Amphibians Flashcards
amphibian skin
- what can they do through their skin
- They breathe through their skin!
- They drink through their skin!
amphibians use their eyes to help with what physiological function?
- swallowing
many amphibians can change their colour to match…
their surroundings!
amphibian RBC size
They have the largest red blood cells in the animal kingdom!
some amphibians can do what with their stomach if they eat something bad
Some amphibians evert their stomach to clean it if they eat something toxic or undesirable!
Amphibian Taxonomy
- how many
- categories
- Over 7,000 species
<><> - Gymnophiona (caecilians)
> More common in zoological collections, not usually pets
<><> - Caudata = Urodela (salamanders, newts, sirens)
> Metamorphosed adults of salamanders are highly terrestrial
> Adult newts are aquatic
> Neotony = mature sexually despite the external
<><> - Anuran (frogs, toads)
Common amphibian Species in Practice
Axolotl
Pixie frog
African clawed frog
Fire belly toad
American bullfrog
Treefrog
Northern leopard frog
Poison dart frog
External Anatomy
* Caecilians:
snake-like body with a short tail (or no tail)
External Anatomy
* Salamanders:
lizard-like body, covered in glandular skin, lack claws on their digits, laterally flattened tail, have four limbs (except for sirens)
* External gills may or may not be present
External Anatomy
* Anurans:
tail-less as adults, glandular skin may be smooth or have protuberances, absent external gills, webbed/unclawed digits, longer pelvic limbs than forelimbs
Normal Things that Appear Abnormal
External anatomy features:
- parotid glands
- Nuptial pads
- Mental glands
- Swollen cloacal lips
<>
- what are these things?
-Parotid glands: caudal to the eyes, can contain toxins
- Nuptial pads: on males, more prominent in the breeding season
- Mental glands: underneath the chin of males in some species
- Swollen cloacal lips: in male salamanders, more prominent in the breeding season
Amphibian skin is unique and one of the most important organs
* Functions:
<>
- drink patch?
- Respiration
- Water balance
- Communication
- Defense
<><>
* Drink patch = modified area of the pelvic ventrum where up to 70-80% of the water intake in anurans occurs
Digestive tract feautures
- length
- teeth
- tongue
- feces
- stomach
Digestive tract – short and simple
* Teeth: variable by species
> Caecilians – multiple rows
> Anurans – only some species have them
* Tongue – attached rostrally (caudal in most mammals) and flips out
* Feces often contain undigested parts (chitin, keratin, bones)
* Some anurans can evert their stomach and wipe the mucosal surface with their forelimb to remove toxic or indigestible substances
Cardiovascular system
- contains what type of hearts?
- typical amphibian heart structure
Lymph hearts
* Multiple beat in synchrony at ~50-60 beats/min
* Composition is the same as blood without red blood cells
<><>
Typical amphibian heart
* 2 atria, 1 ventricle
* In larval form – 1 atria, 1 ventricle > during metamorphosis a septum forms to create 2 atria
amphibian modes of respiration?
Multiple modes of respiration – main are cutaneous, pulmonic, and buccopharyngeal; some species also branchial (gills)
amphibian Anatomy and Physiology
- renal portal
- RBC
- Kidneys and nitrogen excretion
- Renal portal system (like reptiles)
- Very large red blood cells in small
numbers - Kidneys and nitrogen excretion
> Aquatic: typically, ammonia
> Terrestrial: urea (ureotelic) or uric acid (uricotelic)
Physiology of amphibians - how do they maintain body temp
Poikilotherms = rely on a combination of environmental heat and adaptive behavior to maintain a preferred body temperature
amphibian hisbandry
- temp
- humidity
- water loss
Preferred optimal temperature zone (POTZ)
* Require a “temperature gradient” to allow normal thermoregulation
<><>
* Permeable skin = desiccation a threat to survival
<><>
Activities and ranges are limited due to greater evaporative water loss compared to other terrestrial vertebrates
* Most captive species require a relative environmental humidity of > 70%
* Remember this in the clinic, and during exams!
