The Journal of ECT has a case report of patient who endured the terrifying delusion that her body was rotting away and being replaced by parts of a pig.
The lady concerned was admitted to hospital for surgery but later developed psychosis:
Approximately 4 weeks after the surgery, she started expressing somatic delusions that her entire body was slowly rotting away. She claimed that the bones in her body were replaced by those of a pig and her own body parts were decomposing. She expressed that she deserved the ‘punishment’ by God in this way (decomposing her body) because she did not perform certain religious rituals and did not take a promised pilgrimage. Over the next few days, she also voiced delusions referring to her children‚Äôs body parts being replaced by those with pig‚Äôs body parts.
The disturbing false belief is described as a simultaneous case of both Cotard delusion, where someone believes they are dead or their body is decomposing, and lycanthropy, where someone believes they are transforming or have transformed into an animal.
The patient was apparently successfully treated with electroconvulsive therapy (ECT) although the authors, who like their patient, are based in India, give an interesting cultural interpretation of the delusion:
Interestingly, no reports of metamorphosis into pig/swine have been reported earlier. The metamorphosis into pig in our case can be understood from the Indian culture and mythological importance of the same. According to the Bhagavad Gita, Indra, king of the Hindu gods, was once transformed into a pig for lack of respect to guru Brihaspati. The index case also had strong guilt of not being able to perform certain religious rituals and a promised pilgrimage, which is similar to lack of respect to god and being punished for the same.
However, this is not the first case of a patient with simultaneous Cotard and lycanthropy delusions in the medical literature. In 2005, two Iranian psychiatrists reported on a patient who believed he had died and had also been transformed into a dog.
Link to latest combined Cotard and lycanthropy case report.
Mind Hacks 
Absolutely fascinating!
“someone believes they are transforming or have transformed into an animal”.
– or rather, into another species. I think there’s something very interesting in this – a clue to how humans distinguish themselves from other primates/other species in general. After all, we famously don’t know “What it’s like to be a bat”, so how could we possibly know how the bit of us that we believe is turning into a pig feels to identify the experience? Especially if one has doubt about the existence of a “self” as commonly identified……..