Background: Venomous animal injuries remain a relevant cause of severe systemic disease in tropical and subtropical settings. Renal involvement may occur both in previously healthy kidneys, leading to acute kidney injury (AKI), and in chronically diseased kidneys, precipitating severe decompensation and dialysis dependence. Objective: To describe four clinical cases illustrating the spectrum of renal involvement associated with venomous animal injuries, ranging from dialysis-requiring AKI to severe decompensation of pre-existing chronic kidney disease (CKD). Cases: We report four patients treated at a regional referral hospital in Paraguay. Case 1 involved a 44-year-old man with Loxosceles bite complicated by necrotizing fasciitis, septic shock, and AKI requiring 10 hemodialysis sessions, with fatal outcome after referral. Case 2 was a 33-year-old man with multiple wasp stings who developed anuric AKI, severe metabolic acidosis, hyperkalemia, respiratory failure, and death after 9 hemodialysis sessions. Case 3 involved an 81-year-old man with Bothrops snakebite and severe AKI requiring 12 hemodialysis sessions, with subsequent clinical and biochemical improvement. Case 4 was a 48-year-old man with probable spider bite and soft tissue infection, in whom advanced hypertensive CKD suffered severe metabolic and uremic decompensation, requiring repeated hemodialysis and progression toward chronic dialysis support.