Management of Acute Kidney Injury Using Peritoneal Dialysis in a Bottlenose Dolphin (Tursiops truncatus) with Bilateral Ureteral Obstruction
, Thomas H. Reidarson 1, James F. McBain 1, Hendrik H. Nollens 1,†, Amber P. Sanchez 2 and David M. Ward 2Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this paper, the authors provide a detailed description of acute kidney injury (AKI) in a dolphin. Considerable effort was made by the authors in documenting and analyzing the case.
The statement: “however muscle and liver transaminase enzymes were increased (CK = 13,275 IU/L, AST = 1,117 IU/L, LDH = 3,971 IU)” — requires more cautious interpretation. Elevated AST levels may be associated with cardiac involvement, not solely liver or muscle pathology. It is unclear why an electrocardiogram (ECG) was not performed following the marked elevation of AST and CK, which can also be indicative of myocardial injury. The authors should be more precise in using terms such as “elevated liver transaminases” and “persistent elevation of muscle enzymes” without ruling out cardiac causes.
From what I can gather, ECGs were performed twice during the early days of monitoring. Could the ECG findings be consistent with, for example, hyperkalemia or AKI-related changes? Or were they within normal limits? A more thorough discussion of the ECG findings would be beneficial.
Finally, it is unfortunate that fibroblast growth factor 23 (FGF-23) was not measured, as it could have provided further insight into phosphate handling and AKI pathophysiology in this case.
Comments on the Quality of English LanguageWhy is there one extra space at the beginning of every sentence?
Author Response
Reviewer 1 -
Comments 1: Lines 210 -213 and 222-223, regarding muscle and liver transaminases. Requires more cautious interpretation.
Response 1: Thank you for your comment. We agree that it is possible that there may be cardiac and skeletal muscle involvement during early course of the obstructive disease that caused hyperkalemia and evident electrocardiographic changes when monitoring the animal for the multiple procedures. The day prior, the dolphin had a vagal event during an attempted cystoscopy. That bradycardic event was observed and monitored with an EKG and normalized with treatment. At the time there were limited assays to differentiate creatine phosphokinase isoenzymes (skeletal vs. cardiac), none were validated for cetaceans, nor were there assays for troponin or BNP, so we relied on clinical observation and periodic ECG's, if a procedure was being conducted out of the water. We see elevated muscle enzyme change in cetaceans with handling, exertion, invasive procedures, because they are heavily muscled animals. We have measured LDH isoenzymes and found them to be highly correlated with muscle injury in cetaceans following injections.
With that said, it is not wrong to say "muscle and liver" as a general statement in the results. An additional statement was added to the DISCUSSION to emphasize the point that myocardial injury could not be ruled out.
Comment 2: Could ECG findings be consistent with hyperkalemia or AKI-changes? Further discussion would be beneficial.
Response 2: Thank you for this point. Comments about the early ECG findings were suggestive of hyperkalemia and AKI-related changes (that point is made clearer with additional text). Lines 125-128 and lines138-139.
Comment 3: Could fibroblast growth factor 23 provided further insight into AKI pathophysiology?
Response 3: That is an interesting question. This case was in 2010, when FGF-23 was only being used in human research. It has not been validated in cetaceans, but may be a useful test in the future for AKI and CKD.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis study reports a successful case of peritoneal dialysis (PD) in a bottle nosed dolphin (Tursiops truncatus) after acute kidney injury caused by bilateral ureteral stones. It is the first recorded PD treatment in whales and has important clinical reference value. The research provides a new approach for emergency management of hyperkalemia and azotemia in the veterinary field of marine mammals, especially as an alternative to traditional drug therapy when it is ineffective. However, there are several issues that need improvement
1. It is recommended to compare other cases of kidney disease in marine mammals (such as sea lions and whales) to highlight the unique advantages or limitations of PD in such cases.
2. It is necessary to explain how animal pain/stress (such as behavioral scores, physiological indicators) are evaluated during dialysis to comply with modern zoo medical ethics requirements.
3. mentions "months of treatment" but does not describe objective indicators of renal function recovery (such as dynamic changes in creatinine)
Author Response
Reviewer 2
Comment 1: It is recommended to compare other cases of kidney disease in marine mammals to highlight the unique advantages or limitations of PD in such cases.
Response 1: Thank you for your suggestion. We have highlighted the 2 additional cases reported in cetaceans that are applicable. There are no other published cases of AKI or CKD in pinnipeds that are managed with IV fluid therapy, PD or HD. We have inserted a small paragraph following the 2 examples, starting with Line 411, stating the challenges of managing pinnipeds with AKI in our experience. We could find no other suitable examples in the literature that expound upon the central topic of PD in zoo or aquarium-housed animals.
Comment 2: It is necessary to explain animal pain/stress during dialysis and how this complies with modern zoo ethics.
