The Pottenger Cat Study came about, like many great discoveries, by accident. Dr Francis M. Pottenger noticed that his laboratory cats were noticeably healthier when fed a diet containing raw meat rather than cooked meat.
Dr Pottenger, a human doctor, used cats to assess the potency of adrenal extracts for use in human medicine.
Initially, Pottenger's cats were fed table scraps from a local restaurant. When the restaurant closed during the off-season, he was forced to source his meat scraps directly from the local abattoir, which supplied raw meat.
While feeding the raw meat scraps to his laboratory cats, he noticed a dramatic improvement in their overall health, along with a significant reduction in surgical mortality rates.
Study Design and Diets
Between 1932 and 1942, Dr Pottenger conducted a series of feeding experiments involving more than 900 cats over multiple generations. The research investigated the nutritional effects of cooked versus raw food diets.
The two groups were fed as follows:
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Group One: Raw meat scraps, including organ meats and bone, along with raw milk.
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Group Two: The same meat scraps, but cooked, along with pasteurised (heat-treated) milk.
The study is often cited in discussions about the potential nutritional differences between raw and cooked diets for cats.
Reported Observations
The cats fed raw food remained generally healthy. They averaged five kittens per litter, experienced few birthing problems and most lived to old age. Pottenger reported no significant deterioration in their health across the generations observed.
The cats in the cooked-food group, however, began developing health and reproductive problems from the first generation. These included increased kitten mortality, smaller litter sizes, poorer mothering and noticeably dull, rough coats.
From the second generation onwards, Pottenger reported a range of additional problems, including:
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Vision problems, possibly associated with taurine deficiency
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Recurrent infections
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Dermatitis, including miliary dermatitis
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Arthritis and inflamed joints
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Heart disease, potentially linked to taurine deficiency
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Allergies
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Gingivitis and periodontal disease
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Inflammation affecting nervous tissue
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Skeletal malformations
Bone calcium density reportedly declined from 17% at the beginning of the experiment to 4% by the fourth generation.
Fertility also declined, litter sizes became smaller and perinatal mortality increased.
Behaviourally, the cats fed cooked food became progressively more aggressive towards handlers and each other.
Interestingly, gastrointestinal parasitism was reported as a major problem in the cooked-food group, rather than the raw-food group.
The most common causes of death in adult cats in the cooked-food group were pneumonia and lung abscesses. In kittens, diarrhoea and infection were common causes of death.
By the ninth generation, Pottenger reported that the cats fed the cooked diet had become sterile and were no longer reproducing, bringing the experiment to an end.
Could the Effects Be Reversed?
Pottenger found that changing the diet from cooked back to raw could reverse many of the reported symptoms. However, he observed that this was only possible up to the early generations of the experiment.
By the fourth generation onwards, much of the damage appeared to be irreversible.
These observations raised questions about whether prolonged nutritional deficiencies could have compounding effects across generations.
He also conducted an interesting soil experiment. Soil fertilised with faeces from the cooked-food group reportedly failed to grow beans or grass successfully, whereas soil fertilised with faeces from the raw-food group produced vigorous growth.
Questions About the Study
There are arguably other factors involved in the results of this experiment besides cooking alone. Dietary balance is an obvious consideration, particularly as the two groups were fed diets that differed in more than just their cooking method.
However, it raises an important question: even with the added vitamins, minerals and other nutrients now included in premium commercial pet foods, could the cooking process itself still contribute to nutritional differences that affect the long-term health of our dogs and cats?
We continue to see many of the health concerns described in Pottenger's research in animals today.
Pottenger also repeated similar feeding experiments using white mice and reported comparable observations.
The Importance of Taurine
One nutrient worth considering when discussing the effects of cooking is Taurine.
Taurine is an essential amino acid for cats and plays an important role in normal heart function, vision, reproduction and many other bodily processes.
Taurine can be lost during food processing and cooking, although the amount varies depending on the cooking method and whether cooking juices are retained.
Cats have a particularly high dietary requirement for taurine, making adequate intake an important consideration when formulating their diets.