7 year-old, Male, Neutered, Cocker Spaniel

History: One day history of coughing, progressed to labored breathing. No prior medical problems.

Left Lateral
Right Lateral

Questions to ask yourself:

  1. Does the lack of prior medical problems affect the differentials?
  2. Can the tracheal collapse be related to the pleural and mediastinal effusion?
  3. What specific tests should be run and what history can be asked?
  4. What Radiation Safety Violation was committed during this study?


FINDINGS: The cardiac silhouette is normal in size and shape.  The pulmonary vessels are narrowed.  There is severe, diffuse narrowing of the trachea.  A small volume of pleural fluid is present, causing retraction of the ventral lungs, increased soft tissue opacity in the ventral thorax, and small pleural fissure lines.  The lungs are incompletely expanded, resulting in a mild diffuse interstitial lung pattern.  No focal pulmonary parenchymal abnormalities are identified. The cranial mediastinum is wide on the ventrodorsal view.  No abnormalities are detected in the limited view of the abdomen.  No skeletal abnormalities are identified.

CONCLUSIONS: The diffuse narrowing of the trachea is of uncertain cause.  Although rare, there are cases of hemorrhage within the dorsal tracheal membrane secondary to a coagulopathy, which could also explain the small volume of pleural fluid (i.e hemothorax).  Other causes of a narrowed trachea including severe infectious tracheitis or dynamic tracheal collapse are not excluded.  Additionally, other causes of pleural fluid including vasculitis, hypoproteinemia, chylothorax or malignant effusion are not ruled out. The wide mediastinum could also be the result of hemorrhage. The narrowed pulmonary vessels are suggestive of dehydration/hypovolemia.

RECOMMENDATIONS: A platelet count and coagulation panel are recommended.  If a coagulopathy is not present, ultrasound-guided thoracocentesis may be considered.  Additionally, airway sampling via tracheoscopy may be beneficial for cytology and culture/sensitivity.  Depending on the results of those exams, fluoroscopic evaluation of the trachea may be considered to assess for any evidence of dynamic tracheal collapse.

Follow up: A coagulopathy was confirmed and the patient did indeed have exposure to rodenticide. He is doing well with treatment.

References:Berry CR et al. “Thoracic radiographic features of anticoagulant rodenticide toxicity in fourteen dogs.” Veterinary Radiology & Ultrasound 34.6 (1993): 391-396.
Blocker TL and Roberts BK. “Acute tracheal obstruction associated with anticoagulant rodenticide intoxication in a dog.” J Small Animal Practice 40.12 (1999): 577-580.
Lawson C, O’Brien M, and McMichael M. “Upper Airway Obstruction Secondary to Anticoagulant Rodenticide Toxicosis in Five Dogs.” J American Animal Hospital Association 53.4 (2017): 236-241.
Pardali DS et al. “Acute tracheal narrowing presumptively associated with anticoagulant rodenticide intoxication in a dog.” J Hellenic Veterinary Medical Society 62.3 (2011): 235-239.
Thomer AJ and Santoro KB. “Anticoagulant rodenticide toxicosis causing tracheal collapse in 4 small breed dogs”. J Veterinary Emergency and Critical Care (2018): 28(6), 573-578.


  1. Findings: There is diffuse intra- and extrathoracic tracheal narrowing. The cranial mediastinum is widened with soft tissue opacity and there is a small volume of bilateral pleural effusion. Subjectively, there is thickening of the soft tissue in the region of the thoracic inlet, but not sure if this is a real finding.

    Conclusions: Given the acuteness of clinical signs and signalment, my primary conclusion is that this is an example of anticoagulative rodenticide toxicity with mediastinal, pleural, and trachealis hemorrhage of the tracheal membrane, causing diffuse tracheal collapse. Trauma would be on my list if there were signs of trauma.

    Recommendations: CBC and coagulation profile

  2. The trachea is very narrow in a whole length. The cranial mediastinum is wide and of soft tissue opacity; signs of a small amount of pleural effusion. The heart and vessels look normal. From the DV view, the tracheal bifurcation seems wider, but no signs of left atrial enlargement are seen from LL views. Also the perihilar region has increased opacity. The surrounding of the thorax is normal.
    The liver silhouette is smaller.

    1. I think not.
    2. Yes. The cause of all three symptoms could be bleeding.
    3. Bloody clotting tests should be done. Owners need to be asked about access to the anticoagulants and the possibility of its ingestion.
    4. The finger of a person restraining the dog is on the right side of the image.

    Based on these my first differential is bleeding because of possible anticoagulant rodenticides ingestion.

  3. Hello! Cool case!
    Here’s a brief summary of my thoughts:

    Diffuse and severe narrowing of the tracheal lumen greatly affecting the region of the thoracic inlet.
    Diffuse mediastinal widening.
    Moderate amount of soft-tissue opacity material within the pleural space producing mild retraction of the pulmonary parenchyma, multiple fissure lines and effacement with the cardiac silhouette.
    Diffuse increased opacity of the cranioventral lung lobes on the lat projections.
    Minimal amount of gas within the esophagus.
    No other significant findings.

    Diffuse and severe tracheal collapse.
    Pleural and mediastinal effusion.

    Given the relatively acute onset of clinical signs without prior history of medical issues, the radiographic findings are highly suggestive of a rodenticide toxicity – submucosal tracheal hemorrhage, hemothorax and mediastinal hemorrhagic effusion. The interstitial pattern within the cranioventral lung lobes on the lat projections is likely artefactual due to superimposition of the mediastinal/pleural fluid. Other differentials are considered much less likely.
    **Human phalanxes are visible holding the patients right forelimb on the DV projection

  4. Right and left lateral, as well as dorsoventral projections of the thorax of a skeletally mature dog with increased body condition.

    On the DV Projection, on the top left corner of the radiograph (right side of the dog) a finger of the holding person can be identified.

    The thoracic volume is normal.

    The entire mediastinum is severely widened (mostly the cranial medistinum) and has a mild heterogeneous soft tissue opacity.
    The trachea is displaced to the right and severely narrowed through its entire length by a dorsal sharp soft tissue opacity (region of the tracheal band / tracheal membrane).
    In the cranial thorax, there is a large, amorphous, ill-defined soft tissue space occupying lesion (best seen on the right lateral projection), which moderately caudally displaces the cranial lung lobes. The cranial lung lobes have rounded margins and are mildly retracted from the parietal pleura.
    In the ventral thorax, there is a moderate accumulation of heterogeneous soft tissue opaque material.

    The heart silhouette cannot be completely delineated. This is not enlarged. The lung vessels are unremarkable.
    Mild increased soft tissue opacity in the hilar region. The remaining lung parenchyma is unremarkable.

    The musculoskeletal structures are unremarkable.

    The diaphragm is delineable.
    The peritoneal detail is normal.
    The depicted Abdomen is unremarkable.

    Radiographic diagnosis:
    Moderate to severe mediastinal effusion.
    Suspicion of mild to moderate pleural effusion.
    Suspicion of thickening of the tracheal membrane.

    The radiographic findings are highly suspicious for a (rodenticide) coagulopathy with multifocal bleedings (hemomediastinum, hemothorax, bleeding in the region of the tracheal membrane).
    Much less likely: bicavitary effusion caused by neoplasia, soft tissue space occupying mass in the mediastinum with secondary pleural effusion.

    The increased perihilar lung opacity is most likely caused by the mediastinal effusion. Less likely: focal lung bleeding.

    A bleeding time / coagulation test (e.g. PT) is advised.

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