USA Today, 9/18/02, "Illinois Reports 1st West Nile Case in a Dog," pg. 3A.
To summarize: the dog was an 8yo Irish Setter/Golden Retriever mix. There's some conjecture that the dog's immune system may have already been compromised but there's no definitive certainty that that was the case.
"Officials do not expect an epidemic of the virus in household pets, but they caution that older dogs, puppies and dogs that already have weak immune systems could be at risk." (my emph).
The only other confirmed dog-related WN death was in 1978 in Botswana, Africa.
"Squirrel populations nation-wide could be affected....
"Infected squirrels have been reported vocalizing with sounds that indicate they are in pain. Other symptoms include running in circles, biting their paws and falling off tree limbs....
Canine Symptoms: "The infected dog showed neurological symptoms, including unusual head bobbing, lethargy and progressive weakening.
Precautions "Andrews [Dir. of the Vet Diagnostic Lab at U. of I, Urbana-Champaign] recommends pet owners avoid walking at-risk dogs in areas with lots of mosquitoes and keep them indoors in the evening. He says to avoid putting insect repellent on dogs because they lick it off and ingest it. Researchers are developing vaccines for domestic animals."