Sick Horse Symptoms: Early Signs You Should Not Ignore
By Dr. Zubair Khalid, DVM, MS, PhD ·
Sick horse symptoms usually show up as small changes first: your horse eats less, seems dull, or moves differently. Because horses hide illness well, catching these early signs matters. This guide walks you through a body-system checklist, normal vitals to compare against, and clear rules for calling your veterinarian.
This article is educational and is not a substitute for veterinary diagnosis or treatment.
Quick Answer
- A horse that skips even one or two meals, or leaves hay behind, needs a temperature check and a close look.
- Normal adult resting temperature is 99 to 101.5 F, pulse is 28 to 44 beats per minute, and respiration is 8 to 16 breaths per minute.
- Call your vet the same day for a fever, repeated pawing, or a horse that will not eat at all.
- Call immediately (emergency) for severe colic signs, a horse that cannot stand, or heavy sweating with a normal temperature.
- Many serious conditions, including gastric ulcers, cause vague signs or none at all, so trust your gut when something seems off [1].
What Early Sick Horse Symptoms Look Like
Horses are prey animals. In the wild, showing weakness invites predators, so a sick horse often acts almost normal until disease is advanced. That is why you have to watch for small shifts in routine.
Start with the basics. Is your horse at the gate for breakfast? Does he finish his hay? Is he lying down more than usual? A horse that is "just a little off" is often a horse that needs a vet visit.
Signs My Horse Is Unwell: A Body-System Checklist
Appetite and digestion. Dropping feed, eating slowly, or leaving hay are common first clues. Owners often notice this before anything else. Hyporexia (reduced appetite) and anorexia (no appetite) are reported signs in horses with liver disease [2]. Diarrhea, weight loss, and colic signs can also point to liver problems [2]. If your horse is pawing, rolling, or looking at his flank, see Horse Colic Early Signs.
Demeanor. A dull, depressed horse that stands with his head low or ignores his herdmates is telling you something. Changes in demeanor are a recognized sign of liver disease in horses [2]. Depression plus fever often means infection.
Gastrointestinal comfort. Girth aversion, teeth grinding, and irritability under saddle are common owner complaints. Owners often consider girth aversion highly suggestive of gastric ulcers [3]. However, clinical signs of gastric ulcer syndrome are vague and nonspecific, and most affected horses are asymptomatic [1]. In one study of over 1,100 adult horses, only 12 percent showed any clinical signs related to the gastrointestinal tract, performance, behavior, or weight loss [1]. Physical signs (like poor body condition) tend to go with squamous ulcers, while behavioral signs (like attitude changes) tend to go with glandular or mixed ulcers [4].
Feet and legs. Heat in the hooves, a pounding digital pulse, or a horse that shifts weight constantly can signal laminitis. Learn the early clues in Horse Laminitis Early Signs. A sudden severe lameness with no wound may be an abscess. See Horse Hoof Care: Abscess Prevention and Early Detection.
Skin and eyes. Yellow gums or whites of the eyes (icterus), sunburn on white markings (photosensitization), itching, or swelling under the belly can all be signs of liver disease [2]. These signs are often subtle early on and may seem to appear suddenly even when the underlying problem is long-standing [2].
Breathing and temperature. Coughing, nasal discharge, flared nostrils, or heavy breathing at rest deserve attention. Fever is one of the most useful early measurements you can take at home.
Urination and drinking. Drinking much more than usual (polydipsia) is a reported sign of liver disease in horses [2]. It can also point to kidney issues or other problems.
Normal Vitals to Compare Against
Know your horse's baseline before he gets sick. Take a temperature, pulse, and respiration rate once a month when he is healthy, and write the numbers down.
| Vital sign | Normal adult range | How to check |
|---|---|---|
| Temperature | 99 to 101.5 F | Rectal thermometer, lubricated, stand to the side |
| Pulse | 28 to 44 beats per minute | Feel under the jaw or behind the elbow |
| Respiration | 8 to 16 breaths per minute | Watch the flank at rest |
| Mucous membranes | Pink, moist | Lift the lip and look at the gums |
| Capillary refill | Under 2 seconds | Press the gum, count until color returns |
A temperature over 101.5 F in an adult horse at rest is a fever until proven otherwise. A pulse over 60 at rest, or gums that are pale, blue, or tacky, are reasons to call right away.
