Renal Health in Elephants: Bringing Ultrasound and Laboratory Findings Together

Renal dysfunction in Asian elephants can be difficult to recognise from clinical signs alone. Reduced appetite, lethargy, altered hydration and changes in urination are non-specific, while an isolated biochemical abnormality may not establish whether a clinically relevant renal problem is present. 

A more useful approach is to bring together clinical findings, laboratory results and renal imaging rather than relying on any single parameter. 

What can renal ultrasound add? 

A 2025 study evaluated transcutaneous renal ultrasonography in 49 captive Asian elephants and established quantitative reference characteristics for renal echogenicity and echotexture. The technique provided a non-invasive way to examine the kidneys without relying on transrectal imaging^[1]. 

The study demonstrated distinct sonographic characteristics of the renal cortex and medulla and provided baseline data from healthy elephants^[1]. This creates an opportunity to establish an individual imaging baseline and identify changes on subsequent examinations. 

However, an important limitation should be kept in mind: these findings were established in healthy elephants. The study did not determine whether a specific ultrasound abnormality is diagnostic of renal disease. Therefore, changes in echogenicity or echotexture should be interpreted alongside clinical and laboratory findings. 

Structure and function are different questions 

Renal ultrasound primarily addresses a structural question: 

Does the kidney appear anatomically and sonographically appropriate? 

Serum biochemistry and urinalysis provide complementary information about renal function and the urinary system. 

A 2025 study involving 92 Indian elephants under human care established reference intervals for several haematological, biochemical and blood-gas parameters, including BUN and creatinine^[2]. These Indian elephant-specific intervals are useful when interpreting laboratory results rather than relying on values derived from domestic species. 

However, a result within a reference interval does not necessarily exclude early or evolving disease. Reference intervals describe variation within a healthy population; they do not replace clinical assessment of an individual elephant. 

Could season affect interpretation? 

Elephant physiology can vary with environmental and seasonal conditions. 

A longitudinal study of 225 Asian elephants monitored over 26 months identified seasonal variation across multiple health parameters, including kidney-related measures such as BUN and creatinine^[3]. 

This is important when evaluating a mildly abnormal renal value. Hydration status, season, nutritional conditions, workload and previous results should all be considered before attributing a change to progressive renal disease. 

For an elephant with serial laboratory records, the direction of change may be as informative as the comparison with a population reference interval. 

Where does urinalysis fit? 

Urinalysis can provide additional information when renal or urinary disease is suspected. Parameters such as urine concentration, protein, blood cells and sediment findings should be interpreted together with the clinical examination and serum biochemical results. 

The key principle is simple: an isolated urine abnormality should not automatically be interpreted as evidence of renal disease. 

Likewise, an abnormal ultrasound finding should not be treated as a stand-alone diagnosis. The most useful interpretation comes from correlating structural findings with laboratory results and the elephant's clinical status. 

Build an individual renal profile 

When renal dysfunction is suspected, a practical assessment can include: 

• Clinical examination and hydration assessment; 
• Serum BUN and creatinine; 
• Electrolytes where clinically indicated; 
• Urinalysis and sediment examination; 
• Renal ultrasonography; 
• Comparison with previous results from the same elephant; and 
• Repeat testing when findings are equivocal or inconsistent. 

This approach is particularly useful because an individual baseline can provide an important point of comparison when interpreting subsequent changes. 

What if the findings do not agree? 

Consider an elephant with a mildly increased creatinine but an apparently unremarkable renal ultrasound. 

The normal ultrasound does not justify dismissing the biochemical finding. Conversely, altered renal echogenicity in an otherwise clinically normal elephant should not automatically be labelled as renal failure. 

When structural and functional findings disagree, the appropriate response is correlation, reassessment and, where indicated, repeat testing rather than premature diagnosis. 

Clinical takeaway 

Renal assessment in Asian elephants is strongest when clinical examination, laboratory testing and ultrasonography are considered together. Establishing individual baselines and comparing findings over time can make subtle changes easier to recognise, while consideration of seasonal and environmental variation can help prevent overinterpretation of isolated abnormalities.

References:

1. Inthawong P, Huaijantug S, Plangsangmas T, Piyarungsri K, Angkawanish T, Langkaphin W, Kosaruk W, Pabutta C, Kijpraiboon S, Mitchell MA, Wattananit P. Transcutaneous ultrasonography for visualization of the kidneys in captive Asian elephants (Elephas maximus): a quantitative assessment of echogenicity and echotexture in comparison with the liver and spleen. BMC Veterinary Research. 2025 May 26;21(1):376. https://doi.org/10.1186/s12917-025-04835-4
2. Muliya SK, Bindhani UT, Kawlni L, et al. Reference intervals for hematology, serum biochemistry and blood gas parameters in Indian elephants (Elephas maximus indicus) under human care. Front Vet Sci. 2025;12:1602296. Published 2025 Jul 14. https://doi.org/10.3389/fvets.2025.1602296
3. Diogo J Franco dos Santos, Vérane Berger, Robin Cristofari, Win Htut, U Kyaw Nyein, Htoo Htoo Aung, Sophie Reichert, Virpi Lummaa, Seasonal variation of health in Asian elephants, Conservation Physiology, Volume 8, Issue 1, 2020, coaa119, https://doi.org/10.1093/conphys/coaa119