Albumin, Human

Overview

Human albumin (HSA) and canine albumin (CSA) are natural plasma protein colloids used in veterinary medicine to increase intravascular oncotic pressure, improve organ perfusion, and reduce edema in critically ill patients. Albumin therapy is primarily considered in dogs and cats with clinically significant hypoalbuminemia, especially when associated with systemic inflammation, sepsis, increased vascular permeability, or ongoing protein losses.

Albumin contributes approximately 75–80% of normal plasma oncotic pressure. When administered intravenously, it promotes movement of fluid from the interstitial space back into the intravascular compartment, helping to restore circulating volume and support blood pressure. In addition to its oncotic effects, albumin plays an important physiologic role in maintaining endothelial integrity, wound healing, antioxidant activity, and transport of endogenous and exogenous substances.

Human albumin is most commonly used in small animal practice due to availability; however, its use in dogs and cats represents administration of a xeno-albumin product and carries a risk of immune-mediated reactions. Canine-specific albumin products are commercially available in the United States and may offer a safer alternative in dogs, although published safety and outcome data remain limited.

Because of the potential for serious adverse effects and uncertain impact on survival outcomes, albumin administration should be reserved for carefully selected, critically ill patients with reversible disease processes and used only with intensive monitoring in a hospital setting.

Indications

Human albumin (HSA) and canine albumin (CSA) are used as colloid fluid therapies in critically ill dogs and cats when hypoalbuminemia contributes significantly to clinical disease. Albumin therapy is not intended for routine volume expansion and should be reserved for selected cases in which potential benefits outweigh known risks.

• Severe hypoalbuminemia: Considered in dogs (and less commonly cats) with marked hypoalbuminemia, typically < 2.0 g/dL, and especially < 1.5 g/dL when associated with clinical signs such as edema, effusions, or hypotension.
• Critically ill patients with reversible disease: Used in patients with potentially reversible conditions such as sepsis, septic peritonitis, systemic inflammatory response syndrome (SIRS), or acute inflammatory states where albumin loss or redistribution is significant.
• Low colloid oncotic pressure (COP): Indicated when COP is markedly reduced (eg, < 14 mm Hg) and contributing to edema, third spacing, or hypotension despite appropriate crystalloid therapy.
• Refractory hypotension: 25% human albumin has been used in dogs with hypotension unresponsive to crystalloids and other supportive measures, including cases such as gastric dilatation–volvulus or septic shock.
• Protein-losing conditions: May be considered in dogs with protein-losing enteropathy or protein-losing nephropathy when severe hypoalbuminemia results in edema, effusions, or impaired wound healing.
• Septic peritonitis and surgical disease (dogs): Albumin may be considered as adjunctive therapy due to its role in maintaining oncotic pressure and supporting wound healing, though benefits on outcome remain uncertain.
• Marked edema or effusions: Used when severe interstitial or body cavity fluid accumulation is attributable to hypoalbuminemia and is clinically compromising.
• Preference for species-specific products: In dogs, CSA is generally preferred over HSA when available, due to a lower risk of immune-mediated reactions.

Albumin therapy should not be used routinely for mild hypoalbuminemia, simple hypovolemia, or as a substitute for appropriate crystalloid or blood product therapy.

Dosage (Reference)

Dog

Albumin therapy in dogs is considered an advanced supportive treatment and should only be administered in hospitalized, critically ill patients with close monitoring. Human albumin is used extra-label, while canine albumin is preferred when available due to a lower risk of immune-mediated reactions.

Using Human Albumin (Extra-label)

• Test dose (recommended):
  0.25 mL/kg/hour IV for 15 minutes while monitoring temperature, heart rate, and respiratory rate.
  Discontinue immediately if facial swelling, vomiting, or other signs of hypersensitivity occur.
• Continuous rate infusion (CRI):
  0.1 – 1.7 mL/kg/hour (≈0.025 – 0.425 g/kg) IV over 4–72 hours, adjusted to reach low-normal albumin levels.
• Refractory hypotension:
  Slow IV bolus up to 4 mL/kg (1 g/kg).
  Average reported dose ≈2 mL/kg (0.5 g/kg).
• Maximum reported total dose:
  Up to 25 mL/kg (6.25 g/kg) over 72 hours, though most patients receive much lower volumes.

