Traumatic injury to the parotid salivary gland or duct and the subsequent development of ipsilateral severe peripheral dental caries in two horses

Abstract

This report describes two cases of unilateral traumatic injury to the parotid salivary gland or duct and the subsequent development of severe ipsilateral peripheral dental caries. Ultrasonographic examination of the parotid salivary gland and duct was indicative of parotid glandular atrophy in one case and demonstrated parotid duct obstruction in the second case. To the authors' knowledge, the effects of the loss of function of the parotid salivary gland on the horse's dentition has not been documented and should be considered as a potential side effect of surgical ablation of the parotid salivary gland.

Retrospective case review investigating the effect of replacing oaten hay with a non‐cereal hay on equine peripheral caries in 42 cases

“…5,12,13 There were a small number of cases where horses did deteriorate following the change to a non-cereal hay; however, two of these cases were likely due to the difficulties of assessing the peripheral caries from a single image (see Figure 3), where feed, image quality or lighting made it difficult to accurately assess the peripheral caries. The fact that some did not improve or even deteriorated also likely indicates the multifactorial nature of the condition with other factors such as water source, access to pasture, other dietary factors or concurrent dental or oral pathology 1,8,14 likely also contributing to the condition in these cases.…”

“…Equine peripheral caries is well known to affect the molars more commonly, and more severely than the premolars, 1,3,15,16 so more subtle changes may be more difficult to grade. This is likely due to the protective effect of the saliva bathing the premolars 3,14 due to the location of the opening of the parotid salivary duct and may also indicate variability in saliva composition as a reason for the variability in improvements in the premolar teeth.…”

“…These cases highlight the importance of ascertaining the potential causes of the peripheral caries, as they show the ability of the equine oral cavity to recover from even quite severe peripheral caries if the inciting cause is removed. This may be easier said than done in some cases as the condition has been shown to be multifactorial 1,3,8,9,14 and many factors (breed, sex etc.) cannot be changed.…”

“…4,9 Figure 2 shows the progression through recovery and shows quite clearly that equine dentition can recover from peripheral caries if the inciting cause is removed. While the author believes and studies have shown that breed, sex, saliva contribution, concurrent dental pathology 3,8,14 or perhaps an individual horse's susceptibility may make them more prone to the condition or afflicted to a greater degree, even severely affected cases can recover if the inciting cause is removed.…”

Presentation and management of advanced occlusal caries affecting the maxillary cheek teeth of four horses

“…The largest salivary glands communicate with the rostral aspect of the oral cavity (the parotid duct drain at the level of the maxillary Triadan 08 teeth, mandibular salivary ducts under the tongue rostral to the Triadan 06 teeth), so it may be that the buffering capacity of saliva is higher in the rostral area of the mouth. Jackson et al (2019) described two cases of unilateral traumatic injury of the parotid duct and parotid salivary gland, where the horses subsequently developed a much higher grade of caries on the arcades where there was trauma to the gland/duct. Two studies have found that gross examination of equine peripheral caries underestimates the severity of the disease, compared to the histopathological findings (Borkent, Smith, & Dixon 2020;Erridge et al, 2012).…”