The bite spot in dogs is usually their muzzle, especially among the curious ones that explore with their nose, and then accidentally come upon a black widows nest. The Black widow venom contains a number of toxic substances, and one of its components is neurotoxin. The bite itself is not painful, so the owners of dogs and cats hardly ever notice that their pet had been in contact with a poisonous spider. Unlike the turbulent reaction to a painful bee sting or a snake bite, an animal bitten by the Black widow shows no reactions at all.
In case of a Black widow bite the signs of intoxication will appear within an hour. People describe symptoms such as severe pain in the regional lymph nodes, and the bite site looks reddish and swollen.
After several hours the bite spot takes the form of a typical bluish coin circle, which can be easily missed in animals because of their fur. It is also hard to recognize when the animal is in pain, but the main symptom is definitely a distinct discomfort and sometimes painful whimper.