Why diarrhoea hit your sensitive-stomach cat first
Cats lack the enzymes to process heavy salt loads — that jerky strip likely contained more sodium than your cat's entire daily limit. When salt floods the gut, it pulls water from surrounding tissues into the intestines, creating urgent, watery diarrhoea. This is the body's attempt to dilute and flush the overload.
But salt isn't the only culprit. Most commercial jerky contains garlic or onion powder, which irritate the feline gut lining directly. For a cat with existing sensitivities, this creates a double assault: osmotic diarrhoea from salt plus inflammatory diarrhoea from alliums.
The difference between allergy and toxicity
True food allergies in cats usually cause itching or skin issues alongside digestive upset. What you're seeing is almost certainly toxicity — the body reacting to harmful substances rather than misidentifying proteins as threats. The timing matters: allergies often take days to manifest, while salt and allium reactions appear within hours.
That said, repeated exposure could trigger future allergies. The gut damage from this episode might make your cat more prone to developing sensitivities to beef or other jerky ingredients down the line.
When diarrhoea becomes an emergency
Most cats can handle one bout of diarrhoea, but for a 5 kg cat, fluid loss escalates quickly. Watch for sticky gums, skin that tents when gently pulled up, or refusal to drink. These signal dangerous dehydration setting in — small cats have less reserve to draw from.
Blood in the stool or black, tarry feces means the allium compounds are causing deeper intestinal damage. Don't wait for vomiting to appear — cats often hide nausea until it's severe.
The next 24-hour feeding strategy
Withhold food for 8 hours to let the gut rest, but provide frequent, tiny amounts of water or unflavored electrolyte solution. When reintroducing food, skip commercial 'gentle' diets containing onion or garlic powder — ironically, many do. Plain boiled chicken (no skin, no seasoning) is safer.
Monitor litter box trips closely. If diarrhoea persists beyond two meals or the stool contains mucus, the gut lining needs veterinary support to heal — prolonged inflammation can lead to permeability issues.
The full verdict, portion guidance and serving notes are collected on the Beef jerky food facts page.