Nasal Salt Glands - the cause of the white crusts on the nose

[ferretinmyshoes]

There has been some debate for quite some time about the cause of the white crusts sometimes seen around the nostrils of our chameleons. These crusts are not limited to chameleons, as iguanas and other reptile species can have these crusts as well. The most notable example is the marine iguana of the Galapagos Islands, often seen with significant buildup around the nostrils, or visibly sneezing them out.


(Not my image - click on it for the original source)

While they are easily flaked off without causing obvious health concerns to the animals, the questions remain:
- What causes the crusts?
- Do they mean something is wrong?
- How to make them stop building up?

The prevailing theory is that the nasal salt gland excretes salt, which is why the marine iguana always has so much of it after swimming in salt water. But there is a theory maintained by some and perpetuated by rumor that it is actually excess calcium. Consequently the recommendation is to reduce the calcium supplementation, which has dangerous implications given all too common dangers of calcium deficiency seen with metabolic bone disease. I have gathered scientific articles, studies and documentation of research done specifically on the nasal salt glands of reptiles to get to the bottom of this issue. The following is evidence summarized to answer the questions above about the mysterious nasal salt glands and basically prove that calcium is not a substantial contributor or component of nasal salt gland secretions. This will not be light reading.

One must first have an understanding of hypertonicity to make this make sense. http://en.wikipedia.org/wiki/Hypertonicity#Hypertonicity

Linzell and Peaker. Salt Glands in Birds and Reptiles. Great Britain: Cambridge University Press, 1975.
- This book is a very comprehensive review of over 400 (I stopped counting past 200 when I got to H in the list of authors of papers referenced) scientific studies of the research on the nasal salt glands of birds and reptiles by myriad authors. I will provide some relevant quotes and summaries of various chapters of this 300+ page book. Birds and reptiles are evolutionarily closely linked, and therefore they are studied side by side in this regard. All lines in quote boxes are verbatim quotes from the book.

First, marine birds - the first subject of nasal gland secretion described as early as the 1600's:

Typical composition of nasal fluid in the gull (in mmol):
Sodium: 718, Potassium: 24, Calcium+Magnesium: 1, Chloride: 720, Bicarbonate: 13, Sulphate: 0.35

Hence, the nasal secretion is a practically pure solution of sodium chlorise with a concentration twice as high as the maximum renal concentration. The rate of elimination is so high that with continuous secretion the entire sodium content of the body could be eliminated in roughly 10 hours.

This is noteworthy considering according to wikipedia:

Sodium is an essential nutrient that regulates blood volume, blood pressure, osmotic equilibrium and pH...Sodium is also important in neuron function and osmoregulation between cells and the extracellular fluid; their distribution is mediated in all animals by Na+/K+-ATPase. Hence, sodium is the most prominent cation in extracellular fluid: the 4 gallons of it in a 154lbs human have around 50 grams of sodium, 90% of the body's total sodium content.

What does all that mean? Common table salt is made of sodium and chloride. Sodium is the most important ion for water regulation of your body water on a cellular level. Water (and chloride) follow sodium so too much sodium in any area of the body will attract water to flow out of where it is to go to where sodium is. Too much water in your cells will actually cause them to swell so much that they burst, which is incompatible with life. Too many of these cells burst and that organ dies, which can lead to the death of the entire organism. The body has very meticulous control over sodium specifically for this reason and the primary way to get rid of too much sodium is through the kidney. But the kidney can only get rid of so much at a time so in animals exposed to very high levels of salt (like marine birds and reptiles) extra regulatory measures may be needed to complement excretion by the kidney to make sure those devastating effects do not occur. The Na+/K+-ATPase is a cellular pump to exchange sodium for potassium to make sure the balance between the two is very precisely managed. Calcium does not have an effect on water balance and does not partake in ion exchange with this pump. Let’s read on…

The term salt gland…denotes any gland in the head region of marine birds and reptiles which, irrespective of anatomic origin, has an osmoregulatory function and secretes highly hypertonic sodium chloride solutions.

Since calcium has no role is osmoregulatory function why would a gland specifically evolved for that function chose to excrete something unrelated in any significant quantity?