Main Causes of Sick Horse Symptoms
Many conditions share the same early signs. The table below groups common causes by the clues they tend to produce and how quickly you should act.
| Cause | Typical clues | How urgent |
|---|---|---|
| Gastric ulcers | Girth aversion, poor performance, attitude change, weight loss, often no signs at all [3][1][4] | Call your vet soon, not an emergency unless severe |
| Colic (gut pain) | Pawing, rolling, flank watching, not passing manure | Emergency if severe or unrelenting |
| Liver disease | Poor appetite, dull demeanor, weight loss, yellow gums, sunburn, diarrhea, increased drinking [2] | Call the same day |
| Laminitis | Hoof heat, shifting weight, reluctance to walk | Emergency, act now |
| Infection or fever | Temperature over 101.5 F, depression, off feed | Call the same day |
| Heat stress | Heavy sweating, fast breathing, weakness | Emergency if the horse will not cool down |
| Hoof abscess | Sudden severe lameness, heat, digital pulse | Call the same day |
For a broader look at conditions that commonly affect horses, see Common Horse Health Problems Every Owner Should Know.
Why Ulcers Are So Easy to Miss
Gastric ulcers are extremely common, especially in racehorses and horses in heavy training [1]. The problem is that the signs are vague. In a study of 1,125 adult horses, only 12 percent showed any clinical signs tied to the gastrointestinal tract, performance, behavior, or weight loss, yet 63 percent had squamous ulcers and 32 percent had glandular ulcers on gastroscopy [1]. Warmblood horses and geldings were more likely to be affected in that group [1]. The only way to diagnose ulcers for certain is gastroscopy, so if your horse's attitude or performance has changed, ask your vet whether scoping is warranted [3][1].
Fever and Infection
A fever means the body is fighting something. Take the temperature before you call, because that number helps your vet decide how fast to move. Write down the time and the reading. Do not give any medication before you talk to your vet, since some drugs mask signs and complicate the exam.
Red Flags That Make It an Emergency
Call your veterinarian immediately, day or night, if you see any of these:
- Violent or continuous rolling, or a horse that cannot be kept standing
- A horse that cannot rise
- Severe, unrelenting pain that does not respond to walking
- Gums that are pale, blue, or bright red
- Temperature over 103 F, or under 97 F
- Heavy sweating with a normal or high temperature
- Profuse diarrhea with depression or fever
- Sudden severe lameness where the horse will not bear weight
- Labored breathing at rest
- Bleeding that will not stop, or blood in the manure
These signs can move fast. Do not wait to "see how he is in the morning."
Safe Things You Can Do at Home While Waiting
While you wait for your vet, keep your horse calm and comfortable. Do not give any medication unless your vet tells you to. Many drugs, including common pain relievers, can hide signs or cause harm, and your vet will calculate any dose from your horse's weight and health.
- Take a full set of vitals: temperature, pulse, respiration, gum color, and capillary refill time.
- Write down the time each sign started and anything that changed (feed, turnout, travel, weather).
- Remove feed if colic is suspected, but keep fresh water available.
- Walk a colicky horse gently if he is trying to roll and it is safe to do so.
- Move a horse with suspected heat stress into shade and offer cool water. See Horse Heat Stress Signs.
- Keep other horses away if you suspect something contagious.
- Take photos or a short video of unusual behavior. It helps your vet see what you saw.
What Your Veterinarian Will Check and Test
Your vet will start with a physical exam: temperature, pulse, respiration, gum color, gut sounds, hydration, and a lameness check. Then the testing depends on what they find.
