The Latest Dog Food Scare

Since horselovers are almost universally doglovers as well, I want to veer a little bit off path for this blog and discuss a dog food scare that is currently spreading like wild  fire.

On July 12, the FDA announced they were investigating a possible link between diets containing potatoes or legumes (soy, peas, lentils, etc.) and dilated cardiomyopathy in dogs. It was one of the most confusing and least informative bulletins ever written.

As the word spread, the description of the diets quickly morphed and focus was put on diets that were “grain-free”, “exotic” and “boutique” (meaning not a major name brand).  Owners were advised to feed diets from companies with a long track record using more “typical” ingredients (which in most cases means corn/corn products are a major ingredient).

Dilated cardiomyopathy is one of the most common types of heart disease in small animals. It can be caused by a deficiency of the amino acid taurine which is only found in meat protein. Cats cannot synthesize this amino acid but dogs can; making taurine from the sulfur-containing amino acids methionine or cysteine.

The FDA notice talked about 8 dogs – 4 of which (3 Golden Retrievers and 1 Lab) were taurine deficient and 4 were not.  A retrospective study of DCM cases by Dr. Adin found 22 cases over a 2 year period in dogs on grain-free foods but 27 in dogs not fed grain-free. Furthermore, none of the grain-free fed dogs were taurine deficient.  There is also a large online database of taurine levels in dogs on grain-free diets.  Of 169 dogs when I last looked at it, only 68 had low taurine levels in their blood. Of that 68, 22 had no echocardiogram so DCM status was unknown, 24 were positive for DCM and 22 were normal despite low taurine. Clear as mud!

Historically, taurine deficiency DCM was first reported in Goldens 15 years ago and they were all on big name commercial foods – chicken and corn or lamb and rice based.  Another 15 year old study in Newfoundlands with taurine deficiency DCM found they were fed big name lamb and rice food.  Many lamb and rice based formulas are still on the market and most do not contain added taurine despite the known issue.

It has also been found that foods containing beet pulp and other high fiber ingredients can lower taurine levels by interfering with the intestinal reuptake of taurine from bile salts. (Taurine is a major component of bile.)

Not all DCM cases are diet related. Genetic predisposition has been identified in several breeds. It has also been noted that some dogs (Beagles) can conserve taurine by reducing how much is in their urine when diet supply is low, but others cannot.

In summary, it’s much more complicated than a “boutique” grain-free diet with peas or potatoes is a health risk. Dogs on such a diet may or may not have low taurine – and the same goes for grain-free diets from major companies as well as lamb and rice based diets.  It may well be true that some breeds or individual lines within breeds do have a requirement for taurine and/or higher levels of the taurine precursors and these highly vegetarian based diet ingredients, whether grain or not, are not suitable.

To suggest grain-free diets are more often associated with taurine deficiency, let alone DCM, and that more typical corn based diets are safer is currently premature and speculative. Only formal feeding studies and large scale investigations including many different dog food types in dogs both with and without DCM can provide some answers. Hopefully along the way we may even get some useful information about true nutritional requirements of dogs and how to correctly feed them as the carnivores they are or supplement them to prevent adverse health effects if we don’t.

Eleanor Kellon, VMD

Posted in Cacine nutrition | Tagged , , , , , , , , , | 4 Comments

Understanding Pain

Short title for an incredibly complicated topic.  There are many different types, causes and pathways for pain.  For the purpose of this blog I will limit the discussion to acute and chronic pain that involves inflammation.

At the cellular level the horse’s body is in a constant dynamic balance between damage and repair, death and replacement. When this balance is disrupted in favor of death and damage, whether from injury or simply temporarily from overdoing exercise, it triggers the release of cytokines.

Cytokines are small proteins which allow cells to “talk” to each other and directs their activity.  For a long description, see http://www.oc.lm.ehu.es/Fundamentos/Doctorado/cursos/Regenera/Busqueda/citoquinas.htm. There are 45,161 entries to date in the cytokine encyclopedia associated with the above web site.

In most cases, production of cytokines is turned off in default mode. Their production begins in response to cell injury or  death. In addition to directing clean up and repair processes, cytokines are an integral part of triggering pain.  Some, such as one with the deceptively innocuous name BAMBI, react directly with nerve endings or neurochemicals.  Others respond to reactive oxygen species (ROS)/oxidative stress associated with cell injury and keep the reaction going.

