Abstract
Case series summary
Seven cats were found to have postoperative subcutaneous ureteral bypass (SUB) occlusion secondary to blood clot formation. An increase in serum creatinine led to imaging and clot detection in all but one case. Alteplase, a tissue plasminogen activator, was infused into the SUB via the port in four cats, intravesicularly via a transurethral urinary catheter in one cat, and by both routes in two cats. Patency of the SUB was re-established in all cats within 2 days. No short- or long-term complications directly attributed to alteplase administration were observed.
Relevance and novel information
The results of this case series suggest that alteplase infusion via either the SUB port and/or a transurethral catheter should be considered prior to surgical intervention for the treatment of postoperative SUB occlusion secondary to a blood clot.
Keywords
Introduction
Feline ureteral obstruction has been increasing in prevalence over the past decade.1–3 Based on the current literature, the treatment associated with the lowest morbidity and mortality for feline ureteral obstructions is placement of a subcutaneous ureteral bypass (SUB) system (Norfolk Vet Products).1,4–7 While placement of this device has significantly improved the morbidity and mortality associated with ureteral surgery, postoperative occlusion of the device with blood clots has been reported in up to 8% of cats.2,4,5,8,9 Such occlusion results in reobstruction of urinary outflow from the kidney, and may require surgical revision. Alteplase, a synthetic formulation of tissue plasminogen activator (tPA), is a thrombolytic agent that targets lysis of existing clots through the conversion of the proenzyme plasminogen into the active fibrinolytic enzyme plasmin. 10 The activity of tPA is greatly enhanced with binding to fibrin on which the activated plasmin has its action. 10 This characteristic of tPA allows for preferential fibrinolysis at the site of the clot and thus reduces the risk of systemic bleeding vs other plasminogen activators. 10
This case series describes the use of the SUB port and/or intravesicular transurethral infusion of alteplase in seven cats to alleviate postoperative blood clot occlusion of their SUB.
Case series description
Alteplase (Cathflo Activase; Genentech) was used to dissolve postoperative blood clot occlusion of a SUB in seven cats over a 4-year period at two institutions. All cats had a complete blood count, serum biochemistry profile and abdominal ultrasound (AUS) performed prior to SUB placement. All cats were azotemic on presentation prior to SUB placement; cats with a history of chronic kidney disease had an acute progression of their azotemia on presentation. All cats had either unilateral or bilateral renal pelvic and/or proximal ureteral dilation consistent with ureteral obstruction on AUS. A urinalysis and urine culture were submitted for all cats during hospitalization. SUB placement was recommended in each obstructed patient as a treatment option for their ureteral obstruction. SUB placement was performed in the previously described manner by three of the authors (SKB, ACB and/or CWW). 4 Median procedure time was 135 mins. A large port was used in all SUB procedures, and the device was the SUB 1.0 in all cases. At the time of SUB placement, an esophagostomy tube and central venous line were placed using standard techniques in all cats. SUB occlusion secondary to a blood clot formation was diagnosed based on ultrasonographic evidence of a non-vascular homogenous soft-tissue opacity surrounding the SUB catheter with the inability to flush saline through the port of the device using the standard SUB flush procedure. 4
SUB occlusion was discovered a median of 3 days postoperatively (range 0.5–5 days). Alteplase was prepared for instillation by reconstituting 2.2 mg alteplase into 2.2 ml sterile saline to make a 1 mg/ml solution and was used either fresh or thawed after freezing. A median dose of 0.9 mg (range 0.5–2 mg) and 2 mg (range 1–5 mg) was used for the alteplase infusion through the SUB port and transurethral urinary catheter, respectively. A median of two infusions (range 1–2) per site were performed 2–24 h apart. Patency of the SUB was restored in all cats within 48 h (median 24 h).
All cats survived and were discharged from the hospital and no cat needed a repeat surgical procedure to restore SUB patency. Median hospitalization length was 6.9 days from the time of SUB placement (range 5–7 days). Median creatinine decreased from 8.5 mg/dl (range 3.3–26.7 mg/dl) at presentation to 2 mg/dl (range 1.3–4 mg/dl) at the time of discharge. There were no complications observed that were attributable to alteplase administration in any cat. The results are summarized in Table 1 and in more detail on a case-by-case basis as follows.
