Horse Side Vet Guide ®

Equine Health Resource

Not Eating, Loss of Appetite, Not Hungry

Code Red - Call Your Vet Immediately, Even Outside Business Hours

Code Orange - Call Your Vet at Their First Available Office Hours

Code Red - Call Your Vet Immediately, Even Outside Business Hours

  • If this behavior persists without an apparent cause.
  • If the results of the Whole Horse Exam (WHE) in the resting horse indicate fever (Temp >101F/38.3C) or heart rate greater than 48 BPM.
  • The feed is the same as it has been. Nothing has changed.

Code Orange - Call Your Vet at Their First Available Office Hours

  • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.
  • A change in the feed could explain the horse's lack of appetite.

Horses are usually aggressive eaters. When they show less or no interest in feed, it should be a warning sign. Appetite is regulated in all mammals by the hypothalamus part of the brain. Disease processes of different kinds create chemical signals that affect the brain and may decrease appetite. Horses experiencing abdominal pain (colic) are oftentimes (but not always) reluctant to eat.

Horses with pain in their mouth will usually try to eat but have difficulty. Those with pain in the throat and esophagus will chew feed but may have difficulty swallowing. Horses that suddenly experience choke or pain while eating may immediately stop and walk away from feed.

Any time a hay or feed is changed, there is a chance that a horse will be reluctant to eat the new feed, until they become hungry enough to begin eating again. Horses that have recently been given oral medications may not eat until they rid their mouth of the taste of the medication.

It is important to try to determine whether your horse has truly lost their appetite, or is hungry but prevented from eating by something (pain, mechanical obstacle, etc…).


Assess your horse’s general health using the Whole Horse Exam (WHE), and try to determine whether your horse is having difficulty chewing or swallowing. In some cases, it may be helpful to assess their mouth (wear gloves). Offer your horse a small amount of feed and watch what they do. If you recently switched feeds, offer the previous one that they may prefer.

If you cannot clearly attribute this behavior to a simple management or feed change, or if you notice any other abnormal behavior, call your vet to discuss your findings and concerns.


Your vet will take a careful history, considering the above factors. A physical exam offers clues to the body systems that might be involved. Often, laboratory work is needed to help rule out more subtle causes of inappetence

Identify or Rule-Out Possible CausesDIAGNOSES

Within Normal Limits, Normal for this Horse
Retained Placenta
Large Colon Impaction, Pelvic Flexure Impaction
Colic, Undiagnosed Conditions Causing
Salmonella Colitis (in Growing Foal or Adult)
Duodenitis-Proximal Jejunitis, DPJ
Hyperlipemia, Lipemia
Colic, Gas, Large Colon Tympany
Colic, Simple Intestinal Gas or Spasm
Equine Gastric Ulcer Syndrome, EGUS (in Adult)
Intra-Muscular Injection Site Reaction
Foreign Body in Mouth
Liver Failure, Generally
Equine Granulocytic Ehrlichiosis, EGE
Pigeon Fever
Equine Influenza, EI
Small Intestinal Strangulation, Pedunculated Lipoma
Renal Tubular Acidosis, RTA
Enteroliths, Intestinal Stones
Left Dorsal Displacement of Large Colon with Nephro-Splenic Entrapment
Bastard Strangles
Kidney Failure, Acute Renal Failure
Kidney Failure, Chronic Renal Failure
Large Colon Mechanical Obstruction, Generally
Acute Systemic Disease, Generally
Viral Upper Respiratory Tract Infections, Generally
Aflatoxicosis, Aflatoxins
Cholangiohepatitis, Cholelithiasis
Equine Anaplasmosis
Intestinal Lymphosarcoma
Abdominal or Internal Abscess, Generally
Pneumonia, Pleuropneumonia & Pleuritis, Generally
Acute Respiratory Distress Syndrome, ARDS
Red Maple Leaf Toxicosis
Stress or Anxiety, Generally
Equine Proliferative Enteropathy, EPE
Potomac Horse Fever, Neorickettsiosis
Bastard Strangles
Choke, Esophageal Feed or Foreign Body Obstruction
Clostridial, Clostridium Colitis (in Adult)
Recurrent Airway Obstruction, RAO
Viral Infection, Non-Specific
Neoplasia, Tumor or Cancer, Thorax
Hepatic Encephalopathy
Stomach Impaction
Right Dorsal Displacement of Large Colon
Ileal Impaction
Adhesions, Intra-Abdominal
Blister Beetle Toxicity
Fracture of Incisive Bone of Upper Jaw or Mandibular Incisors Lower Jaw
Theiler's Disease, Serum Hepatitis or Sickness
Poisonous Snake Bite, Rattlesnake or Pit Viper
Carbohydrate or Grain Overload
Abscess Near Anus, Vulva or Tail Base
Ascarid Worm Impaction
Cheek Tooth or Molar, Fractured or Broken
Vaccination Reaction
Aging Changes, Generally
Eastern, Western & Venezuelan Equine Encephalomyelitis
Liver Disease, Acute Hepatitis
Conditions Affecting Red Blood Cells, Generally
Monensin Toxicity
Neoplasia, Tumor or Cancer, Kidney
Neoplasia, Tumor or Cancer, Sinus or Nasal Passage
Uterine Torsion
Black Locust Tree Toxicity
Locoweed Toxicity
Liver Abscess
Onion Toxicity
Congestive Heart Failure, CHF
Clostridial Myositis
Equine Viral Arteritis, EVA
Protein-Losing Intestinal Diseases, Generally
Cardiotoxic Plants, Generally
Stomach Outflow Obstruction
Small Strongyle Infestation
Intestinal Foreign Body
Fracture of Mandible or Lower Jaw
Infarcted Intestine or Colon
Equine Herpesvirus 1 & 4, Rhinopneumonitis
Coronavirus Entero-Colitis
Borna Disease
Blue Green Algae Toxicity
Bacteremia, Septicemia (in Adult)
Equine Piroplasmosis, EP
Equine Infectious Anemia, EIA
Nitrate Toxicity
Adrenal Insufficiency
Pyrrolizidine Alkaloid Plant Toxicity
Neoplasia, Tumor or Cancer, Liver
West Nile Virus, WNV
Leukemia, Cancer, Blood or Bone Marrow
Rectal Tear
Vesicular Stomatitis, VS
Smoke Inhalation, Pneumonitis
Burn, Chemical, Toxin, Caustic Substances Ingested & Irritating Mouth, Lips, Tongue
African Horse Sickness, AHS
Internal Ear Infections
Kidney & Ureteral Stones
Sleep Deprivation
White Snakeroot Toxicity
Mare Reproductive Loss Syndrome, MRLS
Temporohyoid Osteoarthropathy
Equine Herpes Myeloencephalitis, EHM
Cecal Disorders, Generally
Japanese Encephalitis
Fractured or Broken Ribs (in Adult)
Guttural Pouch Mycosis
Phenothiazine Toxicity
Buttercups Toxicity
Conjunctivitis, Generally
Screwworm Myiasis
Plant or Weed Toxicity, Generally
Blue Weed, Patterson's Curse Toxicity
Black Walnut Shavings Toxicity
Multiple Myeloma
Arsenic Toxicity
Ruptured Aorta, Ruptured Aortic Aneurysm
Hypoglycemia, Low Blood Sugar
Multisystemic Eosinophilic Epitheliotrophic Disease, MEED
Equine Grass Sickness
Diabetes Mellitus

POSSIBLE TREATMENTS or TherapiesTo Lessen or Resolve the Sign

Author: Doug Thal DVM Dipl. ABVP


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