Haemolytic crisis associated with ragwort poisoning and rail chewing in two thoroughbred fillies.

The study presents a case where two fillies (young mares) died due to a combination of ragwort poisoning and copper accumulation in the liver and kidney from chewing wood treated with copper chrome arsenate, culminating in a hemolytic crisis.

Background and Observations

• The paper revolves around the unfortunate death of two thoroughbred fillies. These young mares were at pasture—grazing and in open fields.
• The fillies had been fed hay that contained the flowering stages of Senecio jacobea or ragwort—a toxic plant for horses—three to four months before their death.
• Six horses on the property had a history of sporadically chewing on railings that had been treated with copper chrome arsenate.

Symptoms and Findings

• Both fillies exhibited signs of haemoglobinurea which is the presence of haemoglobin—the protein in red blood cells that carries oxygen—in urine. It is associated with kidney disease and damaging of red blood cells.
• Analysis of the liver and kidneys showed a high content of copper, with values at 83 mg/kg and 35 mg/kg of wet weight respectively.
• The serum also contained a higher than normal amount of copper, recorded at 1.4 mg/l.

Ragwort Poisoning and Copper Accumulation

• The evidence of seneciosis, a disease caused by ingestion of plants from the Senecio genus including ragwort, in combination with high copper levels in liver and kidney tissue, led to the conclusion that the fillies had suffered from ragwort poisoning followed by copper accumulation in organs.
• This sequence of events escalated into a haemolytic crisis—destruction of red blood cells faster than they can be recreated by the body—leading to the fillies’ deaths.

Source of Copper

• The study found the source of copper to be the treated wood in the paddock. The railings chewed by the horses contained copper concentrations of 0.17% at the core and significantly higher levels, 1.68%, in the shavings from the surface.
• This unintended intake of copper from chewing the treated wood combined with the ragwort poisoning may have triggered the fatal health complications.