The Therapeutic Use of 25% Human Serum Albumin in Critically Ill Dogs and Cats

Comparative studies of structure and dynamics of caprine, leporine, ovine, and equine serum albumins

Serum albumin (SA) is the most prevalent protein found in blood. Human albumin was used as an albumin substitute in hypoalbuminemia pets due to high sequence similarity. SAs from furry animals were also reported to be the major indoor allergens. Sensitizing to one of SAs coupled with high sequence identity can lead to cross-reactive antibodies in allergic individuals. Thus, understanding the structural and dynamic characters of SAs is crucial for not only albumin substitution but also allergen therapy. Herein, Molecular dynamics (MD) simulations were performed to elucidate the structural and dynamic dissimilarity and similarity of economic animals [equine (ESA), caprine (CASA), ovine (OSA), and leporine (LSA)] to albumins from human (HSA), bovine (BSA), porcine (PSA), and pets [cat (FSA) and dog (CSA)]. The aim is to explore the feasibility of HSA substitution and understand how albumins cause the cross-reactivity. Generally, all albumins studied here show the scissoring motion like other mammalian albumins. The uniqueness of each albumin is defined by different sequence identity of domain I. Also, the drug binding affinity of studied albumins differs from HSA, CSA, FSA, BSA, and PSA. Especially, LSA displays the most deviated behavior from the group. So, such albumin may not be suitable for albumin therapy for pets and humans. CASA, OSA, and ESA share similar characteristics, therefore it is possible to use them to monitor the osmotic pressure among their species, but the allergenic response must be seriously considered. An insight obtained here can be useful to develop albumin therapy and understand clinical allergy.Communicated by Ramaswamy H. Sarma.

Retrospective evaluation of indications, transfusion protocols, and acute transfusion reactions associated with the administration of lyophilized canine albumin: 53 cases (2009-2020)

OBJECTIVES

To describe the administration of lyophilized canine albumin (LCA) and determine the increase in serum albumin concentrations post-LCA transfusion. To describe the incidence and types of acute transfusion reactions (TRs) and associated outcome in dogs presenting to a veterinary teaching hospital.

DESIGN

Retrospective and descriptive study from 2009 to 2020.

SETTING

University teaching hospital.

ANIMALS

Fifty-three client-owned dogs included in the study if they received an LCA transfusion and had vital sign monitoring recorded for at least for 4 hours after starting the LCA transfusion.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The 53 dogs available for study inclusion received 64 LCA transfusions. Signalment; underlying disease; indications for LCA transfusion; pre- and posttransfusion serum albumin concentration; volume, concentration, and dose of LCA; duration of transfusion; administration of other blood products or synthetic colloids; occurrence, timing, and type of TR; length of hospitalization; and outcome were recorded. Serum albumin concentrations increased post-LCA transfusion, with a median dose of 0.56 g/kg and a median posttransfusion serum albumin increase of 3 g/L (0.3 g/dL) (P = 0.008). TRs occurred in 13 of 64 (20.3%) transfusion events. Volume per kilogram, dose (g/kg), concentration, duration of transfusion, and additional administration of synthetic colloids were not associated with TRs. Three (23%) TRs were classified as febrile nonhemolytic transfusion reaction, 5 (38.5%) as transfusion-associated dyspnea (development of respiratory distress and limited diagnostics), and 5 (38.5%) had clinical signs that could not be defined by any 1 TR category. Six (46.1%) of 13 events were nonsevere, 5 (38.5%) were severe, and 2 (15.4%) were life-threatening.

CONCLUSIONS

Administration of LCA can be used to increase serum albumin concentrations, although the clinical implications of this increase are unknown. Acute TRs associated with LCA are relatively frequent and can be life-threatening. Careful monitoring is vital.

A survey of emergency and critical care veterinarians regarding IV fluid bolus therapy and monitoring practices in small animals

OBJECTIVE

To determine how veterinary emergency and critical care clinicians define IV fluid bolus therapy (FBT) and what constitutes a positive response to a fluid bolus.

DESIGN

Online survey of 222 emergency and critical care veterinarians between December 17, 2018, and March 1, 2019.

INTERVENTIONS

An online survey was provided to diplomates of the American College of Veterinary Emergency and Critical Care (ACVECC), residents of ACVECC-approved training programs, as well as house officers and emergency clinicians of a corporate multicenter emergency and specialty care veterinary hospital. The survey investigated the administration of various crystalloid, colloid, and blood products for FBT, as well as expected physiological responses.

MEASUREMENTS AND MAIN RESULTS

The majority of respondents considered balanced isotonic crystalloids appropriate for FBT (220/222 [99.1%]). Respondents showed greater variability in acceptance of 0.9% sodium chloride (105/222 [47.30%]), hypertonic (3-7%) sodium chloride (131/222 [59.01%]), and hydroxyethyl starch solutions (90/222 [40.54%]). Most respondents did not consider physiological plasma (44/222 [19.82%]) an appropriate choice. The most commonly used parameters for monitoring FBT responses were heart rate (220/222 [99.10%]), blood pressure (217/222 [97.75%]), capillary refill time (192/222 [86.49%]), lactate (181/222 [81.53%]), pulse pressure (151/222 [68.02%]), and rectal temperature (145/222 [65.32%]). The majority of respondents perceived that 0-20% (165/222 [74.32%]) of hypotensive patients are nonresponsive to FBT.

