SILENT ASSASSINS

MYCOTOXINS AND THE DAMAGE THEY CAUSE

TEXT: CHRISTINE PINNA

Is your horse itchy, grumpy, spooky, prone to developing colic or suffering from general ill health? If you've ruled out all of the obvious causes, you may want to consider mycotoxins as a possible culprit. While still not too commonly spoken about in the equine industry, mycotoxins are well documented in the dairy industry, being known to cause diminished milk production and slowed growth rates in affected cows.

What are mycotoxins?

Mycotoxins are harmful substances that are natural byproducts of moulds or fungi that grow on pasture, hay or grains. They are invisible to the naked eye. Mycotoxins are found in our air, general environment and, most concerningly - in our horse's feed and even their bedding. Some grass species, such as ryegrass and fescue, seem particularly predisposed to developing mycotoxins, but mouldy hay of any kind is ripe for mycotoxin production.

Mycotoxins thrive in hot and wet weather conditions –making our environment here in South Africa particularly appealing to them!

NOTE: Mould grows when hay and feed are not dried properly when harvested or stored. Moisture levels of 14-15%, heat, humidity, and poor ventilation create the perfect environmental conditions for mould growth and mycotoxin production. Hay, in particular, can go mouldy very quickly. Studies have shown that mould can develop in as little as a few hours, given the presence of heat and moisture. This is why it is extremely important to check your hay before feeding. If your hay is damp, has a funny smell, or any visible signs of mould, do not feed it.

How do they affect my horse?

When the offending feed is ingested, the mycotoxins disrupt gastrointestinal function, which affects the gut lining and the microflora of the digestive tract. The mycotoxins are then absorbed into the bloodstream, where they can affect the organs, even causing permanent damage to the liver, kidneys, brain and nervous system. Certain mycotoxins are also harmful to the developing foetus, with late-term abortions being a possibility, as well as poor growth rate.

Symptoms

It is important to note that not every horse will show every symptom outlined below. Still, a horse displaying any of the below (even in isolation) could be suffering from mycotoxicosis:

• Itchy skin

• Head-shaking

• Uncharacteristic spookiness

• Unpredictable behaviour

• Sunburnt nose or photosensitivity

• Greasy heel

• Lethargy

• Dull coat or patchy hair growth

• Cough or runny nose

• Muscle tightness

• Swollen lower limbs

• Lameness

• Shortened stride

• Poor condition despite good feed

• Colic

• Fertility issues

• Poor performance

• Compromised immune system

• Chronic diarrhoea

Early signs of mycotoxin intoxication

Early signs of mycotoxin intoxication include lethargy, reduced appetite, diarrhoea and difficulty breathing.

Which horses are affected?

Younger and older horses whose immune systems may not be operating optimally, as well as immuno-compromised horses, are most likely to be affected, whereas healthy horses should have some resistance to low levels of mycotoxins. Regardless, as horse owners, we should always take preventative measures if our horse is living in an environment where mycotoxins may be a problem.

Types of mycotoxins

Currently, scientists have discovered approximately 400 different types of mycotoxin. Roughly 10 of these are commonly found in feed and hay. These include the following:

• Alternaria

• Aspergillus

• Cladosporum

• Fusarium

• Mucor

• Penicillium

• Rhizopus

But the three most common groups are Fusarium, Aspergillus and Penicillium. The first is a field-borne mould, meaning the mycotoxins are usually present when the forage is harvested. The latter two typically form during storage. For example, Penicillium mycotoxins are often seen in poor-quality haylage, especially if air has penetrated the plastic wrap. Effects in the horse vary across the mycotoxin groups.

What to do?

As horrific as mycotoxins may sound, there are some things one can do to avoid the substantial damage they cause. First, if possible, you must move the horse away from the offending food source. This is the most urgent step. Secondly, you need to consider your hay and food storage suppliers and storage practices. Here are some top tips for preventing mould growth in your hay:

• Dry your hay thoroughly before storing it

• Create space around bales to encourage ventilation

• Allow space above the hay for moisture to evaporate

• Stack bales in alternate directions

• Reduce stack sizes where possible

• Consider feeding hay cubes if mould growth is an ongoing problem

• If you steam your hay, feed it shortly after steaming to reduce the opportunity for mould to grow

Thirdly, an increasingly popular method of preventing mycotoxicosis is to feed a mycotoxin binder. While evidence in this area is still relatively limited, the studies to date suggest the value of incorporating these binders into your horse's diet. This is particularly important during hot and wet periods and during drought. There are a few different types of mycotoxin binders available on the market. Mycotoxin binders seem to bind to the mycotoxins and safely move them through the horse's gut until they are eliminated without causing damage to the horse's intestine or internal structures. It is important to choose a binder that doesn't also bind to important vitamins, minerals or medications.

