The Temporal Gland & Its Function
Authored By Elise Stein | Chameleon Enthusiasts
Clearly visible black pigmentation of the inner space of Trioceros jacksonii xantholophus credit Petr Necas
By now you have heard the words Temporal Gland floating around the reptile community and you may have even seen articles or read first hand accounts on Temporal Gland infections. To help our reptile community better understand the function of these glands, I could not think of a better expert to receive an explanation from than Petr Necas. Read on as he elaborates in a short, but very detailed interview.
Elise: Hello Petr. Thank you for agreeing to this interview today! As you know, the Temporal Gland is a great mystery to the reptile community. Can you help us to understand what a Temporal Gland is, and where it is found?
Petr: With pleasure, Elise. As we all know, chameleons are very unique creatures combining on their bodies many extremely spectacular features, like the zygodactyl feet, prehensile tails, long extendable tongue, color changing skin etc… Amongst all these, the temporal gland is not less spectacular but it is almost unknown…
It is technically just a fold of skin, a pocket (this is where the alternative term “temporal pouch” comes from) that is deeper or shallower, depending on species, situated on the outer face of the mouth angle and above.
While the mouth is opening, it is a thin, closed fissure down along the jaws. Once the jaws are fully opened, then the inner space of the pouch opens and can even be slightly everted outside. In the gland type classification, it is a holocrine type of exocrine glands that discharge their products to the outer world through openings or ducts, not into the blood as is the case of the endocrine glands.
Male Trioceros j. jacksonii credit Petr Necas
Elise: Which species have this Temporal Gland?
Petr: The temporal gland has been reported to be developed in the following genera of chameleons: Bradypodion, Chamaeleo, Kinyongia, Rieppeleon, Furcifer and Trioceros, while it is best developed in the latter one. It seems to be undifferentiated in Calumma and Rhampholeon.
Its presence does not necessarily mean its full functionality, which has really only been studied in Trioceros, since they are the genus with the best developed temporal gland.
Elise: On a healthy chameleon, how does the gland appear?
Petr: The gland is, under normal circumstances, invisible. It becomes visible only if the animal is threatened, attacked or excited. Then the open mouth exposes the lumen of the gland above the mouth angles and its content is visible to the outer world.
Elise: On an unhealthy chameleon, how does this gland appear?
Petr: If the temporal gland gets inflamed, it is visible as a swelling above the mouth angle, often exposing the fissure through which it opens by a pink or red color. Once it gets open, it is full of sticky or cheesy yellowish substance and the lumen is red or pink also, while normally, it is either white or black…
Temporal Gland in Trioceros jacksonii xantholophus credit Petr Necas
Elise: Many keepers have witnessed a yellow cheese like substance on the gland, and detected a foul smell. Can you explain the function of this substance ?
Petr: This is a secret of the gland and it is very spectacular. The cells of the lumen of the gland do not produce any specific secret. They simply die and fill the lumen of the gland with dead cell mass. This is then infected by unspecific aerial bacteria (e.g. Aeromonas, a genus of gram-negative, facultative anaerobic, rod-shaped bacteria) and decayed with their help to form a cheese-like whitish or yellowish, terribly smelling substance.
This substance is used at least for two spectacular functions:
Anti-predatory function: while being approached by a predator, the mouth is opened wide and the lumen of the temporal gland exposed. The smell of a decaying, biological substance is identified by the predators as inedible, dangerous and potentially toxic.
Predation function: the smelling substance is smeared on a branch. The chameleon makes some steps backwards and waits till the oder attracts flying insects, especially Diptera (flies), which are then shot with their tongue and eaten.
Elise: Does the gland appear differently in other species ?
Petr: The development of the gland is different in different species. It is sometimes functional and sometimes nonfunctional, varying in size and color of the lumen (from white to black). Actually, the black coloration indicates a presence of melanin. That very likely protects the gland from UV irradiation, that might kill the useful bacteria. So the chameleon is in fact protecting the friendly bacteria against the outer environmental factors and giving them all:
Shelter (in the volume of the gland)
Good conditions (dark, warm and moist environment)
Food (the dead cells produced by the gland)
Protection against UV (melanin coating of the gland)
Healthy Chamaeleo roperi gland credit Petr Necas
Elise: We see many cases where the gland becomes infected. Can you explain how this happens?
Petr: As you might understand from the description above, the chameleon is cultivating bacteria in two poaches on its body. These bacteria are comensales so long the chameleon is strong and healthy. But they turn to be aggressive pathogens when the animal is weakened.
I have never seen any animal with an inflamed temporal gland in the wild and I have seen thousands of specimens of the the genera and species that possess it. But it, unfortunately, seems to be not uncommon in captivity.
The reasons are as follows:
Weakened immunity – inadequate captive conditions like too high temperatures, absence of night drop of temperatures, too high humidity, low ventilation, inadequate food, disbalance of supplements etc… All this weakens the immune system and invites the bacteria to take over control.
Absence of pollen – if pollen is absent in the captive diet of chameleons, its antibiotic properties do not build the antibiotic shield that controls the bacteria and a TGI is more likely to arise.