Information relevant to the diagnosis and treatment of postoperative subcutaneous ureteral bypass (SUB) obstruction and alteplase administration in seven cats
Reference intervals: blood urea nitrogen (BUN) 22–33 mg/dl; creatinine 1.1–3.5 mg/dl; packed cell volume (PCV) 30–45%; TS 5.7– 8.0 g/dl
NM = neutered male; DSH = domestic shorthair; SF = spayed female; DLH = domestic longhair; IRIS = International Renal Interest Society; CKD = chronic kidney disease; URI = upper respiratory tract infection; UTI = urinary tract infection; HCM = hypertrophic cardiomyopathy; HL = hepatic lipidosis; TS = total solids; PT = prothrombin time; PTT = partial thromboplastin time; NR = not reported; SC = subcutaneous; OD = right eye; pRBC = packed red blood cell
Case 1
A 4.5-year-old neutered male domestic shorthair (DSH) cat was diagnosed with a right ureteral obstruction secondary to ureterolithiasis and left renal agenesis. A right unilateral SUB was placed using a standard technique. Hypothermia and excessive bleeding, including hemorrhage into the bladder with bladder clot formation, were noted during surgery. Postoperative hematuria and progressive anemia occurred, which required four transfusions of packed red blood cells (pRBCs), three of which were administered prior to alteplase administration. Twelve hours after SUB placement, the cat’s serum creatinine increased from 13.2 to 16.0 mg/dl (reference interval [RI] 1.1–3.5 mg/dl), prompting an ultrasound-guided SUB flush. This revealed obstruction of the SUB (both cystostomy and nephrostomy catheters) with suspected blood clots seen in both the renal pelvis and bladder lumen. Two milligrams of alteplase were instilled into the SUB and dwelled for 1 h before attempting a reflush. There was no change noted to the clot via ultrasound so the procedure was repeated with an additional 1 mg alteplase instilled into the SUB port and 1 mg alteplase instilled intravesicularly via a transurethral urinary catheter. The alteplase was left to dwell for 2 h before flushing the device or the bladder with saline. Within 8 h of the second instillation, numerous blood clots were noted in the urinary catheter, urine production increased and the azotemia began to improve. Twenty-four hours later, another flush of the SUB revealed ultrasonographic resolution of the clots, decompression of the renal pelvis and patency of the SUB system. Other postoperative complications were fluid overload, resulting in congestive heart failure 4 days postoperatively, and two neurologic episodes characterized by vocalization, urination, hypotension and collapse, which occurred 1 and 4 days postoperatively. The cat was discharged 8 days after surgery with a blood urea nitrogen (BUN) concentration of 23 mg/dl (RI 22–33 mg/dl) and a serum creatinine of 1.3 mg/dl (RI 1.1–3.5 mg/dl). Intermittent hematuria but no recurrent obstruction was noted at the 6-month follow-up.
Case 2
An 11-year-old spayed female DSH cat was diagnosed with a left ureteral obstruction secondary ureterolithiasis. A unilateral SUB was placed using a standard technique. The cat developed hematuria, bruising and anemia that did not require a blood transfusion in the immediate postoperative period. Three days after SUB placement, the cat’s serum creatinine increased from 1.9 mg/dl to 2.5 mg/dl (RI 1.1–3.5 mg/dl.) This prompted an ultrasound-guided SUB flush, which revealed patency of the nephrostomy catheter and occlusion of the cystostomy catheter caused by a suspected blood clot seen in the bladder lumen. Prothrombin (PT) and partial thromboplastin time (PTT) were measured and found to be normal. Two milligrams alteplase was instilled via the SUB port and left to dwell for 2 h. The next day, the ultrasonographic appearance of the clot was unchanged and serum creatinine increased to 2.8 mg/dl (RI 1.1–3.5 mg/dl). The cat was sedated, a transurethral urinary catheter was placed and 5 mg alteplase was infused intravesicularly via the urinary catheter and left to dwell for 30 mins with the catheter clamped off from flowing before flushing the urinary bladder with saline. The blood clot’s ultrasonographic appearance remained unchanged and thus the 5 mg alteplase infusion was repeated and left to dwell for 2 h. After the dwell time was complete, a SUB flush was performed, which revealed that the cystostomy catheter had good patency. However, there was reduced patency in the nephrostomy catheter secondary to a suspected clot that was seen in the renal pelvis surrounding the nephrostomy catheter tip. Thus, an additional 2 mg alteplase was injected via the SUB port; dwell time was not recorded. Thirty-six hours after the first instillation of alteplase, the clots were found to be completely dissolved on ultrasound evaluation and the creatinine improved to 2.2 mg/dl (RI 1.1–3.5 mg/dl). The cat was discharged 6 days after surgery with a BUN of 30 mg/dl (RI 22–33 mg/dl) and a serum creatinine of 2.0 mg/dl (RI 1.1–3.5 mg/dl). No recurrent obstruction or complications were observed at the 7-month follow-up.
