Research overview: FeLV-related immunodeficiency and secondary infection

FeLV impairs immune function, leaving cats vulnerable to a wide range of secondary bacterial, viral, fungal, and protozoal infections that frequently determine clinical course and survival. The subgroup T variant is directly cytopathic to T-lymphocytes, while broader immune dysregulation undermines defenses even without overt neoplasia or anemia. Affected cats may present with chronic or recurrent infections, poor wound healing, and failure to respond normally to routine illness. This overview synthesizes the immunology literature rather than a single study, describing how the virus undermines cellular immunity, why prompt and sometimes prolonged treatment of secondary infections is central to care, and why immune compromise links FeLV pathology to the broader theme of retrovirus-induced immunodeficiency.