Low level of UV
Increased concentration of germs – in weakly ventilated cages or polluted and not cleaned cages or their parts, bacteria can reproduce and aggregate in high concentrations and contribute to the weakening of the immunity and outbreak of TGI. Any artificial object in the cage (most risky are ropes that can easily keep moisture and get contaminated easily) that does not have the self-cleaning and antibacterial properties as natural ones, may increase the risk level.
Diseases and parasites – TGI is portended by weakening the chameleon through other diseases (such as a Respiratory Infection, eye inflammation etc. and appears often in combination with some or more if those) and parasite infestation.
To sum this up: a healthy chameleon which is kept under perfect conditions simulating its natural environment is very unlikely to get a TGI.
Elise: Are there ways to prevent a chameleon from getting a Temporal Gland Infection?
Petr: Of course, there is:
Proper caging
Live plants and natural branches as cage decoration and equipment
- Proper hydration and humidity
management
- Proper temperatures and temperature fluctuations
- Proper food and supplementation
- Proper UV
- Proper pollen addition to food
- Proper health care
In total, the Naturalistic approach in captive care prevents the outbreak of TGI.
Elise: What early signs should we look for that warn us that something is going wrong with the Temporal Gland?
Petr: As the temporal gland is, under normal circumstances, invisible and an unstressed animal has no reason to open it and expose, the early signs are very hard to see. So even a very cautious chameleon keeper notices the TGI usually only in the acute phase. The early symptoms that can be targeted through detailed observations of the animal state and behavior are:
-
- Pink or red discoloration of the TG opening
- Wide gaping with everting the TG
- Repeated and vigorous scratching the mouth angle against branches
- Swelling in the cheeks area
- Refusal of food
- Untypical hyperactivity and nervous crawling through the cage
Any other disease or infection of the mouth or respiratory tract might accompany TGI as well
Elise: How should one go about treating a Temporal Gland Infection?
Petr: Once a TGI arises, there are two things to do:
Immediately: go to Veterinarian. An antibiotic, after checking the sensitivity of the bacteria, will be administered to boost the powers of the chameleon’s immune system. As a support, careful hydration, pollen and manuka honey can help boost the immunity and add some quick energy to the patient.
Long term: get all aspects of a proper, naturalistic approach to your captive care in line with the needs of the animal to prevent it in the future
Elise: How will veterinarian treat a Temporal Gland Infection?
Petr: It Is upon the discretion of an experienced veterinarian to design the treatment process, but basically, the following activities will be for sure included:
Assessment of the total health and nutritional state of the animal
Inspection of the TG at the widest possible opening of the mouth while paying special attention to the surrounding structure( mainly mouth and throat)
Thorough removal of the product of the TG from its volume and taking a sample for bacteriological analysis and sensitivity test (the bacteria will be cultivated, identified and exposed to different antibiotics to test their sensitivity to them in order to select the most efficient one and eliminate the ones that show weak reaction)
The entire volume of the TG will be disinfected using some disinfectant solution
After the sensitivity tests are done, an antibiotic for holistic application (oral or injection) will be selected and a treatment schedule defined (lasting a minimum of 7, but probably 10 or more days)
A local antibiotic solution or cream will be prescribed to apply locally to the TG area itself
If the animal shows signs of pain, analgesics might be prescribed as well
Disinfection solution or cream will be prescribed as well
Instructions will be given for administration of the medications
Instructions will be given on the periodical treatment of the TGI area consisting of cleaning the TG lumen, disinfection of it, application of the local antibiotic solution/cream
Instruction will be given about hydration, supplementation, pollen, supporting dietary measures
An online care mode will be agreed and next visit scheduled
Treatment for Temporal Gland Infection on Trioceros jacksonii xantholophus as prescribed by a licensed veterinarian credit Elise Stein
Elise: What supplements or foods can keepers implement to decrease the odds of this happening?
Bee pollen granules
Petr: The proper care as discussed above is the key. On top of that, bee pollen is a key factor to be added to the food with each meal. Bee pollen is a natural part of their daily diet, and except of its value in containing amino-acids, antioxidants and vitamins, it contains natural antibiotics building an antibiotic shield against unwanted reproduction of bacteria.
Elise: Have you ever witnessed a Temporal Gland in the wild?
Petr: Sure, any time when you approach a chameleon who possesses it and you make him a bit angry, it opens a mouth and, as a defense mechanism, the temporal pouch is exposed. Some specimens, if handled, even try intentionally to smear the foul smelling content of the temporal gland on the enemy…
Not a single time, however, I have seen a TGI. It does not say that it does not occur, but amongst the thousands of animals I have observed, not any single one showed signs of it.
Elise: Is it good practice to regularly clean the gums and gland?
Petr: No, do not do it. Any unnatural treatment can stress the animals, cause micro trauma and disrupt the gentle homeostasis and as a result, the risk of TGI would dramatically increase!
Elise: Thank you Petr, very much, for sharing this valuable information with us. The Temporal Gland and its function is a great mystery to our community. I am hopeful that our interview today will be helpful to other keepers out there who may encounter an issue with their own chameleons, and will also aid in early detection and prevention.