Toxic Wasting Disorders in Sheep

Abstract

Infectious and parasitic agents have been frequently associated with debilitating and wasting conditions in sheep. The prevalence of these agents has probably undermined the role of toxic causes as contributors to such disorders. In addition, many of these intoxications frequently produce acute clinical disease with specific and characteristic lesions, thus a causal relationship with the toxic substance may be relatively easy to establish. However, persistent exposure to some of these organic or inorganic toxic substances may lead to emaciation, ill-thrift, and poor external aspect. The anti-nutritional factors and alkaloids of several plants, including pyrrolizidine alkaloids, among others, have also been associated with emaciation and/or poor general performance in sheep flocks. In this review, some of these disorders are discussed with an emphasis on clinical signs and lesions, relevant diagnostic aspects, and available therapeutic approaches. In most cases, demonstrating a history of exposure should be one of the most relevant aspects of the diagnostic approach, and removing the animals from the toxic source is the cornerstone of the majority of the treatment strategies.

Summer scour syndrome in weaned dairy calves: case series

“…No calf deaths were reported in the present study, suggesting that acute nitrate or NPN poisonings were unlikely causes of SSS. Nonetheless, it is also probable that SSS calves consumed grass that contained sub-lethal nitrate and NPN over time, causing chronic nitrate or NPN poisonings [ 39 ]. Chronic nitrate poisonings have been reported to cause reproductive problems in adult cattle [ 40 ]; however, to our knowledge no studies have reported effects on growing calves.…”

A form of hepatogenous copper poisoning in fattening cattle associated with the ingestion of mouldy straw

“…‘Hepatogenous copper poisoning’ 6 was described in sheep that developed hepatic pathology caused by the consumption of plants containing hepatotoxic alkaloids; this resulted in decreased liver copper storage capacity and the release of hepatic copper into the circulation, culminating in the acute haemolytic crisis of copper poisoning. Hepatogenous copper poisoning has been reported to be associated with the exposure to pyrrolizidine alkaloids in Senecio species, Echium plantagineum or Heliotropum europaeum plants 7–10 . It is possible that other hepatotoxic agents, which damage the liver's ability to store copper, could also have a similar effect.…”

“…Hepatogenous copper poisoning has been reported to be associated with the exposure to pyrrolizidine alkaloids in Senecio species, Echium plantagineum or Heliotropum europaeum plants. [7][8][9][10] It is possible that other hepatotoxic agents, which damage the liver's ability to store copper, could also have a similar effect.…”

Anaemia in Ruminants Caused by Plant Consumption

“…In the clinical approach to anaemia in ruminants, several causes must be ruled out: internal or external parasites (e.g., digestive parasites, fleas, lice), infectious (e.g., babesiosis, anaplasmosis, leptospirosis, clostridia toxins), metabolic (e.g., vitamin or mineral deficiencies, concurrent chronic diseases or neoplasias), haemorrhagic (e.g., trauma, dystocia, abomasal ulcers, vena cava thrombosis, haemorrhagic bowel syndrome), chemical poisoning (e.g., heavy metals, drugs, rodenticides) or less frequently immune-mediated anaemia (e.g., feeding new-born lambs ( Ovis aries ) with cows’ ( Bos Taurus ) colostrum) and diseases of bone marrow [ 10 , 11 ]. Usually, for the veterinary practitioner, it is difficult to diagnose and include anaemia caused by the consumption of plants in this list.…”