Schmidt-Nelson established that secretion could be initiated by giving cormorants sea water by stomach tube or hypertonic sodium chloride intravenously. In addition they found that hypertonic sucrose given intravenously also induced secretion, and concluded that the nasal secretory mechanism seems to respond to an osmotic load rather than specifically to the plasma concentrations of sodium and chloride.

Even when given something in high concentration other than strictly sodium and chloride, the gland was triggered to secrete more sodium and chloride due to higher osmolality of body fluid (which calcium does not contribute to). This was demonstrated with a variety of hypertonic substances: mannitol, sucrose, sodium sulfate, ammonium chloride, and lithium chloride. Interestingly other hypertonic substances were given that did not affect the gland’s rate of secretion despite increased plasma osmolality: potassium chloride, urea, glucose, physiologic sodium chloride, and dextran. I think this is important because even substances that do affect osmolality do not necessarily cause an effect on salt gland secretion. And calcium does not even have an effect on osmolality.

It seems likely that concentration [of sodium and chloride of nasal salt gland secretion] is genetically determined but a number of studies have provided clear evidence that the concentration of the nasal fluid within a species can be altered by changing the salinity of the drinking water.

There are countless graphs and charts throughout this book illustrating the variations of sodium, chloride and potassium levels of the gland secretions. Why those and no other ions? Because those are the 3 most important ions to osmoregulatory balance and hundreds of papers found those, and only those, in any significant quantity due to the nature of the gland.

Studies giving birds concentrated salt water to drink demonstrated a significant increase in the concentration, rate and even the physical size of the nasal salt glands immediately within hours-days. After being on this type of water for several weeks they were switched back to regular fresh water and the gland immediately shrunk back down and decreased in secretion rate. The opposite was done to sea birds (giving them fresh water instead of salt water) and their glands decreased in size and function similarly, but returned to normal when switched back.

Even hormones (cortisol, deoxycorticosterone, aldosterone or mammalian ACTH) enhanced both the rate and concentration of sodium and chloride from the nasal salt gland.

 

[ferretinmyshoes]

Reptiles specifically

Onto reptiles specifically…Marine reptiles first:
Researchers found high sodium chloride concentration of tears of the loggerhead turtle from a periorbital salt gland, which is one of the cranial salt glands similar to the nasal salt galnd. High sodium chloride concentration was excreted from the mouth of sea snakes through a different salt gland.

Terrestrial reptiles:
The nasal salt glands of 36 species of lizards from 16 families have been studied.

Some lizards have salt glands, which secrete potassium and high concentration, but they do not necessarily play a major role in electrolyte secretion because other lizards and all terrestrial snakes appear to lack a salt gland, even those which occur in deserts.

Schmidt-Nielsen et al (1963) observed that a captive specimen of the Green Iguana was sometimes found to have white incrustations around the nostrils. These deposits were analyzed and found to consist mainly of sodium, potassium, chloride and bicarbonate. The potassium content was three times that of sodium, and the ratio of bicarbonate to chloride was two to three. In other words the secretion resembles that of the ostrich and differs markedly in composition from that of marine birds and reptiles.

We talked about the importance of very precise sodium regulation above, so why is potassium so important? Too much potassium can cause fatal arrhythmias and your heart to stop beating. It can also cause kidney damage, muscle weakness and damage and other serious problems (google hyperkalemia for more). There is actually more calcium in the body than potassium. But potassium has much more important consequences, which is why there is a backup method to get rid of excess.

Analysis of the chuckwalla found twice as much potassium as sodium and chloride content was very low, as the main anion appeared to be bicarbonate. When a captive iguana was given a concentrated sodium chloride solution then sodium was excreted at a higher concentration of potassium that increased to nearly 3 times as much sodium as potassium over the next few days.

In other words the output of cations was being adjusted to excrete sodium in greater quantities.

Templeton found that a group of Ctenosaura pectinata had a higher sodium and lower potassium concentration in their nasal fluid. These animals had been in captivity for some time and the diet included thinned dog food, which contained five hundred times more sodium than the usual food plants; the concentrations of bicarbonate and chloride in the secretion were not affected.

