Chronic kidney disease in domestic cats: renal lipid characterisation and the nutritional modulation of disease progression

Rebecca Brociek

Chronic kidney disease in domestic cats: renal lipid characterisation and the nutritional modulation of disease progression

Publication Date

July 23, 2026

Creator

Rebecca Brociek

Abstract

This thesis aims to determine the composition of previously identified unknown renal lipids and to explore the nutritional aspects of the disease state, with particular focus on deficiency. In study 1, I sought to characterise renal intracellular lipids in the domestic cat, compared to domestic dogs (lipid-negative domesticated animal comparator), Scottish wildcats and zoo wildcats (wild felid comparators). Consistently, domestic felids possessed an unidentified lipid less polar than triacylglycerol (TAG) when separated by HPTLC, which is not seen in dogs or zoo wildcats. An absence of TAG was observed in those with the unidentified band (UB), which appeared to be influenced by age, with younger cats often exhibiting both TAG and the UB. LC-MS and GC-MS confirmed that most lipids were triacylglycerols containing C16:0 and C18:0 fatty acids. Whilst an array of chromatography and mass spectrometry results highly suggest the presence of ether-linked or branched-chain TAGs, the evidence cannot conclusively provide definitive lipid structures. Study 2 explored differences in the nutritional composition of commercially available cat food and the presence of UB to determine whether increased CKD prevalence may have been influenced by modern domestication. The UB was not exclusive to any one food type, and all amino acid profiles met the recommended minimum requirements of AAFCO and FEDIAF. Tubular lipidosis was present in 12/14 domestic cat kidneys preserved from 1930-1950, predating modern cat food, suggesting a possible exacerbating, but not causative role, of diet. Progression of CKD usually requires therapeutic intervention. However, nutritional status monitoring is mainly focused on phosphorus and calcium, and the extent to which the use of phosphate binders affects the bioaccessibility of other minerals, is currently unknown. This study used a modified feline in-vitro digestion model to evaluate how the addition of phosphate binders influences the solubility of key dietary minerals during digestion. Three distinct phosphate binders (aluminium hydroxide, calcium carbonate, and lanthanum carbonate) were tested for their effects on the bioaccessibility of 31 minerals across gastric and intestinal phases. Aluminium hydroxide significantly reduced phosphorus bioaccessibility but significantly increased soluble aluminium. Calcium carbonate and lanthanum carbonate both reduced phosphorus concentrations, but not to the same extent, and in each binder condition, different mineral-mineral interactions were identified. Low-acid conditions (mimicking antacid use) altered mineral solubility in a manner dependent on food type, binder, and dose. These studies highlight the incredible importance of adequate feline nutrition and its potential to underpin health and disease. It is therefore crucial that we consider species-specific nutritional requirements when transitioning therapies from human medicine. In conclusion, this thesis brings together molecular lipid profiling, nutritional biochemistry, and disease pathology to provide a new perspective on feline renal health. It identifies a previously undescribed lipid feature in cat kidneys, characterises how therapeutic diets and binders influence mineral bioaccessibility, and raises important questions about the evolutionary and dietary origins of CKD. These findings lay the foundation for future research in feline-specific nutrition and kidney disease, advocating for deeper investigation into micronutrient adequacy, lipid metabolism, and early dietary intervention.

Item Type

ethesis

Thesis Type

PhD

Supervisors

Gardner, David S