Monday, November 06, 2023

What happens when cats get fat? Scientists weigh in

UNIVERSITY OF ILLINOIS COLLEGE OF AGRICULTURAL, CONSUMER AND ENVIRONMENTAL SCIENCES

cat eating dry food from a bowl — IMAGE:
WHEN CATS OVEREAT AND GAIN WEIGHT, IT AFFECTS THEIR DIGESTIVE SYSTEM AND GUT MICROBIOTA, UNIVERSITY OF ILLINOIS RESEARCHERS FOUND.
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CREDIT: LAUREN QUINN, UNIVERSITY OF ILLINOIS.

URBANA, Ill. – Cat owners want Kitty to be happy, but providing an abundance of food and snacks can have unintended consequences. Feline obesity is on the rise, impacting the health, longevity, and wellbeing of cats. A new study from the University of Illinois Urbana-Champaign looks at what happens in the digestive system and gut microbiota when cats eat too much.

“About 60% of cats in the U.S. are overweight, which can lead to health problems such as diabetes and chronic inflammation. While many studies have investigated feline weight loss, there has been little focus on the opposite process, which is also important. In this study, we wanted to learn more about the metabolic and gastrointestinal changes that occur as a result of overeating and weight gain in cats,” says study co-author Kelly Swanson, professor in the Department of Animal Sciences and interim director of the Division of Nutritional Sciences (DNS), part of the College of Agricultural, Consumer and Environmental Sciences (ACES) at U. of I.

The study included 11 adult spayed female cats. They were fed a standard dry cat food and after two weeks of baseline measurements, they were allowed to eat as much as they wanted. The researchers collected blood and fecal samples at regular intervals and monitored physical activity.

Once the cats were able to overeat, they immediately increased their food intake substantially and started to gain weight. At the onset of the study, their average body condition score (BCS) was 5.41 on a 9-point scale. After 18 weeks of overfeeding, it had increased to 8.27, corresponding to being 30% overweight. BCS is equivalent to body mass index (BMI) for humans, and 6 or above is considered overweight, Swanson said.

The researchers analyzed changes in fecal output, gastrointestinal transit time, digestive efficiency (nutrient digestibility), and microbiota bacterial composition over the 20-week duration of the study.

“We found that as cats ate more and gained weight, gastrointestinal transit time was reduced, and so was digestive efficiency. When the body gets less food, it will be more efficient in extracting nutrients. But when the amount of food increases, it passes through the digestive system faster and fewer nutrients are extracted in the process,” Swanson explained.

The researchers also found significant changes in gut microbial composition between the lean cats at baseline and after 18 weeks of weight gain. The relative abundance of Bifidobacterium, which has antimicrobial activity, inhibits pathogens, and stimulates the immune system, increased, while Collinsella, which degrades fiber and has been linked to pro-inflammatory diseases, decreased. These results are opposite to what has been measured in overweight humans and suggest that their association to weight gain is complex, Swanson noted.

“The change in the gastrointestinal transit time was a novel finding and a potential reason for the change in fecal microbiota. Future studies should consider measuring transit time to better explain modifications to the microbiome of pets,” he added.

As the cats’ food consumption grew, so did their fecal output. In other words, as they ate more, they also pooped more. At the same time, fecal pH decreased, meaning that the stool became more acidic.

“In humans, a low fecal pH indicates poor absorption of carbohydrates and fat. Our findings correlate with this, as reduced fecal pH aligned with higher food intake and reduced digestibility,” Swanson said.

The researchers also measured the cats’ activity level with a monitor attached to a collar. The cats were housed in a group setting where they were able to interact with each other and play with toys, except for the days when stool samples were collected.

“We expected that weight gain might lead to decreased physical activity, but we did not observe any consistent changes in activity level. However, this could vary with individual cats and their environment, and how much their owners interact with them,” Swanson stated.

