The rise of the pet industry has brought both opportunities and challenges to society, including the rapid growth of veterinary medicine. Dogs and cats are the most common pets, and when they suffer from certain diseases—particularly young and elderly animals—fluid therapy with observation is often the primary treatment. Neonates and senior animals naturally produce less body heat, and when compounded by illness, the infusion of cold fluids may cause cold stress and lead to adverse reactions [1]. Therefore, warming intravenous fluids for pets to near body temperature can improve drug efficacy.

I. Fluid Therapy and Hypothermia

Intravenous fluid therapy is a common clinical treatment for pets. It helps regulate water, electrolyte, and acid-base balance, replenishes circulating blood volume, maintains blood pressure, neutralizes toxins, and provides nutrients and medications.

Perioperative hypothermia is a common temperature dysregulation during clinical fluid therapy in pets. For example, the normal body temperature of dogs is generally around 38°C. During anesthesia, a body temperature below 36.0°C is considered hypothermic, with an incidence rate of 60%–80% [2].

In certain special circumstances, hypothermia can be beneficial (e.g., organ protection during hypothermic perfusion). However, it is most often detrimental. When excessively cold fluids are administered, local vasospasm can occur, causing drugs to adhere to the vessel walls. This irritates endothelial cells, triggering the release of inflammatory factors, damaging the vascular intima, increasing vascular permeability, and potentially leading to phlebitis [3].

Fluids in the administration set can also cool over time. Therefore, temperature control of the fluid within the IV line is just as important as warming the fluid in the bag or syringe.

Furthermore, patients with a larger body surface area lose heat more readily. As oxygen consumption increases, hypoxia can ensue. Necessary measures should be taken to mitigate the effects of increased heat loss [4]. Consequently, unwarmed fluids should not be administered to sick animals.

II. Thermal Protection for Pets

A 1990 report indicated that infusion reactions are more likely to occur if the infusion rate and fluid temperature are inappropriate, or if there is an excessive difference between fluid temperature and body temperature [5]. International literature also recommends warming fluids to near body temperature (approximately 37-39°C) prior to administration, especially for puppies and kittens whose tissues, organs, and thermoregulatory functions are not fully developed, making them highly susceptible to cold stress [6].

In human medicine, massive blood transfusion and fluid infusion can easily lead to intraoperative hypothermia and delayed emergence. Infusing fluids warmed to near body temperature can effectively reduce complications such as cold extremities and shivering in patients [7]. Similarly, warming devices are necessary in veterinary practice, particularly during the mid-to-late stages of disease, the postoperative recovery period, or in cold environments like winter when room temperature is low. When an animal's heat production is insufficient or it is in a weakened state, fluids should be warmed to 35–39°C [8].

Benefits of Fluid Warming

Warmed fluid therapy can effectively prevent perioperative hypothermia, maintain normal body temperature, improve tissue microcirculation, and reduce lactic acid accumulation. It also helps reduce vasospasm, maintaining relative vasodilation, stabilizing blood viscosity, and ensuring consistent blood flow velocity [9].

Furthermore, the use of fluid warming ensures effective perfusion pressure to various tissues and organs and facilitates the oxidative utilization of glucose, which is crucial for reducing anaerobic metabolism [10].

III. Conclusion

Determining the correct fluid therapy approach for animals is essential. The decision to warm fluids should be based on the individual patient's condition to prevent hypothermia during surgery or treatment. When combined with appropriate medications for the underlying disease, warmed fluid therapy can contribute to a faster and more effective recovery.

References:

【1】Yu Haibo, et al. Ten Points for Attention in Pet Intravenous Infusion [J]. China Working Dog Industry, 2013(5): 009.

【2】Zhang Guoshi, et al. Perioperative Hypothermia in Dogs and Its Prevention [J]. Chinese Journal of Veterinary Medicine, 2009, 45(8): 63-64.

【3】Zhang Xiaoying. Causes and Prevention of Clinical Infusion Phlebitis [J]. World Latest Medical Information Abstracts, 2013(13): 448-449.

【4】Wang Ao, et al. Anesthesia and Monitoring in Elderly Dogs [J]. China Animal Health, 2016, 18(4): 61-62.

【5】Li Qingfei. Occurrence and Prevention of Transfusion Reactions in Veterinary Clinical Practice [J]. Qinghai Journal of Animal and Veterinary Sciences, 1990(2): 009.

【6】JUSTINE A LEE, et al. Fluid Therapy for Pediatric Patients [J]. Veterinary Clinics of North America: Small Animal Practice, 2017, 47(2): 373-382.

【7】Xie Rong. Modern Anesthesiology [M]. Beijing: Science Press, 1999: 804.

【8】Hu Chouzi. Key Considerations in Veterinary Clinical Infusion Therapy [J]. Breeding Technical Advisor, 2010(9): 101.

【9】Zhang Shanni, et al. Application of Warmed Infusion in Patients Undergoing Laparoscopic Radical Surgery for Ovarian Cancer [J]. China Modern Medicine, 2020, 27(35): 61-63/68.

【10】Wu Yan. Experience with the Use of Infusion Warmers in Surgery [J]. Electronic Journal of Practical Clinical Nursing Science, 2018, 3(11): 166-169.

*Disclaimer: The copyright of the referenced content belongs to the original authors. Images are sourced from the internet. This article is intended for educational purposes only and has no commercial use. If there are any issues regarding text or image copyrights, please contact us for resolution. Thank you!