Common Nephrotoxins
Nephrotoxins are substances that are known to impair renal function and to cause acute renal failure if present in sufficient doses. The following are common equine nephrotoxins.
Phenylbutazone
Phenylbutazone is a NSAID that is commonly called “bute”. If used over long periods or in high doses it causes ischemic necrosis of the tubular epithelial cells by inhibiting the release of . Bute is also known to be directly cytotoxic to renal tissue cells. Horses given bute that are also geriatric, dehydrated or of a pony breed are predisposed to renal damage.
Aminoglycoside Antibiotics
Aminoglycoside antibiotics are a class of broad-spectrum antibiotics. The most well know of this class is . These antibiotics are directly cytotoxic to the renal tissue cells. Foals, dehydrated horses and horses suffering from acidosis or endotoxemia are predisposed to renal damage.
Endogenous Pigments
The endogenous pigments both can trigger vasoconstriction of the renal arteries, leading to ischemic necrosis of the renal tissue. Erythrolysis, exertional rhabdomyolysis and dehydration all increase the probability of renal damage. and
Toxic Plants
The ingestion of onions or red maple leaves causes and erythrolysis releasing the nephrotoxins haemoglobin into circulation where it can affect blood flow to the kidneys. If either of these plants is ingested in significant quantities, the urine will appear maple syrup coloured.
Canthardin Toxicity
Canthardin toxicity, commonly called poisoning, involves the ingestion of the caustic chemical canthardin. This chemical enters the kidneys from the circulation where it irritates the renal endothelium causing nephritis and renal congestion.
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