Understanding the metabolic and gastrointestinal changes that occur with weight gain and obesity in pets may help with future prevention and treatment plans, the researchers conclude.

Pet owners who want to help their cats lose weight can employ various strategies. In another new study, Swanson and his co-authors showed that restricted feeding can promote safe weight and fat loss in cats. The researchers also suggest pet parents encourage activity in their feline companions. For example, they can stimulate foraging by placing food around the home, or use food puzzles during mealtime to promote engagement and mental enrichment.

After the conclusion of the weight gain study, the 11 cats were put on a restricted-feeding diet that helped them return to normal weight.

The first study, “Effects of overfeeding on the digestive efficiency, voluntary physical activity levels, and fecal characteristics and microbiota of adult cats,” is published in the Journal of Animal Science [DOI: 10.1093/jas/skad338]. Authors are Danielle Opetz, Patricia Oba, and Kelly Swanson. Funding was provided by the USDA National Institute of Food and Agriculture (Hatch Grant #ILLU-538–937).

The second study, “Effects of weight loss and feeding specially formulated diets on the body composition, blood metabolite profiles, voluntary physical activity, and fecal metabolites and microbiota of overweight cats,” is also published in the Journal of Animal Science [DOI: 10.1093/jas/skad332]. Authors are Danielle Opetz, Patricia Oba, Darcia Kostiuk, Janelle Kelly, and Kelly Swanson. The funding for this study was provided by Champion Petfoods Holding, Inc., Edmonton, Canada.

JOURNAL

Journal of Animal Science

DOI

10.1093/jas/skad338

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Effects of overfeeding on the digestive efficiency, voluntary physical activity levels, and fecal characteristics and microbiota of adult cats,

Study reveals untapped potential to increase eye donations needed for sight-restoring surgeries

Peer-Reviewed Publication

UNIVERSITY OF SOUTHAMPTON

Eye after cornea transplant — IMAGE:
EYE AFTER CORNEA TRANSPLANT.
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CREDIT: MUST CREDIT NHS BLOOD AND TRANSPLANT

New research highlights the need for routine discussions about eye donation in end-of-life care clinical settings
Less than four per cent of eligible patients in end-of-life care settings were asked to consider eye donation
Patients had positive views about eye donation, but most did not know it could be an option for them
Staff need training and guidance to support discussing eye donation with patients

A new study has found there is significant scope to increase the number of eye donations from patients cared for in hospice and palliative care settings - donations which are desperately needed for sight-restoring surgeries.

Researchers from the University of Southampton and clinical partners, including NHS Blood and Transplant, carried out the study, which has been funded by the National Institute for Health and Care Research (NIHR). It found just a small fraction of eligible patients in hospice and palliative care settings are being approached to consider the option of eye donation. This is despite both healthcare professionals and patients having favourable views towards it.

The researchers say practice needs to change so that patients who wish to donate are being offered the opportunity as a part of routine end-of-life care.

Demand for eye tissue

Over two million people in the UK are living with sight loss, taking a huge toll on their lives and costing the economy a reported £4.34 billion each year. Some conditions, such as Keratoconus and Fuchs’ Corneal Dystrophy, can be treated with surgery which removes all or part of a damaged cornea and replaces it with healthy donor tissue (corneal transplant). But there is a shortfall in the supply of donor tissue needed for operations.

NHS Blood and Transplant aims to achieve a weekly stock of 350 eyes for use in surgery or research. But from April 2021 to March 2022, only 88 eyes on average were donated per week.

The RNIB predicts that by 2050, the number of people with sight loss will double to nearly four million (mainly due to the ageing population), further increasing the demand for eye tissue. Each donor can help restore or improve the sight of up to 10 people.

‘Many potential donors’

Clinical partners across England reviewed the case notes of 1,199 deceased patients in three hospice care and three hospital-based palliative care services.

Although 46 per cent of patients were eligible to donate their eyes, less than 4 per cent of potential donors had been approached or referred for eye donation.