Albumin Deficit Calculation (Optional Method)

Albumin deficit (g) = 10 × (desired albumin – patient albumin) × body weight (kg) × 0.3
The calculated dose is diluted to a 10% solution with 0.9% saline and administered over 6–12 hours using a transfusion filter.

Using Canine Albumin

• Hypovolemic shock:
  Using a 16% solution, administer 1 mL/minute IV up to a total of 2.5 – 5 g/kg
  (≈15.6 – 31.2 mL/kg).
• Hypoalbuminemia:
  Using a 5% solution, administer up to 2 g/kg/day IV based on clinical condition.

Cat

Albumin use in cats is limited due to higher risk of adverse reactions, particularly with human albumin. Only 5% human albumin solutions have been described, and use should be reserved for severe, life-threatening hypoalbuminemia with intensive monitoring.

• 5% human albumin only (NOT 25%):
  2 mL/kg/hour IV over 5–10 hours.
• Maximum daily dose:
  10 – 20 mL/kg/day IV.
• Repeat dosing:
  May be repeated on subsequent days if serum albumin remains < 2 g/dL.

In reported studies, cats showed clinical improvement, and approximately 50% achieved serum albumin concentrations > 2 g/dL following treatment.

Warnings & Precautions

Albumin administration is associated with significant risks and should be reserved for carefully selected patients. Its use requires intensive monitoring and should only be performed in an inpatient or critical care setting by experienced veterinary professionals.

• Hypersensitivity reactions: Albumin products are contraindicated in patients with a known history of hypersensitivity to human or canine albumin. Both immediate (type I) and delayed (type III, serum sickness) immune-mediated reactions have been reported, particularly with xeno-albumin products.
• Xeno-albumin use (human albumin in animals): Administration of albumin derived from another species carries a substantial risk of immunogenicity. Repeat administration of human albumin in dogs or cats is relatively contraindicated due to antibody formation and increased risk of severe delayed reactions.
• Patient selection: Albumin should not be used in otherwise healthy animals that are only volume depleted. It should be reserved for critically ill patients with life-threatening hypoalbuminemia or severe oncotic deficits when safer alternatives are inadequate.
• Volume overload: Hyperoncotic albumin solutions can rapidly expand intravascular volume. Use extreme caution in patients with pre-existing volume overload, cardiac disease, pulmonary edema, or compromised oxygenation. Monitor for tachypnea, increased respiratory effort, and signs of fluid overload.
• Anemia and dehydration: Dogs with severe anemia or extreme dehydration should not receive albumin unless appropriate red blood cell products or crystalloid fluid resuscitation are provided first.
• Infusion reactions: A test dose is strongly recommended when administering human albumin. Infusion should be discontinued immediately if facial swelling, urticaria, vomiting, hyperthermia, hypotension, or shock develops.
• Repeat administration: Repeat dosing of human albumin is discouraged due to antigenicity. In reported studies, dogs were not eligible for repeat administration within 7 days of initial exposure.
• Infectious risk: Although rare, transmission of infectious agents from albumin products is theoretically possible. Strict aseptic technique must be used during preparation and administration.
• Species considerations: Limited safety and efficacy data are available for cats, particularly with human albumin. Use in cats should be approached with heightened caution and lower concentrations (5%) only.
• Monitoring requirements: Continuous monitoring of vital signs (temperature, heart rate, respiratory rate, blood pressure) is required during infusion, with continued observation for delayed adverse reactions for days to weeks after administration.

Drug Interactions

Clinically significant drug interactions with albumin products are uncommon. However, because albumin is a major plasma protein responsible for drug binding and transport, theoretical interactions should be considered in critically ill patients receiving multiple medications.

• Highly protein-bound drugs: Exogenous albumin administration may transiently alter the free (unbound) fraction of drugs that are highly protein bound (e.g., phenytoin, warfarin, NSAIDs, some sedatives). In most cases, this effect is not clinically significant, but close monitoring is advised in unstable patients.
• Vasoactive medications: Rapid increases in intravascular oncotic pressure may influence hemodynamic responses to vasopressors or inotropes. Blood pressure should be closely monitored when albumin is used concurrently with these agents.
• Diuretics: Albumin may enhance the effectiveness of loop diuretics in hypoalbuminemic patients by improving intravascular volume and drug delivery to the kidneys. Monitor hydration status and electrolyte balance.
• Calcium-containing products: Exogenous albumin administration may transiently reduce measured serum calcium concentrations due to protein binding. Interpret calcium results cautiously when administering calcium supplements concurrently.
• Blood products and crystalloids: Human serum albumin may be administered in conjunction with whole blood, plasma, packed red blood cells, saline, glucose, or balanced electrolyte solutions. Compatibility should follow manufacturer recommendations.
• Protein or amino acid solutions: Do not mix albumin with protein hydrolysates, amino acid solutions, or alcohol-containing solutions due to incompatibility.

