Let's hope you never have to deal with rhododendron poisoning. The signs in sheep and goats include spectacular vomiting and intense pain. A few hours after eating rhododendron, the animal is in agony, rumen heaving, and it's plastering the shed walls with green vomit. It's a horrible thing to deal with.
If you are faced with rhododendron poisoning, you must first call your vet and then try to get some activated charcoal into the animal by mouth. It can be difficult to feed them anything when they are vomiting, and you will get covered with green-black foul-smelling gunk!
It's important to keep giving the animals activated charcoal every hour or so for the first 6 to 12 hours, especially when they are regurgitating because they will be losing much of it each time. The actual dose rate will vary with the formulation so read the instructions on the label and give the dose you'd use for a human of the same weight as the animal. This binds the poison and helps prevent further absorption of it, but after 24 hours it's probably not going to do much good.
Your vet may give the animal atropine by injection to help counteract the slowing of the heart rate and drop in blood pressure that the poison causes. He may also give painkiller injections as required.
It seems likely that if you can keep your poisoned goats alive for 24 to 48 hours they have a good chance of survival, as long as they haven't inhaled vomit, in which case they are likely to develop inhalation pneumonia.
My partner and I had the unfortunate experience of dealing with two of our Anglo-Nubian goats that had accidentally been fed a heap of rhododendron prunings. As well as a prompt veterinary treatment it took 48 hours of intensive nursing, but they both recovered fully.
Here's what we did.
We dosed the animals with activated charcoal every hour or so for the first 6 hours then occasionally for the next 6 hours.
When the vet arrived he injected both goats with atropine. He visited several times a day for the first 24 hours to give painkillers by injection, and this seemed to ease the goats' distress quite a lot. The vet also gave the most severely affected goat a litre of electrolyte by injection into the vein and under the skin.
We kept the goats warm in a shed with plenty of bedding, and we gave other supportive treatments - 10 ml brandy as a tonic and 25 ml vegetable oil to soothe the rumen. In retrospect, we should also have given Milk of Magnesia because there are reports of that being a helpful treatment too.
After 48 hours, things started to improve rapidly and we were able to rest!
All in all, it's better to prevent rhododendron poisoning if you can! Let everyone who works in your garden know the risks and keep your paddock gates closed.
Cattle and horses can be poisoned too and they seem to find rhododendron quite tasty. Within a few hours of eating it they will be in pain with colic and they may be trembling and distressed. Horses can't vomit as ruminants can, so they can't get rid of the plant from their stomach. You will definitely need veterinary help with them.