exotics prac

Question 1

Gout is a relatively common condition in captive birds and reptiles.

Use your understanding of renal physiology in these species to briefly explain WHY chronic dehydration is a risk factor for this condition.

For a reptile species of your choice, list some ways in which proper husbandry and diet would help prevent gout

Answer 1

• Uric acid is nitrogenous excretion product in birds and reptiles
• Ammonia is released from breakdown of proteins (catabolism, diet)
• Ammonia is toxic, so converted to uric acid
• Dehydration causes reduction in glomerular filtration rate (GFR)
• Uric acid excretion is by tubular secretion not filtration and so is independent of GFR
• Uric acid still produced and secreted even though the animal is dehydrated, but cannot be flushed out
• Uric acidaemia occurs (i.e. build up of uric acid in the blood)
• Precipitates in tissues (visceral gout) and joints (articular gout)

prevention:
* Adequate supply of drinking water (provided in a way that it appropriate for species)
* Provision of a bath +/- misting
* Adequate humidity for the species
* Appropriate diet (i.e. not too high in protein)
* Measures to prevent renal disease (e.g. good hygiene and biosecurity etc.)

Question 2

Many reptile species live in very hot and dry environments (e.g. deserts).

What adaptations do reptiles have to help them conserve water? (You can refer to mammals as a comparison)

Answer 2

• Fewer nephrons than mammalian kidneys
• Lower GFR compared to mammals
• Excretion of uric acid not urea
• Urea is highly insoluble
• Comparatively lower volume of water is required for excretion
• Dramatic reduction/cease GF in times of stress/water scarcity
• Salt gland for excess Na+/K+ excretion
• Cloacal/colonic reabsorption of water

Question 3

A member of the public brings you a frog which their cat brought in.

The frog has a significant injury to it’s back and appears very dehydrated.

With reference to their unique anatomy and physiology, outline your approach to your initial assessment and management of this patient.

The following day, the frog takes a downturn and you decide it’s injuries are too significant for it to make a full recovery. How do you euthanise it?

Answer 3

• Amphibian skin is very important for osmoregulation/hydration and so injuries to the skin can be significant and catastrophic for health – needs very realistic triage (and plan for hospitalisation & rehabilitation)
• Likely to be underlying damage so to be monitored closely for deterioration
• Assume it is at least 5-10% dehydrated – can rehydrate via skin e.g. sitting in water bath (provided it can hold head up)
• Pain relief!
• Medications can be given via the water (check non-irritant)
• Wear gloves when handling
• Euthanasia – immerse in MS222/Aqua-sed/isoflurane (bubbled through water) until anaesthetised + intracardiac pentobarbital