The results of a questionnaire provided data about owners' perceptions of the cause of death of over 3000 British dogs. The mean age at death (all breeds, all causes) was 11 years one month, but in dogs dying of natural causes it was 12 years eight months. Only 8 per cent of dogs lived beyond 15, and 64 per cent of dogs died of disease or were euthanased as a result of disease. Nearly 16 per cent of deaths were attributed to cancer, twice as many as to heart disease. Neutered females lived longer than males or intact females, but among dogs dying of natural causes entire females lived slightly longer. In neutered males the importance of cancer as a cause of death was similar to heart disease. Mongrels lived longer than average but several breeds lived longer than mongrels, for example, Jack Russells, miniature poodles and whippets. There was no correlation between longevity and cardiovascular parameters (heart rate, systolic, diastolic, pulse and mean arterial pressure, or the combination of heart rate and pulse pressure) but smaller dogs had longer lifespans. The results also include breed differences in lifespan, susceptibility to cancer, road accidents and behavioural problems as a cause of euthanasia.

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The concept of a regulatory link between the gastrointestinal tract and kidneys is not new. The idea that dietary intake and composition can affect renal function is perhaps self-evident, but defining this relationship, especially in terms of sensors and effectors, is proving more difficult. That the gastrointestinal tract can exert some control over renal function was strengthened by the early observation that oral ingestion of a sodium chloride load has a greater natriuretic effect than when the same amount is given intravenously. This effect was subsequently shown to be independent of changes in aldosterone and atrial natriuretic peptide, although not necessarily angiotensin-II. However, the nature of any intestinal natriuretic peptide remains uncertain, despite suggestions that various gut-derived hormones, including guanylin and uroguanylin, may be involved. There is also an emerging concept of gastrointestinal taste and taste-like receptor mechanisms present throughout the gastrointestinal tract, which may govern the excretion of other key electrolytes, including potassium and phosphate. The evidence for gut sensors of nutrients such as proteins, amino acids, glucose, and acid is now becoming more established. Thus, we can anticipate the existence and eventual characterization of several gut ion sensors.