- Bloodwork. A complete blood count and chemistry panel can show infection, anemia, dehydration, and liver or kidney changes.
- Gastroscopy. This is the only way to confirm gastric ulcers [3][1]. Your horse is sedated and a camera is passed through the nose into the stomach.
- Fecal tests. Fecal occult blood tests have been evaluated as a possible screening tool for ulcers, though they are not a replacement for gastroscopy [3].
- Ultrasound. Useful for the abdomen, lungs, tendons, and eyes.
- Rectal exam. Common for colic cases to check for displacements or impactions.
- Liver-specific testing. If your vet suspects liver disease, they may run bile acids and other liver values based on the signs you reported [2].
Prevention and Daily Monitoring
Most of the work happens before your horse gets sick.
- Take vitals monthly and know your horse's normal numbers.
- Weigh or body condition score your horse every month. Slow weight loss is easy to miss.
- Watch feed intake. A horse that leaves hay two days in a row needs a closer look.
- Keep a simple log of attitude, appetite, manure, and water intake.
- Schedule dental exams and deworming based on your vet's plan.
- Manage turnout and forage to reduce ulcer risk, especially during training or travel.
- Check hooves daily for heat, pulse, and discharge.
- In hot weather, monitor for heat stress and provide shade and water.
Limitations and When to Contact a Veterinarian
No article can diagnose your horse. Every case is different, and only your veterinarian can examine your horse, run tests, and prescribe treatment. Use the timing rules below as a guide.
Call now (emergency): violent colic, inability to stand, labored breathing, pale or blue gums, heavy bleeding, temperature over 103 F, or a horse that is deteriorating fast.
Call the same day: fever between 101.5 and 103 F, not eating for more than one meal, repeated pawing, diarrhea, sudden lameness, yellow gums, or a horse that is dull and depressed.
Call for a routine visit: mild attitude changes, slow weight loss, girth aversion, or poor performance that has lasted more than a few days. These can wait for a scheduled appointment, but do not ignore them.
Frequently Asked Questions
How do I know if my horse is sick?
Look for changes from his normal routine. A horse that leaves feed, stands apart, or seems dull is often telling you something is wrong. Take his temperature and compare it to the normal range of 99 to 101.5 F.
What is the first sign of a sick horse?
Going off feed is one of the most common first signs. Owners also notice a dull attitude, less interest in herdmates, or a change in manure. Because horses hide illness, even small changes deserve a temperature check.
Should I call the vet if my horse is not eating?
Yes, call your vet if your horse skips more than one meal or refuses hay for a full day. Not eating can be the first sign of colic, ulcers, or another serious problem. Early treatment usually means a better outcome.
Can a horse have a fever without other signs?
Yes. Some horses run a fever before any other sign appears. That is why a thermometer is one of the most useful tools you own. A temperature over 101.5 F at rest is a reason to call your vet.
What should I do while waiting for the vet?
Keep your horse calm, take a full set of vitals, and write down when each sign started. Do not give medication unless your vet tells you to. Remove feed if colic is suspected, but always leave fresh water available.
Related Articles
- Horse Colic Early Signs
- Horse Laminitis Early Signs
- Horse Heat Stress Signs
- Common Horse Health Problems Every Owner Should Know
- Horse Hoof Care: Abscess Prevention and Early Detection
- Horse Hoof Abscess Signs
References
- Clinical Signs as an Indication of the Presence of Gastric Ulcers in Horses: True or False?. Animals : an open access journal from MDPI, 2026.
- Clinical Signs of Liver Disease in Horses. The Veterinary clinics of North America. Equine practice, 2026.
- Evaluation of Owner-Reported Clinical Signs and Fecal Occult Blood Tests as Predictors of Equine Gastric Ulcer Syndrome in Competition Dressage Horses. Journal of veterinary internal medicine, 2025.
- Physical vs. Behavioral Clinical Signs in Horses with Squamous and Glandular Gastric Ulcers. Veterinary sciences, 2026.