Piling money into more social projects in a pre-election spending spree, Chavez has an edge in polls ahead of the vote.
Yet there is disillusionment among some "Chavistas", as his supporters are known, and surveys show that about a third of Venezuelans remain undecided.
An admirer of Brazil's model of free-market economics with a solid social conscience, Capriles insists he would keep the best of Chavez's welfare programs, and even build on them.
"I want to expand them, and get rid of the corruption and inefficiency that characterizes them," Capriles told Reuters on a recent campaign tour, adding that more than half the Barrio Adentro clinics in his Miranda state were abandoned.
That message, however, has not reached those in the queue for animal neutering in La Vega.
"The opposition wants to stop all this," said Hilda Jimenez, cradling a couple of cats. "Governments did nothing for the poor in the past. Only Chavez has bothered with us."
The opposition paraphernalia plastered all over middle-class Caracas neighborhoods was entirely absent from the tatty streets around her. Instead, the ubiquitous red of Chavez's ruling Socialist Party, and images of "El Comandante", were everywhere.
Down the hill, dozens lined up to shop in a state-run Mercal store, where basic products like milk, chicken, oil, rice, beans and sugar are sold at a quarter of the normal price.