Introduction

Captive bred amphibians are always healthier, and hardier than wild caught. This is partly due to the fact that captive bred individuals are not exposed to nearly as many different pathogens in the wild. However, the main reason captive bred are more hardy than wild caught is probably because they do not have to endure the tremendous stresses involved with capturing and exporting animals from the wild. As a means of ensuring any captives health, as well as ensuring the existence of diminishing caudate species, it is a good practice to only purchase captive-bred specimens. Fortunately, captive breeding successes are increasing around the world.

This article attempts to alert caudate owners and potential buyers of physical signs of illness, and offers some general treatments. Please note that this article is meant only as a guide, and although it does include basic and general treatment instructions, it does not guarantee the successful recovery of any specimen as a result. Because it is difficult to diagnose any illness simply from reading an article, a trip to a vet trained in Herpetology may be necessary before self-treatment is administered. Also keep in mind that it can be detrimental to the health of a weakened specimen to over-treat an illness. It is a good idea to choose one treatment and stick with that one treatment to avoid over-medicating, which can lead to undue stress to the specimen. The following passages describe common illnesses and diseases incurred by amphibians, some with treatment suggestions. 

*NOTE* Because they are sensitive to their environments, it is crucial to house amphibians in proper, and correct environments. If this is not possible, please be responsible and do not purchase or collect animals that can not be cared for properly. Prevention of illness is the key to healthy caudates, and prevention is attained through a firm knowledge of any captive species habitat needs.

Nutritional Disorders

Metabolic Bone Disease (MBD): Caudates, Anurans, Caecilians
MBD is a general term used to describe a deficiency in one or more dietary nutrients, that causes skeletal and other physical problems. MBD occurs often in captivity, when an amphibian is consistently fed nutrient lacking food. Referring to amphibians, MBD is usually associated with an imbalance of calcium, phosphorous, and vitamin D₃, as well as over-ingestion of fat-soluble vitamins, certain minerals, and oxalates. Amphibians use lipoproteins to transport vitamin D metabolite 25-hydroxy-cholecalciferol, which means that over-consumption of fatty acids and fats could have adverse effects, even if calcium, phosphorous, and D₃ dietary levels are acceptable. 

Amphibians afflicted with MBD appear weak, and may be suffering from pathological fractures about the spine and other bones, loss of bone density, splayed limbs, scoliosis, tetany (different than in cows), bloating (gastrointestinal gas), hydrops, subcutaneous edema, gastric or cloacal propolase, or a combination of these conditions. Mandibular deformities, abnormal posture, reluctance to move, splayed limbs, and scoliosis are some external symptoms that could be attributed to MBD.

Most arthropods fed to captive amphibians, namely crickets, possess an inverse calcium-to-phosphorous ratio, making them a calcium-deficient food source for amphibians. Those that are fed a diet of only crickets are at high risk of developing MBD. The calcium-deficiency of crickets can be counteracted by "gut-loading" the crickets 48 hours prior to feeding to amphibians. Gut loading means feeding crickets meals high in nutrients, namely calcium, prior to feeding the crickets to other organisms. When an amphibian eats a cricket it will absorb any nutrients within the cricket, so healthy crickets lead to healthier amphibians, and vice versa. Cricket diets can be purchased at most pet stores that sell crickets, or online from any reptile/amphibian supply company, and should be around 5%-8% calcium to maintain a positive calcium-to-phosphorous balance. A major disadvantage to gut-loading with high calcium foods is that the crickets usually cannot survive more than 48 hours on such a diet, and smaller insects, such as fruit flies and flour beetles cannot survive more than a few hours. Also, it has been shown that amphibians fed a diet of properly gut-loaded crickets still develop calcium imbalances, implying that there are other major factors affecting calcium absorption and utilization.

Another method of increasing the nutritional value of crickets is to dust them with mineral-vitamin powder immediately before offering the insects to amphibians. Dusting is supposed to increase the calcium and D₃ levels upon ingestion, but has been proven sufficiently ineffective. The main problem with the dusting method is that the powder comes off easily as the insects move about the amphibians home, which reduces or eliminates its transfer to the amphibian.

