What are the signs that indicate that a horse's teeth need attention?

Loss of appetite - Slow Feeding - Quidding - Trouble Swallowing - Pocketing feed in cheeks

Difficulty chewing food due to lack of molar occlusion (surface-to-surface contact) or pain in mouth whilst eating; can be protecting sore tongue and cheeks by keeping a quid (partially chewed piece) of food in the mouth.

Undigested food particles in droppings

Indicates probable lack of molar occlusion causing difficulty chewing food.

Loss of condition 

The teeth are the start of the digestive system therefore the horse will not be benefiting from all nutrients available in diet causing weight loss and a dull coat.

Trouble Bridling - Pain Around Face - Discomfort Wearing Noseband

Due to sores on cheeks and tongue caused by sharp teeth

Bad Breath

Can indicate infection, food impaction, retained caps, gum diseases or retained food.

Reoccurring Colics

Caused by impaction in intestine as a result of poorly chewed food.

Jaw Swellings

Possibly retained caps or infected teeth (where heat is present)

Behavioural changes - Affected Performance - Evading the Bit - One sidedness - Rearing

The horse is avoiding what is causing pain such as sharp edges. The horse will not drop it's head due to hooks and ramps. It is unable to turn freely when on the bit due to inhibited side to side movement of lower jaw. If the horse is only able to chew on one side of mouth will cause muscle unevenness affecting horses back.

Nasal Discharge

Could be infected upper molar (or infected nasal sinuses or tear duct)

Facial Muscles Uneven

Muscles will be larger and firmer on the side where most of the chewing occurs. Muscle atrophy can affect the side less used.