The long-term prognosis for FIV-infected cats is guarded, but some cats will survive for many years following diagnosis. A cat should therefore never be euthanased based on a positive test result for FIV<sup>4</sup>. Around 20% of affected cats die within the first two years after diagnosis; this equates to a 20% mortality rate in the first 4.5-6 years after the estimated time of infection<sup>fmc</sup>. In generally, the more chronic and severe the clinical signs, the worse the prognosis is. The duration of the asymptomatic period following FIV infection varies with the infecting strain and cannot be predicted. However, cats affected at a younger age are more likely to progress to an immunodeficient state<sup>4</sup>.