A Basic Guide to Evaluating the Health of an Amphibian Christina Miller Last update: Monday, December 31, 2007.

A general physical exam of a frog, toad, newt, salamander or caecilian is almost nothing like evaluating a dog or cat. There are even many vital differences between examening amphibians versus reptiles. Because health problems are difficult to detect in herps in-general, a health problem may not be noticed in an amphibian until it has developed into a serious and potentially life-threatening illness. Learning how to identify small problems could mean life or death in the long run. This guide is not only for pet owners and breeders, but is also useful to veterinary technicians and nurses, and pet store employees who are not familiar with amphibians or who want a detailed, systematic approach to evaluating a captive amphibian.

Taking a good history

Whether you are a veterinary nurse or technician working with a client, or a pet owner that is trying to figure out what could be wrong with your amphibian, a retrospective look at the animal's life so far can be extremely useful. The following are questions you should ask:

• Is the animal captive bred and born, farm-raised, or wild caught?
  Wild caught and farm-raised animals are much more likely to harbour parasites and suffer from maladaption to captivity, although this cannot be ruled out in captive-bred animals, either.

• How old is the animal, and how long has it been cared for by its current owner?
  Relatively few captive amphibians get old enough to start presenting expected signs of senesence (aging). Potential long-term problems from poor captive care can be compared to relatively acute health issues. If the amphibian has been in the care of the same owner with poor husbandry, or the previous owner's husbandry is unknown, it can be a clue for figuring out a health problem.

• Is the amphibian a breeder? If not, and the amphibian is female, is it exposed to males? Is the environment cycled naturally (seasonal changes in temperature, humidity, photoperiod)?
  Only healthy animals in good condition should be bred. Reproduction is a huge strain on the animal's body, and will seriously debilitate already less-than-healthy animals. Females exposed to males may be stressed by their advances to breed, and females can produce non-viable eggs without the presence of males. Aging animals that are not cycled throughout their life may be more susceptible to diseases of the reproductive organs.

• What is the captive enclosure? Consider the type of enclosure and materials it is made out of, substrate, and cage furniture.
  Enclosures that are too small can be stressful and restrict thermoregulatory and hydroregulatory behaviour. Cage wall materials that are abrasive can cause lesions if the animal is presenting a stereotypic escape behaviour, or if transparent may provoke stereotypic escape behaviour or amplify the injury caused by flight (escape from a "predator") behaviour.
  
  Particulate substrate may accidentally be ingested, or could be a source of irritating dust. Sheet substrate is generally safer, but carpeting may have fine fibres that could wrap around toes or tail tips, and species that like to burrow may be stressed without substrate that suits them. Substrate may also not hold enough humidity, and some substrate promotes bacterial and fungal growth when damp.
  
  Everything in the enclosure should be evaluated for irritating fumes, especially if the enclosure is homemade.
  
  Hiding spots are necessary to allow the amphibian places where it can feel safe from the eyes of predators and competitors. They should be oriented appropriately (ex: do not use a horizontal half log hide on the ground for an arboreal tree frog), and should be appropriately-sized. Hides should be just large enough for the animal to comfortably enter, exit and turn around inside.

• What is the temperature range in the enclosure?
  The temperature gradient provided must suit the species, a warm end and cool end must always be provided to avoid hyperthermia and hypothermia. Daytime/nighttime temperature changes should also be respected.

• What is the provided photoperiod? Is broad-spectrum lighting provided?
  Too many or too few daylight or darkness hours can severely stress an animal. A suitable photoperiod should be respected (this includes having the animal in a room where there are frequently lights on after daylight hours). Broad-spectrum lighting (including the ultraviolet-B or "UV-B" wavelength) is an absolute necessity for some species, and severe calcium-related problems ("metabolic bone disease," or nutritional secondary hyperparathyroidism) will follow if not provided. However, many amphibians prefer darkness or filtered light, and bright, broad-spectrum bulbs can be stressful.

• What is the ambient humidity in the enclosure? Is the enclosure sopping wet and full of stagnant water? If there is a water dish, how often is the water changed, and how often is the container disinfected? If there is a filtration system in a larger water area, what type of filter is it, and how often is it cleaned or changed?
  Many amphibians are highly dependent on humidity instead of sitting in standing water for hydration. Enclosures that are too wet are not optimal for many species, either.
  
