Avon Ridge Equine Veterinary Services

A clinically important finding from a recent cabergoline PPID study was not simply ACTH suppression, but the consistent reduction in appetite following treatment.

Horses receiving intramuscular cabergoline demonstrated a transient but measurable reduction in appetite, most notably within the first 24–72 hours following administration. This reduction is appetite has also been commonly reported with pergolide therapy. While cabergoline effectively reduced plasma ACTH concentrations from a mean of 153.35 pg/mL to 24.1 pg/mL and maintained values within seasonally appropriate reference ranges, appetite suppression remained the most consistent adverse effect identified. Importantly, despite lower appetite scores, there was no statistically significant difference in bodyweight loss compared with controls, suggesting that the reduction in intake was generally short-term rather than associated with clinically significant weight loss.

This finding is highly relevant in clinical practice because appetite suppression in PPID horses should not be regarded as a minor or incidental side effect.

We reported similar findings in our study (Sundra et al, 2024) evaluating cabergoline use in horses with PPID, where transient inappetence was also the most commonly observed adverse effect. This consistency across studies reinforces that appetite suppression is one of the most important practical considerations when selecting and managing cabergoline therapy.

This becomes particularly important when considering concurrent administration of drugs like ertugliflozin (SGLT2 inhibitors).

From a clinical management perspective, initiating cabergoline and an SGLT2 inhibitor simultaneously is difficult to justify.

In reality, for anyone with even the most basic understanding of how these drugs work, it should be obvious that starting both ertugliflozin and cabergoline (or pergolide) at the same time should be avoided.

❗️This is not new information.

It has been widely discussed in the public domain for several years since ertugliflozin first began being used in horses.

Ertugliflozin requires consistent caloric intake, stable nutritional management, and careful monitoring of appetite and triglyceride status to minimise the risk of adverse effects, particularly hypertriglyceridaemia and excessive weight loss.

Furthermore, even starting cabergoline (or pergolide) in a horse receiving ertugliflozin, when transient appetite suppression is expected, creates an entirely predictable management problem.

Reduced intake during SGLT2 inhibitor initiation increases the risk of preventable complications, increases veterinary costs for owners, and most importantly, significantly compromises horse welfare.

👉 These are, more often than not, completely avoidable complications.

Careful case selection, timing of therapy introduction, correct dosing and close monitoring should part of routine endocrine management rather than being considered secondary concerns.
🤷‍♀️ Horse owners: you should be closely monitoring feed intake in your horses receiving these drugs. Report any changes in appetite to your veterinarian immediately.

✅ In many horses, appetite suppression associated with cabergoline or pergolide can likely be mitigated when managed by an experienced veterinarian who understands how to introduce these drugs safely.

Cabergoline is an unregistered medication in horses but may be a valuable alternative to pergolide in selected PPID cases. However, appetite suppression must be recognised as a clinically significant management factor rather than a trivial adverse effect.

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Bracken, A., Tyra, H., Vetter, M., Kiger, K., Rao, S. & Bass, L. (2026) ACTH suppression and adverse effects of cabergoline in horses with pituitary pars intermedia dysfunction. Equine Veterinary Education

New research out of the USA has added to the growing body of evidence supporting the use of SGLT2 inhibitors in horses with equine metabolic syndrome (EMS) and insulin dysregulation.

In this placebo controlled study, researchers evaluated the SGLT2 inhibitor bexagliflozin (a drug currently available in the United States) in horses with naturally occurring hyperinsulinaemia. Horses treated with bexagliflozin showed significantly lower insulin responses following oral sugar testing compared to those receiving placebo.

Why is this important?

High insulin levels are one of the key drivers of laminitis in horses with EMS and therapies that reduce these insulin spikes play an important role in both treatment and prevention strategies. We are now seeing consistent findings across multiple studies and different drugs within this class.

The medication was generally well tolerated over the short study period, although some horses showed increases in triglycerides. This reinforces an important point that these medications require careful veterinary oversight, including baseline testing and ongoing monitoring.

As always, medications are just one piece of the puzzle. Diet, weight management, and individualised care plans remain absolutely critical in managing EMS and reducing laminitis risk.

The takeaway?