Cytokines aren’t all bad. Once damage has been cleaned up by the immune system cytokines are important players in regrowth of blood vessels and cell regeneration.

Pain is the body’s way of signalling that there is a problem. The nervous system will reflexively act to protect injured areas by splinting muscles and limiting movement.  Since horses don’t follow directions, this function of pain is important in reducing the chance of further damage.

Our first impulse on finding the horse is pain is to get rid of it but this must be tempered by realizing pain has a protective role. Anti-inflammatory pain medications are a bit of a sledgehammer approach because they also inhibit pathways needed for healing.

There are ways to work with the horse’s built-in homeostatic functions to assist the body’s own mechanisms for dealing with inflammatory reactions.  For example, MSM (methylsulfonylmethane) helps maintain normal counterregulation of the  cytokines TNF-alpha and IL-6 and supports antioxidant defenses.

Speaking of antioxidant support, you have many effective options there including bioflavanoids, vitamin C, low dose garlic, N-acetyl-cysteine, quercetin, lipoic acid and vitamin E as well as the herbals Turmeric, Boswellia, Ginger, Ginkgo and grape seed extract.

Harpagophytum procumbens (Devil’s Claw) offers powerful nutritional support against oxygen free radicals as well as cytokine TNF-alpha and IL-6 plus harmful prostaglandins. Devil’s Claw also has a direct nutrigenomic effect in maintaining normal activity of genes involved in TNF-alpha and COX-2 enzyme activity.

We hate pain but it serves an important purpose. The trick is to recognize the source of the pain response and assist the body in returning to normal balance without interfering with healing. Targeted supplementation has a lot to offer in that battle.

Eleanor Kellon, VMD

Posted in Equine Nutrition | Tagged , , , , , , , , , , , , , , , , , , | 1 Comment

Is A Salt Block Enough?

It’s a perennial question. Can a horse meet his salt needs from a salt block?  In a way, it’s a trick question.  There is more than enough salt there to meet the horse’s needs.  The real question is will the horse consume all he needs from a block.

While horses can, and do, lick salt blocks it may not be enough

A widespread myth is that horses cannot get enough salt from a lick but  cows can because their tongues are rougher. A cow’s tongue is rougher (like a cat’s) – but not rough or sharp enough to slice salt off a block!  Cows and horses both get salt from a block by dissolving it with their saliva.  Same as licking a lollipop.

All herbivores have a strong drive/taste for salt. The sodium in salt (salt is sodium chloride) is the only mineral consistently at very low levels in the natural diet.  The drive to eat salt comes from the brain. Salt hunger increases with higher levels of the hormones aldosterone and angiotensin II.  The main function of this hormone system is to regulate blood pressure and maintain normal blood volume.  Sodium is important for this because of the major role it plays in holding water in the blood stream and the tissues surrounding the body’s cells.

Both horses and cows prefer loose, coarse salt over salt blocks but are able to meet their needs using a block when at maintenance or even lactating. Factors that may cause a horse to overeat salt are individual taste preference or boredom. For example, stalled horses eat less salt if they have a toy to play with. Insufficient consumption may be influenced by gum disease, oral ulcers or oral irritation from abrasive plant material.

Mild overconsumption (about twice requirement) has been documented in horses and has no negative consequences. Failure to eat enough salt can also occur, even at maintenance. If you are unsure if your horse is eating enough salt  from a block, you need to weigh the block every few days and compare consumption to need. See https://wp.me/p2WBdh-Ao.

Studies have shown horses with large sodium losses through sweating are the least likely to meet their daily needs with voluntary salt intake. There’s a reason for this.

It has been claimed that horses can regulate their salt intake to match their needs.  This is actually what the  aldosterone-renin-angiotensin system attempts to do. However, the focus is not on sodium per se. It’s on blood volume and blood pressure.

When a horse produces sweat it pulls the water and electrolytes needed from the blood stream. To rapidly replace those losses, water and electrolytes are moved into the blood from the cells and tissues surrounding them.  Important factors here:

  • The regulatory system only responds to blood levels
  • Once blood levels are restored, the body thinks all is well even if tissue and cellular levels are still low
  • Equine sweat is more concentrated in electrolytes than blood is

The end result is blood restored to normal but tissue electrolyte and water levels still low. Since the horse has no drive to eat more salt or drink more water when blood levels are normal, this deficiency persists.  If the horse does not have any further large sweat losses the fluid and electrolytes will eventually equilibrate if the horse has access to extra salt but this process can take several days, not a good scenario for horses in regular work.

