Pye, Christine 
ORCID: 0000-0003-1761-8125
(2025)
Physical, Biochemical, Haematological and Metabolomic Biomarkers of Ageing in Cats:
Findings from the Cat Prospective Ageing and Welfare Study.
PhD thesis, University of Liverpool.
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Abstract
Over the past two centuries, the life expectancy of people has increased substantially. As the human population’s lifespan has increased, the same is true of our pets. The median life expectancy of cats in the UK has been estimated to be 14 years of age. However, an increase in lifespan does not necessarily equate to an increase in healthspan, defined as the length of time living in good health. Age is a major risk factor for several chronic diseases affecting the quality of life and welfare of both humans and companion animals. Biomarkers of ageing have been investigated over recent years to improve our understanding of the ageing process. In cats, there is currently a knowledge gap in our understanding of these biomarkers, which could identify targets for preventative treatments to improve the health and welfare of our ageing cats. Furthermore, longitudinal studies of certain biomarkers of ageing, such as metabolomic biomarkers, are rare not just in cats, but in all species. This thesis presents results from a longitudinal prospective cohort study of ageing in client owned pet cats in the North-West of England between February 2017 to January 2024: The Cat Prospective Ageing and Welfare Study. The aim was to define the clinical outcomes in these cats, and identify both physical, biochemical, haematological and metabolomic biomarkers of ageing considering sex and health-related effects. The clinical outcomes of 209 cats from middle-age onwards are described. Median life expectancy was estimated to be 15.2 years in the cohort. Age-related diseases and multi-morbidity were found to be common, with only 4% of cats remaining free of any abnormality on clinical examination over the study period and 84% of cats developing two or more comorbidities. Clinical parameters measured in routine veterinary examinations demonstrated that bodyweight, body condition score and muscle condition score decreased with increasing age in a non-linear fashion. Systolic blood pressure increased with age and was greater in male cats than female cats. Routine serum biochemistry showed increases in albumin, blood urea nitrogen:creatinine ratio, amylase, calcium, osmolality, phosphorous, sodium and urea and decreases in creatinine and alkaline phosphatase with increasing age. Decreases in reticulocytes, monocytes and lymphocytes on haematology testing showed evidence for immunosenescence and reduced haematopoiesis with age in cats. A serum metabolomic study used hydrogen nuclear magnetic resonance spectroscopy to examine longitudinal metabolite changes with age, sex, body condition score and health-related factors in cats for the first time. Alterations in metabolites linked to glycine, serine and threonine metabolism, pyruvate metabolism and glycolysis, as well as lipids were identified with ageing. GlycA, which represents acute phase glycoproteins, was increased with age, showing evidence of inflammageing in cats. Metabolites related to different morbidities were also found. A separate study investigating serum lipidomic changes with age in a subset of the cats at baseline and four years later found that triacylglycerides and free cholesterol were significantly less in senior cats than middle-aged cats. Overall, several clinical, biochemical and metabolomic biomarkers related to the ageing process in cats have been identified for the first time within this thesis. These biomarkers improve our understanding of how cats age and will help to establish future targets to improve healthy ageing in our cats.
| Item Type: | Thesis (PhD) |
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| Uncontrolled Keywords: | Ageing, Biomarkers, Cats, Feline, Metabolomics, Longitudinal, cohort, Morbidity, biochemistry, haematology |
| Divisions: | Faculty of Health and Life Sciences Faculty of Health and Life Sciences > Institute of Life Courses and Medical Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 07 Oct 2025 08:26 |
| Last Modified: | 07 Oct 2025 08:28 |
| DOI: | 10.17638/03194356 |
| Supervisors: |
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| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3194356 |
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