Does loose substrate cause impaction in bearded dragons & other reptiles?

Impaction! Otherwise known as a blockage of the Gastrointestinal tract. But should loose substrate be avoided at all costs? Or is it necessary in achieving even satisfactory welfare? That’s coming up!

Lets put whether or not it causes impaction, aside for now. Don’t worry we will swing back and address that. For now, id like to concentrate on the behavioural need of loose substrate. If we look at the animal welfare act, we will find the 5 animal needs stated, one of which is the “need to be able to exhibit normal behaviour patterns”.
And as we have covered in another video, this is considered as basic and only promotes up to satisfactory welfare. Now if we take two popular species, the bearded Dragon and the leopard gecko. Both of these are shrouded in folklore husbandry beliefs around impaction by ingesting loose substrate. Well, both of these have the evolutionary behavioural need to dig, allowing them to access different microclimates in the wild environment. Well then, by definition, you are restricting their ability to dig and therefore the keeper is failing to even meet the basic requirements of satisfactory welfare.
If we consider the fact that many of the keepers of both bearded dragons and leopard geckos who routinely object to loose substrate end up providing loose substrate in the form of lay boxes when they want to breed the animals, we really start to see how confusing that becomes? If loose substrate is believed to be so hazardous to the animals health, and routinely quoted as “not worth the risk”, then why is it now okay to subject the animal to such a risky substrate when the animal needs to lay?
If the thought process is well, “the animal wont be able to comfortably lay without access to loose substrate, we still believe it to be a unnecessary risk but so is the risk of the animal becoming egg bound. So, we provide it temporarily because its needed in this case.”
Well, that’s fine but aren’t you simultaneously acknowledging the fact that its needed for the animal to engage in a whole area of its natural behaviour? And what about its behavioural need to dig outside of egg laying?
Its when you think about it with criteria of animal welfare in mind the practice really doesn’t make sense in my opinion.
But, does loose substrate actually cause impaction? In a healthy animal? No! A healthy animal whether it be bearded dragon or leopard gecko will not get impacted as long as other aspects of their husbandry are correct. The correct temperatures, Correct uv indices, and adequate hydration all need to be correct for a healthy animal. It is only when an aspect of the husbandry is wrong and leaves the animal compromised that impaction becomes a risk. A compromised animal can become impacted on paper towel, and insect chitin as well as loose substrate. Impaction is a symptom of an underlying issue rather that the root cause of the problem. Removing substrate only masks the issue at hand.
But then how could impaction be caused? One of the main causes is keepers misunderstanding the hydration needs of “desert” species. Many veterinary clients with impacted lizards also have severely dehydrated lizards. Often both go hand in hand. If the lizard is dehydrated, then lubrication of organs and the ability to pass particulates can be reduced. In fact, the ability to even pass urates can be impaired by dehydration. In bearded dragons, when urates are formed, they are transported to the distal colon for storage. This is a site of water absorption, as the colon absorbs the water content, the urate suspension transitions to water and in healthy bearded dragons a semi solid urate plug is discharged during defecation. In a dehydrated dragon, water is withdrawn from the colon, causing the walls to contract around the urate fluid, stripping out more water, causing a solid mass to form and adhere to the colon mucosa. Less lubrication and a desiccated solid mass make passing difficult. I’d argue that the same applies to substrate ingestion. If the temperatures in the basking zone of either leopard geckos or bearded dragons is not at high enough temperatures, then digestion functionality can be decreased, as well as slowing gastrointestinal peristalsis. In less complicated terms, peristalsis is the rhythmic contractions of the intestines to move food along.
In a study conducted in 2019 on humans, lower levels of 25hydroxyvitamin D were linked to reduced colonic transit times and chronic functional constipation.
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Studies:
doi.org/10.1053/j.jepm.2008.07.004
https://www.researchgate.net/publicat...
https://doi.org/10.1016/j.cvex.2005.0...