NOTE: Mycotoxin binders should not be used as a strategy to counteract the adverse effects of feeding mouldy hay or food. If hay or food appears mouldy, you should never feed it to your horse.

It is said by many that the effectiveness of the mycotoxin binder can be further enhanced by combining it with probiotics and botanicals. Herbs with anti-fungal properties may be particularly helpful and complement the action of the mycotoxin binder. If the horse's organs appear to be affected, herbs such as milk thistle, which assist with regeneration, may be beneficial. It is important to consult with an experienced herbalist and nutritionist in this regard. Of course, if your horse is very unwell after exposure, you should urgently contact a veterinarian familiar with mycotoxicosis for assistance.

CASE STUDY AT THE COAST IN THE EASTERN CAPE

When people see my herd of 15 horses out in their green paddock, grazing together in their herd, grooming one another, one horse on lookout, one probably lying down for a roll or a sleep, it's the picture of an idyllic natural horse life. People always say how lucky these horses must be, how happy, how healthy, how fat they look and how shiny their eyes and coats seem. Then they ask if I have livery space for their grey horse, their paint with pink skin around his eyes, their palomino or chestnut with four white feet and a white nose, and I have to explain what we colloquially call "the coastal itch". We have kept horses here for close on 30 years, and have always had to work really hard to manage this condition. Yes, our grass is fabulously nutritious and palatable, and the horses do really well on it. Still, the conditions are humid in the extreme, with summer rainfall, dry winters, heavy dew and, in short, the ideal conditions for fungus of any kind to thrive. The last seven years of drought, which you might think would improve the situation, have, in fact, caused the mycotoxin load to explode in the area, and we have struggled more than ever. One horse, a grey Percheron, had to be given away to an inland home after two years of dealing with the worst case of ringworm I have ever seen. Eventually, he had no hair on his legs and face and instead was covered in scabby, oozing lesions. Another horse, a paint with pink skin, came to us for spelling but had to be sent back home after two weeks because she had lost her hair from the chest down. These were the worst cases, but even the horses that don't lose all their hair, who look relatively fat and healthy and shiny, suffer from various itchy skin conditions. Over the years, we have spent an absolute fortune on vet visits, F10 shampoo, herbal mixtures for skin and coat, cortisone creams and injections, not to mention the time spent washing, picking off scabs, putting on all manner of lotions and potions, bandages and cling wrap - we have literally tried everything. Only at a very late stage, sometime in 2021, did I learn about a wonderful thing called a mycotoxin binder and started all my horses on Mycosorb. This has been an absolute game-changer. Since we started with Mycosorb, we have had no cases of ringworm and no hairless horses in my yard. Now, the two non-negotiable supplements for all horses arriving with me are Immunohoof and Mycosorb, and things are going much better. However, I still discourage the arrival of any horse with pink skin, white legs, hairless noses, etc., as they are just so much more predisposed to these problems in the first place. I have a yard full of brown horses who, I must admit, do still itch, get cellulitis or lymphangitis more than is normal, suffer from rain scald and mud fever on occasion, get more cortisone than is ideal, have more F10 baths than I would like to give, along with more antifungal herbs, liver aid and herbal mixtures for skin than I can really afford; BUT they do have hair, they are happy, they do have quality of life, and the "coastal itch" which has tormented me for so long has become a manageable condition since I started them on mycotoxin binders.

Final words

To learn more about mycotoxins and how to manage them in your environment, speak to your vet or your local equine nutritionist. Sheldene Horne and Royalynne Herbs are also very experienced in managing mycotoxins, and you can contact them at the email addresses below.

Resources

Royalynne Herbs - royalynne@retreat2eden.co.za

Sheldene Horne - sheldenehorne@yahoo.com