Views on donation

To understand attitudes and potential barriers to eye donation, the researchers interviewed over 100 healthcare professionals and over 60 patients and carers receiving palliative care. They also conducted a national survey of 156 service providers.

Dr Tracy Long-Sutehall, Associate Professor at the University of Southampton and lead author of the research which has been published today [3 November] in the Health and Social Care Delivery Research Journal, says:

“Many patients and carers were not aware of eye donation being an option for themselves or their relative. Those we spoke to generally had positive views about eye donation and were open to being asked about their preferences. This suggests there could be many potential donors in hospice and palliative care settings who are willing to donate their eyes after their death so that others might see.”

Knowledge gap

Healthcare professionals were in favour of eye donation being discussed as part of end-of-life care planning but had gaps in their knowledge around eligibility criteria and processes for referral; more than half had received no formal training regarding eye donation. As such, the majority had never, or hardly ever, initiated a discussion about eye donation with patients or family members.

Dr Long-Sutehall added: “Conversations around eye donation need to be sensitively managed, so it’s understandable that healthcare professionals would be reluctant to raise it if they haven’t had suitable training and education.”

Future opportunities

The study demonstrates that there is significant potential for more patients to be given the opportunity to donate their eyes in the future, and for eye donation to be embedded in routine end-of-life care clinical practice.

Emma Winstanley, Lead Nurse for Tissue and Eye Services at NHS Blood and Transplant who was a co-applicant on the study, says:

“This research provides crucial new insight to better understand both patient and healthcare staff views on eye donation. With more patients dying outside of traditional hospital settings, either at home or in hospices, it is essential that patients have the opportunity to donate whenever donation is possible. Eye donation is particularly special as donation can even be possible for patients who have cancer. We know that many patients and families take great comfort and pride from donation. By working closely with hospice colleagues, we can enable more patients to donate and more life-transforming surgeries to take place.”

The researchers highlight several implications for service development, healthcare practice and recommendations for further research, including the evaluation of a Support Toolkit for Eye donation in Palliative care Settings (STEPS) developed by the research team.

Eye Donation from Palliative and Hospice care contexts: the EDiPPPP mixed methods study was funded by the NIHR Health and Social Care Delivery Research programme.

Ends

Placido disk reflected off eye with keratoconus.

CREDIT

National Keratoconus Foundation

Contact

Steve Williams, Media Relations, University of Southampton press@soton.ac.uk or 023 8059 3212.

Notes for editors

Eye Donation from Palliative and Hospice care contexts: the EDiPPPP mixed methods study is published in the Health and Social Care Delivery Research Journal and is available to download here: Eye donation from palliative and hospice care contexts: the EDiPPPP mixed-methods study (nihr.ac.uk)
Interview opportunities
1. Dr Tracy Long-Sutehall, Associate Professor at the University of Southampton and lead investigator on the EDiPPPP study. (Southampton)
2. Dr Sarah Mollart Consultant in Palliative Medicine at St Nicholas Hospice and clinical investigator on the EDiPPPP study. (Bury St Edmunds, Suffolk)
3. Laura – Mum of two who has had two corneal transplants for an undiagnosed illness. This has allowed her to see her children grow up. Her mother has also had a corneal transplant. (London)
4. Angie – Hospice nurse who made the decision (along with her mum and sister) to donate her father William’s corneas, kidneys and heart valves. The hospice she works at promotes discussion about organ donation (including corneas). (Wolverhampton)
Images available to download here: https://safesend.soton.ac.uk/pickup?claimID=ANs4m4SFgmFFfuBh&claimPasscode=a9JAjbHmcAcnCzcC
1. Placido disk reflected off eye with keratoconus - Credit National Keratoconus Foundation
2. Eye after cornea transplant - Credit NHS Blood and Transplant

Additional information

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About the National Institute for Health and Care Research (NIHR)

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