After reading Chad Brouze's eye-opening post on frog dissection practices I began investigating broader amphibian welfare. This led me to discover Chytridiomycosis (or chytrid fungal infection), a panzootic currently devastating frog and salamander populations worldwide while causing extreme suffering in the process. It's hard to get a real sense of scale on the threat that this condition poses to amphibians due to the pace of destruction with severe decline being documented in at least 500 species worldwide. Several extinctions as a direct result of the infection having already occurred. Despite the dire outlook and clear urgency, the research on treatment is underfunded but much of the rudimentary trials in the wild hold potential while being relatively cheap and scalable, at least to my eye. Funding this issue would likely to be a cost-effective way to drastically reduce animal suffering and stave off a biodiversity crash. I intend for this post to be a basic whistle-stop tour of the current literature on the topic to try and convince some folks here to throw some money at the problem. But first, further explanation of the disease and its effects are needed.

Chytridiomycosis in frogs is caused by the fungus Batrachochytrium dendrobatidis (often referred to as Bd).^[1] It transfers through cutaneous contact and harms through compromising skin osmoregulation. Hosts display symptoms such as frequent skin sloughing, lethargy, loss of certain reflex action, hyperkeratosis, hyperplasia, ulcers and more. After infection death usually comes within two weeks from cardiac arrest. Needless to say, this process is extremely distressing and painful for the victim. The emotional complexity of amphibians is still debated but stress-related tachycardia plus other nociceptive indicators are commonly agreed upon. Therefore we can conclude that the suffering of the afflicted frogs is objectively extreme and occurring on an immense scale. As stated previously, chytridiomycosis is classified as a panzootic. It has impacted amphibian populations globally causing needless deaths that number in the billions since its discovery in 1998, the reason for such a sudden explosion in cases is still obscure.

There have been several proposed treatments to eliminate Bd in a population, or simply control transmission, but they have had varying success in the field. The list of proposed solutions that I am aware of is as follows.

• Chemical disinfection - This is performed through manual application of a fungicide to the skin of amphibians or adding trace amounts to their habitats. Use of itraconazole and tebuconazole generally shows a drastic reduction in infection load for a year or two, before returning to an average. Efficacy also differs depending on time of application, varying based on stage of infection and place in the frog's life-cycle. Use of fungicide also poses some environmental risks plus slightly higher incidence of developmental disorders in amphibians. This is particularly troublesome considering that frog colonies would need repeated treatments to effectively combat the presence of Bd.
• Heat treatments - Bd's tolerance for variation in temperature is comparatively limited. Heating beyond this limit poses little to no risks to frogs while being extremely effective in eradicating zoospores. However, this treatment is shown to only be effective if maintained for several days in lab conditions. Also, depending on the strain of Bd, heat tolerance can vary so there is the potential for the fungi to develop greater resistance.
• Salination - Minor increases in a habitat's salt content has been shown to drastically reduce transmissions. Completely eliminating Bd in a body of water through this method may require higher doses which may pose risk to delicate freshwater ecosystems.
• Bacteria cultures - Exposing amphibians to the bacterium Janthinobacterium lividum led to a steep reduction in infection load due to its antifungal properties, however in all field experiments this figure returned to the average in a few months.

While none of these treatments are an absolute solution if refined or applied together I believe they stand a good chance of reducing infection and mortality by a significant amount. I have no qualifications in animal welfare but I can see a future where conservationists create artificial breeding habitats in the field which are equipped with means of applying the above solutions in tandem with monitoring apparatus. I highly encourage anybody with greater expertise to brainstorm in the comments below.

Also, as a little postscript, even if your approach to cause prioritization makes you inclined to not class animal welfare issues as warranting immediate attention I would make the case that this is an exception. The sudden onset of this disease, its virality, as well as its mortality rate raises concern around fungi-based zoonotic disease. You can read more on the topic in this post by emmannaemeka. Conversations around this tend to get a little infohazard-y so discuss with caution.

Sources used:

• Successful clearance of chytrid fungal infection in threatened Chiricahua leopard frog (Rana chiricahuensis) larvae and frogs using an elevated temperature treatment protocol - Whitney L. Heuring et al.
• Effectiveness of antifungal treatments during chytridiomycosis epizootics in populations of an endangered frog - Roland A. Knapp et al.
• In situ treatment of juvenile frogs for disease can reverse population declines - Kimberly Cook et al.
• Amphibian resistance to chytridiomycosis increases following low-virulence chytrid fungal infection or drug-mediated clearance - Anthony W. Waddle et al.
• Frog in the well: A review of the scientific literature for evidence of amphibian sentience - Helen Lambert et al.

1. ^{^}

   There is also a related fungus, Batrachochytrium salamandrivorans, which causes chytridiomycosis in salamanders but addressing both of these issues at once is beyond the scope of this post. A post or comment on this in particular would be great if anyone wants to chip in!