Case 3
A 6-year-old spayed female DSH cat was diagnosed with bilateral ureteral obstruction. The ureters could not be fully evaluated owing to edematous perinephric fat, but the left ureter was suspected to be circumcaval. A bilateral SUB with a PantsPort was placed using a standard technique. Intraoperative hypotension occurred and postoperative hematuria was noted. Five days after SUB placement, serum creatinine increased from 1.3 mg/dl to 6.3 mg/dl (RI 1.1–3.5 mg/dl). Also, packed cell volume (PCV) decreased from 22% to 15% (RI 30–45%) and potassium increased from 3.86 mmol/l to 8.07 mmol/l (RI 3.41–4.71 mmol/l). AUS revealed a large blood clot filling the bladder lumen. A SUB flush revealed that fluid was entering the cystostomy catheter easily but not the bladder lumen owing to obstruction secondary to the clot. A temporary transurethral urinary catheter was placed and 2.2 mg alteplase was instilled intravesicularly and left to dwell for 1 h. An additional 1 mg alteplase was flushed through the SUB port. During the dwell time, the alteplase was aspirated and reflushed several times, and the clot subjectively decreased in size. A SUB flush performed after this procedure revealed that the cystostomy catheter flowed easily into the bladder lumen. The bladder clot was never documented to completely dissolve during hospitalization. After alteplase infusion the cat’s anemia remained stable; however, a pRBC transfusion was eventually required owing to continued weakness. Other postoperative complications included hypothermia and dull mentation starting 1 day after surgery and lasting for 3 days. The cat was discharged after 8 days of hospitalization with a BUN of 18 mg/dl (RI 22–33 mg/dl) and a serum creatinine of 2.0 mg/dl (RI 1.1–3.5 mg/dl). A single episode of non-symptomatic Enterococcus species urinary tract infection (UTI) was observed 3 months after SUB placement. However, no recurrent obstruction was observed at the 12-month follow-up.
Case 4
A 9-year-old spayed female domestic longhair cat was diagnosed with right ureteral obstruction secondary to ureterolithiasis. A unilateral right SUB was placed using a standard technique. Intraoperative complications of hypotension and hypothermia occurred. Two days after surgery, the cat’s serum creatinine increased from 7.6 mg/dl to 8.1 mg/dl (RI 0.8–2.3 mg/dl). This prompted a SUB flush, which revealed partial occlusion of the cystostomy catheter caused by a presumed blood clot. Thus, 0.9 mg alteplase was instilled into the SUB. After 36 h the clot was observed to have dissolved completely on repeat ultrasonographic examination. Other postoperative complications were anemia requiring a pRBC transfusion prior to alteplase administration, fluid overload 1 day after surgery and subcutaneous emphysema 2 days after surgery. The cat was discharged 7 days after surgery with a BUN of 79 mg/dl (RI 22–33 mg/dl) and a creatinine of 4.1 mg/dl (RI 0.8–2.3 mg/dl). Long-term complications of persistent anemia requiring darbepoetin alfa (Aranesp; Amgen) administration and UTIs occurred. However, no recurrent obstruction was observed at the 13-month follow-up.
Case 5
A 17.5-year-old spayed female DSH cat was diagnosed with left ureteral obstruction. A unilateral left SUB was placed using a standard technique. Dried solidified blood (DSB) calculi were retrieved during surgery and thus it was suspected that the left ureteral obstruction was likely secondary to a DSB calculus. Intraoperative hypothermia and hypotension were documented. One day after surgery the cat developed neurologic signs (seizure, blindness, ataxia, circling). Four days after surgery the cat’s serum creatinine increased from 1.9 mg/dl to 2.5 mg/dl (RI 0.8–2.3 mg/dl). A SUB flush was difficult to perform owing to resistance. While no suspected clot was seen with ultrasound in this case, blood clots were retrieved when aspirating back on the SUB port and thus blood clot occlusion was presumed. Therefore, 0.9 mg alteplase was instilled into the SUB. The SUB was flushed easily 12 h later with no blood clots aspirated. The cat was discharged 5 days after surgery with a BUN of 36 mg/dl (RI 15–34 mg/dl) and a serum creatinine of 1.9 mg/dl (RI 0.8–2.3 mg/dl). A single episode of hematuria occurred but no obstruction was observed at the 10-month follow-up.
