November 2024

The Controversy Behind Using Colloids in Veterinary Medicine

By Dr. Justine Lee, DACVECC, DABT, Director of Medicine & Co-Founder of VETgirl

In this VETgirl online veterinary continuing education blog, Dr. Justine Lee, DACVECC, DABT, Director of Medicine & Co-Founder of VETgirl reviews whether you should be using colloids in veterinary medicine at all. With the black-box warning on the colloid, Hetastarch, in human medicine, the concern for acute kidney injury (AKI) exists. But how does that pertain to veterinary medicine, and most importantly, what’s the evidence?

As veterinary professionals, we use fluid therapy every single day. When it comes to treating fluid imbalances and dehydration (e.g., for interstitial rehydration), we typically reach for a balanced isotonic crystalloid such as lactated Ringers (LRS), Plasmalyte (Plyte), Normosol-R, or less commonly, 0.9% saline (“Less commonly” being a FUTURE blog!). However, crystalloids typically leave the intravascular space and move into the interstitial space shortly thereafter (e.g., estimated to be < 1 hour).

It is less common to reach for high-molecular-weight solutes carried in electrolyte and water solutions, such as colloids. There are both natural (e.g., plasma, whole blood, albumin) and synthetic colloids (e.g., hydroxyethyl starches such as hetastarch, pentastarch, tetrastarch, and dextrans). [Synthetic hydroxyethyl starches include common trade names such as Hespan (a hetastarch), Pentaspan (a pentastarch), or Vetstarch or Voluven (tetrastarches).] Colloids vary in molecular weight and can be useful in volume resuscitating the hypovolemic, hypoproteinemic, or septic patient. This is due to the high colloid osmotic pressure (COP), which helps maintain intravascular volume (due to their large size). However, the concern regarding synthetic colloids seems to be focused on their potential side effects, primarily acute kidney injury (AKI).

In 2013, the FDA added a black-boxed warning to Hetastarch due to increased mortality and severe renal injury in critically ill human patients in addition to increased risks of bleeding with use. The FDA recommended that the use of Hetastarch should be avoided in human patients with pre-existing renal dysfunction, those admitted to ICU, with sepsis, with coagulopathy, or those undergoing cardiopulmonary bypass. The FDA also recommended discontinuing the use of Hetastarch at the first sign of renal injury.

Since then, the use of these synthetic colloids has been the subject of controversy in veterinary medicine. Does the same concern exist for our patients? And what causes the potential for AKI from synthetic colloid administration?

Currently, the exact mechanism for colloid-induced kidney injury is unknown but is thought to be due to osmotic injury resulting from the large molecular weight solutes lingering inside the renal epithelial cells. Another hypothesis is that the chloride found in the starch’s carrier solution may play a role in renal injury by acting as a potent renal vasoconstrictor.

How does this apply in veterinary medicine? The author feels comfortable using synthetic colloids and has used them extensively in critically ill patients. However, based on current human literature and recommendations, the author avoids the use of synthetic colloids in veterinary patients with known kidney disease or potential for acute kidney injury (e.g., exposure to a nephrotoxicant, history of chronic kidney disease, etc.); likewise, the author uses them cautiously in septic patients. Keep in mind that the literature in veterinary medicine was originally done with hyperoncotic synthetic colloids (e.g., HES 10%), which were suggested to cause renal damage in dogs with and without sepsis. (1) In other studies, lower oncotic solutions (e.g., HES 6%) appear safe at standard doses for conditions including hemorrhage, intraoperative hypotension, trauma, and others.(2,3) Note, the use of different-sized synthetic colloids generally varies by country use, and the clinician must be aware of which type and size they are using when treating the critically ill patient.

When it comes to the use of synthetic colloids in veterinary medicine, individual patient assessment is crucial. Factors such as underlying renal disease, dehydration, and fluid overload should all be considered before administering synthetic colloids. Furthermore, monitoring renal function after the administration of synthetic colloids should be a top priority.

In conclusion, while the use of colloids – whether synthetic or natural – has been met with controversy, there is limited evidence in veterinary medicine regarding the increased risk of acute kidney injury. However, in this author’s opinion, I would avoid the use of synthetic colloids in any patient with acute or chronic kidney disease, any patient exposed to a nephrotoxicant, or in a patient that may be predisposed to multiorgan dysfunction syndrome (MODS) such as those with sepsis. Patient assessment and monitoring after colloid administration is crucial, due to the risk of coagulopathy (at doses > 20-40 ml/kg), volume overload, and renal injury. In some cases, alternative therapies such as crystalloids may be a better option. Ultimately, the decision to use synthetic colloids should be based on a thorough understanding of the patient’s condition
and the available treatment options.

References:
1. Hayes G, Benedicenti L, Mathews K. retrospective cohort study on the incidence of acute kidney injury and death following hydroxyethyl starch (HES 10% 250/0.5/5:1) administration in dogs (2007-2010). J Vet Emerg Crit Care 2016;26(1):35-40.
2. Yozova ID, Howard J, Adamik KN. Retrospective evaluation of the effects of administration of tetrastarch (hydroxyethyl starch 130/0.4) on plasma creatinine concentration in dogs (2010-2013): 201 dogs. J Vet Emerg Crit Care 2016;26(4):568-577.
3. Boyd Corrin J, Sharp CR, Claus MA. Prospective randomized controlled blinded clinical trial evaluating biomarkers of acute kidney injury following 6% hydroxyethyl starch 130/0.4 or Hartmann’s solution in in dogs. J Vet Emerg Crit Care 2021; https://doi.org/10.111/vec.13056.

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