  Water quality is of extreme importance with amphibians because of the nature of their skin. Standing water should be changed daily (or whenever soiled) and the container disinfected routinely. Dechlorinated water is generally advised for use with amphibians, distilled water should not be used due to its hypoosmolarity, and hard water (water with a large amount of dissolved minerals and salts) should be avoided because of its hyperosmolarity. Ammonia and nitrates should not be at detectable concentrations, and pH should be within a suitable range (typically between 6.5-7.5 is acceptable for amphibians).
  
  Filters should be selected according to the environmental preferences of the species. Some species prefer still water, others prefers a current. Filters should be maintained according to the manufacturer's directions to ensure proper function.

• Does the amphibian have any cagemates? Are they the same species or different species? Were the animals quarantined before being housed together?
  Amphibians are solitary creatures, and some are aggressively territorial. Cagemates are stressful to amphibians, as they compete for food, heat and hiding places. Larger individuals may prevent others from eating or thermoregulating properly,and can possibly cannibalize smaller cagemates. During feeding frenzies, limbs and tails can be accidentally bitten off.
  
  Different species have different environmental needs, so mixed species enclosures are very rarely set up appropriately for both species. This can result in one animal flourishing while the other deteriorates.
  
  Microbes are everywhere, and most do not pose a threat to your health or the animals' health, however if an amphibian is stressed their immune system can falter, allowing an oppurtunistic infection to occur from otherwise harmless microbes. Different species, even different individuals, have their own native microorganisms (like bacteria). However, even healthy amphibians will not be immune to all different microbes, especially if the body has never encountered them before. Housing different amphibians together can introduce them to microbes that they have no previously acquired immunity to, and the stress of being housed with a cagemate can further aggravate the problem.
  
  A strict quarantine period of at least 60 days should be respected when introducing new animals to an established enclosure and only after a clean bill of health has been assured. But, considering the above, even healthy animals may have stress issues when housed together.
  
  Also, the toxic skin secretions of some species can be deadly to others. Ensure that cohabitating species are not potently toxic.

• How often is the enclosure spot-cleaned? Completely cleaned and disinfected? What kinds of cleaning agents are used?
  Dirty enclosures will predispose the amphibian to a variety of illnesses, including bacterial and fungal infections, and even ammonia poisoning from built up waste material. Basic, "sterile" enclosures should be cleaned and disinfected frequently. Naturalistic enclosures must be properly designed and well-maintained to ensure that waste products do not overaccumulate, and that microbial growth is not "super-promoted."
  
  Likewise, the use of noxious cleaning agents can adversely affect the animal's health. Bleach and pine-based cleaners should not be used in or around the enclosure. Even some disinfectants meant for use with animal equipment and enclosures can leave noxious residues if not properly rinsed and/or aired out. A mild detergent, warm water and a good scrubbing arm are often all that is needed to clean.

• What is the animal being fed, how often, and how much is eaten? Is uneaten food left in the cage? Does the animal ever regurgitate after eating? How is the food stored? How often are supplements added to meals (if at all)?
  Anorexia is a symptom, not a disease, and is always important to investigate. Regurgitation is a serious problem and warrants immediate veterinary attention in amphibians.
  
  Nutritional problems are often overlooked in all herps; live prey should always be gut-loaded, and pre-killed prey should be bought from a reputable source. Multivitamin and mineral supplements should be used with caution, as vitamin and mineral toxicities can be caused by overzealous use of supplements.
  
  Many owners either underestimate the appetite of their amphibian and underfeed them, or feed calorie and fat-rich prey that results in an obese animal. The latter is especially true with sit-and-wait predators (like the horned frogs, Ceratophrys sp.) that are oppurtunistic predators and are not naturally very active.
  
  Frozen food should be stored so that it will not spoil. Live food should be kept appropriately for the species, and any live food containers growing mould should be discarded and not fed to the amphibian. Mouldy food items can cause illness or death if fed to a reptile or amphibian.
  
  Injuries from unsuitable or improperly offered prey are not uncommon. Leaving uneaten food items in the cage also presents a risk, as hungry prey may decide to eat the amphibian during its inactivity periods (i.e.: when it is sleeping). Uneaten food items may also die and spoil in the enclosure, promoting microbe growth.

• How often does the animal eliminate? Do the stools look normal?
  Most species defecate at least once three days, if not more often. Abnormal feces may be caused by parasites, improper diet, or improper thermal gradient. This includes a particularly bad odour, runny consistency, discolouration, presence of blood or mucous, visible parasites (which is rare, parasites are more reliably diagnosed by the vet using a microscope).