Husbandry of amphibians
- lighting
Full-spectrum UV light
* Position ~25-45 cm from amphibian
* Gradual dimming if possible
* In general, use a 12hr/12hr day/night cycle
Husbandry of amphibians
- water quality, toxins
- Essentially the same as for fish
- Toxins: high levels of ammonia, nitrites, heavy metals, pesticides, disinfectants, chlorine, chloramine can lead to cutaneous and systemic signs
amphibian nutrition and eating habits
- adults?
- larvae
- BCS?
In general, all adult amphibians are carnivorous, and usually swallow their prey whole
* Challenging to feed insects in captivity due to a lack of variety
* Most invertebrates have a markedly inverse Ca:P ratio
> Exceptions: soldier fly larvae, pinhead crickets, earthworms
* Gut loading AND dusting (vit A supplementation, etc.) is essential
* Don’t leave prey items in the enclosure
<><>
* Larval amphibians vary – some are herbivorous
<><>
* Assess body condition score (BCS) and weight regularly
amphibian physical exam
- considerations, cautions for handling
- Remember their unique skin – use caution when handling
- Safest choice for handling is nitrile gloves, NO powder
- Can use a moist paper towel to wrap the patient for short manual restraint or medication administration
Physical Examination
- how to assess skin, etes, mouth, heart
- Evaluate skin and eyes carefully – can use a guitar pick or old credit card to open the mouth
- Doppler to assess heart rate
what parameters to look at for water quality during amphibian physical exam
pH Ammonia (un-ionized) (<0.01 mg/L) Alkalinity (20-100 mg/L)
Nitrite (<0.1 mg/L)
Nitrate (0-5 mg/L)
Hardness (75-100 mg/L)
Dissolved oxygen (> 5 mg/L)
Clinical Techniques for fluid admin in amphibians
- SQ route effective in anurans only
> Skin tightly adhered in caecilians and salamanders - Intracoelomic is an alternative option
- Oral fluids: absorption of water from GI tract negligible in most species
- Shallow water soaks are effective – utilizes the drink patch
Clinical Techniques
- osmolarity
- fluid recipes
- renal portal?
- Osmolality is lower than in mammals, so typical fluid types are not appropriate
- Amphibian Ringer’s recipes
> 2 parts 5% dextrose + 1 part 0.9% NaCl
> 7 parts 0.9% NaCl + 1 part sterile water - Injections and effects of the renal portal system??
Venipuncture
- site
- anticoagulants
- lymph contamination?
- Site depends on species/size
- Lithium heparin: anticoagulant of choice due to EDTA hemolysis in some species
- Lymph contamination possible from many sites
<><><><> - Femoral: may require sedation or anesthesia
- Ventral abdominal: large in size, but challenging to hit (rolls); forms hematomas
- Lingual: limited to large amphibians
- Ventral coccygeal: readily accessible in
salamanders - Jugular: lies between the tympanic region and the shoulder
- Facial, musculocutaneous: recently described, no lymph contamination
Radiographs for amphibians
- sedation
- positioning methods
- view
- Often performed without sedation or anesthesia
- Plastic bags or moistened foam blocks for
positioning - Use horizontal beam for lateral view
Ultrasouns for amphibians
- quality
- relaxation
- Improved image quality if the patient is placed in water (like fish)
- Placing a branch in the water may help arboreal species to relax
CT/MRI in amphibians - useful?
Can utilize, but may need them to be micro due to patient size
Anesthesia for amphibians
- drugs, route
- what shouldnt be used?
