BIOCHEMISTRY OF HEALTH AND DISEASE IN CAMELIDS

New World Camelids have a fairly unique physiology, although they are outwardly similar to ruminants. This physiology presumably gives them survival advantages in the harsh environments where they thrive, but also gives them different blood biochemical characteristics during health and disease. Among the better known biochemical differences between healthy ruminants and camelids are the higher blood glucose, urea and sodium concentrations in camelids. While these were originally postulated to be curiosties, we now surmise that they offer deeper insights into the paths of energy metabolism in these animals. Specifically, the higher blood urea values hint at a greater rate of protein degradation, which likely results from a system of irrepressible hepatic gluconeogénesis. The higher blood glucose concentrations likely are a result of this constant gluconeogénesis, but also may result from low insulin concentrations and peripheral tissue insulin resistance. The higher sodium concentrations may relate to osmotic balance issues, where camelids are perhaps uniquely adapted to suffer intermittent dehydration followed by rapid rehydation.

With illness, a number of other interesting characteristics arise, some of which relate to camelids’ normal physiology and others of which are unique. Aside from vitamin D related issues, and potentially Krafft’s disease in camels, camelids suffer relatively few disorders of involving blood minerals. Electrolyte issues have some commonalities with ruminants and some unique features. Similar to ruminants, sick camelids have a strong tendancy toward hypokalemia, reflecting on a similar dietary need to replace potassium frequently. Unlike ruminants, sick camelids also have a strong tendency toward hypernatremia and hyperchloremia. This may reflect anatomic differences – the tubular camelid third compartment may allow greater gastric outflow with anorexia than the ruminant abomasum – but also probably occurs as a result of stress hyperglycemia. In camels, it has been postulated that they maintain high blood sodium concentrations to preserve wáter, but our research suggests that they actually develop worsening hypernatremia through excessive wáter loss, the result of diuresis of excess blood glucose.

Other common abnormalities and how they reflect unique camelid conditions will be discussed as well.