Comparative effect of two probiotic lactic acid bacterial strains on nutrient digestibility and health status in geriatric dogs

Similar to humans, the population of elderly companion animals is increasing. As dogs age, they experience diminished physical capabilities and metabolic changes, necessitating specialised senior care. Although the use of probiotics as functional food in animal feed is rising, research specifically focusing on geriatric dogs remains limited. This study evaluated the impact of two probiotic strains for their potential on nutrient utilisation and improving health among senior dogs. Fifteen neutered, medium-sized, non-descript geriatric dogs were randomly assigned to three equal groups and fed a basal pelleted diet (CP-25.5%, ME-3100 Kcal/kg) either without probiotics (control; T1) or supplemented with the probiotic strain Lactobacillus johnsonii (109 CFU)( T2) or Enterococcus faecium (3x108 CFU)( T3) of canine origin for 30 days. A three-day digestibility trial was conducted starting from the 28th day. Blood samples were collected on days 0 and 27 to assess haematological parameters. After the 30-day supplementation period, probiotics were discontinued and selected parameters were measured on day 40 to assess the persistence of the effect by the organisms. The study results indicated no significant variations (p > 0.05) in voluntary food intake between the groups. While the digestibility of most macronutrients remained consistent across groups, fibre digestibility improved significantly (p=0.008) in dogs receiving either of the probiotic strain. Additionally, both period-wise and treatment-wise values assessed on 0th, 27th and 40th days were similar across the group with respect to haematological parameters such as haemoglobin level, haematocrit values, differential leucocyte counts and total leucocyte counts. The supplementation L. johnsonii reduced serum glucose level but the persistence effect after the withdrawal of the probiotic was not evident. Overall, the Lactobacillus strain demonstrated superior effects compared to the control and enterococcus in geriatric dogs. Keywords: Geriatric dog, probiotics, Escherichia coli, Clostridium, Lactobacillus johnsonii, Enterococcus faecium