The pet food that has been in the news lately has caused many reported cases of nephrotoxicity. The compound believed to be the cause was identified today as Aminopterin . There is a very good summary of the chemical on Vetcetera, and a fact page on VIN.
Several ACVR diplomates have commented on the ultrasound findings in suspected cases. While preliminary, they may help to alert ultrasonographers to the possibility of acute renal failure.
Ultrasonographic signs of Aminopterin in dogs and cats include:
- moderate to marked renal cortical hyperechogenicity
- small amounts of perirenal fluid
- minimal pyelectasia (1-2 mm)
- poor corticomedullary distinction
- increased resistive index
- patches of increased echogenicity in the medulla (dog)
- small cortical cysts
While the cortical echogenicity, perirenal fluid and pyelectasia appear to be present in most cases, the other findings have been seen in one or two animals. Information from more cases will help to clarify the specific findings. Many of these findings are common in cases of acute renal failure, and several diplomates have commented that the hyperechoic cortex appears similar to cases of ethylene glycol toxicity.