- Alfaxalone IM (variable results), MS-222 immersion (works great), sevoflurane topically
<><> - Mixed results with propofol IM,
sevoflurane/isoflurane immersion - Not recommended: eugenol IM and immersion, propofol immersion, isoflurane jelly mixture
Anesthesia in amphibians
* Assessing planes of
anesthesia
- Righting reflex
- Loss of withdrawal reflex, corneal reflex, superficial pain, deep pain, limb adduction
Anesthesia
* Intubation and intermittent
positive pressure ventilation
> considerations
Intubation and intermittent positive pressure ventilation
* Short, small trachea that bifurcates quickly into main bronchi = careful intubation
* Delicate pulmonary tissue = use caution not to overinflate the lungs
Analgesia for amphibians
* Pain responses
- Decreased activity, swiping of back with pelvic limb, decreased appetite, skin color change, hunched posture, eyes held closed
Analgesia in amphibians
- options
- Options – evaluated in very few species
- Dexmedetomidine SC – provides analgesia as in mammals, but without notable sedation (VERY high doses)
<><>
Opioids – most studies evaluate μ receptors, VERY high doses - Morphine 100 mg/kg
- Buprenorphine 50 mg/kg
- Butorphanol 0.5 mg/L also appeared to provide analgesia
<><> - NSAIDs – most studies evaluate meloxicam, shown to have some efficacy
Amphibian Infectious Diseases: Viral – Ranavirus
> type of virus
> geographic spread, effects
>when susceptible
> transmission
- Large, double-stranded DNA virus; OIE reportable disease
- Found on most continents, but the majority of mortality events have occurred in North America
> Die-offs in wild populations of frogs, toads, tiger salamanders
> Inbred populations have higher mortality - Most susceptible to disease during, and immediately after, metamorphosis
- Transmission: water, sediment, cannibalism of morbid/dead individuals, direct transmission
Infectious Diseases: Viral – Ranavirus
- clinical signs
CS: erratic swimming, lethargy, anorexia, buoyancy problems, erythema of limbs/ventrum, swelling of limbs/body, cutaneous erosions
Infectious Diseases: Viral – Ranavirus
- Dx
- Tx
- Dx: not possible from clinical signs alone – use PCR on liver, kidney, skin
- Tx: supportive care only – decrease stress, increase the temperature to the high end of POTZ
Infectious Diseases: Bacterial General
- most common types that cause issues?
- normal flora?
- typically assoc with?
- Gram-negative aerobic or facultative
anaerobic are the most common - Normal flora in healthy captive amphibians = Aeromonas sp., Proteus sp., Escherichia coli
<><>
Typically associated with immunosuppression
secondary to - Stress – poor husbandry, shipment, hibernation
- Concurrent diseases – iridovirus, Batrachochytrium dendrobatidis
Infectious Diseases: Bacterial General
- clinical signs
> general
> Bacterial dermatosepticemia
> Mycobacteriosis
CS: erythema, ulceration, hemorrhages, edema
* Bacterial dermatosepticemia = “red leg
syndrome” = any generalized bacterial infection in amphibians
* Mycobacteriosis = military lesions, gray nodules of skin and internal organs
Infectious Diseases: Bacterial General
- Dx
- Tx
- Dx: culture (blood and coelomic fluid,
if present), CBC, PCR - Tx: systemic AND topical antibiotics,
soaking in amphibian Ringer’s
Infectious Diseases: Bacterial Mycobacteriosis
- bacterial species
- cause disease in what anatomical locations
- found where in environment
- Species: Mycobacterium avium,
M. marinum, M. fortuitum, M. xenopi, M. ranae, M. chelonae, M. liflandi, M. ulcerans - Often disease of the integument, secondary to dermal wounds
- Ubiquitous bacteria
Infectious Diseases: Bacterial Mycobacteriosis
- clinical signs
Miliary lesions/ multiple gray nodules of
* Skin: digital tips, digital webs, lips, mouth, +/- hindlimbs
* Internal organs: liver, spleen, respiratory tract (mucopurulent nasal and
oral secretions), intestines, and kidney (if lesions on hind limbs
secondary to lymphatic spread)
<><>
* +/- weight loss despite good appetite, emaciation
Infectious Diseases: Bacterial Mycobacteriosis
- Dx
- Tx
- Humans?
