Improper Diet Cascade

Improper Diet Cascade (IDC) is a theory by bird veterinarian Greg J. Harrison, DVM that links a wide variety of illnesses, behaviors, etc. to problems in the diet. It is similar to proposals made about human and other animal diets as we find that more and more issues are interconnected. The over-simplified version is “you are what you eat”. If we offer foods that are too high or too low in nutrients (even  “micro- nutrients” like selenium)  or foods that have lost nutritional values or gone “bad” due to poor handling or storage, etc. then it will have real effects on whatever eats it.
The effects may start small – pH imbalances, cellular issues, etc. – but the “cascade” part kicks in as effects snowball and little issues start building into major problems.

We already know that the foods we offer tortoises in captivity are nothing like what they get in the wild: most wild foods are much higher in available calcium and fiber for example. We try to make up for this with additional variety or pelleted diets, and yet we still see many issues that can be traced to diet: soft shells, pyramiding, respiratory illnesses, listlessness, unusual growth patterns, reproductive failures…

The visible symptoms of IDC do not show up until things have been going wrong on a cellular level for some time.The first signs often show up in the feathers in birds, so probably show up on the skin on tortoises, although we probably cannot easily see it.  There may be small changes such as dry, flaky skin, loss of color, loose scales, excess
shedding, overgrown scute edges, long nails, or beak overgrowth
. Unusual feces are another early sign that something is not right.  These feces may be pale, wet, loose, or dark, dry, hard, or otherwise “unusual”. The next signs would show up in the slower-growing tissues: soft bones, soft shells, pyramiding.

IDC is fatal in severe cases, but would more likely cause long-term problems, like shorter lifespans, increased susceptibility to disease or parasites, reduced reproduction, increased medical problems, and so on.

While there is no single, quick fix to IDC,  the original article makes several suggestions that we can adapt for use with tortoises. While many of these are mentioned elsewhere on this site, here are the main ideas:

  1. Make sure fresh water is always available.
  2. Combine appropriate, fresh, wholesome foods with prepared diets formulated for your species of tortoise. (We would suggest that this also include as much natural grazing on “good stuff” as possible.)
  3. Supplement as needed, especially calcium, vitamins A, D, and E, fiber, iron, etc. but do not overdo it. See “Vitamins and Nutrients”.
  4. Do not overfeed, especially things like proteins, fats, sugars, salts, dairy, raw grains, and  chemicals and preservatives.
  5. Store all foods correctly. Follow expiration dates and store prepared foods in air-tight, air-free containers or bags at cool temps to avoid rancidity.
  6. Handle all foods properly to prevent contamination.
  7. Consider adding grit. Wild tortoises routinely eat sand and may need this to help process tough plants. Small amounts of “calcium sand”, bird grit, or clean fine sand in the food should work.
  8. Offer “enrichments” that help offer natural opportunities: bones or cuttlebone to gnaw on, hard-rind fruits to work at biting, hanging bunches of greens from a hook, etc.
  9. Variety balanced with consistency. Feed at about the same time every day, in about the same place, but vary what is offered and toss in some surprises occasionally, like hiding mushrooms or strawberries in the habitat.
  10. Keep doing your homework to learn the best practices.