While Domestic Cat Hepatitis B Virus is more properly called Domestic Cat Hepadnavirus, we will keep using the more accepted naming system.
. In 2016, a seven year-old male-neutered domestic shorthair cat was presented for vomiting and weight loss. Diagnosed with Feline Immunodeficiency Virus (FIV), the cat was eventually euthanized.
To identify potential viral pathogens infecting domestic cats scientists performed high-throughput transcriptome sequencing of tissues from cats infected with Feline Immunodeficiency Virus (FIV).
During that investigation several cats, that had previously died as a result of FIV, also seemed infected with a virus. The virus itself was elusive and it showed only 73–94% amino acid identity with known Hepatitis B viruses. This suggested the presence of a novel virus that was divergent from currently known Hepatitis B viruses. Such a large genetic distance merits assignment of a new species within the genus Orthohepadnavirus, which was tentatively named Domestic Cat Hepadnavirus or Domestic Cat Hepatitis B Virus.
Further research revealed that it exhibited no close phylogenetic relationship to any other known Hepatitis B virusses.
 Aghazadeh et al: A Novel Hepadnavirus Identified in an Immunocompromised Domestic Cat in Australia in Virusses – 2018. See here.