- Diagnosis: culture, acid-fast,PCR
- Treatment: euthanasia of infected individual + cage mates
- Zoonotic
Infectious Diseases: Fungal
Batrachochytrium dendrobatidis
- significance
- life cycle
- OIE reportable disease, aka chytrid
- Responsible for widespread amphibian
die-offs around the world
> Amphibians are the only vertebrate group
affected by this organism - Life cycle: motile zoospores (infective
stage) attach to the epidermal layer and penetrate the stratum corneum > forming zoosporangium with a discharge tube that allows escape of
the zoospores when the cap is lost
> Complete in 4 days at 62-72 F, dies at 90 F
> Transmission: contact water with zoospores
Infectious Diseases: Fungal
Batrachochytrium dendrobatidis
- clinical signs
CS: excessive shedding, hyperemia of skin
* Digits and drink patch are FIRST – contact
substrate the most
* Affects keratin
Infectious Diseases: Fungal
Batrachochytrium dendrobatidis
- Dx
- Tx
- Dx: unstained skin smears, histo, PCR
- Tx: no one treatment fits all – itraconazole,
increased temperature, terbinafine, chloramphenicol
Infectious Diseases: Fungal
Batrachochytrium salamandrivorans
- significance?
- infects what cells? vs Bd?
- effects?
- thermal range?
- Emerging disease
- Infects epidermal cells skin
ULCERATION with significant destruction of the epidermis - Contrast to Bd – causes hyperplasia
and hyperkeratosis - Mass mortality and population decline
in European salamanders - Thermal range 10-15C (lethal 25C)
Trauma in amphibians
- most common?
- other common ones? Tx?
- amputations, strategy?
- Rostral abrasions most common
- Lacerations, foot abrasions also common
> Acute Tx: debride, topical antibiotics
> Chronic Tx: aggressive debridement,
culture - Traumatic amputations, skeletal fractures
> May require debridement, external coaptation, amputation (in the case of fractures)
Edema Syndrome
- what is it, what is it often due to
- Dx
- Tx
- Often due to an infectious process that affects water homeostasis, but also ovarian neoplasia, hepatic failure, renal failure, malnutrition, osmotic imbalance, hypocalcaemia
- Dx: evaluate fluid microscopically, perform chemistry on fluid, blood work, culture
- Tx: antibiotics, supportive care, focus on underlying cause (when possible)
Nutritional Secondary Hyperparathyroidism in amphibians
- how common?
- etiology?
- clinical signs
- Dx
- Tx
- Second most commonly reported nutritional disorder
- Etiology: imbalance of dietary Ca, P, D3
- CS: mandibular deformity, abnormal posture, scoliosis, reluctance to move, fractures, SQ edema, prolapses (gastric, rectal, cloacal)
<><><>
Dx: radiographs, +/- blood work - Thin long bone cortices, angular limb deformity,
pathologic fractures - Calcium and phosphorus can vary a lot, but if they are both low, it is supportive
<><><> - Tx: calcium, vitamin D3
Short Tongue Syndrome
- etiology
- clinical signs
- whats the name from? actual cause
- Etiology: hypovitaminosis A
- Clinical signs: able to sight and
target prey, but unable to prehend
the food - The name comes from the old belief
that the tongue was too short and that was why they could not eat their prey - ACTUAL cause – squamous metaplasia of the lingual glands > lack of sticky mucous on the tongue > unable to pick up prey
Corneal Lipidosis
- what is this? etiology?
Lipid keratopathy
* Cholesterol is required in the diets of many insects
* Domestic crickets have high cholesterol content
* Etiology: suspect that cholesterol in a diet composed of domestic insects is too high for amphibians to metabolize