Treatment of MBD can be arduous because it's nearly impossible to tell from appearance just what element is missing from the diet, or if something undesirable is present in the diet. Proper diagnosis is obtained from radiographic studies that show symptoms such as abnormally shaped mandibles, thin cotices of long bones, expansion of marrow cavity, loss of bone density, limb deformities, and pathologic fractures. Initial treatment generally consists of calcium and vitamin D₃ supplements, with regular radiographic tests to check results. It has also been shown in a few cases that lack of exposure to ultra violet B radiation can have negative effects on D₃ levels in some anurans. Although this is not well researched or documented, it is recommended that a UV exposure regimen, in the range of 280-300nm, also be administered, with the exception of those species that are known to have neutral or adverse effects to UV exposure.

Hypervitaminosis A and D₃, and Vitamin Deficiencies: Caudates, Anurans, Caecilians
Domestic mice may contain high levels of vitamin A, which can interfere with the absorption and utilization of D₃ in amphibians. Hypervitaminosis A has been linked to MBD (metabolic bone disease) in certain anurans, where the animal was fed a diet consisting only of rodents. Small mice are sometimes fed to larger amphibians, which is probably okay on occasion, as a supplement to their regular diet. Rodents can also be fed calcium and D₃ supplements prior to occasional feedings, which aids in offsetting the high vitamin A levels found in rodents.

At least one case of Hypervitaminosis D₃ has been shown in an anuran fed a diet consisting only of goldfish. The specimen experienced lethargy, anorexia, weakness, hydrops, edema of the thighs, and possible renal disease.

Paralysis has been linked to thiamine and other B-vitamin deficiencies in some Dendrobatid frogs. Paralysis can also be caused from other ailments, such as botulism, or hypocalcemia.

Thiamine deficiency is also common in aquatic and semi-aquatic species that are fed frozen or live fish as a main diet. Many fish possess the enzyme thiaminase, which inactivated thiamine. Thiamine deficiency is thought possibly cause tremors, seizures, fasciculation (muscle twitching), and opisthotontos (severe back and head arching). 

Vitamin deficiencies are also known to cause scoliosis (crooked spine) in the larvae of some Hylid frogs, and spindly leg syndrome (underdeveloped skeleton) in larval and metamorphosed Dendrobatid frogs, and some Hylid frogs. Scoliosis and spindly leg are thought to result from the leeching of B vitamins from fish food, and may occur if fish food is the sole diet of the larvae. Vitamin deficiencies can be avoided by using high quality fish foods in addition to a varied diet, and can usually be corrected by adding vitamin supplements to the water.   

Obesity, Anorexia, and Starvation (Cachexia): Caudates, Anurans, Caecilians 
There is some controversy over the existence of medical problems associated with obesity in amphibians with slower metabolisms, namely caudates. Although there aren't any documented deaths associated with obese amphibians, it can be assumed that, as in mammals, obesity can cause strain on certain organs. If the heart is severely strained, there is a high risk of cardiac arrest. Obesity is common in some larger amphibians, such as Ceratophrys spp., Ambystom mavortium, Ambystoma tigrinum, etc. These, and other species, may consume as much as is available, and in captivity, their food supply is usually more regular and stable than in the wild. Over feeding can easily lead to obesity in some amphibians, but is also easily corrected by monitoring the amount of consumption.

An extremely skinny amphibian is a result of one of two things. 1)The salamander is underfed, or is fed nutrient-lacking food (starvation). 2) The salamander is sick and/or stressed and is rejecting food (anorexia). It is hard to tell the reason for a malnourished amphibian without examining it for a period of time, but often times in captivity it is because of a improper habitat, stress due to aggressive tank mates, internal or external bacterial infection, parasites, etc. When amphibians are sick or stressed they usually reject food. The rejection of food is a major warning sign of an illness. In cases of starvation, semi-aquatic and aquatic amphibians may take on a bloated appearance due to protein catabolism, which causes water gain. Terrestrials, on the other hand, often appear dehydrated, with severe weight loss. Starvation can be treated simply by  introducing food items slowly so as not to send the amphibians system into shock. Starvation is often the result of inappropriate food items, or simply underfeeding. Food items should be the proper size, non-toxic, non-biting, and capable of being captured. Some individuals are picky eaters, and may only eat certain types of food. Redworms (a type of earthworm) are often rejected by amphibians because they secrete a noxious mucus, small insects that bite may also be avoided, and some amphibians will only take live foods, rejecting any frozen or freeze dried offerings. The first thing to do with a starving amphibian is to make sure tit is not just waiting for a more suitable food item to come along. Also, keep in mind that new amphibians may take a few days, sometimes more than a week, to adjust to a new environment. It is common for new amphibians to reject food for some time in their new home, until they are comfortable and.

