The Pottenger cat study came about like many great discoveries, Dr Francis M Pottenger accidentally found that his laboratory cats were noticeably healthier when fed on a diet of raw meats rather than cooked meats.
Dr Pottenger, a human doctor, was involved in using cats to assess the potency of adrenal extracts for use in human medicine.
Pottenger’s cats were fed on table scraps from the local restaurant. When the restaurant closed during the off season, he was forced to source his meat scraps directly from the local abbatoir (which came raw). During the time he was feeding the raw meat scraps to his laboratory cats, he noticed a dramatic improvement in their overall health, and also a significant reduction in surgical mortality rates.
Between 1932 and 1942, Dr Pottenger conducted a clinical trial, involving over 900 cats and over 9 generations, into the nutritional effects of cooked versus raw food diets. This study is still, to date, the single largest trial conducted on the effects of feeding cooked food versus raw food to domestic cats (or dogs).
Group one was fed raw meat scraps including organ meats and bone, and raw milk.
Group two was fed the same scraps but cooked, and were given pasteurised (heat treated) milk .
The cats on raw food were healthy, averaged 5 kittens per litter with few birthing problems, and most died of old age. After 9 generations there was no change in their health status.
The cats in group two however began developing problems from the first generation, with increased deaths in the litters, smaller litter sizes, poorer mothering, noticeable dull rough coats.
From the second generation onwards there were vision problems (probably taurine* deficiency), common infections, dermatitis (miliary dermatitis), arthritis, heart disease (possibly taurine again), allergies, gingivitis and periodontal disease, inflamed joints and nervous tissue, skeletal malformation. (Calcium bone density fell from 17 % at the start, to 4% by the fourth generation). Fertility declined rapidly, as did litter size and perinatal mortality increased.
Behaviourally the group on cooked food became progressively more aggressive to handlers and each other.
Interestingly gastrointestinal parasitism was a major problem in the cooked food group, not the raw food group.
The most common cause of death in adults in the cooked food group was from pneumonia and lung abscess, and in kittens was from diarrhoea and infection.
By the ninth generation on cooked food the cats were completely sterile and had stopped reproducing, so the trial had to be ceased.
Pottenger found that by changing the diet from cooked back to raw he could reverse most of the symptoms, but only until early in the third generation. From the fourth generation onwards much of the damage was irreversible. This suggests that damage from a cooked food diet has a generationally compounding effect.
He also found that the soil he fertilised with the faeces of the cats on the cooked food diet did not grow beans or grass, whereas the soil fertilised from the raw food group grew beans and grass vigorously.
There are arguably other factors involved besides just cooking that are causing the results of this experiment, dietary balance being an obvious one, but can we assume that even with all the added vitamins, minerals, etc, that are now in the most premium brand commercial pet foods, that the very act of cooking the food is not still contributing to the poor health our of our present day dogs and cats. (We still see many of these above problems in practice today).
He repeated the experiment on white mice and got similar results.
* Taurine is very sensitive to heat, and 50-75% of its natural value is destroyed by cooking and can result in significant deficiency. Cats require approximately 200-300mg of taurine per meal, which is easily supplied by a diet that is more than half raw meat.
By Dr Bruce Syme