I know what youre thinking. Why not skip all this rescuing brouhahathe chases and the panic and the risk of bitesand just, you know, drug the dog? (Just sayin.)
Heres why rescuers leave drugs and tranquilizers for a last resort. (And no, its not because theyre penance-loving masochists.)

ITS A GUESS-TIMATE
Tranquilizers are prescribed based on weight. If youre keeping your distance for fear of being bitten, you havent been close enough to judge the dogs weight right. And you really dont want to miscalculate. A wobbly, disoriented dog will be way less discriminatory when it comes to biting.
RISK OF OVERDOSE
Give them too little and it wont work; give them too much and you could kill them. At the very least, you could do serious harm. The dog could have all sorts of medical conditionsheartworm, for instance, or anything that reduces their lung or cardiac capabilities, or liver diseasethat could wreak havoc on the drugs effect.
RISK OF LOSING THE DOG
The dog wont conveniently pass out within your sight. When a dog begins to feel the effects of the tranquilizer, theyll look for a safe place (i.e., away from you) to crash. Youll need to follow, at a non-threatening distance, to avoid losing them.
YOURE ONLY POSTPONING THE INEVITABLE
Drugs arent the easy way out. If your reasoning for using drugs is based on the dogs aggressiveness, think again. Tranquilizers wont turn this Cujo into Lassie. Youll still have to deal with a mouthful of teethand an intensified motivation to use themwhen s/he wakes up.
So When does a rescuer administer tranquilizers?
When every other option has been exhausted. The dog hasnt responded to any sort of approach, every attempt to catch him/her has gone awry, s/he sees you (or any other rescuer) and bolts
And you (and the dog) are out of time.
Tranquilizers can be administered in one of two ways:
Dart Guns
PROS: Great choice for ferals that shy away from even the most conservative human contact. Because the drug goes in intramuscularly, and gets into the bloodstream faster, this is a fast-working tranquilizer.
CONS: You need a dart gun. And darts. With the right dose. And you need to be a very, very good shot. If you hit anything but pure muscle, you can kill the dog. Also, the sound of the shot will scare the dog away, which means itsliterallya one-shot deal. S/he wont be eager to get within twenty meters of you ever again.
Note how fast the dart workedand how far the rescuers had to follow the dog before she collapsed. (As a follow-up on the Botched post from Saturday, note how the dog reacted to the rescuer trying to touch her head. I have nothing but respect for this rescuer; hes awesome, and has amazing experience. His decision to go for her head was probably based on his assessment of her behaviorand she did accept it, in the endso its not a criticism of his method, just an illustration of how much dogs dislike the head pat.)
Pills
PROS: You dont need any special equipment. No chance of accidentally nicking an artery or otherwise harming the dog. No need to scare the dog with the gunshot sound; inserting them in a chunk of liverwurst or sausage or other nifty tidbit gives a good chance theyll be consumed.
CONS: They can end up eaten by the wrong animal. They also take longer to work than darts, which gives the dog more time to get away from you. Pills need to be absorbed by the digestive system, so theyll work best on an empty stomach; youll need to make sure the dog hasnt eaten, at least not much, before giving him/her the pills.
As with any other medication, you need to consult with a veterinarian regarding the dosage to administer. Gauging the dogs weight will be the main challenge; remember that long-haired breeds will tend to look heftier than short-haired ones, and larger breeds, even when emaciated, will probably weigh more than you think.
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Thank you so much for visiting, and for your interest in learning about dog rescue. As a disclaimer, let me say again: Im no expert. The only thing that qualifies me to talk about rescue is that, in a lifetime of doing it, Ive botched more than my share. Thats the learning Id like to pass on to those interested in rescue or getting involved in it for the first time. And, if you have your own rescue experiences or advice, Id love it if you shared. A fresh point of view is always welcome.