Doctors have long noticed the healing characteristic of pet animals - they seem to improve the health of patients, be they suffering injury, illness, or mental anomaly. While the biochemical proccesses of this phenomenon are well-known, that doesn't diminish the effect. Indeed, it has led to many innovations in health care. Patients may now get pets, be they dogs, cats, birds, or even more unusual creatures like snakes, scorpions, tarantulas, or creatures evolved on alien worlds, and these pets are designed to improve the health of the patient.
A medicinal pet is usually designed to be "cuter" than normal, perhaps by giving it cuter noises to make, by inducing mild to moderate neoteny, or by any number of other means. A hedgehog might not make cute chirpy noises, but a medicinal hedgehog will. Most of the more dangerous aspects of the pet are removed or altered - a scorpion is compelled not to sting the patient, while a kitten's claws are more dull. The animals then have pheremonal manipulations so that they produce calm, contentment, and a sense of ease in the patient. They have slight behavioral modifications to make them "cuddlier" (within limits - most people enjoy porcupines for reasons other than snuggling), to enhance the pheremonal effect.
In addition to pheremones, the medicinal pet has a lens installed that will cause it to induce memetic signals. The semiotic patterns of the animal's behavior are designed to make the owner feel as though things are going to go alright, or at least that things aren't hopeless. In cases where the patient is inevitably terminal, the pet will instead emit a sense of peace and wonder at the oncoming change in a patient's life, hopefully to replace the normal terror at the prospect of death. The pet is also given enough augmentation to be able to determine a rough cut of the patient's health, and can transmit to local emergency services if the patient's health needs attention or if the patient is no longer able to contribute to their own medical care (passed out, raving, etc.).
Truly advanced medicinal pets go a step further, producing an aggressive immune system in the form of a medical nanophage. This will disinfect wounds, sterilize hostile organisms, accelerate coagulation around minor wounds, and otherwise act as a nurse. Persons with an advanced medicinal pet count as having a full-time nurse attendant for the purposes of recovery, but the pet cannot function as an EMT (though it will, as stated above, summon emergency services if emergency care is needed).
Tech Level: Biotech 4, Cognitech 4, Metatech 4, Nanotech 3. For a pet that can function as a personal nurse, Biotech 6 and Nanotech 6.
Cost: Low to Public Domain, though the advanced nurse versions are technically available at lower tech levels for outrageous costs that neutralize any conceivable benefit they might offer.
Descriptors: Life Form.