Intraoperative hypothermia, typically defined as a core body temperature drop below 37 degrees C (98.6 degrees F) in dogs and cats, is well known to increase the risk of adverse outcomes in surgical patients. As a physician anesthesiologist, I understand that these adverse outcomes translate into considerably higher costs of hospitalization, more complications, longer operating room time, increased postoperative recovery time and more blood transfusions and surgical site infections. A meta‐analysis found that mild hypothermia as small 1.5 °C below normal body (human) temperature added $2,500 to $7,000 per surgical patient in medical hospital costs. Since health care insurance companies no longer pay for complications due to hypothermia, medical surgical personnel are very fastidious about maintaining normothermia throughout the perioperative period.

In veterinary medicine, the consequences of intraoperative hypothermia are similar. As improvement in intraoperative veterinary care evolves, pet insurance companies may follow suit and no longer pay for complications of intraoperative hypothermia and clients may be loath to reimburse the consequences of inadequate temperature management.

Implementing an effective warming system and patient warming protocols can yield economic savings, fewer complications, shorter OR room time, shorter postoperative recovery time, higher throughput, less staff time, and improved client outcomes. This blog will attempt to quantify those savings, discuss the drivers, and extrapolate to your veterinary practice.

Incidence of Intraoperative Hypothermia

Intraoperative hypothermia is the most common complication of general anesthesia, as several studies show below.

• A Cornell study showed that the incidence of intraoperative hypothermia in their studied dogs was 33 percent, and in cats was 70 percent
• A large study in Science Daily showed that the incidence of intraoperative hypothermia was 83.6 percent in their studied dogs and 96.7 percent in cats.

These studies show the problem of intraoperative hypothermia is significant and pervasive.

Clinical and Economic Drivers of Cost

Here are the key mechanisms by which intraoperative hypothermia increases cost and how they translate into veterinary settings:

1. Increased surgical site infection (SSI) and impaired wound healing
   Hypothermia impairs immune function (neutrophil activity, phagocytosis), causes vasoconstriction (reducing tissue oxygenation), increases blood viscosity, and slows enzymatic pathways which contributes to surgical site infections and poor wound healing. SSI‐related increased cost in veterinary soft tissue surgery has been reported in one study in PubMed Central (PMC) in dogs to be $500 without infection and $820 with a surgical site infection. A difference of $320.
2. Increased blood loss, transfusions, and coagulation issues
   Hypothermia leads to coagulopathy due to platelet dysfunction, increased bleeding and delayed clot formation. This increases surgery time and the potential for costly blood transfusions.
3. Prolonged anesthesia recovery, increased peri‐operative monitoring and ICU/Cage stay
   Hypothermic patients take longer to emerge from anesthesia due to decreased metabolism of anesthetic drugs by hepatic enzymes, have impaired drug/metabolite clearance, and consequently require extended monitoring or ICU/cage stays. Faster emergence translates directly into improved perioperative efficiency and increased revenue.
4. Extended hospitalization and ICU time
   Longer OR/ICU/hospital stays multiply fixed facility costs (beds, staff, monitoring, drugs). Longer stays increase staffing costs, client bills, and decrease case throughput.
5. Additional complications, reoperations, and downstream costs
   Hypothermic patients may require re‐operation or management of postoperative complications such as wound dehiscence and sepsis that add cost. Cardiac arrhythmias, most commonly bradycardia, can complicate the patient’s intraoperative and postoperative course.
6. Opportunity costs / lost efficiency
   In veterinary practice, OR time is a revenue‐generator. A patient who has intraoperative complications like platelet dysfunction and cardiac arrhythmias takes longer to recover and requires extra monitoring, which ties up staff and equipment, causing a reduction in case throughput and profitability. Clinical efficiency has a direct impact on clinic revenue.

