The next day, Neville notices that his sun lamp has killed the vampiris germs in his slides. He tries to kill the vampiris bacterium—taken both from living vampires and from dead vampires—with allyl sulphide (the chemical found in garlic), but to no avail. He becomes frustrated again, and eventually becomes so unstable that he knocks over the microscope. He tries to console himself by thinking about everything he’s learned so far: 1) there is a vampiris germ; 2) the people who have the germ are sensitive to sunlight and garlic; 3) the people with the germ can be killed with wooden stakes. Neville makes a list of all the aspects of the vampire germ that need explanations: mirrors, garlic, germs, running water, crosses, etc. He tries to work, but finds himself craving a drink. Angry, he drinks directly from a whiskey bottle until he’s very drunk.
At times, Neville’s scientific investigations comfort and reassure him that his life if worth living. However, Neville often becomes impatient and restless: he wants to know everything about vampires, right now. Neville tries to force himself to remain calm, and gradually accumulate more information about his enemies. But in the end, he gives in and pours himself a glass of whiskey. Tragically, Neville’s curiosity about vampirism isn’t enough to stave off his alcoholism and depression.
Neville have continued to drink himself to death, the narrator notes, had it not been for a “miracle”—after a few days of drinking heavily, he hears a noise outside during the day. Neville finds a dog roving about on the lawn. Although Neville knows from experience that dogs can become vampires, it’s obvious to him that this is no vampire—it seems to be an ordinary animal. Neville calls the dog toward him, but the dog runs away. He tries to follow the dog, but then it occurs to him that the dog might be afflicted with the vampire germ, and therefore is already sensitive to Neville’s garlic. But how, then, could the dog be roaming around during the day?
Neville is desperate for contact and companionship of any kind, even with a pet, so he’s extremely excited when he encounters the dog. The arrival of the dog is the first sign that creatures (including, perhaps, human beings) can both be infected with the vampire germ and survive during the daylight.
It also occurs to Neville that, if he doesn’t try to help the dog, the vampires will kill it at night. He leaves a bowl of milk and some hamburger meat outside for the dog, and surrounds it with garlic so that the vampires won’t touch it. The thought of the dog’s death makes Neville conscious of his own mortality. He wonders how much longer he’ll be living in Los Angeles, fighting off the vampires every day—perhaps for another thirty or forty years. Much to his own surprise, Neville finds himself praying for the dog’s survival. He realizes that he “needed the dog.”
Many people who’ve survived prolonged isolation report that they developed imaginary friends, or formed a close emotional bond with animals or inanimate objects. Human beings need companionship, even if this companionship is largely imagined. Thus, it’s revealing that Neville almost immediately feels a close connection with the dog: even though the dog might be a vampire, Neville sees himself and the dog as engaging in the same struggle for survival. Thus, by taking care of the dog, Neville is really taking care of himself, in the sense that he’s giving himself a purpose to go on living.