Impaction: Caudates, Anurans, Caecilians 
Impaction can occur when amphibians ingest foreign objects, that they cannot pass normally. This is common in captive specimens that lunge at their food. Ambystoma mexicanum is notorious for swallowing bite sized pebbles, and many terrestrials may consume bits of soil and bark from their substrate.  Foreign objects can become impacted in the stomach, intestine, or colon. Lethargy, abdominal bloating, or large lumps in the abdomen can be indicative of impaction. Some species have rather thin epidermal layers about the abdomen, and objects may be seen through the skin. Palpation (examination by touch) of thicker-skinned species may reveal hard masses of impacted substance.

Gastric overload occurs when amphibians consume way too much food at one time, or large food items, and results in decreased inspiratory volume. The expanded stomach can create a strain on the circulatory system, causing hypoxia (O₂ deficiency), and hypercarbia (excess CO₂), as the systemic veins are compressed. Severe cases result in shock, and usually death within a few hours. If the specimen does survive the physical stresses involved, there is a risk of poison from toxins associated with putrefying food items in the gut.

Chytridiomycosis (Chytrid Infection): Anurans
Chytridiomycosis is an infectious disease caused by the bacterium Batrachochytrium dendrobatidis, a zoosporic fungus related to water molds. B. dendrobatidis resides in keratin found in the host, restricting it to the superficial layers of skin, and other keratin-rich areas. Chytrid infections has a high mortality rate, for reasons unknown. 

Infections of this type are unique in amphibians because other documented Chytridiomycetes are not vertebrate pathogens. Chytridiomycosis epidemics have been documented in wild populations in the US, Central America, Ecuador, Australia, and New Zealand, and Spain. B. dendrobatidis lives independently of a host in aquatic environments, and often invades tadpoles that may be developing in the same aquatic habitat. Although some species may not show signs of illness, others may display abnormal posture of the hind legs, abnormal behavior and disposition, thickened skin, anorexia, lethargy, excessive shedding, pale skin and hyperemia, and disfigured beak (tadpoles). The first diagnosed case was in Bufo microscaphus californicus, which displayed anorexia, lethargy, and later pupillary miosis, and lack of muscle coordination. Obvious signs of illness have also been documented in other species, as well. Chytrid infection can usually be determined with skin scrapes, or toe clips.    

B. dendrobatidis can survive in a moist environment without an amphibian host, as in a laboratory, and anti-fungal medications have been shown to effectively kill B. dendrobatidis cultures. However, their effectiveness in infected amphibians is varied. Other treatments include exposure to artificial UV light, and salt solutions with anti-fungal medications. Studies show that Dendrobatids have been successfully treated with bathes in a dilute, saline solution of itraconazole (Sporanox, Janssen Pharmaceuticals, Inc.).  

Mucormycosis: Anurans 
Mucormycosis is an infectious disease caused by  Mucor amphibiorum, a dimorphic fungus endemic to Australia. M. amphibiorum reside in the skin and internal organs of amphibians, and foment formations of inflammatory cells and fibrous tissue. Small nodules containing microscopic fungi may be found in the liver, kidneys, lungs, mesentery, bladder, subcutaneous sinuses, and epidermis.

The infectious spore phase of M. amphibiorum reside in moist soils, and are thought to enter amphibians through accidental ingestion. Mucormycosis in wild amphibians has been documented in Queensland, Northern Territory, Western Australia, and New South Wales, and in platypuses in Tasmania. Mucormycosis has also been known to cause death in exported captive Australian frogs, as well as captive Dendroabtids that were exposed to the fungus.   

In short, bacterial infections are usually the result of an attack on an already weakened animal. This is further supported by the isolation of anti-microbial peptides in the external mucous of some anurans. This discovery probably explains why amphibians can reside in waters and on substrates full of pathogens, without ever becoming infected. 

