Yellow Skin Disease or Yellow Fungus in Bearded Dragons & other Reptiles

Bearded Dragon lizards (Pogona vitticeps) have become extremely popular pets in recent years, perhaps the most popular and suitable reptile pet for beginning reptile keepers. And for good reason as they are relatively hardy, easy to cater for (as far as reptiles go) and have outgoing, engaging personalities akin to our more common mammal pets. They do, like other reptiles, require specialist knowledge and equipment to keep healthy and well however, and often the cost of providing appropriate lodgings and husbandry far exceeds to value of the animal itself. Because they are such common reptile pets, and also many beginner keepers start out with this species I frequently see them in clinic for a range of conditions, many of which can be attributed at least partly to shortcomings in their husbandry (how they are kept and managed) or nutrition. They can suffer from various infectious diseases caused by bacterial infections, various parasites and less commonly fungal infections.

Necrotic ulcer left after sloughing of lesion, with topical ointment

Necrotic ulcer left after sloughing of lesion, with topical ointment

One of the worrying trends being observed worldwide, but noticeably in the past several years in the UK is the spread of a specific fungal pathogen that can cause severe skin infections or fungal dermatitis and ultimately death in Bearded Dragons primarily, but also some other reptile species. The pathogen responsible is a fungal organism with the rather long-winded scientific name of Chrysosporium Anamorph of Nanniziopsis vriesii (CANV) which is colloquially known amongst hobbyists as ‘Yellow Skin Disease’ of Bearded Dragons. This is an aggressive fungus which invades the superficial and deep layers of the skin and causes discolouration of the skin, necrotic lesions which slough off revealing sensitive ulcerated tissues underneath the scales and diffuse painful subcutaneous swelling and inflammation. In severe cases the hyphae of the fungus, which are microscopic root like filaments, can extend deeper into the animals body cavities and internal organs often causing marked pathology and eventually death.

Beardie with ulcerating, hyperkeratotic necrotic lesions, skin swelling & discoloration

Beardie with ulcerating, hyperkeratotic necrotic lesions, skin swelling & discoloration



Transmission of the fungus responsible is thought to be from direct contamination with the fungal agent encountered in the environment, and is easily spread throughout reptile collections and other facilities housing large numbers of animals by keepers and on equipment. The incubation period from the time infection occurs to the development of visible signs can be several weeks to over a month so it is often difficult to pinpoint the exact source of infection, especially in newly acquired animals. Suboptimal husbandry conditions such as low temperatures and poor hygiene practices are often responsible for predisposing animals to this disease. However many well cared for and otherwise healthy animals can become infected if exposed to the pathogen also.

After infection, the early signs of disease usually present as dry, crusty, hyperkeratotic lesions and discoloration of the skin which can lead to patches of retained skin after shedding. Excessive or more frequent shedding is common at this stage of disease also. These lesions generally progress over several weeks to months and become necrotic and exudative meaning the skin starts to die and release infectious discharge. Wet, scabby lesions form on the surface of the skin and eventually slough off or can be lifted off when cleaned to reveal pustular discharge underneath and ulcerated inflamed soft tissue devoid of the superficial skin layers or scales. These ulcers are obviously very painful and prone to secondary bacterial infections. Once the disease has advanced this far it can be quite difficult to treat successfully. Recovery and regeneration of new skin takes a considerable period of time, and the animal is often left with extensive scar tissue if it survives. Lesions are commonly found on or near the mouth or head but can be found anywhere on the body. Other diseases which may be confused for this condition include bacterial dermatitis, stomatitis, thermal burns and indeed other fungal skin infections. Diagnosis is made based on clinical signs, appearance, and testing skin samples or tissue biopsy for the organism itself using PCR, microscopy or culture techniques.

