Renal disease in birds and reptiles

Question 1

Differences with birds and reptiles:
How do they concentrate urine?
how do they store urine?
how is urine modified?
how is blood flow different?
how is nitrogen excreted?

Answer 1

• Birds and reptiles have limited ability to concentrate urine.
• All birds and most reptiles lack a urinary bladder (exceptions include chelonia, chameleons). - urine not stored but can be pushed back to the colon for reabsorbtion
• Urine may be modified in bladder/colon (e.g. reabsorbed).
• Renal portal system - blood flows from the tail and hindlimbs through the kidneys and then on to the heart.
• Nitrogen is excreted as uric acid.

Question 2

What are the clinical signs of renal disease in birds?

Answer 2

Early signs of disease are often subtle.
Signs of advanced disease are often non-specific e.g. fluffed-up, lethargic, anorexic, dehydration.

More specific clinical signs may include:
* PU/PD
* Unilateral or bilateral hindlimb paresis/paralysis (due to enlarged kidney, with nerves running close by)
* Haematuria
* Feather plucking over kidneys
* Articular (& visceral) gout

Question 3

What are the clinical signs of renal disease in reptiles?

Answer 3

Early signs of disease often subtle.
Signs of advanced disease are often non-specific e.g. lethargy, anorexia, weight loss, dysecdysis, abnormal thermoregulation/behaviour.

More specific clinical signs may include:
* Hindlimb weakness
* Constipation (renomegaly in pelvic canal)
* Gout
* Oedema (nephrotic syndrome)

Polyuria and polydypsia are usually not a feature of reptile renal disease

Question 4

What are the key aspects of the clinicla exam of birds and reptiles?

Answer 4

• Assess patient from afar - take RR before stressing them out
• Ensure you have everything to hand
• Inspect cage, droppings, food etc
• Thorough history from owner.
• Birds - may need to place in warm, humidified oxygen cage first.
• Reptiles - ensure patient is kept at warm.

Question 5

what are the clinical signs of dehydration in birdss?

Answer 5

Assume all ‘sick’ birds and reptiles are 5-10% dehydrated
* Mouth = mucous membranes are hard to assess, but they might look dry.
* Skin = skin tent elasticity is not a reliable indicator in birds.
* Eyes = dull and sunken (skin around the eye wrinkled)
* Circulation = Basilic wing vein refill time is a good indicator.- > 2s = 7% dehydration
* Weight loss (especially if sudden)

Question 6

what are the clinical signs of dehydration in a reptile?

Answer 6

Skin = dry, wrinkled or puckered skin. Loss of skin elasticity and flexibility. Dysecdysis.
Eyes = sunken, receded eyes.
Musculoskeletal = generalised weakness and lethargy.
Mouth = tacky or dry mucous membranes. Thick saliva.
Celomic = doughy on palpation, constipation or infrequent defecation.
Weight loss (especially if sudden)
Appearance of urates and urine.

Question 7

Waht are the common causes of primary renal disease in birds?

Answer 7

• Inadequate diet
• Hypovitaminosis A
• Hypervitaminosis D3
• Lipidosis
• Heavy metal toxicity
• Infection (primary or secondary from a systemic infection causing nephritis)
• Neoplasia
• Amyloidosis

Question 8

what are the common causes of primary renal disease in reptiles?

Answer 8

• Inadequate Husbandry
  
  • Low humidity (chameleons will only drink from drops on leaves)
  • Temperature
  • Diet (high protein)
  • Hypovitaminosis A
  • Hypervitaminosis D3
• Chronic dehydration
• Bacterial infection (primary or secondary from a systemic infection causing nephritis)
• Neoplasia

Question 9

What is gout?
what are the different types?
why does it happen?

Answer 9

• Gout is a sign of renal failure in birds and reptiles.
• Visceral gout = accumulation of urate (uric acid) deposits in soft tissues e.g. liver, pericardium and kidney
• Articular gout = accumulation of urate (uric acid) deposits in and around joints e.g. often feet and hocks.

Gout occurs when uric acid secretion is decreased and/or uric acid production is increased.
Increased: Excess dietary protein
Decreased:
* Dehydration
* Renal tubular disease
* Hypovitaminosis A
* Infection/inflammation
* Post-renal obstruction e.g. uroliths, egg binding

Question 10

Biochem

what does urea tell you about in birds and reptiles?
what about creatinine?
what about uric acid?
what about phosphorus?
what about calcium?

Answer 10

Urea:
Birds - may help assess dehydration but NOT kidney dysfunction.
Reptiles - may be elevated in dehydration or anorexia. Renal disease likely if uric acid also raised.

Creatinine
Not very useful in birds or reptiles.

Uria Acid:
* Elevated only when >70% kidney function is lost.
* Mild to no elevation in dehydration.
* Post-prandial rise in carnivorous birds and reptiles.
* Fast carnivorous birds for 24hrs before sample
* Fast carnivorous reptiles for 24-36hrs before sample (most presented anorexic!)

Question 11

biochem

what does phosphorus tell you about in birds and reptiles?
what about calcium?
what about potassium?
what about sodium in birds?

Answer 11

Phosphorus:
Birds - May be elevated in renal failure (& haemolysis)
Reptiles - May be elevated, renal failure more likely if phosphorus higher than total calcium. Hyperphospatemia is often the first biochemistry abnormality.

