Your Horse’s Hunger Signals May Change as They Age
Horse appetite hormones — the chemical signals that tell your horse’s brain it is hungry or full — vary by age and breed, according to a preliminary study published in BMC Veterinary Research. Researchers measured ghrelin, often called the “hunger hormone,” in 35 horses and ponies (19 horses and 16 ponies) and found that levels dropped after feeding, as expected. Welsh ponies had higher baseline active ghrelin concentrations than other represented breeds. Post-prandial active ghrelin showed a weak positive association with age, though baseline levels were not linked to age. Separately, the researchers also investigated where ghrelin receptors appear in equine tissues using archived tissue samples. While the research is early-stage, it adds a piece to the puzzle of equine appetite physiology.
If you have ever wondered why different breeds seem to have different relationships with food, or noticed changes in a senior horse’s feeding behavior, this study offers a glimpse at one possible hormonal dimension — with important caveats about the assay methods used.
Why Hunger Hormones in Horses Have Not Been Well Studied
We know a lot about ghrelin in people and in dogs and cats. In those species, ghrelin has been studied as a key player in appetite, body weight, and metabolic health. But in horses and ponies, this hormone has received far less attention — and that matters, because equine owners and vets often grapple with feeding challenges: underweight seniors, easy-keeping ponies prone to weight gain, or horses with metabolic conditions like equine metabolic syndrome.
To manage a horse’s diet well, you first need to understand how their hunger signals work. This study was designed to fill part of that gap by measuring ghrelin levels in healthy horses and ponies across different ages and breed groups.
How the Study Was Conducted
The research involved two separate components:
Component 1 — Active ghrelin in blood (35 horses and ponies): The team measured active ghrelin — the form of the hormone that signals hunger to the brain — in blood samples from 19 horses and 16 ponies with no evidence of insulin dysregulation or metabolic disease. Blood was collected before and after feeding to capture prandial changes. Breed and age were recorded to look for associations.
Component 2 — Receptor expression in tissues (separate tissue samples): Using archived abattoir tissue samples, the researchers performed endpoint RT-PCR to investigate where ghrelin receptor sequences appeared in equine tissues. This experiment was conducted independently of the 35-animal blood cohort. Outside the sequenced pituitary and adrenal-medulla controls, tissue bands were suggestive of receptor presence rather than confirmed expression, and the method did not quantify expression levels or compare them across breeds.
Important assay limitations: The total-ghrelin assay validation failed, so total ghrelin results are not reported. Active-ghrelin measurements were obtained using a non-equine (human-based) assay and are reported as human-equivalent immunoreactivity. Because equine ghrelin is predominantly C4-acylated rather than C8-acylated as in humans, this assay may not fully recognize the predominant equine form. These caveats are important when interpreting the absolute values.
What the Researchers Found
Feeding Drops Hunger Hormone Levels — and Post-Prandial Levels Weakly Correlate With Age
The team confirmed that active ghrelin dropped after horses ate, which lines up with what we see in other species. When a horse eats, its body lowers the hunger signal — a basic feedback loop that makes biological sense.
On the age question, the picture is more nuanced. Baseline (pre-meal) active ghrelin was not associated with age. However, post-prandial (post-meal) active ghrelin did show a weak positive correlation with age (r = 0.34, p = 0.05). This means that in older animals, ghrelin dropped less sharply after eating, or remained somewhat higher afterward — a subtle pattern. The practical meaning of this weak association is not established by this study, and it should not be interpreted as evidence that older horses are generally hungrier or have stronger hunger signals overall.
Welsh Ponies Had Higher Baseline Active Ghrelin Than Other Represented Breeds
Among the breed groups assessed, Welsh ponies had higher baseline active ghrelin concentrations than the other breeds represented in the study. This is an observational finding from a small, preliminary cohort, and the sample included only a few breeds. It does not establish a cause, and it should not be extended to broad conclusions about “easy keeper” metabolism or all pony breeds.
Ghrelin receptor expression, assessed separately using archived tissue samples, was not compared across breeds in that component of the study.
