Dogs eating poop

Question
I read your answer to this type of question, but had an additional question
about my dog (a 6 month old Schnauzer).  He is basically an indoor dog
eating Eukanuba dog food (which I assumed was a good brand).  But I know
he likes to run, so we let him loose in our unfenced yard sometimes just to
get some energy out.  If he is eating deer and coyote poop in the yard, can
he get diseases and perhaps transfer them to us?  I try to discourage him
from doing it, but then it becomes a game where he grabs it, runs away, I
chase, he eats it quickly and runs back for more.  I know I should ignore it in
order to stop playing with him about that, but I am worried about disease.  
What do you recommend?  Thank you in advance.

Answer
You are helping him ingest this stuff by chasing him. You need to ignore him and teach him to 'leave it'. That is beyond what I can tell you here but get a trainer or a good book and teach that command. It is one of the best ones you can teach them.

He can get many things from eating coyote poop- roundworms, tapeworms, who knows what else.

As far as deer poop goes, thousands of dogs here eat that and I don't know of any worms they can get but deer carry things such as leptospirosis which affects the kidneys and liver and can be fatal to dogs and make people very sick. So yes, you should be concerned and he needs to stop it. While deer are not the vectors of the disease, they can carry it when they urinate into water and onto the ground.

Dogs then pick it up by eating things off the ground and possibly in the stool.

Some facts about leptospirosis

What causes leptospirosis?
Leptospirosis is caused by spirochete (or spiral-shaped) bacteria called leptospires. The leptospires live in fluids from infected animals, including urine, saliva, blood and milk.

What are the symptoms?
In general, the disease resembles the flu with fever, headache, chills and myalgia (muscle pain).

How is leptospirosis treated?
Dogs are treated with a course of antibiotics and with intravenous fluid to overcome dehydration. Diagnosis is based on clinical signs and laboratory tests.

Do humans catch leptospirosis?
Leptospirosis is a so-called zoonotic disease that can be transmitted from animals to humans. People can catch the disease from water that is contaminated by infected wild or domestic animals, as well as from more direct contact with animals, such as rodents, raccoons, skunks and cattle.

Why are cats not affected by leptospirosis?
Tests for antibodies show that some cats are exposed to the disease, but cats almost never show clinical signs of leptospirosis. Some experts believe that cats have developed a kind of immunity to leptospirosis from their longtime association with rodents.

Your best protection here is to clean up the yard before you let him out and stop chasing him around when he eats what he finds. If it is no longer a game then he will tire of it.
Teach him "leave it" and be FIRM when you say it. Think of a small child getting ready to put their hand on the wood stove. That is something you want to prevent!