Acute and chronic diarrhoea in dogs and cats: when to worry

Acute diarrhoea appears suddenly and lasts a short time, often a few days. In an adult, otherwise healthy animal it is frequently self limiting, linked to a diet change, to something swallowed or to a passing upset. Chronic diarrhoea, by contrast, lasts more than two or three weeks, or comes and goes returning constantly, and in this case it is no longer an accident but a signal that something in the digestive tract or the body is not working as it should.

This distinction guides everything else. The acute form in a healthy animal is observed with attention and support, while the chronic form always requires a veterinary assessment, because behind it there can be food intolerances, chronic inflammation, parasites, pancreatic problems or general causes. Even acute diarrhoea, however, changes meaning if it strikes a puppy, a kitten, an old animal or one with known diseases, because in these cases fluid loss is riskier and the margins for waiting shrink.

The appearance of the stools is a source of information often thrown away without a look. Colour, consistency, presence of mucus or blood and frequency tell a lot, and reporting or photographing them helps frame the problem. The table gathers the most useful observations.

The last two rows deserve particular attention. A few traces of bright red blood at the end of a stool in an otherwise bright animal are less alarming than black tarry stools, which can indicate digested blood from the upper tract. In both cases, when the blood is abundant or the animal is unwell, contact with the vet should not be postponed.

Most acute diarrhoea in healthy adult animals is not an emergency, but some situations completely change the picture and require quick contact. Recognising them avoids waiting when waiting is dangerous.

• Abundant, continuous diarrhoea that will not stop, with signs of dehydration such as lethargy, sticky gums and sunken eyes.
• Presence of a lot of blood, black tarry stools or vomiting adding to the diarrhoea.
• Marked depression, abdominal pain, a swollen belly or a total refusal to drink.
• Diarrhoea in a puppy or kitten, which dehydrate very quickly and can deteriorate within hours.
• Diarrhoea in an old animal or one with known conditions such as diabetes or kidney failure.
• Suspected ingestion of toxic substances, dangerous plants or foreign bodies.

When the diarrhoea is mild and the animal is adult, lively and well hydrated, the observation time is handled with a few simple measures, remembering that support does not replace the visit if the picture worsens or fails to improve.

1. 1

   Ensure constant access to water

   Hydration is the priority. Leave fresh water always available and check that the animal drinks, because lost fluids must be replaced.

2. 2

   Offer a light, easily digestible diet

   For a few days a light, suitable food in small frequent portions reduces the load on the intestine. Avoid leftovers, treats and rich foods in this phase.

3. 3

   Record the frequency and appearance of the stools

   Keep a diary with times, consistency and presence of blood or mucus. Photograph if you can: it helps the assessment and shows the trend over time.

4. 4

   Observe the general state

   Energy, appetite, thirst and presence of vomiting tell whether the picture is stable or changing. An animal that stays bright reassures more than the stools alone.

5. 5

   Avoid unprescribed remedies and drugs

   Many human diarrhoea drugs are unsuitable or toxic for dogs and cats. Do not give anything on your own initiative: ask the vet what is safe.

6. 6

   Set a time limit for calling

   If after a couple of days it does not improve, if it worsens sooner or if alarm signals appear, contact the vet instead of continuing to wait.

Diarrhoea that lasts weeks or keeps coming back is not a nuisance to be managed at home indefinitely: it is a signal that deserves a diagnostic path. The causes are many and include food intolerances and allergies, chronic inflammatory bowel disease, parasites, pancreatic problems and general causes reflected in the intestine. None is diagnosed by observing the stools: it takes the history, the visit and often targeted tests.

Precisely because the possibilities are so many, the diary you kept becomes valuable. Frequency over time, relationship with meals, diet changes, presence of weight loss or vomiting, appetite trend: these are the data the vet starts from to choose the investigations. In cats in particular, chronic diarrhoea with weight loss should never be considered trivial, because it can signal problems best addressed when caught early.