Hemorrhagic diathesis, mesenteric hematoma, and colic associated with ingestion of sweet vernal grass in a cow

Abstract

A 4-year-old Holstein cow from a farm where 2 cows had recently died suddenly was referred for evaluation of acute severe colic. Right flank laparotomy revealed a large mesenteric hematoma. Within 14 layer chromatographic analyses of the moldy hay and blood from the necropsied cow and the hospitalized cow were positive for dicumarol. A diagnosis of sweet vernal poisoning was confirmed on the basis of clinical and toxicologic findings. The cow was treated with supportive therapy, blood transfusions, and vitamin K1 and recovered without complications. Because sweet vernal grass is becoming common in certain areas and the use of round bales is commonplace, practitioners should be aware of the potential for this toxicosis.

Dicoumarol toxicity in neonatal calves associated with the feeding of sweet vernal(Anthoxanthum odoratum)hay

“…9 Sweet vernal grass is reported to make up 5 to 10% of the pasture in Great Britain, 9 and up to 14% in Victorian pasture (Hamilton Laboratories, personal communication). Hay samples that contained up to 80 to 90% of sweet vernal grass were found in cases from the United Kingdom and North America, 9,10 substantially higher than in the current report. Higher levels of dicoumarol toxin are reported in the outer section of the hay bales, probably as a result of increased levels of oxygen available for fungal growth.…”

“…Higher levels of dicoumarol toxin are reported in the outer section of the hay bales, probably as a result of increased levels of oxygen available for fungal growth. 2,10 This may explain why not all calves were affected, as the inside of the hay bales may not have contained sufficiently high levels of dicoumarol to affect cows or their calves. Dicoumarol was not present in a milk sample collected from a cow that had calved 3 days after consuming the toxic hay.…”

“…14 The use of a small gauge needle is recommended to prevent haemorrhage at the injection site. 10,15 We treated any calves showing abnormal clinical signs with once daily 2.2 mg/kg bodyweight of vitamin K1 (Koagulon) IM. Calves responded if treated immediately signs developed, often progressing from clinical recumbency to clinically normal within 2 to 3 days.…”

Acute hemorrhage and death in calves following chlorophacinone exposure

“…However, dicoumarol-associated hemorrhage has also been reported in cattle consuming sweet vernal grass (Anthoxanthum odoratum). 2,12 To our knowledge, there is only one prior report of chlorophacinone intoxication in cattle. 4 In February 2021, sudden death was reported over 5 d in fourteen 1.5-mo-old, crossbred calves.…”