall.

I can relate to your mare, as I too am a boredom grazer. I don’t think you need to worry about a nutritional deficiency here, as the diet you describe is more than enough to meet her needs especially if your hay is of good quality. Horses are naturally driven to forage constantly so her behaviour is normal from an evolutionary standpoint, and there is no scientific evidence that horses can detect nutritional deficiencies other than the most vital nutrient of all-water. In this case, ripping up your trees and ground is probably an entertaining and occasionally rewarding way to pass time in the paddock. If she is making a real mess you may want to wrap the tree trunks with wire since she will eventually kill them completely.

Melissa McKee DVM

Effects of Limited Turnout

What are the effects and physical short- and long-term repercussions of limited turnout? Four hours a day in a field, twenty hours a day in the stall. I understand the mental cost – development of boredom-related vices, but I’m more curious about the effects this has on the horse’s body, particularly the joints?

Four hours a day in the field is not bad considering there are many show and race horses that do not get any unsupervised outdoor activity at all. Although this is certainly not ideal, many of the top competitive equines in the world are managed in this fashion and are still sound and supple enough to perform. There are few studies done on this topic although one interesting one was published this year, where they basically divided yearlings into two groups- one had turnout and moderate exercise while the others stood in their stalls. At the end of the study, the “trained” active yearlings had lower incidence of developmental orthopedic disease and better quality subchondral bone and cartilage (they studied the fetlock but this probably applies to all the joints). They concluded that controlled moderate exercise was beneficial for joint health in the young horse. While not exactly in the same vein, it makes sense that allowing a horse several hours per day to move about is better for the musculoskeletal system than total confinement. It would be difficult to objectively measure this effect since every horse is different and it would be too big an investment for most research companies to design a study to prove what most people already believe to be true.

Melissa McKee DVM

Eating Salt Licks

I have normally always provided the small brown salt mineral blocks for my horses to lick in their stalls. I have heard that they will lick these to the extent that their system requires it. I have noticed the one horse wants to devour the block like it is candy. His salt block can be gone in a week from him chomping on it. I don’t know if he is bored and simply playing with it or really likes it. My question is, is it harmful for him to keep trying to eat it like candy and should I stop leaving a salt lick in his stall altogether?

Although your horse is unlikely to do himself any harm consuming these mineral licks, it is an expensive habit and the excessive salt consumption can make for a very wet stall from all the drinking and peeing that will result. This behaviour is usually a learned one that a horse will do to alleviate boredom while enjoying a tasty snack, rather than a sign that something is missing from his diet. Fortunately, horses are not prone to salt related diseases like hypertension, but this level of consumption will cause a horse to have increased thirst and resulting urination as the body attempts to restore normal balances and excrete the excess sodium. I would be inclined to try giving him a toy that will distract him from the salt block, and if that does not work I would take the block away and supplement his diet with a couple of tablespoonfuls of salt in his feed. You can also offer a separate water bucket with electrolytes in it to ensure he can “self supplement” without devouring endless mineral licks!

Melissa McKee DVM