An early sign of a spider bite on a dog is swelling at the site of the bite. Upon close inspection, puncture wounds or an abnormal lesion may be visible. There may be redness and indications that the dog is in pain by excessive licking.
The most vulnerable places on a dog for spider bites are those not covered by thick fur, including the ear flaps, eyelids, nose and mouth.
Once bitten, symptoms begin to appear and vary from dog to dog, depending on potency of the bite. There may be sharp pain at the puncture site followed by weakness, fever and muscle tremors. As the toxins move through the dog’s body, other symptoms such as rigid muscles, tremors, a lack of coordination and anxiousness can occur. Blood pressure and heart rate may increase, and respiratory failure often occurs.