Localized Infections (infection restricted to a specific area of the body): 

Superficial Wounds: Anurans, Caudates, Caecilians 
Superficial wounds on amphibians usually contain a wealth of bacteria, possibly including Acinetobacter spp., Aeromonas spp., Citrobacter spp., Flavobacterium spp., Provdencia spp., and Pseudomonas spp.

In most cases, antibiotic topical ointments can be applied one to several times per day, until the wound is healed. Aquatic and semi-aquatic species may benefit more from short bathes in antibiotic solutions. Some medications available from vets are silver sulfadiazine cream, Gentamicin ophthalmic ointment or drops, Oxytetracycline ointments, Bactine™ (Miles Laboratories, Ltd.), furazolidone, Plasticized hydrocarbon pastes, etc.

Systemic Infections (infection of the systemic structures, i.e. organs, bloodstream, tissues, etc.): 

Aeromonas spp. & "Red-Leg" Syndrome: Anurans, Caudates 
"Red-Leg" syndrome is a common sign of systemic infection, and is characterized by reddening of the legs, and sometimes abdomen. The red appearance is caused from broken capillaries under the skin, and was originally thought to be the result of an internal infection of Aeromonas hydrophila, a  bacterium found in colder freshwater bodies, and moist soils. Today, many agents have been linked to red-leg syndrome, including ranaviruses, other bacteria, Chlamydia psittaci, and Basidiobolus ranatum. 

Red-leg syndrome in captive amphibians usually occurs in specimens experiencing poor immune response, resulting from improper husbandry. Aeromonas hydrophila is thought to be responsible in the majority of cases of Red-Leg Syndrome, however, there are several more Aeromonas species thought to cause illnesses within amphibians. Aeromonas are found mainly in freshwater systems, and often in the surrounding moist soil. Such bacteria are motile, gram-negative, pollar-flaggelated bacilli (rods). For the most part, Aeromonas, namely A. hydrophila, are thought to be secondary or opportunistic invaders, meaning that severe infections are often secondary to a separate, primary infection that has already weakened the specimen, and opened an opportunity for bacterial infection. In some cases, infection may actually be primary, although this has not been proven extensively. It has even been suggested that Aeromonas hydrophila are decomposers that happen to be present in amphibians living within or near water. In essence, studies have not concluded any specific targeting of A. hydrophila in fish or amphibians, and the "opportunistic" or "secondary" theory may only be partially correct.

To add to the vagueness of the effects of bacterial infections in amphibinas, the genus Aeromonas has been rather ambiguous in recent times. Currently, there are approximately 12 recognized species, depending on who is asked. It can be concluded that certain infections that have previously been linked to one particular bacterium, may have in fact been resultant from several different species. Such conclusions cast a shadow of doubt over the accuracy of some of our current thoughts about the effects of some bacterium in amphibians. 

Several virulence factors have been identified in Aeromonids. At temperate climates, several motile species are psychrotrophic, and capable of producing hemolysins and enterotoxins. Hemolysins are bacterial toxins that destroy red blood cells, thereby liberating hemoglobin. Enterotoxins are another type of bacterial toxin that target the intestinal cells, sometimes causing vomiting and diarrhea. One study showed that 72% of A. hydrophila strains, and 100% of A. sorbia strains procured from fish produced enterotoxins. A. sorbia may have been the primary cause of death in such experiments. An inactive form of hemolysin is released by Aeromonids, and is activated by extracellular proteases. The proteases of Aeromonids include a thermostable metalloprotease, and a thermolabile serine protease, which would allow these bacteria to act as opportunistic pathogens in susceptible hosts. It is unknown whether the cellular and serum proteases of amphibians are capable of activating hemolysin.

A. salmonicida are primarily found in salmon, but some cases have been documented in captive frogs that presumably contracted the bacterium from salmon. Symptoms included reddened skin, dermal hemorrhages, and dermal ulcerations.  