Calcium:
Birds - May be reduced in renal failure.
Reptiles - May be reduced in chronic renal failure but normal or increased in acute renal failure.
Measure ionised and total calcium in conjunction with albumin.

Potassium:
Elevated in acute renal failure (and haemolysis).

Sodium
Birds - hypernatraemia in dehydration and hyponatraemia in renal failure.

Question 12

What are the key factors of urinalysis in birds and reptiles?
what is noral on urinalysis?
Is it helpful?

Answer 12

• Difficult to obtain ‘pure’/sterile sample. Hard to avoid faecal contamination.
• Normal urine contains crystals and bacteria.
• Look for renal casts, abnormal cells, glucose (birds), Hexamita parasite (reptiles) etc.
• Urine can be modified after the kidneys in many exotic species. - dosen’t show kidney function
• USG not very helpful in most cases.
• in reptiles pH may change from normal alkaline to acidic in anorexic herbivores and post-hibernation.

Question 13

what is the murexide test?

Answer 13

• Test used to confirm gout. - but in practice normally rely on clinical signs as don’t have the tools
• Sample of material (e.g. joint aspirate) is mixed with nitric acid and dried over flame.
• Add 1 drop concentrated ammonia.
• If turns mauve = uric acid

Question 14

How are radiographs used to diagnose renal disease in reptiles?

Answer 14

2 or 3 views: ventrodorsal, horizontal-beam lateral +/- horizontal-beam craniocaudal (chelonia).
Kidneys often difficult to see unless enlarged or increased density.
Look for changes in size, density & contour. Eggs, uroliths, gout and bone density (MBD). (concequence of kidney disease)

Question 15

what is the treatment for all sick birds?

Answer 15

• Keep warm, quiet, away from predators.
• Fluid therapy:
  
  • SC, IV, IO depending on severity of dehydration, the bird’s demeanour and whether the gastrointestinal tract is functional.
  • Use clinical exam, PCV and TP to determine dehydration %.
  • 50ml/kg/day for maintenance + 50% of the fluid deficit daily.
• Commence oral fluids once bird is more stable
• Crop feed once bird tolerates oral fluids (build up).

Question 16

what antibiotic is nephrotoxis?
what drug can be used to reduce hyperuricaemia?
what drug can be used for crop stasis?

Answer 16

• Aminoglycosides are nephrotoxic!
• TMPS can potentially be nephrotoxic if a bird is severely dehydrated.

Allopurinol (xanthine oxidase inhibitor) for hyperuricaemia

Metoclopramide - 0.5-1mg/kg IM q 8-12 hrs if crop stasis.

Question 17

what husbandary do all sick reptiles need in vet practicies?

Answer 17

• Heat: patients should be kept at preferred body temperature.
• Light: Appropriate UVB light for the species.
• Ensure correct humidity and appropriate access to water e.g. bath, spray.
• Bath them daily - Encourages drinking, voiding urine/faeces and some can suck fluid into the cloaca/bladder. Can add medication or supplements to the bath e.g. Reptoboost

Fluid therapy:
* SC, IV, IO depending on severity of dehydration.
* Rehydration take 3-4 days but, may take 10-14 days in severe cases. (not as worried about circulatory shock from dehydration)
* Overzealous fluid therapy can cause pulmonary/tissue oedema, hypokalaemia and death.
* All fluids should be warmed to the upper level of the POTZ.
* Can add an electrolyte/ammino acid e.g. Duphalyte.
*

Question 18

what anitbiotics are not used and used for renal disease in reptiles?
what drug can be used to reduce hyperuricaemia?

Answer 18

antibiotics:
* Most infections are caused by gram negative bacteria
* Ceftazadime is commonly used (but not first line so make sure used on C&S)
* Aminoglycosides are nephrotoxic!

Allopurinol (xanthine oxidase inhibitor): to reduce hyperuricaemia

Question 19

What is the prevention of hypovitaminosis A in reptiles and birds?
How do herbivoires get vit A?
in what types of animals fo hypo vit A occur?
what is the treatment of hypo vit A?

Answer 19

• Prevention = give a balanced diet with multivitamins, such as Nutrobal by Vetark (calcium, A, C, E, D3, K3 and group B vitamins).
• Herbivores can covert vitamin A from plant material.
• Typically an issue in omnivore or carnivore species. Carnivores have to get vitamin A from animal sources (e.g. liver).
• Only use injectable Vitamin A to treat hypovitaminosis A if severe, due to risks of over-dosing (toxicity).
• Will generally have other nutritional deficiencies as well due to imbalanced diet - so diet always needs correcting!

Question 20

what is the prevention of renal disease in birds and reptiles?

Answer 20

• Correct husbandry (temperatures, humidity, lighting etc).
• Fed the correct, balanced diet.
• Correct use of supplements in insectivore reptiles to correct the Ca:P imbalance.
• Keep hydrated by offering daily fresh water correctly.
• Bathe reptiles regularly.

Question 21

How are radiographs used in birds to diagnose renal disease?

Answer 21

• Two views: ventrodorsal and lateral (wings and legs extended).
• Normal kidneys difficult to see especially on VD view.
• Gonad and pelvis may obscure lateral view.
• Small rim of air dorsal to the kidneys on lateral view. This is absent in renomegaly.
• Look for changes in size, density & contour. Eggs, cloacaliths, evidence of gout and whole of body. (concequence of kidney disease)