Incidence, clinical signs, and videofluoroscopic swallow study abnormalities associated with airway penetration and aspiration in 100 dogs

Abstract

Background: Videofluoroscopic swallow studies (VFSS) utilizing penetration-aspiration (P-A) scoring assesses airway protection in people. On VFSS, penetration (ingesta or secretions immediately cranial to the vocal folds) and aspiration (material caudal to the vocal folds) are associated with increased risk of lung injury in people. Penetration-aspiration (P-A) scoring has been validated in animal models, but the incidence of P-A, clinical signs (CS), and dysphagic disorders associated with P-A in dogs are unknown.

Objectives: Using VFSS, identify the incidence of P-A, compare CS between dogs with and without P-A, and identify predisposing dysphagic abnormalities for P-A.

Animals: One hundred client-owned dogs.

Methods: Sequential VFSS and associated medical records from dogs presenting to the veterinary teaching hospitals at Auburn University (n = 53) and the University of Missouri (n = 47) were retrospectively reviewed. Statistical comparisons were made using Mann-Whitney tests, one-way analysis of variance (ANOVA) on ranks, multiple linear regression, and Spearman rank order correlation (P < .05).

Results: On VFSS, the incidence of pathologic P-A was 39%. No significant differences in CS were found between dogs with or without P-A (P > .05), with 14/39 dogs with P-A presenting without respiratory CS. Pharyngeal (P < .001) and esophageal (P = .009), but not oral-preparatory (P = .2) dysphagia was more common with P-A. Pharyngeal weakness (P < .001) and esophago-oropharyngeal reflux (EOR; P = .05) were independent predictors of P-A and were moderately and weakly positively correlated with P-A score respectively (P < .001, r = 0.489; P = .04, r = 0.201).

Conclusions: Penetration-aspiration occurs in dogs in the absence of respiratory CS (i.e., occult P-A). Dogs with pharyngeal weakness and EOR should be considered at risk for P-A.

Keywords: aerodigestive; dysphagia; pharyngeal; pneumonia; reflux.

FIGURE 1

Still images from VFSS of the same dog showing the epiglottis (E) in a resting position (A) and elevated protect the larynx (B). A 1 cm size marker is denoted by *. The head is oriented to the left and the tail to the right

FIGURE 2

Still images from videofluoroscopic swallow studies (VFSS) showing penetration (P) and aspiration (Asp). The head is oriented to the left and the tail to the right. A 1 cm size marker is denoted by *. A food bolus is present in the proximal esophagus (proximal E). In the left image (A), a large volume of liquid containing iohexol is found within the supraglottic space (cranial to the vocal folds) following an episode of extraesophageal reflux (EER). The contrast remains in the supraglottic space after the end of pharyngeal swallow (P‐A score: 4) and a new bolus (kibble) begins accumulating in the valleculae (K). In the right image (B), liquid containing iohexol is shown in the ventral aspect of the trachea (caudal to the vocal folds). No effort is made to eject the material (not shown in still image; P‐A score: 7). The bolus in the proximal esophagus in image B reflects multiple rapid swallow inhibition and is considered a normal variant. Epi, epiglottis

FIGURE 3

Still image from a videofluoroscopic swallow study (VFSS) showing spontaneous opening of the upper esophageal sphincter (UES) denoted by the bracket and asterisk (*). The opening is not associated with either pharyngeal swallow or eructation. A bolus of kibble is being formed within the valleculae (arrowhead). A residual bolus in the proximal esophagus (arrow) abuts the open UES