Some Aeromonids are capable of producing aerolysin. Aerolysin is a water-soluble, pore-forming toxin that can change form to produce a transmembrane channel that destroys sensitive cells by disrupting their permeability. Aerolysin is considered the main mechanism of microbial pathogenicity. Although the effects may be different in poikilotherms, aerolysin from A. hydrophila induces G-protein activation and Ca₂+ release from intracellular stores in humans granulocytes. Proaerolysin is capable of binding to human granulocytes and activate aerolysin, resulting in the depolarization of the membrane, and indicating that granulocytes are potential targets for this toxin.

Wild amphibians often host an array of bacteria, including many species of Aeromonas. Wild populations of Rana pipiens have been shown to host a significant number of A. hydrophila, with no ill effects. However, mortality can be induced under the influence of endotoxins and hemolysin. This indicates that A. hydrophila is not always pathogenic, and mortality is likely to be the indirect result of other, pre-existing factors, such as poor water quality, disease, weakened immune system, and other stress factors.  

Symptoms of "red-leg" include the reddening of limbs and body parts, lethargy, food rejection, paralysis, and twitching. This condition is more common in anurans, but is sometimes  found in poorly kept caudates, especially the more delicate species. For more information on this bacteria and photos of fishes and humans that have been infected, please visit Oregon State University's article on Aeromonas hydrophila.

Successful treatment is varied, and dependent on the particular species, and the species state. Some species have been successfully treated by keeping them in a cold environment of 30°F - 40°F for one to two weeks, however many Aeromonids have been shown to adapt quickly to such temperatures. This could also be detrimental to the health of some species, especially those from the tropics. A. hydrophila, once isolated, have been shown to show susceptibility to enrofloaxacin (in vitro), gentamicin, and neomycin. The National Aquarium in Baltimore has successfully treated A. hydrophila infections in Phyllomedusa bicolor with oral trimethoprimsulfa. Resistances have been shown to ampicillin, amoxicillin, amoxicillin/clavulinic acid, cephalothin, erythromycin, lincomycin, penicillin, and sulfa/trimethoprim.

Flavobacterium, Pseudomonas, Acinetobacter Infections: Anurans, Caudates 
under construction 

Chlamydia (Chlamydia psittaci, Chlamydia pneumoniae): Anurans, Caudates 
Chlamydia spp. are gram-negative, coccoid (spherical) bacteria that reside intracellularly within the amphibian host. Chlamydia infections have a moderate to high mortality rate in amphibians.

Infected individuals display lethargy, patchy coloration, and may develop edema. Semi-aquatic and aquatic species may float at the surface, with increased breathing. Internally, subcutaneous edema, coelomic effusion, and hepatosplenomegaly (enlargement of the liver and spleen) may occur, and possibly hepatitis, granulomas, glomerulonephritis (inflamed kidney), and spenic hystiocytosis. 

Mycobacterioses (Mycobacterium spp.): Anurans, Caudates 
Mycobacterioses refers to infection by bacillar (rod-shaped) bacteria. Formerly, mycobacterial infections have been referred to as tuberculosis, but this is incorrect. Mycobacterial infections are typically seen in weakened specimens (weakened immune system) as secondary infections, where Mycobacterium spp. enters the system through an open wound. However, infection by ingestion has also been documented. Weight loss and emaciation are not common indications, however, the infection itself may cause emaciation due to damage of the intestinal tract, and some individuals may become anorexic. Large numbers of bacilli are present in the nasal and oral secretions of infected specimens.

Several Mycobacterium species are found in a typical captive environment, and there is controversy as to which ones actually affect amphibians. For every species that is thought to be harmful to amphibians, there are possible subspecies and synonymous species, making this a rather foggy issue. Mycobacterioses causes gray nodules in the skin, liver, spleen, respiratory tract, and intestinal tract. Fingers, toes, webs, and the mouth are common areas of infection. Lesions of the skin and internal constructs may also occur. The kidneys are also often infected. 

Severe and advanced case of bloat in Cynops orientalis (Chinese Fire Belly Newt), for which this ailment is common in. Notice the grossly swollen throat and abdomen. This specimen survived for nearly two days after these photos were taken.

 * - Weakened specimens often do not respond well to medication, and treatment can sometimes be detrimental to the health of the specimen. The treatment of an ill animal is a judgment call by the owner of the specimen. If you are not sure if treatment is necessary or should be administered, consult a veterinarian trained in Herpetology for advice and possible treatment.