ti Jan., 1909.] Diseases of Farm Animals. ^5 



DISEASES OF FARM ANIMALS. 



5. S. Cameron, M.R.C.V.S., Chief Veterinary Officer. 

 POISONINGS. 



OccLTRREN'CE IN Australia. — Evidence of plant poisoning. 



Classification. — Mineral, vegetable, animal — Irritant poisons — Narcotic poisons. 



Antidotes, mechanical, chemical, phj'siological. 



Mineral Poisonisos. Arsenic — Lead — Phosphorus — Mercury — Acids — Alkalies — Carbolic — Cyanide — Brine. 



Plant Poisonings- — Native Tobacco (tobacco blindness) — Strychnine — Nightshade — Sorghum — Homeria 

 (Cape Tulip) — Zamia — Tutu or "Toot" — Eaphorbium Drumniondii — Potato — Stinkwort — Yellow rash 

 lily — Castor plant — Indian Mutter— Native Lucerne — Darling Pea or Indigo — Other plants reputed as 

 poisonous to stock, exotic, indigenous. 



Moulds. —Rust — Smut — Scum — Fungi — Ergot of rye. 



Animal Poisonings. — Snake bite — licks. 



In Australia the subject of animal poisoning is vested with more than 

 ordinary interest, particularly that form of poisoning whicli is attributed to 

 the eating of noxious plants. As in all new countries, the vegetation is 

 unfamiliar, and consequently many plants which in reality are quite harm- 

 less are apt to be suspected as harmful to stock. There exists a tendency 

 to ascribe any sudden or considerable mortality amongst sheep or cattle 

 to the eating of some supposed poison weed. Even when the idea of any 

 particular plant being poisonous has been thoroughly discredited, as in the 

 case of Euphorbiiim Drunimondii and Black nightshade, the plant poison- 

 ing tradition still lingers. Oftentimes also, when no evidence is adducible 

 that poisonous plants have been eaten by stock, or that they even exist 

 on the pasture, the plant poison theory is stuck to. It affords the most 

 ready explanation of fatalities, and is consequently more acceptable to the 

 illiterate than any hypothesis regarding anthrax, blackleg or other con- 

 tagious disease, as accounting for the mortality. 



The minimum evidence that should be required before a reliable deter- 

 mination is come to that the cause of death is plant poisoning should 

 include : — ■ 



(a). The finding of undigested parts (leaves, stem, berries, etc.) of the 

 suspected plant mixed with the paunch contents. 



(b). The finding of evidence in the pasture that the suspected plant had 

 been recently nibbled or eaten in quantity sufficient (according to the 

 number of animals affected within a given time) to produce poisonous 

 effects. 



(c). The experimental feeding of other animals with the suspected plant 

 or the drenching of them with a decoction made from the plant. 



(d). The identification of the plant by a competent scientific authority 

 as a recognised poisonous plant, or, failing that, the finding of a dele- 

 terious poisonous principle on analysis, and in such quantity as to constitute 

 a poisonous dose. In the latter case the analysis must be corroborated by 

 experiments on animals. 



The statement may be ventured that, if these conditions are complied 

 with, not more than five per cent, of the reputed fatalities from eating poison 

 plants will be proved to have been so brought about. To hold this view 

 it is not necessarv to deny that many indigenous Australian plants possess 

 poisonous properties, nor that a large number of exotic poisonous plants 

 have been introduced and flourish here ; it is onlv necessary to know that 

 healthy animals but rarelv, either wittingly or unwittingly, eat vegetation 

 that is poisonous. Animal instinct is usually sufficient to prevent herbivorous 

 animals eating a sufficient quantity of noxious plants to produce toxic 



