This study investigates periodontal disease to clarify if it has systemic effects and if they progress with the treatment of the former. They compared numerous parameters of two groups of cats from a colony, with or without dental treatment, during 3 months. They found a positive association between severity of periodontal disease and age, bodyweight, total globulins, ALT and IgG, and a negative association with albumin, haemoglobin, haematocrit and AST. Treatment prompted a quicker consumption of dry food and reduced IgG, globulins and AST, but didn’t change some other variables. They conclude that periodontitis impacts on systemic health and wellbeing.