Age affected: Sows.
Causes: Boredom in stalls/tethers; painful disease or injury.
Effects: Teeth surfaces ground together repeatedly.
Tooth grinding is usually an indicator of pain in the pig and occurs in animals with serious internal injuries or disease. It may occur in animals with gastric ulceration, torsions, heart disease, pleuropneumonia or broken limbs. In some circumstances it may be a feature of boredom in stalled animals. The teeth being ground are the cheek teeth and they may become worn.
The condition is not transmissible as such. It occurs in association with chronic pain of any origin and, when behavioural in origin, may recur when fresh animals are kept in the same accommodation.
Animals may be seen grinding their teeth, but usually tooth grinding is heard after approaching or disturbing an injured or sick pig. The sound is quite distinctive and appears to resonate. It is most common in older pigs and usually occurs while the animal is dull and lying down. Occasionally it may be seen or heard in a stalled sow, but these animals often bite their bars rather than grind their teeth. There may be clinical signs of the underlying problem, such as a broken leg or a difficult parturition.
Tooth grinding is usually diagnosed by hearing the characteristic sound and sometimes by seeing rhythmic movements of the jaw. It can be mistaken for the sound of sows or pigs playing with stones in their mouths and is quite different from the chomping sounds associated with anger.
Once the sound has been heard, the animals responsible should be identified and examined more closely. The actual cause may then be determined. If there is no organic cause and inspection of the mouth is being considered, animals should be tranquillised, restrained physically and a gag inserted before any inspection of the oral cavity takes place. On no account should the hand be inserted into a pig’s mouth without these precautions.
If grinding is a feature of a particular pig, then the cheek teeth may be worn when inspected at slaughter and the cause of the grinding may be apparent. Wear of the cheek teeth may be noted incidentally during extra-thorough post-mortem examinations, but is distinct from wear to the incisors, which is a feature of floor-fed pigs on limited rations.
As tooth grinding is a sign of pain or boredom, then treatment and prevention is dependent upon correcting the underlying problem. Where pain is associated with a broken limb, the animal should be killed humanely. Where the pain is associated with a problem such as painful farrowing, assistance should be given and where it is associated with some systemic disease, the disease should be identified and treated. Where the cause is boredom, the animal can be freed if confined or be given a plaything or straw to reduce boredom.