• Has the amphibian had any illnesses in the past, and are there any other reptiles or amphibians in contact with the animal's caretaker? Have any of these other animals been sick previously, or currently?
  Past illnesses may reappear if husbandry is poor, and new illnesses could be the result of previous ones. Owners may unwillingly pass disease from animal to animal within their collection, especially if they do not wash their hands or instruments thoroughly between animals, or recycle uneaten prey with other pets, or even by housing sick animals near healthy ones.

Testing the water

Because water is a large part of the amphibian's captive environment, a water quality test should be done, especially if the species is aquatic or if you are dealing with larvae. If you are a vet or vet tech, advise clients to bring a sample for the consultation. Ammonia/nitrate, pH and hardness are some basic tests, but particular clinical signs may warrant other tests to be done such as calcium, magnesium and phosphorus. Generally, the same tests that are performed for fish aquarium water are suitable for amphibian enclosure water.

General appearance of the amphibian

Posture is unimportant in many species because they are either cryptically camouflaged or nocturnal, so they may be hunched up trying to hide from you. Species where general posture and stature are important include the dendrobatids, atelopids, mantellids, heliothermic hylids and most newts (some members of Salamandridae). These species should be alert and responsive during the day. If an amphibian, even a nocturnal species, fails to respond in any way to your touch, its health is seriously compromised. Testing a diurnal amphibian's feeding response is a quick way to check if the animal is in decent health, although in a stressful handling or observation situation not all animals will eat. Terrestrial and arboreal anurans can easily hold the front end of their body off the ground when healthy (awake and alert). A frog or toad that hunches with its eyes shut may be stressed or sleeping, but a distinction must be made between the defensive “hunching” posture when the anuran is disturbed or sleeping and when the animal cannot lift itself off the ground. Body condition scoring can be achieved by observing the visibility of the pelvic bones. In powerful jumping species like the members of Ranidae, the musculature of the hind limbs can be a clue, as well. Locomotion: Terrestrial and arboreal caudates locomote with an alternate leg extension and flexion and an alternate trunk side bending. Any deviation from this should be considered abnormal. Members of Ambystomatidae are particularly well-known for their enthusiastic attempts to eat human fingers. It is not abnormal for a salamander to become very still and undulate its tail when disturbed. Some aposematically coloured species of both caudates and anurans will display the unken reflex when disturbed. Aquatic anurans are dorsoventrally compressed, and typically use all limbs when moving, the powerful hind legs doing most of the work. Aquatic caudates and caecilians will undulate their tails and the rest of the body follows in a less exaggerated motion. Aquatic amphibians that list or float to one side are abnormal and should be more thoroughly examined for health issues. Aquatic frog body condition can be scored by observing the musculature of the hind legs, which should be very large and thick. Aquatic caudates may be scored using the visibility of the pelvic bones from a dorsal perspective, and the general fullness of their body and tail. Terrestrial caecilians locomote by a wave of muscle undulations from the head backwards. Body condition scoring is difficult on some species because of bony annulations along the entire body. The body should be well-filled. Obese amphibians are not uncommon, but a bloated appearance is more typically due to gas or fluid accumulation and should be further investigated by a veterinarian. Note that some anurans will inflate themselves with air as a defense mechanism. Amphibians prone to obesity are the “sit and wait” or ambush predators that have a rather sedentary lifestyle, and owners are prone to overfeeding since they almost never refuse a meal.

This female American bull frog, Lithobates catesbeianus [Rana catesbeiana] , is at nearly ideal body weight. It is well muscled and slender, but not skinny.

From head to tail in detail

Examining every external aspect of the amphibian is important.

Head: The eyes should be bright, clear and symmetrical. Many eye problems, such as corneal lipidosis, cataracts and glaucoma have all been diagnosed in amphibians. Many anuran species have a nictating membrane, but aquatic species may lack eyelids altogether. Eye vasculature is normally visible in some species, some have very odd-shaped pupils and brilliantly coloured irises, and others may have elaborately decorated nictating membranes covering the eye when resting. The animal's nares (nostrils) should be clear of debris and bubbles. Rostral abrasions are common in amphibians, like reptiles, and are most often the result of stereotypical environmental search or escape behaviour. The oral exam may require the use of a speculum (a plastic card, laminated paper, small rubber spatula) to gently pry open the mouth. Some species may gape in defense or attempt to bite at wiggling fingers, facilitating an easy view of the mouth. Care must always be taken to avoid fracturing the mandibular (lower jaw) bones, especially if the animal is suspected to have a calcium deficiency or brittle bones. Large aquatic caudates like amphiumas, sirens and Cryptobranchus sp. can deliver painful bites, so chemical restraint is usually necessary for the oral exam and so it should only be done by a veterinarian. The mouth should be evaluated for colour and uniformity. Pentastomids and leeches may be observed attached to the inside of the mouth.

