Author: Chloe Casalis de Pury

When your horse has a problem with their liver it can be difficult to find out exactly what caused it. Occasionally owners of horse with hepatopathies (liver disease) worry that their grass could be causing the issue. A quick internet search pulls up something called “fescue toxicity”. Could fescue toxicity be a cause of liver disease in horses in the UK?

What is fescue toxicity?

“Fescue toxicity” is caused when a fungus that lives within some species of fescue grass produces certain metabolites (ergot alkaloids and lolines). These metabolites cause liver disease when they are eaten by some animals. Horses are particularly sensitive to these fungal toxins. Fescue toxicity can be a cause of liver disease and reproductive in horses and cattle in the US; it causes over $1 billion of livestock damage per year in the US alone.

Does fescue toxicity occur in the UK?

Luckily, the main serovar (type) of tall fescue in the UK is S170. S170 is endophyte free i.e. it does not contain the fungus that produces the toxic metabolites. For this reason, fescue toxicity IS NOT a cause of liver disease in horses in the UK.

However, similar metabolites are produced by certain funguses, such as Aspergillus, when they grow in hay in the UK, which is why testing the hay is an important step in finding the cause of any liver issues.

Had you heard of “fescue toxicity” before? If you are worried that your horse may have a liver issue it is important to talk to your veterinary surgeon. For more information on nutritional management of liver disease contact us to help rule out issues and put a support plan in place.

The importance of diet, correct exercise and photos!

Helping your horse build topline, or develop and maintain muscle mass, is key to performance. It also helps to reduce injury by ensuring that your horse is strong enough to complete the work you ask of them. Here are two examples of horses who I have been working with to improve muscle development. For each horse, these photos were taken 2-3 weeks apart.

Both horses are fed a high-quality balancer alongside an amino acid supplement, which is given 30 minutes post-exercise. I will go into the details of feeding to help your horse build topline and muscle in my next post.

They are also worked correctly, using a combination of long-reining, pole-work and cavaletti, hill-work and cross-training.

Finally, by photographing these horses every two weeks we are able to monitor their progress and adjust their diet and training as needed.

Once you get your nutritional building blocks in place and use appropriate strength-building exercises it all comes together! 💪

What does the research say about hay soaking?

Surveys suggest that around 40% of horse owners soak their hay before feeding it, either to try to reduce starch and sugar content or to reduce dustiness. BUT hay soaking may not actually achieve either of those things!

Soaking hay for 12 hours in cold water may only reduce the combined starch and sugar content by 1-5%, this can be increased by up to 10% when warm water is used. So in reality on yards, soaking hay may have very little effect on the sugar content. If your hay has a high starch and sugar content it could still be well above maximum level recommended for feeding to laminitics – 10%.

What about reducing dust?

Dust may be leaf breakage (usually harmless) or moulds and spores (found to some level in all hay but can cause respiratory disease if present at high levels). If your hay is contaminated with a high level of moulds and spores, soaking it will only stick these to the hay, not remove them. Your horse can still breathe them in and, even worse, soaking actually increases the amount of bacteria and fungi present within the hay.

What should you do instead?

There are several commercial haylage growers producing timothy haylage that reliably has a starch and sugar content of less than 10%. This is my go to forage source for horses and ponies prone to laminitis or weight gain. Examples include Yeoman, Devon and Horsehage timothy haylages.

Steaming hay using a commercial steamer is the only way proven to reduce bacterial and mould contamination and improve its safety for respiratory health. Personally, my favourite is the Haygain system as they have plenty of research on the effectiveness of their steamers. Many of the commercial haylages mentioned above are also lower in some types of contaminants than most hay, although there is significant variation between bales.

If you want to be sure that your hay or haylage is suitable for your horse then I recommend getting it tested. Equicare provides a forage analysis service that will tell you how clean your forage is and the exact nutritional breakdown.

Take home message

Soaking hay is almost never effective or necessary in my opinion – using either a commercial haylage appropriate for your horse or a hay steamer is better for your horse’s health, and a lot easier!

The “80:20 rule”

There’s been a lot of discussion recently about the so-called 80:20 rule of forage feeding – or feeding 80% of your horse’s hay allowance in the day and 20% at night. Ultimately, it’s not wrong BUT it’s the definition of “night” that’s important.

What does the research say?

A lot of this has stemmed from a research paper published in the Equine Veterinary Journal in 2009 by L. Husted et al. In the study, they fasted a group of horses for 12 and 24 hours while monitoring the pH of the upper portion of their stomach. Predictably, stomach pH dropped (became more acidic) when food was withheld BUT they found that this natural fasting behaviour happened in stabled horses overnight even when offered ad lib hay.

The study found that the horses offered ad lib hay ate 63% of their total daily hay intake between 9am and 9pm and had a correspondingly lower stomach pH between 3am and 9am. So yes, horses do naturally eat less overnight and it makes sense to take this into account when allocating forage amounts. HOWEVER, your horse’s idea of “night” may be different to yours – 9pm onwards is when they show reduced feeding behaviour. They eat a significant amount of their daily hay amount during the early evening.

What do I recommend ?

For me, wherever possible I recommend allowing ad lib forage feeding. Grazing is a huge part of normal horse behaviour and a key component in good welfare. It’s up to us to find a forage source that matches their nutritional needs and allows our horse’s to eat a normal volume while avoiding excess calorie, starch and sugar intake. Tricky, I know, but definitely possible.

Ref: Husted, L., Sanchez, L. C., Baptiste, K. E. and Olsen, S. N. (2009) Effect of a feed/fast protocol on pH in the proximal equine stomach. Equine vet. J. 41 (7), 658-662.

EQUICARE IS HERE FOR YOUR HORSE.

While I am awaiting further guidance from the RCVS, they have confirmed that vets do not need to return to emergencies only, as in the previous lockdown.

If your horse needs nutritional support for a medical issue then I can visit your yard as usual, following a risk assessment and taking appropriate COVID precautions.

For routine nutritional check ups, if you are shielding or would rather not meet in person then I offer remote consultations over the phone or via Zoom. I also offer evening or weekend appointments if you are struggling with childcare or work commitments.

My thoughts are with all our frontline workers and with everyone affected during this difficult time.