CONCLUSIONS

Small animal emergency and critical care clinicians favored balanced isotonic electrolyte solutions and hypertonic sodium chloride solutions for FBT over other options. When monitoring responses to FBT, heart rate, blood pressure, capillary refill time, and plasma lactate were among the most commonly monitored parameters, and there was a lack of familiarity with others. Despite the widespread use of FBT, these findings outline the need for further prospective clinical trials regarding the ideal fluid type and rate, as well as the appropriate responses to FBT.

Update on Albumin Therapy in Critical Illness

Albumin is among the most important proteins and plays a significant role in maintenance of colloid osmotic pressure, wound healing, decreasing oxidative damage, carrying drugs and endogenous substances, and coagulation. Hypoalbuminemia is common in acute and chronic illnesses. Replenishment of albumin can be in the form of fresh frozen, frozen or cryopoor plasma, or in the form of human or canine albumin concentrates. Infusion of human albumin concentrate to healthy and critically ill dogs can induce acute and delayed hypersensitivity reactions. Death has been reported. Therefore, allogenic transfusion in the form of plasma products or canine albumin concentrate is recommended.

Prospective Review of Clinical Hypersensitivity Reactions After Administration of 5% Human Serum Albumin in 40 Critically Ill Cats

This prospective study assesses the presence of immediate and delayed clinical hypersensitivity reactions in 40 hypoalbuminemic critically ill cats during and after an intravenous administration of 5% human serum albumin (HSA). Twenty hypoalbuminemic critically ill cats with no known exposure to HSA (control group) were also checked in order to highlight any clinical signs related to the underlying disease which could mimic hypersensitivity reactions. The administration of 10-20 mL/kg of 5% HSA at 2 mL/kg/h in critically ill cats did not lead to clinical signs of types I and III hypersensitivity reactions at days 0, 7, 14, 21, and 28, unlike previous findings with 25% HSA in this species.

Applicability of 99m Tc-Labeled Human Serum Albumin Scintigraphy in Dogs With Protein-Losing Enteropathy

Background

Diagnosis of protein loss into the gastrointestinal tract using noninvasive techniques is challenging. In people, scintigraphy not only is a sensitive tool to confirm protein‐losing enteropathy (PLE), but it also allows for localization of protein loss.

Hypothesis/Objectives

To investigate the feasibility of ^99mTc‐labeled human serum albumin (HSA) scintigraphy in dogs with PLE in comparison with control dogs.

Animals

A total of 8 clinically healthy control research dogs and 7 client‐owned dogs with gastrointestinal clinical signs and hypoalbuminemia (serum albumin concentration <2.0 g/dL).

Methods

Prospective case–control study. After IV injection of 400 MBq freshly prepared ^99mTc HSA (30 mg/dog), images of the abdomen were obtained 10, 60, 120, and 240 minutes postinjection. Additional images of the salivary and thyroid glands were obtained to rule out free ^99mTc. A scan was considered positive for PLE when radiopharmaceutical exudation was detectable in the intestinal tract.

Results

Only 1 control dog showed exudation of the radiopharmaceutical into the intestinal tract. No free ^99mTc was detected in any dog. In dogs with PLE, focal small intestinal and diffuse small intestinal radiopharmaceutical exudation into the bowel was detected in 2 and 3 dogs, respectively, whereas in 2 dogs, there was disagreement about whether radiopharmaceutical exudation was focal or diffuse.

Conclusion and Clinical Importance

^99mTc‐labeled HSA scintigraphy was feasible to diagnose PLE in dogs.

Natural and Synthetic Colloids in Veterinary Medicine

This review article covers basic physiology underlying the clinical use of natural and artificial colloids as well as provide practice recommendations. It also touches on the recent scrutiny of these products in human medicine and how this may have an effect on their use in veterinary medicine.

Retrospective evaluation of the administration of 25% human albumin to dogs with protein-losing enteropathy: 21 cases (2003-2013)

OBJECTIVE

To describe the administration of 25% human serum albumin (HSA) to dogs diagnosed with idiopathic inflammatory bowel disease (IBD) and protein-losing enteropathy (PLE). The secondary objectives were to report any acute and delayed adverse events and the effect of corticosteroids on the development of these reactions.

DESIGN

Retrospective study (2003-2013).

SETTING

Private referral hospital.

ANIMALS

Twenty-one client owned dogs diagnosed with PLE and idiopathic IBD that received ≥ 1 transfusion of 25% HSA. Dogs were included in the study if they had panhypoproteinemia, serum albumin concentration < 15.0 g/L [< 1.5 g/dL] or extravascular fluid accumulation, idiopathic IBD confirmed on histopathology, and complete medical records.

