Hydroxyethyl Starch (HES)
Hydroxyethyl Starch
Also known as: Hespan · Hextend · Voluven · Hetastarch · Tetrastarch · Pentastarch · Etherified starches
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Shock bolus (resuscitation) | 10-20 mL/kg | IV | once | — | 🌎 NA |
| Infusion | 1-2 mL/kg/hr; not to exceed 20 mL/kg in a 24 hour period | IV | CRI | 24 hours | 🌎 NA |
| Emergent situations / Colloid oncotic pressure support | 20 mL/kg /day | IV | slow bolus over 15-30 minutes OR 24-hour infusion | — | 🌎 NA |
| Shock resuscitation | 20 mL/kg | IV | bolus | — | 🌎 NA |
- Shock bolus (resuscitation): Rate determined by patient requirements.
- Emergent situations / Colloid oncotic pressure support: For supporting colloid oncotic pressure in hypoalbuminemic patients, give as a 24-hour infusion with low-rate crystalloids.
- Shock resuscitation: Standard dose. Patients may have elevations in PT and aPTT without evidence of bleeding.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Shock bolus (resuscitation) | 5-10 mL/kg | IV | once | — | 🌎 NA |
| Infusion | 1-2 mL/kg/hr; not to exceed 10 mL/kg in a 24 hour period | IV | CRI | 24 hours | 🌎 NA |
| Emergent situations / Colloid oncotic pressure support | 10/mL/kg/day | IV | slow bolus over 15-30 minutes OR 24-hour infusion | — | 🌎 NA |
| Shock resuscitation | 20 mL/kg | IV | bolus | — | 🌎 NA |
- Shock bolus (resuscitation): Administer slower than in dogs to avoid nausea/vomiting.
- Shock resuscitation: Slower in the cat. Rapid administration to cats can cause nausea and vomiting.
Small Mammals
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Camelids - Volume expansion | 15 mL/kg | IV | once | — | 🌎 NA |
- Camelids - Volume expansion: Significantly increased COP for up to 96 hours. Transient mild hemodilution and mild increases in PT/PTT noted.
Birds
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Volume replacement | 10-15 mL/kg over 20-40 minutes, up to four times daily, OR 10-15 mL/kg bolus over 20-40 minutes followed by 1-2 mL/kg/hr continuous rate infusion | IV | up to q6h or CRI | — | 🌎 NA |
| Small volume replacement/CPCR resuscitation | 3-5 mL/kg over 5 min | IV | once | — | 🌎 NA |
| Volume replacement | 3-5 mL/kg IV or IO over 10 minutes, one to two boluses | IV/IO | 1-2 boluses | — | 🌎 NA |
- Volume replacement: Recommended maximum dose is 20 mL/kg/24 hours, though author notes exceeding this without side effects.
- Small volume replacement/CPCR resuscitation: Given after hypertonic saline (3-5 mL/kg). Follow with crystalloids and repeat every 15-20 mins until stable.
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Adult horses - volume support | 8-10 mL/kg/day | IV | daily | — | 🌎 NA |
| Foals - rapid volume support | 3-5 mL/kg | IV | once | — | 🌎 NA |
| Hypo-oncotic, well hydrated horses | 0.5-1 mL/kg per hour, up to 10 mL/kg/day | IV | CRI | — | 🌎 NA |
| Volume replacement | 3-10 mL/kg | IV | once | — | 🌎 NA |
| Fluid resuscitation and management of hypoproteinemia | 8-10 mL/kg IV bolus or as a CRI at 0.5-1 mL/kg/hr (max. of 10 mL/kg/day) | IV | bolus or CRI | — | 🌎 NA |
- Foals - rapid volume support: In addition to crystalloids.
- Volume replacement: Total daily doses of 10 mL/kg should not be exceeded due to risk for coagulopathies.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Hydroxyethyl Starch (HES) is a synthetic colloid volume expander derived from a waxy starch composed primarily of amylopectin. It is used in veterinary critical care to treat hypovolemia and provide oncotic support.
Key Clinical Features:
- Intravascular Persistence: HES provides better and more prolonged intravascular volume expansion compared to crystalloid fluids.
- Capillary Leak Syndromes: It can help reduce vascular permeability and downregulate pro-inflammatory mediators in patients with systemic inflammation.
- Molecular Weight & Substitution: Products are classified by their mean molecular weight (MW) and degree of substitution (DS) (e.g., HES 450/0.7, HES 130/0.4). Higher MW and DS generally prolong intravascular half-life but increase the risk of coagulopathies.
Clinical Pearl: In recent years, the use of synthetic colloids like HES has declined in both human and veterinary medicine due to human studies linking HES to an increased risk of acute kidney injury (AKI) and mortality, particularly in septic patients. While veterinary data is less conclusive, many critical care specialists now use HES more conservatively.
Mechanism of action
HES acts as a synthetic colloid to expand plasma volume through oncotic forces.
