Effectiveness of a Feed Supplement in Advanced Stages of Feline Chronic Kidney Disease

Background: Chronic kidney disease (CKD) is a very common pathology in cats, especially in the geriatric age. A proper renal diet is considered the current standard of care to enhance patients’ long-term survival and quality of life. However, when diet alone is not sufficient, it is necessary to supplement it with specific substances: these are phosphate binders and alkalinizing agents. The aim of this study was to evaluate the effectiveness of a feed supplement containing calcium carbonate, calcium lactate gluconate, chitosan and sodium bicarbonate in controlling hyperphosphatemia and metabolic acidosis in cats with severe CKD (IRIS, International Renal Interest Society, stage 3 and 4). Materials, Methods & Results: 10 cats (median BW 4.00 (3.20; 5.70) Kg, BCS 3/5 (2.25; 3.75), 11 (8.25;12.00) years) fed with a balanced renal diet were included in the study. To be enrolled in the study cats had to be affected by CKD in stages 3 or 4 and show hyperphosphatemia. Treatment consisted in oral administration of the product (Renal, Candioli Pharma) at 0.2 g/kg/day mixed with the food for 60 days. The animals were evaluated at the beginning of the study and at 15, 30, 60 days (T0, T15, T30, T60) for: clinical condition, BW, BCS, blood pressure and for routinely hematochemical, biochemical and urinary parameters. Owners were asked to assess appetite of the cat, palatability of the supplement, presence of vomit and/or diarrhoea, general health and vitality. All statistical analyses were performed using SAS software. After checking normality data were analyzed using Kruskal-Wallis and Wilcoxon tests. Results are expressed as median (interquartile range). For the parameters P (P < 0.0001), iCa (P = 0.0008) and HCO3 (P = 0.0002) there were statistically significant differences among times of supplementation (T0, T15, T30, T60). Statistically significant reduction of serum phosphorus concentration was obtained through the study (reduction of 59% at T60 vs T0). Also a statistically significant increase of bicarbonate was seen (7% from T0 to T60). At T60 was also recorded an increase of ionized calcium level, which however was in normal range. For the other laboratory parameters, no statistical difference was recorded. All the owners reported a good palatability of the product. The decrease of vomit and diarrhea episodes and the increase of the appetite reported were statistically significant (P < 0.05). Discussion: The restriction of available dietary phosphorus is now recognised as one of the major contributors in slowing the disease progression and improving survival rates. Phosphate binders are able to absorb phosphate (P) in the intestine, forming insoluble products that are eliminated with the faeces, thus decreasing serum phosphate levels. The phosphate binders contained in the product tested in the present trial were chitosan, calcium lactate gluconate and calcium carbonate. During the study P decreased significantly from T0 to T60, reaching the target post-treatment plasma P concentration for IRIS stage 3 after 30 days. Another important recommendation for CKD treatment is to use alkalinisation therapy if metabolic acidosis is present. The feed supplement tested in this study also contained sodium bicarbonate. In our study, 90% of the patients at the inclusion examination had metabolic acidosis. At the end of the study, the median blood bicarbonate concentration was in the normal range, thus reaching the IRIS treatment target. The feed supplement tested was therefore effective in reducing blood phosphate levels and in increasing blood bicarbonate levels, thus improving the cats’ clinical conditions for the duration of the study without any adverse effect.