The bottom line is that horses doing no or only very light work may meet their needs from a block but you have to measure to make sure. Horses that are exercising and losing significant amounts of water and electrolytes in sweat will need supplementation if in regular work.

Eleanor Kellon, VMD

Posted in Equine Nutrition | Tagged , , , , , , , , , | 2 Comments

Picky Eaters

Most horses are good examples of what it means to “eat like a horse”.  The few that don’t dig in as well can drive their owners nuts.

To make things worse, Murphy’s Law often kicks in so the pickiest horses are those that have restricted diets or really need the supplements or medications you are trying to get them to eat.

Like people, individuals vary in their preferences for specific flavors as well as textures. Most healthy horses will eat just about anything but the picky ones can pose a real challenge in finding something they will accept, especially if you have to add supplements or medications to it.

Even horses with robust appetites usually object to having powders puff up their noses when they eat. To prevent this, wet the feed lightly with water or oil (best is CocoSoya which also smells wonderful). This also prevents powders from sifting through and being left in the bottom of the bucket. Mixing powders into the feed thoroughly works for some horses but there are others that prefer to have them top dressed without mixing. I never could come up with a reasonable explanation for why that would be the case but nevertheless it’s true!

If the horse absolutely refuses to eat something you can try a few things:

  • Start by putting just a tiny amount in the meal, increasing slowly
  • Syringe it all directly into his mouth
  • My favorite, a hybrid, is to syringe most of the dose into the horse before feeding then feed the meal with progressively larger amounts of the offending substance in the meal. This method has the taste of the supplement or drug in his mouth already before feeding.
  • Some owners report the horse will accept things better when placed on the hay. This can work if you make sure the entire dose is actually sticking well to wet or oiled hay, and that the horse is truly eating and swallowing all of the hay, not spitting it out or sorting through it.

Sprinkling small amounts of the supplement or drug around the stall, on ledges as well as the floor, can also help desensitize the horse.

Texture can make a difference. You need some water or oil to make sure there is good adherence but too much water may cause the horse to refuse the meal.  Others like it more soupy. You have to experiment.  Also be aware that water may actually enhance the taste or odor of whatever you are adding, while oils tend to mask it.

Some horses are remarkably picky even when nothing is added to their basic meals.  This is a common problem when trying to switch from sweet feeds to low molasses options, or from high starch to low starch items. Important: If the horse is refusing to eat something that had previously been well accepted, suspect a problem with the feed even if you can’t tell anything is off, dental issue causing pain or some other illness. Refusal of concentrates and preference for hay is highly suspicious for gastric ulcers. Involve your veterinarian.

Otherwise, first try to wait out the boycott by not allowing any hay or turnout until the meal is cleaned up. If the horse has more staying power than you do, you’ll need to ramp up the appeal.  My three  favorite options are:

  • CocoSoya oil – even barn cats have trouble resisting it!
  • Crumble the horse’s favorite dry herbs or treats on top of the meal
  • Stevia-based flavorings (don’t use other artificial sweeteners).  Some people use Stevia sweetened pancake syrup but there are other options in horse agreeable flavors like apple, banana, peppermint, fenugreek and cherry.

It may take a lot of trial and error but with persistence you can overcome the picky eater problem.

Eleanor Kellon, VMD

 

 

Posted in Equine Nutrition | 4 Comments

Do Feeds and Supplements Go Bad?

They sure do – but the labeling laws don’t make it easy for you to figure out which ones may be out of date.  To be fair, a big part of the problem is determining when “out of date” (best not to feed) is likely to be.

Human supplements are clearly labeled with both a lot number and an expiration date.

When we buy fresh dairy or meat products, canned or boxed foods, we expect to see “best by”, “expiration” or “use by” dates. These are based on expected room, refrigerator or freezer temperatures. With horse feeds, there’s no such thing as a standard room temperature. Feeds are stored under a huge range of temperatures and humidity depending on geographical location, time of the year and the facility itself. Another complicating factor is the composition of the feed and how it was manufactured.

Properly dried whole plain grains and very dry ingredients like beet pulp retain their nutrition and have low risk of molding for about a year but processed/broken grains, added fat or added molasses decrease the safe storage time to as short a period as 90 days.  High heat and humidity also lead to loss of vitamin potency.