- Oncotic Pull: Large HES molecules remain in the intravascular space → increase plasma oncotic pressure → draw fluid from the interstitial space into the blood vessels → expand circulating blood volume.
- Enzymatic Degradation: To prevent rapid breakdown, the glucose units of amylopectin are substituted with hydroxyethyl ether groups.
- Metabolism: Larger molecules are slowly degraded by serum alpha-amylase into smaller fragments → fragments < 50,000 Daltons are rapidly excreted by the kidneys.
Safety & warnings
Contraindications
- Severe heart failure
- Severe bleeding disorders
- Oliguric or anuric renal failure
Adverse effects
- Coagulopathies (prolonged PT/PTT, altered Factor VIII and von Willebrand Factor)
- Nausea and vomiting (especially in cats if administered too rapidly)
- Volume overload leading to pulmonary edema
- Hypersensitivity/anaphylactic reactions (rare)
- Falsely elevated serum amylase levels
- Transient increases in indirect serum bilirubin
- Potential risk for acute kidney injury (extrapolated from human data)
Precautions
Important Warnings & Precautions:
- Coagulation: HES can precipitate Factor VIII and interfere with von Willebrand Factor. Use with extreme caution in patients with pre-existing coagulopathies (e.g., von Willebrand's disease), thrombocytopenia, or those undergoing CNS surgery.
- Renal Risk: Human data suggests a risk of acute kidney injury (AKI), particularly in septic patients. Use cautiously in veterinary patients with pre-existing renal dysfunction or sepsis.
- Volume Overload: Can cause severe circulatory overload. Use with caution in patients with congestive heart failure (CHF), oliguric renal failure, or pulmonary edema.
- Capillary Leak: In severe sepsis, SIRS, or trauma, HES may extravasate into the pulmonary interstitium, potentially causing or worsening pulmonary edema.
- Administration in Cats: Rapid IV boluses in cats frequently cause nausea and vomiting; administer slowly (over 15-30 minutes).
- Not a Blood Substitute: HES has no oxygen-carrying capacity and does not replace the need for RBCs in anemic patients.
Drug interactions
Do not administer Hextend simultaneously with blood through the same administration set due to a risk of coagulation.
Monitoring
- Fluid status (blood pressure, heart rate, capillary refill time, central venous pressure)
- Coagulation parameters (PT, PTT, platelet count), especially in high-risk patients or with high doses
- Clinical signs of pulmonary edema (respiratory rate/effort, lung auscultation)
- Blood gases
- Renal function (BUN, creatinine, urine output)
Pharmacokinetics
Absorption
Immediate volume expansion following intravenous administration. Maximum volume expansion occurs within a few minutes of the completion of infusion.
Distribution
Remains primarily within the intravascular space to exert oncotic pressure. In patients with severe capillary leak, it may extravasate into interstitial spaces.
Metabolism
Larger molecules (>50,000 Daltons) are slowly degraded enzymatically by serum amylase to a size where they can be excreted.
Elimination
Lower molecular weight molecules (<50,000 Daltons) are rapidly excreted by the kidneys. About 40% of a dose is excreted in the first 24 hours. Practically all the drug is excreted after about 2 weeks.
Overdose
Overdosage primarily results in intravascular volume overload, which can lead to pulmonary edema and congestive heart failure in susceptible patients. Treatment involves stopping the infusion, carefully monitoring fluid status, and administering diuretics (e.g., furosemide) if pulmonary edema develops.
Available products
Formulations
- 6% HES (450/0.7) in 0.9% sodium chloride (Hespan)
- 6% HES (670/0.75) in lactated electrolyte (Hextend)
- 6% HES (130/0.4) in 0.9% sodium chloride (Voluven)
Human-labeled
- Hetastarch Injection: 6% (6 g/100 mL) HES (450/0.7) in 0.9% sodium chloride (Hespan)
- Hetastarch Injection: 6% (6 g/100 mL) HES (670/0.75) in lactated electrolyte (Hextend)
- Tetrastarch Injection: 6% (6 g/100 mL) HES (130/0.4) in 0.9% sodium chloride (Voluven)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store at temperatures less than 40°C (104°F); freezing should be avoided. Exposure to temperature extremes may result in the formation of a crystalline precipitate or a color change to a turbid deep brown. Do not use if this occurs.
Client information
Information for Pet Owners:
- Emergency ICU Use: Hydroxyethyl starch (HES) is an intravenous fluid used exclusively in a hospital setting, typically in the Intensive Care Unit (ICU).
- Why it is used: It is a "colloid" fluid, meaning it contains large molecules that stay in the blood vessels longer than standard IV fluids. It is used to rapidly treat shock, dangerously low blood pressure, or severe protein loss.
- Monitoring: Because it is a potent fluid, your pet will be closely monitored for signs of fluid overload (which can affect breathing) and changes in blood clotting.
- Cost: Colloid therapies and the intensive monitoring they require can add significantly to the cost of emergency care. Your veterinarian will discuss the specific reasons this therapy is necessary for your pet's stabilization.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.