Processing of dry complete foods for domestic felids detrimentally alters lipid composition for obligate carnivores

Domestic felids, even when young, have a preponderance of cytoplasmic
lipid droplets of unknown origin in their kidneys. Comparable other species such as domestic dogs or
feral species such as wildcats are largely free from such ectopic lipid, as are humans, particularly in
their kidneys. The domestic cat is unusual in being an obligate carnivore, but living in a domesticated
environment eating highly processed, refined foods. Refining of foods, particularly lipids can alter
their characteristics such that the body recognises them as foreign, mounting a sterile inflammatory
response - the pathogen associated molecular patterns. In this project, we will investigate the
proposition that refining of dry pet food for domestic felids alters their lipid composition provoking a
PAMP in domestic cat kidney, that could contribute to organ interstitial fibrosis.
Liver and kidney tissue will be obtained from participating veterinary practices from which full
ethical approval has already been obtained i.e. the animals are euthanised by a vet for reasons
unrelated to this project. Pet foods will be bought from commercial suppliers. Lipid will be extracted
and profiled using a number of techniques: thin-later chromatography to separate lipids according to
polarity; LC-MS/MS to identify accumulated lipids, GC-MS(-MS) for detailed and in-depth fatty acid
profiling (i.e. fatty acid methyl esters), total lipid quantification by Soxhlet method and total
nitrogenby the Dumass method. Free carbohydrate will be measured using a megazyme kit. Training
will also be given in other key research techniques such as data presentation and analysis (e.g. using
Prism, Genstat and SIMCA) and how to read and critique the scientific literature. They will also have
to have rudimentary histology and histochemistry techniques, including TEM to characterise the
lipids in situ in organs or foods.