Case 6
A 10-year-old spayed female DSH cat was diagnosed with a left ureteral obstruction secondary to ureterolithiasis. A unilateral left SUB was placed using a standard technique. Postoperative bruising on the cat’s limbs and anemia were observed. On routine SUB flush and evaluation 2 days after surgery, the cystotomy catheter could not be flushed secondary to suspected blood clot formation. Thus, 0.5 mg alteplase was instilled into the SUB. Serum creatinine on the day of clot discovery had decreased from the previous day. However, on the next day, serum creatinine had increased from 2.9 mg/dl to 5.6 mg/dl (RI 0.8–2.3 mg/dl). AUS revealed left pyelactasia and hydroureter 24 h after alteplase infusion. A clot was aspirated from the SUB port and the pyelactasia and hydroureter resolved. While no immediate complications of the alteplase were observed, the cat’s anemia progressed over the 48 h after its administration. A blood transfusion was recommended but not performed. Profound hematuria, which started 1 day after surgery (before alteplase administration) and lasted for 2 days, was also observed as a postoperative complication. The cat was discharged 5 days after surgery with a BUN of 29 mg/dl (RI 22–33 mg/dl) and a creatinine of 2.2 mg/dl (RI 0.8–2.3 mg/dl). A single episode of stranguria and no recurrence of obstruction were reported at the 3-month follow-up.
Case 7
A 15-year-old spayed female DSH cat was diagnosed with a left ureteral obstruction secondary to a suspected stricture. A unilateral left SUB was placed using a standard technique. While obtaining the postoperative lateral fluoroscopy image, the nephrostomy catheter was found to be obstructed. The incision was reopened and a J-wire was used to manually remove a blood clot after which the system’s patency was confirmed. Mild hypotension and hemorrhage occurred intraoperatively. Four days after surgery, the cat’s serum creatinine increased from 4.1 mg/dl to 5.8 mg/dl (RI 0.8–2.3 mg/dl). A SUB flush revealed occlusion of both the nephrostomy and cystotomy catheters. Blood clot obstruction was suspected owing to the cat’s perioperative obstructive blood clot. Thus, 0.9 mg alteplase was instilled into the SUB and left to dwell for 1 h after which a large clot was retrieved from the SUB port. This procedure was repeated after 24 h at which time the cystotomy catheter was patent but the nephrostomy catheter remained occluded. Serum creatinine decreased from 5.7 mg/dl to 4 mg/dl (RI 0.8–2.3 mg/dl) 48 h after initial alteplase administration. Owing to this improvement, an additional SUB flush was not performed to confirm the dissolution of the clot and the cat was discharged later that day (6 days after surgery). Other postoperative complications included corneal ulceration and seroma formation 1 day after surgery. Four days after discharge, the cat was found to be progressively azotemic (creatinine 6.6 mg/dl; RI 0.8–2.3 mg/dl) due to recurrent nephrostomy catheter occlusion documented on SUB flush. Nephrostomy catheter exchange was recommended instead of repeat alteplase administration owing to the recurrent nature of the occlusion. A pRBC transfusion was administered in preparation for surgery. The morning of planned nephrostomy catheter exchange (14 days post-SUB placement), however, a SUB flush revealed nephrostomy catheter patency and creatinine had improved to 3.7 mg/dl (RI 0.8–2.3 mg/dl). At the 13-month follow-up, the cat had persistent anemia, progressive azotemia and recurrent UTIs but no recurrent SUB obstruction.
Discussion
Blood clot formation resulting in obstruction of the SUB system has been reported in up to 8% of cats post-SUB placement in the largest retrospective study on the SUB to date. 5 This finding makes it a significant complication of the procedure and a condition that should be evaluated for in patients. Previously, serial flushing with saline has been attempted to resolve such obstructions, but 64% of those cats still required a surgical revision for persistent obstruction. 5 Other minimally invasive options for clot dissolution are obviously desirable.