This Pickerel Frog, Rana palustris, has an obvious eye defect. This Green Frog, Rana clamitans, has good eye symmetry.

Body: The vent should be examined for prolapse. The coelomic cavity can be gently palpated for ingested objects, but care must be taken to not damage the organs. Transillumination of smaller species that lack dark pigmentation can be done to evaluate some organs and vasculature or to confirm the presence of foreign bodies. Do not use a high wattage bulb and/or expose the tissue to the light for too long and overheat the animal!

Skin: The amphibian's skin should be appropriately coloured for the species, so reference books with photos of healthy animals should be commonplace in clinics that treat amphibian patients. Colour and pattern may vary greatly even between conspecifics. Note that some hylids will take on a darker colouration overall from night to day, but a colour change in most other species is considered abnormal. Note that even very cryptically patterned amphibians have mostly symmetrical body patterns. Observing these animals from above for any asymmetries is a useful technique to identify lumps and bumps that may be problematic. All amphibians except toads (Bufonidae) and any rough-skinned newts (Taricha sp.) should have a moist, slimy feel to their skin. Phyllomedusa sp. (waxy tree frogs) and large hylids (such as Litoria sp.) can produce waxy skin secretions to prevent desiccation. A “tacky” feel can indicate dehydration, which is usually accompanied by lethargy and minimal response to stimuli. The skin should be clear of cuts, scratches, bumps, and discolourations abnormal to the species. Discolourations are particularly found on the ventral surface of the hind limbs and the drink patch (a semi-translucent patch of skin just anterior to the vent used for water uptake in many species). A normal, reddish ventral colouration can be mistaken for the petechial hemorrhaging of “red leg” syndrome, but this is a common illness in captive amphibians so it must be certain whether or not the colouration is caused by an infection. Burns are uncommon in amphibians because of their husbandry needs, but may still occur if the owner uses a heat lamp or hot rock. Burns are serious in amphibians due to the nature of their skin, and must be seen by a veterinarian for treatment. Ectoparasites are rare in amphibians. Trombiculid mites are occasionally encountered. Erythematous vesicles are suspect, and a skin scraping can confirm the presence of mites. A vet visit is strongly urged if mites are suspected.

The venter of an American Toad, Bufo americanus, showing the dark-coloured drink patch. This toad is also displaying the air inflation defense mechanism.

Limbs, digits and tails: Limbs should be fleshed enough so that long bones are not obvious, but musculature varies according to the species. Long bones should not bow, and should be smooth when palpated. Bowed limbs and/or a “knobby” feel to bones can be indicative of a metabolic bone disease. Missing digits and limbs are commonplace in amphibians that are kept in multiple animal enclosures. Caudates are able to regenerate lost limbs and tails. The tail of caudates are to be treated like other limbs, although palpation should be gentle as some species may autotomize their tails. Note that amphiumas have reduced limbs, and sirens have a single pair of legs.

A thorough physical exam is the first step for every amphibian presented to the veterinary clinic. It should be used to help determine whether other diagnostic tests are needed to diagnose the presenting problem.


Sources:

• Christoffersen. 2004. “Amphibian Limb Regeneration.” Dept. of Zoology, University of Guelph. Guelph, Ontario. Accessed March, 2006. <http://www.uoguelph.ca/zoology/devobio/210labs/regen1.html>

• Fowler, ME. 1986. Zoo and Wild Animal Medicine, 2nd ed. Philadelphia: W.B. Saunders.

• Girling, S. 2003. Veterinary Nursing of Exotic Pets. Iowa: Blackwell Publishing.
  
• Halliday, T and K Adler. 2002. The Firefly Encyclopedia of Reptiles and Amphibians. Toronto, Ontario: Firefly Books Ltd.
  
• Whitaker, BR. 2001. The Amphibian Eye. In: Wright, KM and Whitaker, BR (eds), Amphibian Medicine and Captive Husbandry. Malabar, FL: Krieger Publishing Co.
  
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