Finally, parotiditis may, in some cases, constitute only a localisation of a general disease. It seems a fact that in rare circumstances parotiditis may assume an epizootic character, and attack a large number of animals in a particular stable or in neighbouring stables; and if, under these circumstances, we are unable to blame the food (which has not been done), we are forced to admit the influence of infection and contagion.
Symptoms. Whatever the cause, the symptoms are generally well marked. In many cases the first indication of the disease is apparent or real want of appetite, always complicated with difficulty in swallowing, and often accompanied by trifling fever.
Salivation, resulting from irritation of the gland and inability to swallow, becomes abundant, and at once draws attention to the buccal cavity and adjacent parts. Inspection of the patient then reveals the existence in the parotid region of a diffuse swelling, which on palpation is found to be hot and painful, and to occupy the whole of the parotid region between the lower jaw and the upper extremity of the neck. The lesion is usually unilateral, but occasionally bilateral.
Parotiditis may terminate in resolution, suppuration, or necrosis. The suppuration may either be simply subcutaneous and extra-glandular, or may involve a portion of the salivary gland and of the parotid lymphatic gland in addition.
Necrosis is exceptional, though Moussu saw double and total gangrene of both parotids, complicated with septicæmia, in the animal, of which a sketch is given herewith.
Fig. 63.—Acute parotiditis.
If the disease is due to violent injury by a foreign body, traces of a wound may be found, but it is often useless to search for these, even when the parts have been pricked with a sharp goad. When the inflammation has resulted from ascending infection of the salivary ducts, exaggerated sensibility may sometimes be detected throughout the whole length of Stenon’s duct, particularly at the point where the duct crosses the jaw. There is always marked difficulty in moving the head, particularly towards the side, and sometimes in a vertical plane. The head is extended on the neck, and is held stiffly in such a way as to suggest the possibility of tetanus. Some observers have described as an important symptom marked swelling of the orifice of Stenon’s duct. It is certainly difficult to detect, and furthermore is of no great significance.
Diagnosis. Although diagnosis is easy, it is a difficult matter to detect the point of origin of the disease. The salivation and difficulty in swallowing might seem to suggest pharyngitis, a condition which sometimes exists simultaneously. The distinction between this disease and the forms of chronic parotiditis, or tumour formation in the parotid (due to actinomycosis, lymphadenoma, melanoma), is also easy, on account of the slow development of the last-named conditions. The only condition liable to be confused with that under consideration is abscess of the subparotid gland.
Prognosis. The gravity of the disease varies greatly. When inflammation is slight, resolution usually occurs in eight to fifteen days. The onset of suppuration is announced by renewal of the fever, by more marked swelling, which becomes localised at a given point, and by the existence of deep or superficial fluctuation. Care, however, is required to detect the last named.