Raw food for dogs and cats: what the microbiological data actually says

Very different things live under the same label. There is the industrial frozen or freeze dried product, formulated as a complete food and subject to production controls. There is the ration prepared at home from meat, bone and organs bought at the counter. There is raw meat used as an occasional topper on a commercial diet. And there is raw fish, which brings its own problems linked to parasites and to thiaminase. The risk profile differs considerably between these categories, and generalising leads to wrong conclusions in both directions.

One point deserves clearing up immediately, because it recurs in every discussion: a dog's stomach is acidic, but it is not a steriliser. Gastric acidity reduces the bacterial load, it does not abolish it, and it does not stop a healthy animal from shedding pathogens in its faeces for days after a contaminated meal. That mechanism, more than illness in the animal itself, is what brings the problem into the house.

Several research groups have bought commercial raw products and analysed them the way food for people is analysed. The results are not anecdotes and they do not concern a single brand: they concern raw preservation as a method. Two surveys are cited particularly often because both sample size and method are declared.

The most discussed finding concerns antibiotic resistant bacteria. Detecting enterobacteria that produce extended spectrum beta lactamases in the majority of products means the bowl can become an entry route for resistance into the home, regardless of whether the animal falls ill. It is a risk that produces no symptom and can only be measured with targeted testing, which is exactly why it gets underestimated.

The question most often asked is whether the dog is fine, and in most cases the answer is yes. The point is that the animal's health is not the only outcome that matters. A healthy animal shedding salmonella in its faeces contaminates the garden, the litter tray, its paws and its coat, and from there the surfaces of the house. The people who get infected are not the ones eating from the bowl: they are the ones who touch a surface and then eat a sandwich.

• Young children: they put their hands in their mouths constantly and play on the floor, which is exactly where the risk concentrates.
• Older people: the immune response is slower and the consequences of an intestinal infection are more serious.
• Pregnant people: some infections carried by raw meat, such as listeriosis and toxoplasmosis, have specific consequences in pregnancy.
• Immunosuppressed people: anyone on chemotherapy, on immunosuppressive therapy or after a transplant operates on entirely different risk thresholds.
• Animals visiting hospitals and care homes: many animal assisted activity programmes exclude raw fed animals by protocol, precisely because of bacterial shedding.

The case of animals used in assisted activities is instructive because it comes not from prejudice but from a risk assessment in a setting where the people met are by definition fragile. The same logic applies to a home shared with a newborn and a grandparent, with the difference that no written protocol is there to remind anyone.

The first misconception is that freezing sterilises. It does not. Cold halts bacterial multiplication and kills part of the population, but the survivors become active again as soon as the temperature rises, and any toxin already produced is not destroyed. Freezing preserves, it does not decontaminate.

The second concerns parasites. Some are genuinely inactivated by domestic freezing if the temperature stays low enough for long enough, as is the case for the cysts of certain protozoa. Others require temperatures far below what a household freezer reaches, and for those the cold offers no guarantee at all. So there is no single rule along the lines of three days in the freezer and you are safe: it depends on the parasite and on the appliance's real temperature, which is often higher than the display suggests.

The third concerns bones. The idea that a raw bone is harmless because it is natural does not survive clinical caseloads: fractured teeth, particularly molars, mouth injuries, oesophageal or intestinal obstruction, stubborn constipation and perforation are all documented complications. Cooked bones are worse still because they splinter into sharp fragments. The dental cleaning argument also needs scaling down: chewing reduces plaque deposition to a degree, but it does not replace oral hygiene, and the cost of a fractured molar is high.

Alongside microbiological risk sits nutritional risk, which produces no emergency but accumulates over time. Raw rations prepared at home without professional formulation show the same defects with striking regularity: a wrong calcium to phosphorus ratio, deficiency or excess of vitamin A and vitamin D, iodine outside range, shortage of copper and zinc. In a growing puppy these deviations have skeletal consequences that only become visible once they are structural.

• Calcium and phosphorus: muscle meat is poor in calcium and rich in phosphorus, so a meat only ration is unbalanced by construction.
• Vitamin A: liver is extremely rich in it and generous daily use leads to toxic accumulation that affects the skeleton.
• Taurine in cats: it depends on the cut used and on storage time, and prolonged deficiency has cardiac and ocular consequences.
• Iodine and copper: hard to get right without targeted supplementation, and the consequences appear after months rather than days.

Anyone choosing a home prepared ration, raw or cooked, should have it formulated by a veterinary nutrition professional and revised whenever weight, age or health status change. That step does not remove microbiological risk, but it removes nutritional risk, which is entirely avoidable.

Reducing risk is possible, and most of the measures are the same ones you would apply handling raw chicken for dinner, with a higher level of attention because the frequency is daily and because the animal then walks around the house.

1. 1

   Choose products with declared controls

   Ask the manufacturer which microbiological tests are run and on what proportion of batches. A supplier answering with data is preferable to one answering with adjectives. Keep the batch reference until the pack is finished.

2. 2

   Thaw in the fridge, never on the counter

   Thawing at room temperature leaves the surface in the bacterial growth zone for hours. In the fridge the process is slower and stays under control, on a plate that catches the liquid.

3. 3

   Separate equipment and surfaces

   Dedicated boards, knives, bowls and containers, washed with hot water and detergent immediately after use, better still in a dishwasher on a hot cycle. No contact with surfaces where food for people is prepared.

4. 4

   Manage the meal and the leftovers

   Bowl removed after twenty to thirty minutes, leftovers not left at room temperature, feeding area cleaned straight away. If the animal eats in the garden, prevent it from carrying food to where children play.

5. 5

   Protect vulnerable people

   Hand washing after every contact with food, bowl and animal, no licking of faces, care with litter trays and faeces. Where there is a newborn, an immunosuppressed person or a pregnancy in the household, the choice of a raw diet is worth reconsidering.

Finally, it is worth telling your vet. Not to invite judgement, but because it changes the reading of certain clinical pictures: bloody diarrhoea, a fever of uncertain origin or a urinary infection resistant to the usual treatments are approached differently when raw meat is known to enter the house every day.