For best nutritional value and safety it is best to only use commercial feeds that are less than 3 months old. You will never find an expiration date on a feed bag, or even a clearly marked date of manufacture.  However, you will likely find a code on the tag or bottom of the bag that includes a Julian date format, or some variation of it, for date of manufacture.  Never assume a feed is fresh just because it’s on a store shelf.

When date of manufacture is straightforward it is likely to look like day-month-year, e.g. 5Feb2018 would be February 5, 2018.  In the Julian system, month and date of the month are replaced by day of the year (first through 365th or 366 in a leap year). A manufacturer may use year-Julian day so 2018043 where year is 2018 and day of the year is 43.  Still others use a format that starts with a number or letter code of varying length to identify the mill where the feed was made, followed by a Julian date code.  This gets very complicated as you go through the decades of a century and have to figure in leap years https://landweb.modaps.eosdis.nasa.gov/browse/calendar.html. Bottom line is if your feed doesn’t have an easy to read date on it, call the manufacturer to get details on their coding system.

For the very freshest feed possible, look for a local mill that makes their own feed. These small mills have limited storage space, know their market and often make fresh feed every week.  Large barns that can quickly use up a minimum order of half ton to a ton of feed can often contract with the mill to have a custom formula of their choice made – usually for half what it would cost to buy the same feed from a large feed company.

Supplements are even more of a mine field than feeds. You will never see a clear manufacturing or expiration date. Even lot numbers are not required on the label but you may see one there or elsewhere stamped on the package. It may or may not be identified as a lot number. Before you buy a supplement, contact the manufacturer, ask where the lot number is located and if you can be told the manufacturing date if you call with the lot number.

The longest shelf life is for inorganic minerals, e.g. oxides, sulfates, chlorides, phosphates, that have no flavorings or organic base such as alfalfa or flax seed. These will not support bacterial or fungal growth, keep potency virtually forever and the only issue may be clumping over time. Because they have an organic base, organic minerals do support organism growth and their shelf life is around 2 years.

Liquid supplements of all types, including liquid fats, have the shortest shelf life unless preservatives are added. Supplements with a flax seed base may also go rancid in as short as 6 months depending on storage conditions. Horses can detect, and refuse to eat, levels of rancidity that are not obvious to us.

Whenever possible, it is best to buy directly from a manufacturer rather than at the local level or even through a distributor. The more middle men are involved, the more likely the supplement may have had periods of improper storage conditions or have been in inventory too long. The manufacturer will have a vested interest is not selling old product – distributors often do not.

If despite your best efforts you end up with a feed or supplement with obvious molding, an off or “old” odor, excessive crumbling or one that your horse does not want to eat – take or send it back. Such a product is high risk of making your horse sick and has little chance of doing him any good.

Eleanor Kellon, VMD

 

 

Posted in Equine Nutrition | Tagged , , , , , | Leave a comment

Vitamin E and Selenium Are Powerful Protectors

Vitamin E and selenium are nutrients familiar to most horsepeople.  They are among the most common deficiencies in unsupplemented animals – and also the only two where deficiency diseases are still routinely seen.  Suboptimal levels also impact health and performance at levels below those that will trigger full blown deficiency syndromes.

Vitamin E and selenium are powerful protectors of muscle as well as immune function.

E and Se are often supplemented together but contrary to popular belief they do not actually work together, nor is their absorption from the intestinal tract interrelated in any way. However, they complement each other to provide broad spectrum protection to the body’s cells.

E and Se are both important antioxidants. E works to prevent fats within membranes from oxidative damage.  Se, as part of the glutathione peroxidase enzymes, works to protect the internal watery portions of cells from free radical injury. Free radicals are a by-product of cells generating energy for work or cell division and of immune system activity.

Vitamin E and selenium status is documented to significantly impact:

  •  The nervous system
  • Muscular function
  • Fertility/sperm quality
  • Antibody levels in colostrum
  • Immune function
  • Red blood cell integrity in exercising horses
  • Heart health
  • Cancer surveillance

Selenium is also integral to the enzyme which converts the inactive form of thyroid hormone (T4) to the active T3.

In most areas of the US and Canada, selenium is barely adequate to frankly deficient.  https://wp.me/p2WBdh-ha.  Horses not being maintained on pasture have extremely low levels of vitamin E in unsupplemented diets. E added to feeds or multi-ingredient supplements often acts more like a natural preservative than a supplement because even stabilized forms of the vitamin can breakdown easily.