In contrast when potassium salts of organic acids (acetate, bicarbonate or succinate) were given instead, a substantial proportion of the anionic content was bicarbonate.

Interesting that even when given other substances in long term captive animals that the secretions really did not change in the type of ions that were secreted, merely the ratio. Dog food has significant amounts of calcium. Back in the day when reptiles had MBD vets recommended giving dog food, which corrected the MBD with its natural calcium content. It also obliterated their kidneys due to the high protein content and caused death from renal failure later, but that wasn’t known at the time the recommendation of dog food was popular. Even in long term captive animals on a calcium rich diet calcium is still not found. I also found it interesting that when given salts of varying composition the ability of the gland to adapt was simply secrete more bicarbonate, regardless of the type of salt given. Secretions did not take on any of the ions attached to the carbonate of the salt. So even giving calcium carbonate like our supplements there is no evidence that anything but plain bicarbonate would result in the secretions.

Mannitol and sucrose did not stimulate increased secretion of the salt gland in terrestrial reptiles as it did in marine birds. Aldosterone had a distinct effect on secretions causing more potassium when given and letting sodium prevail when removed. Aldosterone does not have an effect on calcium, nor vice versa.

Most terrestrial lizards secrete more potassium than sodium, at least when taken straight from the wild, but the Galapagos Land Iguana, whose vegetation is rich in sodium and a species of monitor lizard which is carnivrous secrete more sodium than potassium.

Even in carnivorous reptiles where calcium is clearly going to be in high concentration there is no increase of calcium found in the secretion of nasal salt glands.

Sokol has suggested that in terrestrial lizards the presence of nasal salt glands is associated with a herbivorous diet (rich in potassium) and that the role of the glands may be to regulate the body’s sodium and potassium balance rather than to conserve water. This line of reasoning would certainly explain the presence of salt glands in such lizards as the common iguana which eat plants but normally have access to fresh water.

 

[ferretinmyshoes]

In conclusion...

So how often did I see calcium listed as a component of nasal salt gland secretions? One time. On page 3 out of 307 comparing hundreds of studies. It was the chart that I posted above that shows a sodium:calcium+magnesium ratio of 718:1 in nasal salt gland secretions. This book included several chapters on the evolution and physiology of the nasal salt gland that allows for adaptation. Since the evolution of the gland is largely connected to that of birds I felt it relevant to include some of the research done on birds. Nowhere does any author suggest that the gland may in any way deviate from the secretion of sodium, potassium, chloride or bicarbonate. The evolution and adaptation is very definitively proven to be for the sole purpose of osmoregulatory function.

The reason that sodium, potassium, chloride and bicarbonate are the only substances discussed in the entirety of this compilation is because those are the things found in notable quantities from the nasal salt glands of dozens of species from different environments and adaptations and those are the things that actually drive the gland and regulate its function throughout evolution.

So what could be causing these crusts in our captive animals? Herbivorous reptiles in wild are getting these crusts purely from the vegetation they eat. Some chameleons eat vegetation directly and we feed lots of vegetation to our crickets during gutloading. All of the foods that we use for gutloading do have sodium and potassium in them. How often have we paid attention to that? We worry about the calcium content and whether there are oxalates, etc. but we often completely ignore the salt content of our gutloads. Many people also use tap water for their chameleons. The city sources of water have varying concentration of sodium, chloride and potassium that vary wildly depending on your location and water quality. Perhaps the salt content of the food is not enough to trigger secretion, but coupled with high salt concentration in drinking water is enough to manifest in these crusts. I cannot say for certainty what the perfect amount is, or what to do to make them go away. But as they are completely harmless to begin with and easily wiped away, I don’t really even see the need to make changes.

