Amphibian Medicine & Diagnostics Flashcards
What are the 6 general steps of metamorphosis in frogs? In what 3 general ways does the lifestyle change?
tadpole —> tadpole with rear legs —> tadpole with front and rear legs —> froglet with small tail —> adult frog
- gills to lungs (aquatic to terrestrial)
- herbivorous to carnivorous
- immune system develops
What are 2 important reportable diseases that commonly affect frogs?
- Chytridiomycosis (Bd)
- Ranavirus
What is the most important factor of amphibian health?
environment —> poor husbandry causes disease, can use wild frogs to monitor changes in the environment
What environmental information is important to ask about when getting a history on amphibian patients?
- water quality - oxygen, ammonia, temperature
- soil/substrate - humidity
- cleaning equipment - chemicals used, proper rinse following
- cagemates - quarantine
What 3 reflexes are tested on amphibians?
- blinking reflex
- righting reflex - should turn upright when places upsidedown
- withdrawal reflex - back legs should tuck in when pulled out
How should an examiner maintain hygiene and health of the amphibian when handling them? Why?
- ensure hands are moist
- avoid leaving soap, lotion, or latex gloves on
amphibian skin is responsible for absorption, excretion, and respiration
What is a drinking patch?
patch on the ventrum where frogs absorb water directly through their skin
Other than reflexes, what other tests are useful for amphibian patients?
- fecal exam
- CBC/chem
- skin swabs (Chytrid!)
- biopsy
- necrospy
+/- urine tests
What is a common difference in amphibian RBCs?
elliptical and nucleated
Where does hematopoiesis occur in Caecilians and aquatic newts?
LIVER, kidney, spleen, thymus —> NOT in bone marrow
(hematopoietic tissue in liver can look like hepatitis!)
Where does hematopoiesis occur in frogs, toads, and terrestrial salamanders?
- ANURANS (frogs and toads) = bone marrow and kidney
- CAUDATA (salamanders) = liver*, kidney, thymus
- BOTH = spleen produces RBCs in adults
How does the thymus develop in amphibians?
present for life and produces CD3+ T lymphocytes (most IHC stains work!)
What 3 bleeding techniques are less commonly used for collecting blood from amphibians? What is an alternative method?
- toe clipping - doesn’t bleed much
- ligual plexus
- cardiocentesis - commonly terminal collection, can cause tamponade
facial venipuncture - vein runs over maxillary bone
On what amphibians can facial venipuncture be performed on?
- true frogs (Ranidae)
- tree frogs
- toads (Bufonidae)
What equipment is required to perform blood collections on amphibians?
- needle for pricking vein
- capillary for collection
What is the most important diagnostic ran on amphibian blood samples first? What information is gained?
blood smear
differential counts
Label the following amphibian WBCs.
- heterophil
- eosinophil
- basophil
- lymphocyte
- monocyte
- thrombocyte - can look like clumps of lymphocytes, do not count as WBCs!
Why must a hemocytometer be used for amphibian RBCs? What is it used to do?
their RBCs are nucleated and won’t be properly counted by normal counters used on other species
total cell count - no published data —> check cagemates or data based on another similar genus
How is blood prepared for total blood counts with amphibian blood?
- collected in a heparinized capillary tube
- known volume placed into an unopette
- diluted in Natt-Herrick solution, which differentially stains WBCs, RBCs, and thrombocytes
- charged into a hemocytometer, which is used to count the cells and calculate the concentration per liter (10^12 or 10^9 /L)
What is the major downfall of hemocytometry? What are 2 alternatives?
needs time and skills
- back-calculation from smear
- automated cell counters - impedance cell (particle) count works well, flow cytometry is untrustworthy
How is the centrifuge used for amphibian hematology?
- PCV
- plasma - manual TP, chemistry profiles
What biochemical metabolite can be manually counted? What are the most important analytes automatically colored?
TS —> refractometer
- TP*
- cholesterol and triglycerides*
- albumin
- globulins
- enzymes (LDH, etc.)
(plasma of amphibians is commonly varying colors)
What nitrogen waste products are excreted by different species of amphibians?
- AMMONIA - metabolized in the skin and gills of tadpoles and aquatic species
- UREA - metabolized in the liver and kidney of terrestrial species
- URIC ACID - metabolized in the liver and kidney of tree frogs
How does the specific gravity of plasma compare to urine in amphibians?
should be the same —> kidney does not concentrate urine
How do erythrocyte size, TP, thyroid hormones, glucocorticoids, and calcium differ as amphibians go through metamorphosis?
decreases - adults have slightly smaller RBCs compared to tadpoles
increases - higher osmotic pressure needed in the blood of terrestrial amphibians
increases - metamorphosis controlled by T3 and T4
increases - results in lymphopenia and neutrophilia
increases
In what 3 ways do amphibians prepare for extreme climates?
- lower freezing point by producing proteins that force ice crystals to form parallel to cell walls
- PCV increases as temperature drops (especially in bullfrogs)
- glucose, fibrinogen, heat shock protein, and plasma osmolality increase prior to overwintering
need time to adapt, cannot handle quick changes in temperatures