Response 2: We appreciate this point and have added a paragraph, line 494 - 515 to highlight the perspective of welfare for this individual animal.
Comment 3: Mentions months of treatment but does not describe objective indicators of renal function recovery.
Response 3: Thank you for this suggestion. We added verbiage to address this in the Discussion, 580-588.
Reviewer 3 Report
Comments and Suggestions for AuthorsManuscript Number: jzbg-3749290
Management of acute kidney injury with peritoneal dialysis in a bottlenose dolphin (Tursiops truncatus) with bilateral ureteral obstruction.
Journal – Journal of Zoological and Botanical Gardens
This interesting paper provided details of the treatment of a bottlenose dolphin in human care during a period of acute kidney injury and thereafter. This paper outlined details of the protocol used to treat the animal for two uroliths that were causing uretral blockages and post catheterisation treatment for secondary health effects.
The paper is clear, concise and well structured. I would suggest the inclusion of a schematic figure outlining the treatment and post-treatment timeline as a summary. The paper provides clear information of the treatment of the individual involved and recommendations/lessons learned from this event which I believe can be a of great value to improve husbandry and the standard of care for any similarly afflicted animals. Given the individual variability in the described event the results could not be reproduced by another but if an individual under human care suffering from a similar condition was identified, I believe the advice in this paper would prove invaluable.
Specific comments below:
Line 20 – amend to – …junctions of the urinary bladder.
Line 48 – italicize Tursiops truncatus
Line 53 and 54 – italicize Clupea harengus, Mallotus villosus and Scomber japonicus
Line 58 – amend to – The blood analysis demonstrated leukocytosis…
Line 136 – amend to – … (St. Paul, MN) and found to consist of…
Line 169 – amend to – … was analyzed and found to have a K concentration…
Line 217 – amend to – … was analyzed and found to have…
Line 219 – amend to – … the collected dialysate was found to have…
Line 223 – amend to – … were further increased…
Line 232 – amend to – … analyzed and found to have…
Line 285 – amend – liv-er to liver
Line 295 – amend – there-fore to therefore
Line 309 – remove (E. coli) and italicize Escherichia coli
Line 347 – amend – dys-function to dysfunction
Line 349 – amend to – uniquely adapted to the weightless aqueous medium…
Line 351 – amend to – and dehydration of their skin [4,5].
Line 371 – amend – re-placement to replacement
Line 384 – amend – circum-stances to circumstances
Line 394 – amend – com-plicated to complicated
Line 424 – amend – sup-press to suppress
Line 452 – amend – hu-man to human
Comments for author File: 
Comments.pdf
Author Response
Reviewer 3
Comment 1: Schematic provided to see if it provides clarity to timeline.
Response 1 : Thank you for that suggestion, case chronology is complicated with multiple different treatments. Attempting to provide a schematic that will provide simple but clarify timeline is in works, need a little more time.
Comment 2: Specific comments to word corrections
Response 2: Word corrections made from specific listed comments, most of these were secondary to formatting. thank you
Reviewer 4 Report
Comments and Suggestions for AuthorsThe authors present a case report on the use of peritoneal dialysis to treat acute kidney injury resulting from bilateral ureteral obstruction in a bottlenose dolphin. The novelty of this intervention is clearly explained. The clinical procedures are thoroughly documented. The treatment timeline and outcomes are well monitored. I have a few comments below for the authors to consider.
- While it's understandable that refs for PD in aquatic animals are limited, could the authors elaborate on how the frequency and duration of PD sessions were determined? Was there a specific protocol referenced for daily PD in such cases?
- How does the dialysate composition used in this case compare with formulations used in humans? How were the dosage and infusion volumes adapted for the dolphin?
- For blood draws, IV and catheter placement, were designated ports (or entry sites) used throughout the treatment process? Considering the dolphin's aquatic environment, how did the team mitigate infection risk at these access points?
- The time entries in Table 2 would benefit from a consistent format. If time info for Day 5 and 6 is available, please consider including it.
- The ref list should be revised for consistency and completeness. Some entries contain unclear journal names/abbreviations, such as Ref. 1 and 15. Using a ref management tool like EndNote is recommended to ensure alignment with the journal’s formatting requirements.
Author Response
Reviewer 4
Comment 1: Could the authors elaborate on how the frequency and duration of PD was determined, was there a specific protocol to reference?
Response 1: Thank you. The frequency, goals and duration of PD is expounded upon in the DISCUSSION. Lines 443-475.
Comment 2 : How does the dialysate solution compare to formulations used in humans and how was the infusion volume adapted for the dolphin?
Response 2: Thank you. Additional verbiage to this point was added. Lines 443- 475.
Comment 3: Can times be added to Table 2 to make table headings more concistent?
Response 3: Thank you, the Table 2 has been amended.
Comment 4: Can Reference list be revised for consistency.
Response 4: Thank you, the Reference list was amended.