Side Effects & Overdose

Side Effects

Adverse effects associated with albumin administration vary widely depending on the product used (human vs canine albumin), the species receiving it, dose, infusion rate, and the patient’s underlying disease and immune status. Reactions are more commonly reported with xeno-albumin products (e.g., human albumin in dogs or cats).

• Immediate hypersensitivity reactions (Type I): Facial edema, urticaria, vomiting, hyperthermia, tachycardia, hypotension, shock, or anaphylaxis may occur during or shortly after infusion. These reactions can be life-threatening and require immediate discontinuation of the infusion.
• Delayed hypersensitivity reactions (Type III – serum sickness): May develop days to weeks after administration and include lethargy, fever, lameness, peripheral edema, vasculitis, cutaneous lesions, vomiting, inappetence, renal failure, and coagulopathies. Deaths have been reported in dogs receiving human albumin.
• Gastrointestinal signs: Vomiting and diarrhea have been commonly reported, particularly in retrospective studies of critically ill dogs and cats.
• Hyperthermia and tremors: Transient increases in body temperature and muscle tremors have been observed in both dogs and cats following infusion.
• Volume overload: Tachypnea, pulmonary edema, increased central venous pressure, or worsening respiratory effort may occur, especially with rapid infusion or in patients with cardiac disease.
• Injection or catheter site reactions: Perivascular inflammation and phlebitis have been reported at IV catheter sites following albumin administration.
• Electrolyte changes: Transient decreases in measured serum calcium concentrations may occur due to protein binding.
• Canine serum albumin (CSA): Reported adverse effects appear to be less frequent and less severe than with human albumin, but safety data remain limited.

Overdose

Acute toxicity from albumin overdose is uncommon; however, excessive dosing or overly rapid administration can result in clinically significant complications related to hyperproteinemia and intravascular volume expansion.

• Hyperalbuminemia / hyperproteinemia: Excessive increases in serum albumin may increase blood viscosity and impair microcirculatory flow.
• Volume overload: Pulmonary edema, respiratory distress, hypertension, or worsening congestive heart failure may occur, particularly in patients with limited cardiovascular reserve.
• Management: There is no specific antidote. Treatment is supportive and includes stopping the infusion, providing oxygen, managing fluid balance, and treating hypersensitivity reactions as indicated.
• Target concentrations: During therapy, serum albumin concentrations are generally maintained at or below 2.0–2.5 g/dL to minimize the risk of adverse effects.
• Monitoring: Frequent assessment of vital signs, respiratory status, serum albumin, total protein, and colloid osmotic pressure is essential during and after administration.

Key Notes

Practical clinical pearls to guide the safe and judicious use of human and canine albumin products in small animal critical care, without repeating previously discussed warnings or adverse effects.

• Indication-driven therapy: Albumin should be reserved for clearly defined, high-risk clinical scenarios (e.g., life-threatening hypoalbuminemia with clinical consequences) rather than used as routine volume support.
• Species specificity matters: Canine serum albumin is biologically more appropriate for dogs than human albumin, but outcome data remain limited and availability may be restricted.
• Infusion strategy: Slow, controlled infusions reduce complications and allow early detection of intolerance; rapid administration is rarely justified outside of refractory hypotension.
• One-time consideration: Xeno-albumin is generally considered a single-use therapy due to antigenicity; repeat administration markedly increases immunologic risk.
• Not a volume substitute: Albumin does not replace appropriate crystalloid or blood product therapy and should be integrated into a comprehensive fluid and perfusion plan.
• Effect beyond COP: Potential benefits may extend beyond oncotic pressure support, including endothelial stabilization and improved microvascular function, but these effects are not fully characterized in xeno-albumin use.
• Case-by-case decision: Use requires individualized risk–benefit assessment, particularly in dogs versus cats, and should not follow rigid protocols.
• Client consent: Clear discussion with owners regarding uncertainty of outcome, cost, and monitoring intensity is essential before administration.