Amphibians

Amphibians are a large class of vertebrates

• Live at least part of the life cycle in water

• Diverse group

• Increasing popularity

• More than 400 species alive

  • Only a few commonly seen

Amphibian groups

• Anurans (Salentia)

• Urodela (Caudata)

• Apoda (Gymnophinoa)

Urodela (Caudata)

• Newts

• Salamanders

Anurans (Salentia)

• Largest group

• Frogs and toads

Apoda (Gymnophinoa)

• legless amphibians

Most commonly used species in biomedial research

• African clawed frog - Xenopus laevis

  • Used for embryologic development

• Mudpuppies - Necturus

• Leopard, meadow, or grass frogs - Rana pipiens

• Salamanders - Ambystoma

Use of african clawed frog in biomedical research

• Used for embryologic development

Amphibians and their tissues in biomedical research

• Embryology

• Pharmacology

• Skin permeability

• Limb regeneration

• Agriculture waste

  • Unique susceptibility to dissolved toxins

Amphibians in clinics

• Dwarf clawed frogs

• Ornate horned frogs

• Toads

• Poison dart frogs

• Frogs

• Tree frogs

Integument of amphibians

• Common characteristics

  • Highly glandular

  • Permeable skin

  • Two types of skin glands

    • Mucous

    • Granular

what are the 2 types of skin glands

• Mucous

• Granular

Mucous skin gland

• Keep skin moist to allow for respiration through skin

• Prevents desiccation

Granular skin gland

• Secrete toxins

• Defense

Amphibians are ectotherms

• External heat source

• Hypothermia

  • Lethargy

  • Immunosuppression

  • Often fatal

Respiratory system of amphibians

Gas exchange at alveoli and through skin

Reproductive system for amphibians

Sexual dimorphism common

Heart for amphibians

3-chambers

Handling and restraint of amphibians

• Transported in primary enclosure if possible

• Skin covered in slimy mucous

  • Protects from infections and its environment

  • Always handle with wet hands or gloves (nonpowdered)

Primary enclosure for amphibians

• Dependent on species

• Plastic cage or aquarium

• Smooth sides

  • Delicate skin

• Bottled or conditioned tap water

• Mimic native environments

Housing for amphibians

• Aquatic vs. arboreal

• Temperature species dependent; high humidity - 80%

• Proper lighting, heating, water quality parameters, and cleanliness

• Most diseases from poor husbandry and improper diet

• Newts and grass frogs

• Require both wet and dry areas in cage

  • Inclined ledge

• Clear plastic or glass aquariums

• Water changed every few days

• Cage completely cleaned weekly

Group size for housing newts

can be in groups of 10-15 animals

Water quality for enclosures

• Regular water assessment to ensure the health of aquatic animals

• Municipal tap water avoided

  • Chlorine

• Excrement and food chemically changes water

• Filtration system

• Test water for pH, temperature, ammonia, nitrites, hardness, and alkalinity

What is tested when we test water

• pH

• temperature

• ammonia

• nitrites

• hardness

• alkalinity

Xenopus frogs

• Aquatic

• Housed singly or in breeding groups

• Water changed several times a week

• Cage cleaned with soft brush weekly

  • No harsh detergents

• Alternative - continuous water flow

  • Complicated to manage

Adult amphibians specifics

Carnivorous or insectivores

Tadpole specifics

Herbivores

Species specifics

• Replicate natural diet

• Variety of different types of foo

• Improper diet - bad

• Feed correctly

Improper diet can lead to..

severe, life-threatening nutritional disorders

Correct feeding

• Water feeding

• Flying insects

• Live prey

Administration of sedation or anesthesia

• Immerse the animal in tank of water containing anesthetic

• Or place an anesthetic -soaked gauze pad on skin

Post anesthetic

Placed in fresh water to allow to disperse

Administration of medications for Xenopus

Injections in dorsal lymph sac

Blood collection in amphibians

Do not use alcohol

Blood collection in salamanders

Caudal tail vein

Blood collection in Frogs

• Femoral vein, ventral abdominal vein, and lingual vein

• Insulin syringe

• Heparinized Microtainer tube

• No more than 1% of the body weight should be taken in blood volume from healthy amphibians

Diagnostic testing for amphibians

• Culture collection - simple swabbing

• Endoscopy - rigid

• Fecal examination - flotation or direct smear

• Skin scrape and touch smear - impression smears,

• Standard x-ray machine

• Dental x-ray machine

• Mammography films

Bacterial diseases in amphibians

• Majority of pathogens and gram negative organisms

• Red-leg bacterial syndrome

Red-leg bacterial syndrome in amphibians

• Infectious disease of amphibians

  • Hyperemia of ventral skin

  • SQ edema

  • Petechia

  • Ecchymotic hemorrhage

Amphibians require a humidity of approximately __% to remain healthy.

80

The best method of achieving anesthesia in amphibians is:

Immersing the animal in water containing an anesthetic

Which species is unique in that it retains a tadpole-like appearance throughout its adult life?

Axolotls

If a blood sample is required from a frog, the preferred vessel to obtain the sample is the:

Ventral abdominal vein

A frog presents with hyperemia on the ventral skin, subcutaneous edema, petechia, and ecchymotic hemorrhage. What is the most like cause of these symptoms?

Cutaneous bacterial infection

Which unique feature of amphibians allows for respiration through the skin?

Mucous glands

All amphibians can be maintained or housed in a plastic or glass aquarium. Why is this the recommended type of housing?

Smooth sides to prevent damage to skin

Why is it best to handle amphibians with wet hands or gloves?

To prevent abrading the delicate skin of the animal

The amphibian heart has how many chambers?

3

The goal for proper nutrition of amphibians is:

replicate the natural diet as much as possible