Horses absorb inorganic selenium (e.g. sodium selenate) well but absorption of this form may be reduced by high levels of competing minerals in the diet. For this reason, some or all of the selenium supplement should be in the form of high selenium yeast.

As above, vitamin E can be unstable. I prefer to supplement it separately. Because this is a fat soluble vitamin it is best given dissolved in fat.  If your supplement is powdered,  mix it into some oil or sprinkle it on top of oil top dressed on the feed.

E and  selenium are two of the most important and the most often deficient nutrients in the horse’s diet.  Make sure your horse’s intake is adequate.

Eleanor Kellon, VMD

Posted in Equine Nutrition | Tagged , , , , , , , | Leave a comment

Salt to the Rescue

I do some version of this post every year for good reason.  At the least it will safeguard your horse’s well being and performance in the heat.  At best it could save his life.

Sweating is the horse’s major mechanism for cooling off.  Human sweat has the same concentration of electrolytes as plasma but equine sweat is much higher.  Sodium and chloride, which together make salt, are by far the major electrolytes lost in sweat.  Even a lightly sweating horse will double his  sodium requirement with one hour of work.  When sweating heavily for an hour, the sodium requirement goes up 500%.

Every cell in the horse’s body works like a mini battery. It performs its functions by maintaining a gradient between the concentration of sodium outside versus inside the cell. Electrolyte fluxes are involved with everything from absorption of nutrients in the gut to brain, heart and muscle function.   Sodium and chloride are also the major electrolytes in blood and the fluid around cells.  Without sufficient sodium, the body tissues cannot hold normal levels of water and the kidney is unable to conserve water. Dehydration rapidly ensues.

The consequences of salt and water depletion begin before you can even tell that the horse is dehydrated by common tests like the skin pinch.  Reduced performance is the first sign. Muscle cramping is common. Humans report experiencing nausea (? colic or gut motility changes in a horse).  This is followed by more obvious weakness and “hitting the wall”.

Exercising a horse with suboptimal salt and water levels greatly increases the risk of heat stroke.  To prevent this, and make sure your horse performs comfortably and up to his best potential in the heat, you must understand what your horse’s needs are and make sure you meet them.

Before even worrying about sweat losses, the average horse has a basic salt (sodium chloride) requirement of approximately 1 oz/day.  An average size horse weighs about 450 kg. You can estimate sweat losses for moderate sweating at about 10 mL/kg/hour so 4500 mL each hour.  This is the equivalent of about 1 1/4 gallons of water and another 1 oz of salt.  This takes care of the sodium. There is also a large loss of chloride, which will be replaced partially by the hay/grass and partially by the salt.  Potassium losses also occur but are covered easily by the hay/grass as long as sodium needs are being met.

Adding only more salt will work for horses exercising up to 2 hours. Beyond that you will also want to use a balanced electrolyte supplement to make sure potassium is covered as well.  A supplement balanced to sweat will have twice as much chloride as sodium and about twice as much sodium as potassium. When deciding how much you need to feed, don’t rely on product instructions.  Find out how much sodium is in the product and figure on giving 11 to 12 grams of sodium for each hour. For example, if the product is 30% sodium, to get 12 g you need to feed 12/0.3 = 40 grams (1.4 ounces) of the product.  This is on top of the 1 oz basic salt requirement and 1 oz/hour for the first 2 hours of exercise.

Timing is important. Water should be freely available at all times. Horses that have water restricted after work do not drink sufficient amounts. It does no good to give extra salt/electrolytes several hours before work  because they will end up in the urine. You can give the first hour’s dose within 30 minutes of starting exercise and the rest during or after exercise. Mix in food or syringe in after the horse eats and drinks.

The hardest part about supplementing electrolytes correctly is ignoring all the bad information out there.  If you follow these guidelines you will help protect your horse from the heat and will likely be pleasantly surprised at how much better he performs.

Eleanor Kellon, VMD

Posted in Equine Nutrition | Tagged , , , , , , , , , , | Leave a comment

Thiamine for Horses

Thiamine (B1) is a member of the water soluble group of B vitamins.  Following absorption it is metabolized to its active form, TPP – thiamine pyrophosphate. TPP is an essential cofactor in multiple reactions involving energy generation from carbohydrate (glucose) and branched chain amino acids.