Exudative, crusting lesion typical of Yellow Skin Disease of Bearded Dragons

Exudative, crusting lesion typical of Yellow Skin Disease of Bearded Dragons



Treatment is multimodal and involves the use of an oral antifungal drug called Itraconazole which needs to be given every day for 4-6 weeks in most cases. Antibiotics are sometimes used also to treat or guard against secondary bacterial infections. Topical cleaning with chlorhexidine is recommended as well as the application of topical antifungal agents such as miconazole or F10 ointment. Topical agents alone are not indicated for a successful outcome however, as it appears that most success is achieved using systemic antifungal treatment with oral itraconazole at the correct dose rate. For this reason it is crucial if you have an animal you think might be affected to seek the advice of an experienced reptile veterinarian. The disadvantage of using this drug is that it can have severe side effects with long term use however, especially with regard to liver function and particularly in already debilitated animals. It is crucial therefore that affected lizards are treated early, appropriately and that supportive care is given in the form of supplemental feeding and hydration if necessary. Monitoring of liver function during treatment may be necessary in some cases, which requires blood sampling. Aggressive surgical debridement of lesions is sometimes warranted also to reduce the presence of the fungal agent and aid in treatment. I have treated several suspected and confirmed cases of this disease in Bearded Dragons and one suspected case in a chameleon. Sadly not all of them have survived. In two cases where a single limb was affected I amputated the affected limb and the Beardie went on to live a very happy life.

If caught early, this disease can be treated successfully. It is critical to prevent the spread of the organism to other reptiles so isolation of the affected animal and great care to prevent mechanical transmission on owners hands, clothes or equipment is recommended. Rigorous cleaning and disinfection of cages, furnishings and equipment is also crucial in limiting spread of the organism or re-infection as well as discarding all contaminated substrate or porous materials from the affected animals vivarium. The disease is not zoonotic meaning it does not readily transmit to humans as it is primarily a reptile pathogen. However there have been a few reports of CANV isolated from severely immunocompromised human patients so sensible hygiene precautions that should be implemented with any ill pet need to be taken.


8 thoughts on “Yellow Skin Disease or Yellow Fungus in Bearded Dragons & other Reptiles

  1. I recently lost my bearded dragon due to yellow fungus, which he had from the pet store we bought him from. I was hoping you might have suggestions about how to sanitize my reptile’s environment properly, so that all remaining fungal spores can be killed.

    • Hi Riley, sorry to hear you lost your Beardie. Yellow fungus is a terrible disease. Firstly I would advice disposing of all porous cage furnishing sand accessories that may harbour fungal spores such as wood, fake plants as well as any loose substrates. Then you should clean and disinfect your caging and accessories including all heating and lights using a reptile safe disinfectant such as the F10 range of products which kill fungi, viruses and bacteria when used correctly. Anywhere your lizard has been could potentially be an infection risk so be careful.

  2. I have a bearded dragon that my vet has been treating for a very long time. We have done oral medication and bactril shots every other day. We done medicated bathes, etc. He is continuing to get new spots and is about to lose one foot. Every limb has issues and he is now showing signs on the top of his head. Is there anyway to cure this or at what point do I put him to sleep. If there is a way to save him I WILL but he has to be in some sort of pain with open sores.

    • Sorry to hear that Barbara, the treatment of choice as I said in my blog post is a drug called Itraconazole but it can have harmful side effects, and is by no means guaranteed to be successful. If your Beardie is that bad and about to lose a foot that’s obviously a big quality of life issue and is causing terrible pain so I think you need to have a chat with your vet about the next steps. Putting him to sleep at this stage isn’t unreasonable as he is suffering and the prognosis is guarded to poor once it’s that far advanced.

  3. Is Canv curable in dragons under a year old if it is treated before the fungus creates open sores and gets necrotic? My beardie had/has pin head sized yellow spots and had a crusty scarred like part of her face. The scarring/crust has gone down a lot since i started topical antifungals and daily voriconazole oral medication. My vet has seen her three times now and i removed all wood and porous materials. The substrate is nat geo faux grass that i wash by hand once a week and dry on high heat in my dryer. I also use cleaners on all her other bowls/decor when i do that. My vet seems unworried that it will get worse but ive heard that canv is always fatal. Which is true?

    • There are no hard and fast rules in veterinary medicine. Some patients do better than others. From my research and experience, CANV is most often fatal especially if treatment is started late in the disease progression which is in most cases. So although there is a possibility if caught early that appropriate treatment could be successful, the prognosis is still always guarded and you would be one of the few lucky ones if you manage to get your Beardie through this especially considering the duration of treatment with antifungal drugs can also cause fatal side effects. Good luck, I hope she makes a recovery!

  4. Great information, thanks! Regarding the picture of the beardie on the blue towel: is the yellow color part of the disease on this beardie or is the darkened spots on the tail the only diseased skin visible?

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