The use of alteplase to dissolve central venous line catheter occlusions has been described in the human literature for decades.11,12 More recently, the use of alteplase in central venous catheters used for renal replacement therapy in dogs and cats has been reported. 13 Alteplase infusion is often successful in improving catheter occlusion, with reported success rates of 50–90% and 79% in human pediatric and veterinary patients, respectively.11,13 In human pediatric patients, adverse effects of alteplase, including bleeding, are very rare when it is used for this purpose. 12 There are also reports, in both the human and veterinary literature, of intravesicular administration of alteplase to successfully and safely dissolve urinary bladder blood clots.14–16 Given this background, investigation of the intra-device use of alteplase to dissolve SUB blood clot occlusions in cats seems warranted. However, only anecdotal mention of it has been reported.2,5,8 To our knowledge, this is the first report to focus on the use of alteplase to relieve postoperative SUB blood clot occlusions in cats.
In this series, SUB occlusion was found in 6/7 cats due to an increase in serum creatinine after an initial postoperative decrease in serum creatinine from presentation. One cat’s serum creatinine increased the day after clot discovery, which was believed to be a result of the clot formation causing a partial and then complete occlusion of the system. The median serum creatinine increase was 1.7 mg/dl (range 0.5–2.8 mg/dl) and this occurred a median of 3 days after surgery (range 0–5 days). This timing is significant as typically around day 3 postoperatively is when fluid therapy weaning is started. Thus, while a postoperative rise in serum creatinine can occur after weaning intravenous fluid therapy, it should prompt clinicians to perform an AUS and SUB flush in these patients to evaluate for blood clot formation and patency of the SUB system. Given this information, consideration should also be given to perform ultrasound and SUB flush 3 days postoperatively in all patients.
Postoperative blood transfusion was required in 4/7 (57%) of cats and 2/7 (29%) cats developed excessive postoperative bruising. This is more frequent than the reported 14% of cats that required transfusion after SUB placement. 5 The cats in this series had several risk factors that may have increased their likelihood of bleeding and subsequent SUB occlusion with blood clots. Metabolic acidosis and intraoperative hypothermia were common in this series, occurring in 5/7 (71%) and 3/7 (43%) cats, respectively. Surgery time was longer than the previously reported average of 70 mins in 4/5 (80%) cats with surgery time data available and may have contributed to development of hypothermia. 5 Both hypothermia and acidosis have been shown to induce a coagulopathy.17,18 This coagulopathy is not always reflected in PT and PTT and thus despite all cats tested in this series having normal PT and PTT, such a coagulopathy cannot be ruled out.17,18 It is possible that other coagulation testing such as thromboelastography may have revealed coagulopathies in some of the cats included in this series.
Additionally, the cats in this series were markedly azotemic, with a median preoperative serum creatinine of 8.5 mg/dl vs 6.6 mg/dl and 4.4 mg/dl reported in two large case series of cats with ureteral obstruction.5,19 Azotemia has been shown to induce platelet dysfunction and predispose patients to bleeding complications and paradoxical blood clot formation.20,21 The role of acidosis, intraoperative hypothermia and degree of azotemia on risk of postoperative bleeding in SUB cats should be investigated further. Preoperative hemodialysis has historically been considered in cats with oliguria/anuria, severe hyperkalemia or overhydration causing the cat to not be stable enough for anesthesia. 5 If severe azotemia is found to increase the risk of perioperative bleeding, hemodialysis could be considered in these cases as well.
Overt hemorrhage secondary to nephrostomy catheter placement occurred in 2/7 (29%) cats and may have contributed to clot formation. Although some bleeding is inevitable with nephrostomy catheter placement, in the human literature, Doppler ultrasound-guided percutaneous nephrolithotomy has been shown to have less blood loss than traditional B-mode ultrasound guidance owing to better visualization of the arcuate arteries. 22 Thus, using Doppler ultrasound as well as fluoroscopy for guidance during nephrostomy catheter placement may provide a method for reducing the risk of hemorrhage and complications such as clot formation, and should also be investigated further.