Specifically, TPP is involved in steps needed to get energy sources burned by aerobic metabolism.  For example, TPP is required for the pivotal enzymatic reaction that sends pyruvate from glucose into aerobic metabolism instead of conversion to lactate. In fact, elevated lactate is one sign of thiamine deficiency, as is impaired muscular function.

Since the primary and preferred fuel of the brain and nervous system is glucose, thiamine also is critical to their normal functioning.  Thiamine deficiency has been linked to a host of neurological conditions – confusion, weakness, gait abnormalities, impaired thinking are among the signs of severe deficiency. Thiamine status has also been linked to depression or anxiety in times of stress.

Other signs of deficiency noted specifically in horses include loss of appetite, poor growth, low heart rate, even death.

Should you supplement?  How much?

Full blown, potentially life threatening, thiamine deficiency has never been reported in horses eating typical diets.  The minimum requirement to sustain life has been set at 3 mg/kg of dry matter in the diet – about 30 mg/day for the average horse not in significant work. Exercising horses need about 50 mg/day.  There is also evidence that growing horses have more efficient growth and weight gain when fed diets that have twice the density of thiamine as the adult minimum requirement.

These are the bare minimum requirements. Do they differ from optimal intake?  The answer is most likely yes.  A 2017 paper in the Israel Journal of Veterinary Medicine (Laus et al) found that horses given intravenous supplementation in the form of TPP (the active form of thiamine) produced significantly less lactate on a standardized exercise test compared to horses of identical fitness.

This is similar to findings in human athletes where oral thiamine supplementation in higher than typical recommended minimums reduces lactate, ammonia and fatigue to an even greater extent than formal endurance training.  Supplementary thiamine has also been found to support performance and mood under stressful conditions.

Thiamine is virtually nontoxic, with the only noted side effect of even massive doses being nausea. Horses at maintenance or in light work may not need any supplemental thiamine.  Horses in heavier work schedules and/or under stress could benefit from supplementation of between 300 and 1000 mg/day for the average size horse for maximal support of metabolism and the brain.

Eleanor Kellon, VMD

 

Posted in Equine Nutrition | Tagged , , , , , , , | Leave a comment

Parasite Resistance – Where Do We Stand

The doomsday scenario of parasites resistant to all deworming drugs has not materialized but we are facing some challenges.  This will give you current information on resistance, your treatment options and future directions.

Note: I have deliberately not used any brand names. There are several brands associated with the same active ingredient in dewormers and it’s a good idea to get in the habit of actually looking at the active ingredient rather than the brand name to be sure you are getting what you need.

From bots in the stomach (above) to pinworms at the anus, the horse is home to many    different parasites, many of which have developed some dewormer resistance.

Ascarids (Parascaris, roundworms).  This is a major health threat for young horses. Healthy adults are rarely infected but aged horses may lose their ability to resist.  These are large worms and can even obstruct the intestine in foals.  Their immature forms migrate through the liver and lungs. They are a common cause of “snots” in young horses.

Ascarids in many areas are resistant to ivermectin, moxidectin and in some instances also pyrantel pamoate. They are still sensitive to the benzimadazoles (e.g. oxibendazole, fenbendazole) and piperazine.

Small Strongyles (Cyathostomin sp.).  These parasites of the large intestine are the major parasite of adult horses.  The immature forms can go into a dormant cyst in the wall of the intestine and cause considerable damage when they emerge.

The small Strongyles are resistant to all drugs except the macrocyclic lactones ivermectin, abamectin and moxidectin.  Even these drugs don’t work like they did in the past. Fecal egg counts are reduced for approximately 30 days in contrast to the several months previously obtained with these drugs.

Pinworms (Oxyuris).  Pinworms occupy the most distal portions of the intestinal tract and emerge from the anus to lay eggs around the anal area. This produces intense irritation and itching.

There are multiple reports, both anecdotal and formal research, of macrocyclic lactones failing to remove pinworms. However, there are other reports showing the expected effectiveness. It is unclear at this time whether there is emerging resistance or if some issues may be related to inaccurate dosing. Resistance of pinworms to other dewormer drug classes has not been reported.

There are no known resistance problems with tapeworms, Strongyloides westerii (a problem in young foals), lungworms or large Strongyles (Strongylus species). However, large Strongyles are relatively rare since the introduction of the macrocyclic lactones and may actually share the resistance profile of the small Strongyles.

