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Aid to digestion
Diseases, other serious conditions of equine salivary glands often overlooked


Treatment of these salivary calculi often requires a surgical approach, with location and removal of the stone. Newer surgical approaches allow access through the buccal mucosa and, while sialothiaisis is almost always a one-sided problem, attention to this condition has brought up the fact that stones are twice as common on the right side of the horse and that adult females have a two-fold higher increase in the incidence of ductal stones.

Trauma to the jaw

Trauma can be a significant cause of problems with salivary glands and their related ducts.

If a small jaw laceration includes tissue along the medial surface of the head, then the parotid duct may be irritated to partially lacerated to completely transected.

These horses will show a constant leaking of fluid that increases when the horse is fed and begins to chew. Because the volume of saliva produced in the horse is quite large, they may show a stream of fluid being released from the site of trauma while the horse is eating. There may be so much saliva draining on the skin that care must be taken to keep the surrounding surface moist and covered with a protectant salve so that the skin does not become scalded or irritated.

Many of these horses are repaired surgically, and more and more papers are being published describing successful resolution of a partial parotid defect using catheters and time. Occasionally these horses may spontaneously resolve their partially torn and leaking ducts, but repair more routinely requires general anesthesia and dye-contrast examimation along with duct recannulization.

The techniques for dye-contrast studies of the various salivary ducts in the horse have been worked out and well described in "Sialography in the horse: technique and normal appearance," by Drs. Seifollah Dehghani, Mina Tadjalli and Alireza Seifali of the School of Veterinary Medicine at Shiraz University in Iran. "Because of the close relationship between the parotid gland, the guttural pouch, retro-pharyngeal and cranial cervical lymph nodes," writes Dr. Dehghani, "and because of the clinical importance of the retromandibular fossa in the horse, diagnosis of disease conditions of the salivary glands is of prime importance." Sialography or a dye study of the salivary ducts is the best way to clearly see which structures are involved in various conditions.

Infections and tumors

Infectious agents can significantly affect the salivary glands. The highest concentration of organisms in a rabies infection are found in saliva and in the lining of the salivary ducts.

Salivary glands can become infected by Streptococcus Equi bacteria, and there are many other infectious disease agents that can infect the salivary glands.

Tumors of the salivary glands do occur, with melanomas and sarcomas the most commonly reported.

In any case of salivary-gland or duct problems, it is important to infuse a dye into the partially or fully torn end segment. The films taken after an infusion of dye allow the practitioner to evaluate the damage/problem and begin formulating a solution.

Routine review and re-evaluation of your horses might help you recognize these various salivary-gland conditions and needs and to be ready to treat them.

Marcella is an equine practitioner in Canton, Ga.


Source: DVM360 MAGAZINE,
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