Spider bumps cause large swollen bumps on the dog's skin. If the dog is bitten on the nose or mouth, it can have trouble breathing. Spider bites are extremely painful, and the dog can exhibit signs of pain. Although most spider bites do not penetrate the skin, black widow and brown recluse spider bites do, and they are extremely venomous, according to Pet Assure Newsletter.
If a dog has been bitten by a toxic spider, it can develop fever, weakness, muscle spasms and intense excitability. Black widow bites cause seizures, shock and death, according to WebMD. Even if a bite does not seem serious or deep, infections can still develop because of a dog continuing to scratch and lick the affected area. If a dog seems to be suffering from a spider bite, always take it to the veterinarian for confirmation and treatment. The vet prescribes an anti-venin to treat the bite and prevent symptoms from worsening or killing the dog.
However, without visible puncture marks, it is very difficult to confirm a spider bite diagnosis, states Best in Show Daily. Not all dogs develop symptoms, but those that do display severe reactions about eight to 10 hours after the initial bite. Brown recluse spider bites cause the dog's skin to die, alerting the owner.