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Foul Breath Odor in a Horse

i David De Lossy/Photodisc/Getty Images

Unless your horse is experiencing a health or dental problem, you are unlikely to ever pay much attention to your horse's breath. A foul odor coming from the mouth or nostrils of a horse is a sign that there is a medical problem, and you need to get a veterinarian out to examine your horse.

Dental Problems

Dental problems are one of the most common causes of bad breath in a horse. If your horse has bad teeth or an abscessed tooth in his mouth, his breath is likely to smell like decaying flesh or infected tissue. Your veterinarian or an equine dentist has to treat this condition and determine the cause to prevent it a recurrence. In many cases, a horse will need to have his teeth floated -- filed or rasped -- so he can chew more easily and effectively.


If the bad breath is accompanied by coughing, sneezing, green or yellow mucous, fever or any other symptoms of illness, then the bad odor may be caused by an infection in your horse's respiratory system. Respiratory infections can be serious and cause lasting damage as well as breathing problems. If you suspect your horse is seriously ill, contact your veterinarian as soon as possible.

Ulcers and Tumors

The development of an ulcer or tumors in your horse's digestive system can be responsible for bad breath odor. These problems affect your horse's entire system and can cause serious or even fatal heath complications. Tumors or stomach ulcers can be diagnosed by your veterinarian if he uses a gastroscope to examine the inside of the horse's stomach and stomach lining.


Your horse salivates as he chews. If he is not eating properly or being deprived of food, then he may not be producing enough saliva to keep his mouth clean, and a foul odor may develop. Of course, if eating is causing your horse significant pain due to an abscess or another medical condition, then the starvation may be a side effect rather than the problem in and of itself.