We are continuing to see strong, emerging evidence that SGLT2 inhibitors can be a powerful tool in the right cases, but they need to be used thoughtfully with the right monitoring and alongside a well structured management plan.

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Lowndes CR, Luethy D, Skelton G, Kulp J, Stefanovski D, van Eps AW. Bexagliflozin controls hyperinsulinemia in horses with naturally occurring insulin dysregulation: a placebo-controlled crossover trial. J Am Vet Med Assoc. 2026 May 8:1-10. doi: 10.2460/javma.26.02.0098. Epub ahead of print. PMID: 42102868.

Part 3: Supplementation, dosing, and what actually works

When a horse is deficient in vitamin E, supplementation is recommended regardless of whether clinical signs are present.

However, not all vitamin E supplements are equal, and this is where things often go wrong.

There are two main forms of vitamin E used in equine supplements.

Synthetic vitamin E, often listed as all-rac-alpha-tocopherol, is less bioavailable and not as effectively utilised by the horse.

Natural vitamin E, listed as d-alpha-tocopherol or RRR-alpha-tocopherol, is significantly more bioavailable and is the preferred form for supplementation.

Within natural forms, there are also differences in formulation.

Powder or pellet forms are typically esterified, which improves shelf life but requires additional processing in the horse’s digestive system before absorption.

Liquid formulations are water-dispersible and generally result in a more rapid increase in blood vitamin E concentrations, often within 24 hours. These are particularly useful when actively correcting a deficiency.

Current NRC daily recommendations for vitamin E in horses are 1 -2 IU/kg body weight. This means maintenance levels can be anywhere between 250-1000IU per day depending on the size of the horse or pony.

In clinical cases of deficiency where signs are present, doses around 5,000 IU per day for a 500 kg horse are commonly used, although requirements can vary depending on baseline levels, underlying disease, and individual response.

Follow-up blood testing is important to ensure that supplementation is achieving the desired increase in vitamin E concentrations.

❓ A common question is whether horses can receive too much vitamin E.

In humans, very high doses can interfere with vitamin K metabolism and affect blood clotting. It is not yet clear whether the same effect occurs in horses, and this is still being investigated. However, it reinforces an important point.

More is not always better.

This is another reason why supplementation should be targeted and guided by testing, rather than adding products in without a clear plan.

It is also important to recognise that some horses may have impaired absorption of fat-soluble vitamins, which can result in an inadequate response to supplementation. In these cases, further investigation is warranted.

Long-term, the most effective way to maintain adequate vitamin E status is regular access to fresh pasture. However, for many horses, particularly EMS horses, this is not possible.

This means supplementation and monitoring become essential parts of managing both metabolic health and muscle function.

If your horse is on restricted pasture, on a hay-based diet, or struggling with muscle development, vitamin E status is something that should be considered as part of a broader clinical assessment.

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Part 1: Why vitamin E matters more than you think**

**This is the first of a 3-part educational series on vitamin E in horses.**

Vitamin E deficiency is one of the most overlooked problems in horses.

In almost all mammals, Vitamin E is essential for the integrity and optimum function of several systems in the body, including nervous, immune, reproductive, muscular and circulatory systems.

Vitamin E is not just another vitamin. It is a potent antioxidant that protects cell membranes from oxidative damage. Importantly, vitamin E levels are associated with the maintenance of normal muscle and nerve cell function.

Horses rely almost entirely on fresh green pasture for vitamin E intake.

Once forage is cut and dried into hay, vitamin E levels decline rapidly. By the time hay is fed, the vitamin E content is often negligible. To make matters more challenging, the vitamin E added to many feeds is synthetic and has significantly lower bioavailability compared to natural forms.

This means many horses on hay-based diets are likely not meeting their requirements, even when their diet appears otherwise balanced.

Importantly, vitamin E is not stored efficiently in the body. Horses require consistent daily intake to maintain adequate circulating levels.

Deficiency does not always present with obvious clinical signs early on. Instead, it often shows up as subtle issues such as:
▪️poor topline
▪️reduced muscle development or muscle wasting
▪️underperformance
▪️weakness

By the time more significant signs develop, deficiency may have been present for some time.

Stay tuned for tomorrow’s post, specifically tailored for horses with EMS.

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https://avonridgeequine.com.au/book-an-appointment/

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