Sorry to hear about J.J.
You have probably already scoured the internet and available info, but here is some good info on organophosphate poisining from the Merck Vetrinary Manual:
Organophosphates (Toxicity): Insecticide and Acaricide (Organic) Toxicity: Merck Veterinary Manual
Treatment is at the end of the article:
"Three categories of drugs are used to treat OP poisoning: 1) muscarinic receptor–blocking agents, 2) cholinesterase reactivators, and 3) emetics, cathartics, and adsorbents to decrease further absorption. Atropine sulfate blocks the central and peripheral muscarinic receptor–associated effects of OPs; it is administered to effect in dogs and cats, usually at a dosage of 0.2–2 mg/kg (cats at the lower end of the range), every 3–6 hr or as often as clinical signs indicate. For horses and pigs, the dosage is 0.1–0.2 mg/kg, IV, repeated every 10 min as needed; for cattle and sheep, the dosage is 0.6–1 mg/kg, one-third given IV, the remainder IM or SC, and repeated as needed. Atropinization is adequate when the pupils are dilated, salivation ceases, and the animal appears more alert. Animals initially respond well to atropine sulfate; however, the response diminishes after repeated treatments. Overtreatment with atropine should be avoided. Atropine does not alleviate the nicotinic cholinergic effects, such as muscle fasciculations and muscle paralysis, so death from massive overdoses of OPs can still occur. Including diazepam in the treatment reduced the incidence of seizures and increased survival of nonhuman primates experimentally.
An improved treatment combines atropine with the cholinesterase-reactivating oxime, 2-pyridine aldoxime methochloride (2-PAM, pralidoxime chloride). The dosage of 2-PAM is 20–50 mg/kg, given as a 5% solution IM or by slow IV (over 5–10 min), repeated at half the dose as needed. IV 2-PAM must be given very slowly to avoid musculoskeletal paralysis and respiratory arrest. Response to cholinesterase reactivators decreases with time after exposure; therefore, treatment with oximes must be instituted as soon as possible (within 24–48 hr). The rate at which the enzyme/organophosphate complex becomes unresponsive to reactivators (due to ageing phenomenon) varies with the particular pesticide.
Removal of the poison from the animal also should be attempted. If exposure was dermal, the animal should be washed with detergent and water (about room temperature) but without scrubbing and irritating the skin. Emesis should be induced if oral exposure occurred <2 hr previously; emesis is contraindicated if the animal is depressed. Oral administration of mineral oil decreases absorption of pesticide from the GI tract. Activated charcoal (1–2 g/kg as a water slurry) adsorbs OPs and helps elimination in the feces. This is particularly recommended in cattle. Continued absorption of OPs from the large amount of ingesta in the rumen has caused prolonged toxicosis in cattle. Artificial respiration or administration of oxygen may be required. Phenothiazine tranquilizers, barbiturates, and morphine are contraindicated."