What you see. The starting point for addressing any equine health related issue is your observation.


Lump, Bump, Growth on Jawbone or Under Jaw


The structures under and behind the jaw include the left and right jawbones, and the structures in-between, the lymph nodes, salivary gland, and large vessels. All of these structures can suffer from injury or illness that results in a well defined lump or bump.

Fractures (from a kick or fall), tumors, cysts, granulomas, foreign bodies, hematomas, dental or oral conditions can all appear this way.

However, hard bumps along the jawbone itself may be normal in young horses (a bony reaction associated with tips of the tooth roots).

  • Code Orange

    Call Your Vet at Their First Available Office Hours
    • If the swelling is large, painful or growing rapidly.
    • 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.
  • Code Yellow

    Contact Your Vet at Your Convenience for an Appointment
    • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.
    • If the mass is small, non-painful or seems to be only growing slowly.

your role


What To Do

Assess the horse's general health using the Whole Horse Exam (WHE), paying particular attention to attitude and appetite, and whether your horse also has a fever.

If possible and it is safe to do so, assess the horse's mouth while wearing gloves. Carefully look and feel around and behind the jaw for other swelling or drainage. Look for obvious signs of injury. Can you feel the lump or bump? If so, is it soft or hard? Is it symmetrical? Is it along the jaw bone on left or right, or is it associated with the softer tissues between the jaw bones? If possible, take a photo.

Share your findings and concerns with your vet.

Since this observation can be associated with Strangles (an infectious disease), wear gloves when handling the horse and use isolation measures until more is known.

If the lump or bump is draining, or if your horse also has a fever consider placing them in quarantine to reduce exposure to other horses until your vet makes a diagnosis.

What Not To Do

Do not assess your horse's mouth if it is not safe to do so. Do not assess your horse's mouth without using gloves. In these cases, wait for veterinary assistance.

your vet's role

Your vet uses clues from the horse's general health in combination with careful assessment of the location and characteristic of the lump to determine the nature of the problem.

Other diagnostics, like biopsy or needle aspirate are sometimes used to determine the tissue type. Ultrasound and x-ray may also be helpful.
Questions Your Vet Might Ask:
  • Do you notice signs of any other problems?
  • What is the horse's age, sex, breed and history?
  • Is there nasal discharge?
  • When did you first notice this problem?
  • Does your horse seem normal otherwise?
  • Does the horse have a fever?
  • Can you tell whether the mass is painful to your horse?
  • Do you notice other masses or swellings?
  • What is the size, shape and feel of the mass?
  • Is it changing in size or appearance over time?
  • Is the horse a gray horse?
  • What are the results of the Whole Horse Exam (WHE)?

Diagnoses Your Vet May Consider

The cause of the problem. These are conditions or ailments that are the cause of the observations you make.

Very Common
Less Common
more diagnoses

Author: Doug Thal DVM Dipl. ABVP