So why do I care enough to spend several hours of my hard-earned weekend pouring over very dryly written scientific documents? Because the recommendation to decrease calcium supplementation to eliminate the white crusts is dangerous and even more importantly completely unfounded. There have been hundred and hundreds of scientific studies specifically focused on the nasal salt gland secretions of many, many species of birds and reptiles over the last 40+ years and not one of them has ever shown the primary components of the secretions to be anything other than sodium and potassium with small amounts of chloride and bicarbonate and absolutely negligible amounts of calcium, if it’s even present at all, despite genetic, environmental, wild or captive, herbivorous or carnivorous lifestyles. I believe I have conclusively provided enough solid, scientific evidence to say that no one should be recommending a decrease in calcium supplementation as a way to address the white crusts around the nostrils. If it bothers you I would suggestion evaluating your city’s water source for salt content first and change over to a water source with less salt if you’d like to see them go away. It worked for me when my panther had crustiness…

I will be happy to discuss this further, especially if there is a part that was difficult to understand, and provide additional documentation from other authors and sources if needed.

 

[tkilgour]

Excellent thread. + rep for this!

 

[Zen Reptiles]

Great post.

When this has been brought up in the past, I have always asked what kind of water the person with the affected chameleon was using; I hypothesized it had more to do with other elements than calcium as well.

I would like to make note that Chlorine combines (ionic bond) with any naturally occurring sodium in the body to form Sodium Chloride (table salt) as you mentioned in your posts.

If you are using chlorinated tap water, even without sodium in it, the resulting reaction within the organism will create an ionic bond between these two elements to form table salt.....even if table salt is not present in the diet at the same time the water has been given....thus you will have nasal crust to expel this excess sodium chloride. (on a separate note, drinking tap water causes the same reaction in people and this causes an excess strain on the heart, leading to cardiovascular problems and heart disease.)

The only time I have had this nasal crust problem in the past was at an Expo in Alberta, where the water was very hard and heavily chlorinated. All of my 3 month old panthers had both nasal crust and slight gular edema....which was evidence enough for me that I was at least on the right track about water being directly responsible for these problems in chameleons.

All symptoms were gone within a few days of arriving back home where I use Reverse Osmosis water.

I'd also like to add that the first time I ever saw other animals doing this was watching Leatherback Turtles lay eggs in Bundaberg, Australia. They were crying and had some slight crust around the nose while on land, digging the holes and laying eggs. The herpetologist that was attending the turtles said that is their way to excrete the excess salt they accumulate from the ocean!

 

[ferretinmyshoes]

I would like to make note that Chlorine combines (ionic bond) with any naturally occurring sodium in the body to form Sodium Chloride (table salt) as you mentioned in your posts.

If you are using chlorinated tap water, even without sodium in it, the resulting reaction within the organism will create an ionic bond between these two elements to form table salt.....even if table salt is not present in the diet at the same time the water has been given....thus you will have nasal crust to expel this excess sodium chloride. (on a separate note, drinking tap water causes the same reaction in people and this causes an excess strain on the heart, leading to cardiovascular problems and heart disease.)

That is a very interesting point! Our chlorinated water is definitely something reptiles wouldn't be encountering in the wild, and it's another potential source of salt that could be accountable. Excellent post sir!

 

[ataraxia]

Very interesting, good read!

 

[ferretinmyshoes]

I'd also like to add that the first time I ever saw other animals doing this was watching Leatherback Turtles lay eggs in Bundaberg, Australia. They were crying and had some slight crust around the nose while on land, digging the holes and laying eggs. The herpetologist that was attending the turtles said that is their way to excrete the excess salt they accumulate from the ocean!

Did I mention that I am absurdly jealous that you got to see nesting leatherback turtles!?!? One of the things on the list of things I must see before I die.

 

[clarkrw3]

Thank you for this post Ferret!!! Great reading.


Zen- I will say that I have seen these salts in my collection and all the water I use is 0 TDS water from a reef system. I am not saying you are not totally correct with the water causing issues and increased salt discharge, however, there is more at play at least in my population.

 

[sandrachameleon]

Good post Ferritinshoes

 

[Elizadolots]

Since birds seem to count:

http://jp.physoc.org/content/540/3/1039.full.pdf

A postsegmental outflux of Ca2+, Mg2+ and Cl_ in the medial and lateral collecting ducts and/or nasal epithelium may be of adaptive significance when birds inhabit calcium- and magnesium-richmarine environments.

Where is the study on animals kept in calcium rich environments?

