I think I’m just going to let the description of SHAT by S. Lawrence Parrish speak for itself:
In a post-plague world where plants have suffered as much as animals, a colony of human survivors has gathered in a fortified former-luxury condominium complex they call “The Park”. These remnants of humanity are inextricably bound to their domestic cats, from which Dose (a temporary plague vaccine) is derived.
A forager army is rumored to be heading toward The Park. The Park people must prepare to defend themselves and all they have worked for, because they have made a discovery: not all cats are created equal; while regular Dose only staves off plague symptoms, the dose derived from Simon, The Park’s only Siamese cat, can be refined into SHAT, a super-dose that rejuvenates the growth of plant life. . . and which also may hold the secret to a permanent plague-cure. Problem: Simon is a neuter. If he should die, so, too, dies humanity’s one hope for survival.
Enter Sasha, a purebred female Balinese of breeding age that also produces SHAT. With the sky-rocketing tensions of increasing militarization, Sasha’s humans want to take their cat and leave The Park. But The Park people will use whatever means necessary to make them stay.