Three cats had neurologic signs observed postoperatively (cases 1, 3 and 5). Two cats (cases 3 and 5) developed these signs after dramatic improvement of their azotemia and thus dialysis disequilibrium was suspected. However, one cat (case 1) had progressive azotemia at the time of the neurologic event and thus dialysis disequilibrium was not considered a possible cause. Other differentials considered were intracranial hemorrhage, thromboembolic event and thiamine deficiency. While the brains of these cats were not evaluated with MRI and the definitive etiologies of these neurologic signs were unknown, the possibility of intracranial hemorrhage cannot be discounted.
No direct adverse events secondary to alteplase administration were observed. Three cats did receive or were recommended pRBC transfusions after alteplase administration. However, one cat (case 1) had already received three pRBC transfusions prior to alteplase administration and was found to have recurrent progressive anemia on morning bloodwork before alteplase administration. As this cat was progressively anemic with hematuria before alteplase administration, we suspect that its bleeding and neurologic event were unrelated to alteplase administration. However, the possibility that alteplase contributed to the anemia or neurologic event cannot entirely be ruled out. The second cat (case 3) had a stable anemia after alteplase administration but received a pRBC transfusion due to continued weakness. The final cat (case 6) developed a progression of its anemia that started 24 h after alteplase administration. The half-life of alteplase is <10 mins in humans, and while prolonged thrombolytic activity beyond half-life has been observed in dogs, 23 it seems unlikely that at 24 h after intra-device administration alteplase caused the observed anemia. Even though no major complications directly attributed to alteplase were observed, this should be evaluated in a larger number of animals, ideally in a prospective fashion. Alteplase has not been studied in human patients weighing <10 kg and thus extrapolation of its safety profile in humans may not be applicable to the cat population. 24
Blood clot formation did not affect short-term outcome. All cats were discharged from the hospital, though median postoperative hospitalization length was longer than previously reported (6.9 vs 4.6 days). 5 Median serum creatinine at discharge was similar to previously reported creatinine at time of discharge after SUB placement.5,8 No long-term complications related to alteplase were observed.
The limitations of this series include that it was a small retrospective study and a protocol was not established for the administration of the alteplase. Further studies are required in order to standardize alteplase infusions. A review of alteplase used in pediatric human catheter occlusions reported a dose range of 0.5–2 mg alteplase. 11 It would seem reasonable to use the lower end of this range for our feline patient population, yet the median dose for infusion via a SUB port was 0.9 mg in this series. Additionally, the intravesicular doses used (especially in case 2) were much larger than the typical range of 0.5–1 mg reported in both the both the human pediatric and veterinary literature.14–16 Finally, in this series, cats with large intravesicular blood clots received intravesicular infusion of alteplase via a transurethral urinary catheter alone or in addition to infusion through the SUB port. Thus, the importance of the intravesicular route of infusion in this subset of cats also needs to be determined. Further investigation of dosing, method of infusion, appropriate dwell time and number of infusions needs to be determined.
Conclusions
Postoperative occlusion of a SUB with blood clots is a frustrating complication that often requires surgical revision. An increase in serum creatinine (median increase 1.7 mg/dl) corresponded with clot discovery in 6/7 cats. Thus, such increases should be investigated via an ultrasound-guided SUB flush to evaluate SUB patency. Alteplase was able to restore SUB patency in all cats, as evidenced by improvement of serum creatinine and ultrasonographic monitoring. No adverse events directly secondary to alteplase administration were observed. Thus, alteplase administration should be considered before pursuing surgical intervention (such as catheter replacement) or humane euthanasia due to postoperative SUB occlusion secondary to blood clots. Further studies are warranted to establish the etiology of postoperative hemorrhage in cats undergoing SUB placement and the standardization and safety of alteplase administration to these patients.
Footnotes
Author note
These findings were presented as an oral presentation at the Veterinary Interventional Radiology and Interventional Endoscopy Society (VIRIES) annual meeting in 2017.
Conflict of interest
Drs Berent and Weisse are consultants for Infiniti Medical, LLC.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Ethical approval
This work involved the use of non-experimental animals only (including owned or unowned animals and data from prospective or retrospective studies). Established internationally recognised high standards (‘best practice’) of individual veterinary clinical patient care were followed. Ethical approval from a committee was therefore not specifically required for publication in JFMS.
Informed consent
Informed consent (either verbal or written) was obtained from the owner or legal custodian of all animal(s) described in this work (either experimental or non-experimental animals) for the procedure(s) undertaken (either prospective or retrospective studies). No animals or humans are identifiable within this publication, and therefore additional informed consent for publication was not required.