New Imaging Insights for Diagnosing Antifreeze Toxicity in Pets

Ultrasonographic and Radiographic Findings of the Kidneys in Six Dogs and One Cat with Ethylene Glycol Intoxication

O. Eberlé, C. Pouzot-Nevoret, A. Barthélemy, B. Drumond, M. Harel, S. Belluco, E. Ségard-Weisse

Background:
Ethylene glycol, commonly found in antifreeze, is a highly toxic compound in dogs and cats, causing acute kidney injury (AKI) primarily via renal tubular necrosis and calcium oxalate crystal deposition. Traditional imaging findings have been described decades ago, but modern ultrasonographic advancements—especially the use of high-resolution linear probes—offer improved diagnostic precision. This study revisits the imaging characteristics of ethylene glycol intoxication, focusing on both ultrasonographic and radiographic features.

Methods:
This retrospective case series included six dogs and one cat diagnosed with ethylene glycol intoxication between 2009 and 2020. Inclusion criteria required confirmed diagnosis through history, ethylene glycol detection, or histopathology, along with completed abdominal ultrasonography. Radiographic assessments were performed in two dogs. Imaging findings were evaluated for medullary echogenicity changes, including the medullary rim sign (MRS), hyperechoic outer medulla (HOM), and medullary band sign (MBS).

Results:
Severe cortical hyperechogenicity was observed in all dogs, with one showing acoustic shadowing due to extensive calcification. MRS was the most common medullary abnormality, present in all dogs, while MBS and HOM were less frequent. The cat demonstrated severe HOM and MBS without MRS. Radiographs in two dogs showed diffuse kidney opacification, likely due to calcium oxalate crystal deposition. Notably, none of the imaging findings were pathognomonic, though their combination supported the diagnosis. Three animals survived, while three dogs died and one was euthanized.

Limitations:
The study's small sample size limits generalizability. Histopathological confirmation was limited to one dog, and imaging follow-up was sparse. Additionally, as a retrospective study, standardized imaging intervals and techniques were not uniformly applied.

Conclusions:
While no ultrasonographic or radiographic feature is exclusive to ethylene glycol poisoning, the presence of marked cortical hyperechogenicity, medullary abnormalities (especially MRS), and increased renal opacity on radiographs should prompt suspicion. Modern imaging techniques enhance diagnostic capabilities, reinforcing the importance of early recognition to improve outcomes in ethylene glycol intoxication.

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