Quote:
The term salt gland…denotes any gland in the head region of marine birds and reptiles which, irrespective of anatomic origin, has an osmoregulatory function and secretes highly hypertonic sodium chloride solutions.
*******
Since calcium has no role is osmoregulatory function why would a gland specifically evolved for that function chose to excrete something unrelated in any significant quantity?

The salt gland is responsible for osmoregulatory function. The dissolved solids involved in osmosis do not perform regulatory functions, they are regulated by the function of the gland. The gland regulates the dissolved solids. When there are too many for osmosis, they are expelled.

That calcium has no role in osmoregulatory function means nothing. Neither does sodium or potassium. They are REGULATED by the gland, they don't control it.

What you've said is like saying that since illegal aliens play no role in border control, they are not involved in immigration issues.

Even when given something in high concentration other than strictly sodium and chloride, the gland was triggered to secrete more sodium and chloride due to higher osmolality of body fluid (which calcium does not contribute to)

What? You're saying calcium carbonate does not increase the osmotic load? I'd sure love to see even one study suggesting that's true.

Also, note that Dr. Hazard's research proved that the salt gland was able to adapt to whatever salt was in prevalence during the animal's growth. As her only examples were animals raised in sodium and potassium, she drew no factual conclusions about other salts but offered the theory that an animal raised in "another salt" rich environment would develop a salt gland which excreted that salt preferentially.

http://bio.research.ucsc.edu/~barrylab/Lisa/PDFs/Hazardchap06proof.pdf

The ontogeny of salt glands in lizards has not been studied, and it is possible that individuals exposed to different ions early in life may retain a tendency to secrete different ions in a laboratory situation

Note that there is no footnote saying "different means anything but calcium".

Even in carnivorous reptiles where calcium is clearly going to be in high concentration there is no increase of calcium found in the secretion of nasal salt glands.

Where is the support for proposing that carnivorous reptiles get an excess of calcium (because it is only an excess that is at issue)?

Your quote in support actually had nothing to do with calcium or carnivores...

Sokol has suggested that in terrestrial lizards the presence of nasal salt glands is associated with a herbivorous diet (rich in potassium) and that the role of the glands may be to regulate the body’s sodium and potassium balance rather than to conserve water. This line of reasoning would certainly explain the presence of salt glands in such lizards as the common iguana which eat plants but normally have access to fresh water.

I should be ashamed to admit I found that funny.

Here's the deal (and, I've posted this in at least one other thread but hey...)

WE DO NOT KNOW what the crust is.

It might well be true that it's comprised entirely of potassium and sodium...or, it might be comprised of calcium.

We do not know. The study has not been done.

However, the overwhelming history on this board is that reducing the daily calcium supplementation makes it go away.

Unless you're prepared to declare all of those posters over the years liars, we have to conclude that the calcium is causing the crust.

I would argue that if it's calcium that makes it okay because the animal is self regulating its calcium absorption. If the animal can't do that then there is a danger of the body forming "stones".

I would further argue, that if it's not calcium, it might not be okay because that means the calcium is pushing the animal's body to excrete potassium and sodium that it might well need. (they do need those things)

Thank you for taking this discussion outside of a poster's problem. That always felt very uncomfortable.

 

[Zen Reptiles]

Clarkrw3 I would be curious to know what you gutload with?

Many vegetables and fruits (especially processed or canned) contain sodium and the common gutload items including spirulina or any type of seaweed or algae do as well.

A lot of processed meat also contains high levels of sodium, including common gutload items as dog, cat, or ferret food...depending on brand.

 

[ferretinmyshoes]

In the paper you linked about birds the calcium to sodium secretion rate of the ducks was 0.46 to 559. So ~11,400x more sodium than calcium. You're right, it does count.

 

[fluxlizard]

Geez- this topic surprises me.

Rather I should say the worry/mystery surrounding it here on the forums surprises me.

I have always believed from reading 30+ years ago that this is simply a way that lizards get rid of excess salt type waste- stuff that would normally come out in urine in mammals, but more efficiently gotten rid of this way because it does not require as much water loss.

I did not even know this fact was up for debate. It is funny to me that it is. Many of the iguanids especially.