So far these problems are troubling but surmountable. However, there are no new drugs on the horizon to come to the rescue if issues worsen. There is another solution though, and it’s ready to break onto the scene.  Duddingtonia flagrans.

I first wrote about the potential for predatory fungi to assist in parasite control about 20 years ago. D. flagrans is a fungus naturally found in the environment which feeds on the infective larval stages of multiple parasites including large and small Strongyles, roundworms, threadworms (Strongyloides) and pinworms (although it would not help with roundworm larvae since they don’t hatch in the manure, and pinworm larvae are rarely in the manure). D. flagrans traps and consumes the larvae before they can infect the horse.  They are fed to the horse in an inactive spore state and remain inactive until passed in the horse’s manure.

For detailed safety information see this document from the EPA:  https://www.federalregister.gov/documents/2018/05/07/2018-09647/duddingtonia-flagrans-strain-iah-1297-exemption-from-the-requirement-of-a-tolerance.

D. flagrans has been approved for use in horses in the USA, New Zealand and Australia. It is set to hit the market in New Zealand and Australia very shortly. Although already approved by the EPA, USA use will require approval by the individual states before it can be marketed.

Smart control of intestinal parasites requires a knowledge of the species threatening your horse, how various parasites respond to each dewormer class and environmental control to limit exposure.  D. flagrans will make the job of limiting exposure much easier.

Eleanor Kellon, VMD

Posted in Equine Nutrition | Tagged , , , , , , , , , , , , , , | 4 Comments

Common Issues of the Older Horse

With a lifetime of good care there is no reason a horse can’t remain active and useful well into their 20s or even longer. However, just like us, there are some health issues that become more common as a result of the passage of time.  Joint disorders and digestive complaints are two of the most common.

When thinking about joint health, our tendency is to focus on the cartilage but many other tissues can be involved.  The horse’s body is equipped with mechanisms to repair damage as it occurs.  It doesn’t just pile up over time.  Problems can occur when the damage overwhelms the healing  capacity (e.g. serious trauma, very hard work) or when regenerative capacities slow down due to age. Most horses fall in the second category.

The big three of joint support supplements – hyaluronate, chondroitin sulfate and glucosamine – are involved in helping to maintain the homeostatic mechanisms that protect chondrocytes (cells producing cartilage) from things like oxidative stress. MSM and hydrolyzed collagen have similar properties.  They also help with maintaining a normal balance of potentially damaging enzymes in the joint fluid.

Regular antioxidant supplementation benefits the older horse by working with the body’s own antioxidant defenses to help alleviate potentially harmful free radicals. Ingredients in this category include grapeseed, bromelain, olive extract, Devil’s Claw, Curcumin and Boswellia.

Older horses are likely to benefit from additional support for soft tissue/connective tissue and bone from silicon (as the bioavailable orthosilic acid), vitamin C, copper and hydrolyzed collagen. Key nutrients for both collagen and hooves are L-lysine and L-methionine. Hooves also benefit from zinc and biotin.

Older horses may face several challenges in digesting their food. Natural wear and overaggressive dentistry can lead to loss of the enamel ridges on their chewing surfaces. There is also a change in the angle of the chewing surface which reduces the force of chewing. Although not investigated in horses, ageing can result in decrease in stomach acid production and pancreatic digestive enzyme activity. Older horses also often have reduced numbers and diversity of microorganisms in their intestinal tract.

When chewing is an issue, switching the diet to one based on hay cubes/pellets and/or a complete feed, fed thoroughly moistened or even as a “soup”, is highly beneficial.  Adding psyllium to every meal improves ease of swallowing and is also prebiotic.  You can leave hay available to keep the horse busy unless choke is a problem, but don’t count on it to supply significant calories.

Digestive support from digestive enzymes can help with small intestinal absorption of nutrients. These may come from enzyme preparations such as Pancrelipase and pepsin.  Bacterial and yeast fermentation products are also rich sources of digestive enzymes as well as growth factors for beneficial organisms.  The best probiotics are a blend of bacterial strains and yeast.  The number of live organisms is extremely important.  One  CFU = 1 colony forming unit = 1 live organism.  You need to think in terms of tens of billions to have an effect.

Ageing has its challenges in some key areas but the correct choice of supplements can help the horse maintain more youthful normal functioning.

Eleanor Kellon, VMD

Posted in Equine Nutrition | Tagged , , , | 2 Comments