Comparison of lung ultrasound, chest radiographs, C-reactive protein, and clinical findings in dogs treated for aspiration pneumonia

Abstract

Background: Comparison of clinical findings, chest radiographs (CXR), lung ultrasound (LUS) findings, and C-reactive protein (CRP) concentrations at admission and serial follow-up in dogs with aspiration pneumonia (AP) is lacking.

Hypothesis: Lung ultrasound lesions in dogs with AP are similar to those described in humans with community-acquired pneumonia (comAP); the severity of CXR and LUS lesions are similar; normalization of CRP concentration precedes resolution of imaging abnormalities and more closely reflects the clinical improvement of dogs.

Animals: Seventeen dogs with AP.

Methods: Prospective observational study. Clinical examination, CXR, LUS, and CRP measurements performed at admission (n = 17), 2 weeks (n = 13), and 1 month after diagnosis (n = 6). All dogs received antimicrobial therapy. Lung ultrasound and CXR canine aspiration scoring systems used to compare abnormalities.

Results: B-lines and shred signs with or without bronchograms were identified on LUS in 14 of 17 and 16 of 17, at admission. Chest radiographs and LUS scores differed significantly using both canine AP scoring systems at each time point (18 regions per dog, P < .001). Clinical and CRP normalization occurred in all dogs during follow up. Shred signs disappeared on LUS in all but 1 of 6 dogs at 1 month follow-up, while B-lines and CXR abnormalities persisted in 4 of 6 and all dogs, respectively.

Conclusion and clinical importance: Lung ultrasound findings resemble those of humans with comAP and differ from CXR findings. Shred signs and high CRP concentrations better reflect clinical findings during serial evaluation of dogs.

Keywords: acute phase proteins; canine aspiration pneumonia score; community-acquired pneumonia; point of care ultrasound; simplified canine aspiration pneumonia score.

FIGURE 1

Division of a lateral CXR into 9 regions grossly corresponding to the recorded LUS regions

FIGURE 2

Chest radiographs scores according to the CXR‐CAPS, as described in Table 2, at each time point. Percentage of regions with different CXR scores according to the CXR‐CAPS at admission (T0, n = 17, 306 regions), 2 weeks (T1, n = 13, 234 regions), and 1 month (T2, n = 6, 108 regions) after diagnosis

FIGURE 3

Percentage of regions classified as showing no lesions (score 0), an interstitial pattern (score 1), or an alveolar pattern (score 2) according to the CXR‐sCAPS at admission (T0) (n = 17, 306 regions), 2 weeks after diagnosis (T1) (n = 13, 234 regions), and 1 month after diagnosis (T2) (n = 6, 108 regions)

FIGURE 4

Lung ultrasound scores according to the LUS‐CAPS, as described in Table 3, at each time point. Percentage of regions with different LUS scores according to the LUS‐CAPS at admission (T0, n = 17, 306 regions), 2 weeks (T1, n = 13, 234 regions), and 1 month (T2, n = 6, 108 regions) after diagnosis

FIGURE 5

Percentage of regions classified as showing no lesions (score 0), B‐lines (score 1), or lung consolidation (shred sign or air/fluid bronchogram, score 2) according to the LUS‐sCAPS at admission (T0) (n = 17, 306 regions), 2 weeks after diagnosis (T1) (n = 13, 234 regions), and 1 month after diagnosis (T2) (n = 6, 108 regions)

FIGURE 6

Still image and schematic of a LUS in a dog with aspiration pneumonia. 1: Pleural line; 2: Coalescent numbers of B‐lines; 3: Lung tissue visible because of severe decrease in aerated lung; 4: Shred sign; 5: Fluid bronchogram (longitudinal image); 6: Air bronchogram (longitudinal image) and Air bronchograms (transverse image)

FIGURE 7

Serum C‐reactive protein (CRP) concentrations at each time point. Box plot showing CRP concentrations in dogs presented with aspiration pneumonia at admission (T0) (n = 17, mean (+): 129 mg/L, median (−): 137 mg/L, range, 24‐267 mg/L), 2 weeks after diagnosis (T1) (n = 13, mean (+): 7 mg/L, median (−): 5 mg/dL, range, 3‐32 mg/L), and 1 month after diagnosis (T2) (n = 6 dogs, mean (+): 5 mg/L, median (−): 5 mg/dL, range, 3‐8 mg/L)