Arsenic
Cattle readily eat arsenic compounds. They will eat grass sprayed with monosodium methanearsonic acid (MSMA). Cattle will also ingest calcium arsenate powder and liquid sodium arsenite herbicide still found in old farm buildings. All of these materials are highly toxic to livestock.
Arsenic damages small blood vessels, which affects the blood supply, to major organs. Membranes of the digestive tract are inflamed causing diarrhea, abdominal pain, thirst, weakness and collapse. Because of these symptoms, poisoned cattle are often found near a water source or in a pond or ditch. Death may come quickly with no lesions seen during a necropsy (autopsy). If an animal survives for 7 to 10 days, it may then die of kidney failure. There is no practical, effective antidote.
Confirmation of arsenic poisoning requires analysis of blood, urine, liver, kidney and stomach samples. The suspected source of the poisioning must also be examined. Locating and confirming the source of arsenic may be as easy as sampling forages where an herbicide was applied or finding evidence of where a can leaked or a spill occurred,
Organochlorine Insecticides
Organochlorine insecticides include DDT, lindane, toxaphene, and heptachlor. Residues accumulated in the aquatic food chain, leading to harmful levels in fish-eating birds. Residues can also build up in the fat of livestock. Toxicity to livestock resulted from effects on the nervous system. Muscle tremors and twitches, seizures, and unusual behavior were signs of poisoning. Death is caused by respiratory failure during sustained seizures and/or high body temperature. Today, lindane and endosulfan have labels for uses in the garden. Endosulfan is a significant risk to cats, cattle and dogs due to its acute toxicity. One spring it was used as an aerial application in pecan orchards....and killed large numbers of cattle across the state.
Organophosphates and Carbamate Insecticides
This class of insecticides has been used on row crops and on animals including livestock and pets. There is a wide range of toxicity with OP’s. Malathion is one of the least toxic with terbufos (Counter), coumaphos (Co-ral), parathion, methyl parathion, guthion and di-syston being highly toxic. These compounds are absorbed through the skin, lungs, eyes, and from the digestive tract. Young animals and starved animals are more susceptible to poisoning. Their action is to bind with and block the enzyme cholinesterase which metabolizes the neurotransmitter acetylcholinesterase at nerve endings. This leads to overstimulation causing watering of the eyes, constricted pupils, constricted airways in the lungs, overactive intestines with diarrhea, and the skin may wrinkle continuously like a “bag of worms.” Death is the result of respiratory failure. OP’s containing chlorine atoms tend to be slowly eliminated from the fat and have caused prolonged signs of poisoning in cats and mature bulls. Chlorpyrifos is the best example. It was also discovered that certain families of Brahman cattle are more susceptible to cholinesterase inhibiting compounds.
Carbamates have a similar mode of action but the binding with cholinesterase molecules is reversible and a faster recovery can occur. Highly toxic carbamates like carbofuran (Furadan), aldicarb (Temik), oxamyl (Vydate), and methomyl (Lannate) have killed livestock and pets that were accidentally or deliberately poisoned. Concentration of a product is important...five percent (5%) sevin dust is labeled for dogs and plants is safe but probably doesn’t kill fleas but 50 % sevin will kill fleas and the dog.
Atropine by injection is the primary antidote used in livestock. Ruminants that have ingested toxic levels of insecticides are difficult to treat successfully because of the reservoir of toxicant in their stomachs. Recovery from OP poisoning can require days to weeks.
Sodium Chlorate Herbicide
Ingestion of concentrate or forages recently sprayed at rate of 12 pounds per acre is likely to cause fatal poisoning. The toxic action is oxidization of hemoglobin in red blood cell producing a brown pigment called methemoglobin. Red blood cells are destroyed, the blood, muscles, and urine are brown and inflammation of the intestines causes diarrhea. No specific labeled antidote is available, a veterinarian may have methylene blue solution for intravenous administration.
Paraquat
Forage sprayed at 2 pounds per acre may irritate the mouth of horses. Animals that consume concentrate would be at risk of poisoning. Dogs and cats will lick concentrate from their feet and may be fatally poisoned. Liver, kidney and progressive lung damage occur in dogs.
Amitraz
This miticide has labels for use on livestock (Tactic), in tick collars for dogs, and as a treatment for demodectic mange in dogs (red mange). Concentrated agricultural products are a distinct hazard to horses. Never apply to a horse. Amitraz causes severe colic in horses.
Pyrethroids
Avoid using row crop products on animals. The concentration and carriers make this hazardous. Pyrethroid poisoning in livestock treated with approved animal products is rare. Cats are severely poisoned by 40% spot-on type of dog products containing permethrin.
Proper disposal of unused pesticide products will prevent accidental animal poisoning.