What This Could Mean for Horse Owners
Interesting Early Signals, but Not Management Guidelines
This study describes associations — it does not establish causes or recommend specific feeding changes. The findings are from a small preliminary cohort, the assays have material limitations, and the age association was weak and limited to post-prandial ghrelin. This research should not be taken as support for adjusting feeding strategies based on breed or age alone.
What this research does support is the value of further study into equine appetite physiology. Understanding how horses and ponies regulate hunger at a hormonal level may eventually inform veterinary guidance — but that work is still ahead.
Practical Points Worth Keeping in Mind
- Senior horses deserve attention around feeding. If an older horse is losing weight, showing changes in appetite, or struggling to maintain body condition, speak with a veterinarian. Many factors can contribute, and a proper assessment is needed before drawing any conclusions.
- Pony metabolic health is a real concern. Ponies are often at higher risk for conditions like laminitis and equine metabolic syndrome, which are linked to how their bodies handle energy and hormones. Any signs of easy weight gain, cresty neck, or foot sensitivity warrant veterinary evaluation — not based on this study, but because those are well-established clinical concerns.
When to Talk to Your Vet
Reach out to your equine veterinarian if you notice:
- Unexpected weight loss or gain despite no change in feeding
- Changes in appetite — either eating significantly more or less than usual
- Signs of metabolic issues such as a cresty neck, abnormal fat deposits, or foot soreness (laminitis symptoms)
- Difficulty maintaining a healthy body condition score in an older horse
An equine veterinarian or equine nutritionist can assess your horse’s individual needs and recommend an appropriate diet based on age, breed, body condition, and health status.
Study Limitations: This Is Early Science
It is important to take this study’s findings with appropriate caution. Several factors limit what we can conclude right now:
- The active-ghrelin cohort was 35 animals (19 horses, 16 ponies), which is relatively small for drawing broad conclusions. The breed groups represented were limited.
- Total-ghrelin assay validation failed, so only active-ghrelin results are reported. Active-ghrelin values were measured using a non-equine (human-based) assay and are reported as human-equivalent immunoreactivity. Because equine ghrelin is predominantly C4-acylated (rather than C8-acylated as in humans), this assay may not fully recognize the predominant equine form — meaning absolute values should be interpreted with caution.
- The receptor expression work used separate archived tissue samples and endpoint RT-PCR. Outside the sequenced pituitary and adrenal-medulla controls, the tissue bands were suggestive of receptor presence rather than confirmed, and expression was not quantified or compared across breeds.
- The study describes associations, not causes. A weak post-prandial age correlation (r = 0.34, p = 0.05) does not establish what it means for horses’ day-to-day appetite or management needs.
- The animals were healthy — these findings may not apply to horses already dealing with metabolic disease.
The authors acknowledge that this is preliminary research. Important assay limitations apply, and future studies will need to build on these findings — ideally with equine-validated assays and larger, more diverse cohorts — before they can guide specific management changes.
The Bottom Line
This preliminary study investigated ghrelin in a cohort of 35 healthy horses and ponies alongside a separate tissue receptor expression experiment. Active ghrelin dropped after feeding, as expected. Welsh ponies had higher baseline active ghrelin concentrations than other represented breeds. Post-prandial active ghrelin showed a weak positive association with age (r = 0.34, p = 0.05), though baseline levels were not associated with age. Receptor expression was examined in separate archived tissue samples using endpoint RT-PCR and was not compared across breeds or quantified. Both the total-ghrelin assay and the non-equine active-ghrelin assay carried material limitations. These are early, observational findings.
For horse owners, the best takeaway from this research is that equine appetite physiology is an active and under-studied area. Age and breed may eventually prove relevant to feeding considerations at a hormonal level, but this study does not provide a basis for changing your feeding approach. Work with your equine vet or nutritionist — they can assess your individual horse’s needs based on health status, body condition, and history.
This article summarizes peer-reviewed research for educational purposes. Always consult with your veterinarian for personalized advice about your pet’s health and behavior.