Equine salivary glands secrete saliva to keep the horse's mouth moist. If the glands are blocked, the horse will suffer from a dry mouth, which causes pain when they try to chew or swallow.
The horse has four different salivary glands in its mouth. The glands include the large parotid salivary gland behind the jaw, the mandibular salivary gland, the sublingual salivary gland and two buccal salivary glands.
A blocked salivary gland is caused by sialoliths, or salivary gland stones. If one of the horse's salivary glands is blocked, it will swell and cause inflammation in the area around the gland such as the cheeks or around the jaw. You will also notice little or no saliva in the horse's mouth.
If you gently rub the area where the blockage occurs, it is possible to dislodge the sialoliths if the stone is small and near the surface. However, the safest bet to prevent infection is to have the stone removed by a veterinarian.