So many lizards do this - if you think a little crust around the nostrils of a veiled chameleon is a cause for alarm- you should try owning a green iguana sometime. They snort the stuff all over the place- very noticeable if you have a glass enclosure or if they hang out in front of a window because they soon coat the surface of the glass with it.

Many lizards I have bred do this.

20 years ago when I bought my first veileds, the care sheet from the guy I bought them from knew what this was and that it was natural and normal.

It's conservation of water loss - in veileds it is important because they come from sometimes very harsh arid environments where water must be conserved to the extreme (there are reports of these lizards living in very arid regions where it had not rained for 3 or 4 years living on plants practically void of leaves (probably because the lizards ate them for water content long before). Any waste that can be removed through nasal glands to conserve water would be a plus in this type of environment.

 

[ferretinmyshoes]

Flux, you bring up an excellent point that I should have mentioned a long time ago. I have a green iguana who gets ZERO calcium supplements (lives outside year round with a good diet - she's 18 years old with full tail and toes intact so you can't tell me my husbandry isn't good ) and she has crusts up the wazoo all the time. She sneezes salts out several times a day and always has a little rim of crusts. Been that way her entire life.

I too never thought this was a topic worth this much debate since it's really well known and kind of obvious, but the argument kept coming up so I decided to provide the proof anyway.

 

[sandrachameleon]

I too never thought this was a topic worth this much debate since it's really well known and kind of obvious, but the argument kept coming up so I decided to provide the proof anyway.

same here - never worried about it, rarely even experienced it (despite using straight TAP water LOL)

but it is one of those things that keeps coming up
and its nice you took the time to try to cover it in detail.

 

[fluxlizard]

same here - never worried about it, rarely even experienced it

Are you using a drip or mist system.

I would think those using drips would find it more noticeable because mist would regularly wash it away before it accumulates.

 

[Elizadolots]

My suspicion would be that sandrachameleon does not over do calcium dusting on her feeders if she does it at all. It's feeding them "ghost" crickets that seems to cause the crust to form.

Since birds count.

The ostrich (Struthio camelus), which lives in the arid parts of Africa and Arabia, was found by Technau (1936) to have large nasal glands with one duct entering the nostril from each side (Fig. 11.7). Schmidt-Nielsen et al. (1963) discovered nasal salt secretion in this species...The fluid they collected from the nostrils was found to contain high concentrations of potassium, sodium, calcium and chloride.

Because the recommendation to decrease calcium supplementation to eliminate the white crusts is dangerous and even more importantly completely unfounded.

So, all the many, many posters who've described that experience are lying? That's nice.

 

[ferretinmyshoes]

Since birds count.

You like to keep pointing out that calcium exists. I'm not denying that so it's not proving anything or helping your case at all.

So, all the many, many posters who've described that experience are lying? That's nice.

The only lie is that the secretions are a direct cause of the calcium, because there is absolutely no evidence of that whatsoever as I've proven.

Did you know dandelion greens, mustard greens, turnip greens and carrots are really high in sodium? Those are very common gutload items. You can't just ignore those and say there is no plausible explanation except calcium when you have highly variable salt content in gutload foods and water sources. That just doesn't make sense.

Did you follow up with every one of those cases and evaluate the water and food salt content and see what happened if those changed? When newbies have problems, even innocuous ones, we almost always make them fill out the husbandry form. So at the time they see the crusts people are also making husbandry recommendations, which usually include better gutloading recommendations. That's a confounding variable that may explain the changes they may see later (which we often don't even see because the newbies stop posting). It more than likely has absolutely nothing to do with calcium supplementation.

You are the only person arguing this.

 

[clarkrw3]

Clarkrw3 I would be curious to know what you gutload with?

Many vegetables and fruits (especially processed or canned) contain sodium and the common gutload items including spirulina or any type of seaweed or algae do as well.

A lot of processed meat also contains high levels of sodium, including common gutload items as dog, cat, or ferret food...depending on brand.

I will also say I have never been bothered by these salts, and have never thought of decreasing Ca due to them...

I gut load with Sandrachameleons recipes for wet and dry gutload as well as repashy bug burger. So yes I use seaweed paper and spirulina but have never used any animal products in my gutloads.