How do you know if your lizard, or your snake, or your tortoise is stressed?

Muhammed Mahdi Karim photo is here

When animals are under stress, the nervous system responds by releasing adrenaline and other hormones to prepare the body for action. The adrenal glands flood the body with hormones like adrenalin (epinephrine) to prepare the animal for action. Similar hormones are produced in the brain.

For a long time it was thought that cold-blooded animals were “primitive” and therefore did not suffer from stress as much as “higher” animals.Yet reptiles respond in a very similar way to warm-blooded mammals, though their adrenal glands and their hormones are slightly different.

If the snake or lizard or tortoise has to run away, or hide, or do something in response to a threat, then these hormones help them to do it. For instance some lizards shed their tail when chased by predators. But if there is no action available, the hormones just flood the system to no avail. The animal has no relief from emotions like fear. Reptiles in bad conditions of captivity that cannot escape, for instance, will experience the emotion of frustration in countless escape attempts.

This means that they suffer.

And if the stress is chronic, this affects the animal’s welfare. Chronically stressed reptiles (and humans) have a lowered immune system. They are more likely to get various diseases and disorders.

One problem in measuring tis in reptiles is that their response will vary according to their temperature. They cannot produce their own body heat, so when a reptile is cold, its body functions slow down. So the stress hormone levels in a cold reptile will be different from the stress hormone levels in a warm one.

What can we look for? We can look for harmful repetitive behaviours, like the way lizards or tortoises repeatedly push at transparent barriers. We can look for lack of appetite, aggression, and even a change in skin colour in some lizards.  We need to know how a normal reptile behaves, before we can tell how a stressed one behaves.

What can we look for? Diseases and disorders due to stress may involve inability to reproduce, susceptibility to infections, emaciation from lack of appetite or its opposite, obesity.

What can we look for? We can measure the stress hormones or other chemicals in the blood, but taking blood samples, for instance, will cause even more stress. Or we can measure them in the faeces – a better way as it doesn’t hurt the animal.

But….. we don’t still know enough about what is normal for a corn snake, say, or a crocodile, or a boa constrictor, or a Hermann’s tortoise, or a bearded lizard. Each species may differ in the way it responds to stress. We have a lot of research to do.

Read

Silvestre, A. M. (2014) ‘How to Assess Stress in Reptiles, Journal of Exotic Pet Medicine, 23, 240-243.

Too much or too little vitamin D for reptiles? What do we know so far?

Some lizards may use basking not just for heat but for UV light.

By now most reptile keepers realise that too little vitamin D is bad for reptiles. Vitamin D is either absorbed through natural light or through the diet. Although carnivorous reptiles can get vitamin D in their diet: strictly herbivorous reptiles will not get enough just from diet. And it now looks as if relying on diet along, even in carnivores snakes, risks vitamin D inadequacy.
What do low levels of vitamin D do? Vitamin D is important for the growth and development of bones, for the immune system, artery and vein health, and reproduction. So low levels will impact badly on all these functions. We now know for sure that good vitamin D levels are important for the successful reproduction of several captive reptile species.
Vitamin D can be found in supplements that are given to reptiles. But there is a downside to this. It looks as if dietary vitamin D can lead to too high a vitamin D level if supplements are used incorrectly. In reptiles with an overdose of vitamin D, the aorta gets furred up with minerals.  So supplementing vitamin D by diet can be tricky.
Vitamin D levels are also affected by ultra violet light. But there have been no reports yet of vitamin D overdosing because of UV light. Yes, there can be skin damage from "too much" UV light but not vitamin D overdose. There seems to be a mechanism in the skin hat prevents overdose.
So.....
It is safer to use UV lighting or access to natural daylight to give your reptile enough vitamin D. The animal can probably regulate its vitamin D levels to prevent overdose.
Moreover, some (probably not all) carnivorous captive reptiles that get their vitamin D from a diet of mice etc. may well benefit from UV lighting as well. Carnivorous Komodo dragons get more vitamin D from UV light than dietary vitamin supplement. Conversely ball pythons were able to get their vitamin D equally well from either.
What is the take-home message from this? Use of dietary supplements may not be enough and risks overdose if used incorrectly. UVB light on its own will not lead to overdose and is therefore safer. Some reptiles will benefit it even though they get vitamin D from a carnivorous diet.
AND MOST IMPORTANT OF ALL - Keep up with modern developments. This is an area which is still being researched. What was best practice ten years ago is not best practice now. If you think you know it all, you probably don't.

To read more about this go to:

Watson et al (2014), 'Vitamin D and ultraviolet B radiation considerations for exotic pets,'Journal of Exotic Pet Medicine, 23, 369-379.

 

How iguanas need their vitamin D - from light or a supplement?

There are two ways to get vitamin D - eat it or absorb it through the skin from light. Does it matter which? In the wild green iguanas would regulate their body temperature and their vitamin D by basking in the sun (an ultra violet light source) then going to the shade (without ultra violet light) when too hot. As they are herbivores they cannot get the vitamin from their food.
In 2004 a study suggested that dietary supplements of vitamin D were a good source rather than UV light. The problem with UV light then was that a reliable source of light was then not available.
You will find the details of the study here - http://www.anapsid.org/pdf/jody-hibma-uvb.pdf
In l996, a more complicated study was set up. This time different lighting was used and some of the iguanas showed very high levels of vitamin D, if they were given both a dietary supplement and an UV light. Strangely, though, these high levels didn't seem to poison them - though igs have been known to die of vitamin D overdose. Read the full account here - http://www.anapsid.org?iguana/bernard-d3.html.
So do iguanas need UV light and dietary supplements. They certainly need UV light and when you do put in UV light, you must give the iguana a place in the shade where it can escape the light if it chooses. It will regulate its temperature so the UV light needs to be in the same place as the heat lamp. If it is not the lizard will spend most of its time in the heat lamp area and miss the benefits of UV lighting.
Do they need a vitamin supplement as well? This seems to be doubtful. A lot of the general reptile supplements on the market will do them no good and may do harm. Again, read up on the topic here - http://www.anapsid.org/vitamin.html
It's difficult. It's complicated. And we don't know as much as we should. All this means that a green iguana is a pet for the experienced reptile person, not for a beginner.