INTERVENTIONS

None.

MAIN RESULTS

Two of the 21 patients (9.5%) developed signs consistent with an acute reaction; 1 of these dogs was euthanized due to the severity of the reaction. Two patients (9.5%) showed signs consistent with a delayed reaction; 1 of these dogs was euthanized 5 days after the reaction, though it is unclear whether the reaction and the euthanasia were related. Corticosteroid administration did not appear to affect the occurrence of adverse reactions.

CONCLUSIONS

This retrospective study demonstrated that the administration of 25% HSA to dogs with moderate to severe hypoalbuminemia from PLE was associated with occasional acute and delayed adverse events, some of which were severe or fatal.

Controversies in the use of hydroxyethyl starch solutions in small animal emergency and critical care

OBJECTIVES

To (1) review the development and medical applications of hydroxyethyl starch (HES) solutions with particular emphasis on its physiochemical properties; (2) critically appraise the available evidence in human and veterinary medicine, and (3) evaluate the potential risks and benefits associated with their use in critically ill small animals.

DATA SOURCES

Human and veterinary original research articles, scientific reviews, and textbook sources from 1950 to the present.

HUMAN DATA SYNTHESIS

HES solutions have been used extensively in people for over 30 years and ever since its introduction there has been a great deal of debate over its safety and efficacy. Recently, results of seminal trials and meta-analyses showing increased risks related to kidney dysfunction and mortality in septic and critically ill patients, have led to the restriction of HES use in these patient populations by European regulatory authorities. Although the initial ban on the use of HES in Europe has been eased, proof regarding the benefits and safety profile of HES in trauma and surgical patient populations has been requested by these same European regulatory authorities.

VETERINARY DATA SYNTHESIS

The veterinary literature is limited mostly to experimental studies and clinical investigations with small populations of patients with short-term end points and there is insufficient evidence to generate recommendations.

CONCLUSIONS

Currently, there are no consensus recommendations regarding the use of HES in veterinary medicine. Veterinarians and institutions affected by the HES restrictions have had to critically reassess the risks and benefits related to HES usage based on the available information and sometimes adapt their procedures and policies based on their reassessment. Meanwhile, large, prospective, randomized veterinary studies evaluating HES use are needed to achieve relevant levels of evidence to enable formulation of specific veterinary guidelines.

Type III hypersensitivity reaction with immune complex deposition in 2 critically ill dogs administered human serum albumin

OBJECTIVE

To describe 2 cases of vasculitis that were attributed to a type III hypersensitivity reaction in critically ill dogs occurring 8-16 days postadministration of human serum albumin (HSA).

CASE OR SERIES SUMMARY

Skin biopsies were obtained from 3 different sites in 2 critically ill dogs that developed vasculitis 8-16 days following treatment with HSA. Histopathological findings from both dogs indicated epidermal pallor, widespread edema and hemorrhage, degenerative neutrophilic perivascular infiltrates, and multifocal areas of neutrophilic or leukocytoclastic vasculitis. Immunohistochemical staining using an anti-human serum albumin rabbit antibody suggested that the antigen-antibody complexes seen in the dermis were associated with the administration of HSA.

NEW OR UNIQUE INFORMATION PROVIDED

In this case series, we documented a leukocytoclastic vasculitis and probable antigen-antibody complexes to human albumin in the dermis of 2 critically ill dogs after administration of HSA. Previously, type III hypersensitivity reactions had only been reported in healthy dogs that had received HSA. This report also describes the potential use of immunohistochemical staining to detect the HSA antigen in tissue sections through the use of specifically labeled antibodies.

Severe burn injury, burn shock, and smoke inhalation injury in small animals. Part 2: diagnosis, therapy, complications, and prognosis

OBJECTIVE

To review the evaluation and treatment of patients suffering from severe burn injury (SBI), burn shock, and smoke inhalation injury. Potential complications and prognosis associated with SBI are also discussed.

DIAGNOSIS

Diagnosis of burn injury and burn shock is based on patient history and clinical presentation. Superficial burn wounds may not be readily apparent for the first 48 h whereas more severe wounds will be evident at presentation. Patients are diagnosed with local or SBI by estimating total body surface area involved using the 'Rule of Nines' or the Lund-Browder chart adapted from the human literature.

THERAPY

Patients suffering from SBI require immediate and aggressive fluid therapy. Burn wounds require prompt cooling to prevent progressive tissue damage. Due to significant pain associated with burn wounds and therapeutic procedures, multimodal analgesia is recommended. Daily wound management including hydrotherapy, topical medications, and early wound excision and grafting is necessary with SBI.

COMPLICATIONS

There are numerous complications associated with SBI. The most common complications include infections, hypothermia, intra-abdominal hypertension, and abdominal compartment syndrome.

PROGNOSIS

The prognosis of SBI in domestic animals is unknown. Based on information derived from human literature, patients with SBI and concomitant smoke inhalation likely have a worse prognosis than those with SBI or smoke inhalation alone.