Anaemia in Ruminants Caused by Plant Consumption

SIMPLE SUMMARY: Plant poisoning is an underdiagnosed condition affecting livestock, and is especially important in ruminants. It is necessary for the veterinary practitioner to consider these aetiologic agents when confronting anaemia in ruminants. Although many of these plants are well-known by veterinarians and farmers, their toxic effects remain unnoticed by many of them. Due to the poisonous clinical signs, anaemia caused by plant consumption should be divided into two groups: haemorrhagic disorders and haemolytic disorders. The knowledge of their presence and possible consumption of the plant, together with the clinical signs, will lead to early diagnosis and appropriate treatment of the affected animals. The objective of this review is to show and organise the plants that most frequently produce anaemia in ruminants based on the two groups previously described. ABSTRACT: Plant toxicology has affected animals throughout evolution. Plants have adapted themselves to the environment. This adaptation has led to the development of defensive strategies to avoid being consumed. Plants have several chemical compounds, which can cause deleterious effects on people or animals that consume them, causing a wide variety of clinical signs. Plants from various latitudes, both cultivated for human and animal feeding or decorative purpose and even wild growth plants are able to generate anaemia in ruminants. Coumarins or ptaquiloside predispose bleeding and haemorrhages, causing a haemorrhagic disease in affected animals. In this group, some important fodder plants, such sweet clover (Genus Melilotus spp.), or other weeds distributed worldwide, such as bracken fern (Pteridium aquilinum) of giant fennel (Ferula communis), are included. On the other hand, sulfur-containing chemicals (e.g., n-propyl disulfate and S-propyl cysteine sulfoxides (SMCOs)) may cause severe direct damage to the erythrocyte and their membrane, leading to their destruction and causing haemolytic anaemia in the animal. This review presents the most frequent intoxication by plants causing anaemia in ruminants. Toxic compounds, clinical signs, diagnosis and possible treatments are also presented.