Veterinary Facility Costs

The 2019 Well Managed Veterinary Practice Benchmarks Study, although 6 years behind today’s elevated practice costs, still provides us with excellent, although conservative, practice cost guidelines that can be used in our derivations. The benchmark costs are shown below

• Clinic overhead costs per DVM - $3 to $4 per minute ($180 to $240 per hour)
• Operating Room procedural costs:
  • Soft tissue surgery: $5 to $6 per minute ($300 to $360 per hour)
  • General surgery: $8 to $9 per minute ($480 to $540 per hour)
  • Orthopedic surgery: $9 to $10 per minute ($540 to $600 per hour)
  • Average OR procedure costs: $8 per minute ($480 per hour)
• Post-anesthesia recovery cost: $100 to $150 per hour (2025 - $150 to $200 per hour)
  • Average post-anesthesia recovery cost: $175 per hour (2025)

Maximize the Cost Savings from Your Warming System; Follow Strict Patient Warming Protocols

Patients don’t maintain normothermia without clinical intentionality. Patients must receive active warming preoperatively, during induction, preop prep, transfer to the OR, in the OR and postoperatively until awake. The following is a suggested patient warming protocol which if strictly followed will maximize the benefit of your patient warming system.

1. Preoperative Warming
   There is a temperature gradient of 3.6 to 7.2 degrees F between the Core and Peripheral (limbs, skin and tail) compartments of the patient. This gradient must be equalized before induction of anesthesia so that the warm blood of the Core compartment is not cooled in the Peripheral compartment.
   
   -Warm the patient preoperatively for a minimum of 30 minutes in a warmed cage.
   -Place a General Use – ConRad Thermal Blanket, PATIENT SIDE up on the floor of the cage to prevent conductive heat loss to the floor of the cage.
   -Use a cage door connector like the HoverHeat Cage Warming Combo to attach the hose of your warm air blower to the cage door and blow warm air into the cage chamber to provide preoperative warming for at least 30 minutes.
   
   
   HoverHeat Cage Warming Combo
   
   
2. Active warming during Anesthesia Induction and Preoperative Prep
   Upon induction of anesthesia there is immediate vasodilation of the vasculature in the Peripheral compartment of the body with shunting of warm Core blood to the colder Peripheral compartment. The patient becomes a heat radiator with 81 percent of heat loss that will ultimately transpire during the course of that anesthetic, occuring in the first 30 to 60 minutes after induction.
   
   -Start active warming immediately upon induction with the patient on an active warming pad like the HoverHeat and keep the patient covered with a thermal retention blanket such as the Conrad Thermal Blanket. If possible, place the patient on an active warming pad prior to anesthetic induction.
   -Keep the patient on an active warming pad during application of monitors and preoperative prep. Keep the patient covered with the ConRad Thermal Blanket as much as possible.
   
   
   
   HoverHeat Patient Warming
   
   
   
3. Minimize the delay between preoperative and intraoperative warming.
   For every minute of delay between preoperative and intraoperative warming, the likelihood of a drop in body temperature is increased by 5 percent.
   -Circumferentially wrap the patient with a General Use – Conrad Thermal Blanket to prevent heat loss for rapid transfer to the OR. Continue active warming in the OR.
   
   
4. Active intraoperative warming
   General anesthesia with its neurogenic effects on heat loss, decreases the patient’s metabolic rate which causes a loss of body heat production by 20 to 40 percent. The rate of body temperature decrease depends on the difference between the heat lost and the body heat produced. The surface area to mass ratio of the patient also has a significant effect on the amount of heat lost (example – Chihuahua vs St. Bernard).
   
   -Begin immediate active warming by placing the patient on an active warming pad like the HoverHeat and cover with the ConRad Thermal Blanket to prevent heat loss.
   -Place a General Use – Conrad Thermal Blanket between the OR table surface and the underside of the active warming HoverHeat to prevent conductive heat loss to the OR table.
   -Heat loss occurs through the patient’s foot pads. Place neonatal booties or socks, over the feet.
   
   
5. Active postoperative warming
   Maintain active warming until the patient emerges from anesthesia when normal thermoregulatory defenses (compensatory peripheral vasoconstriction, metabolic heat production) return to enable a return to normal core body temperature.
   
   -Place the patient on an active warming pad like the HoverHeat and cover the Patient with a ConRad Thermal Blanket to prevent heat loss.
   -If an active warming pad is unavailable, place the patient on a General Use – ConRad Thermal Blanket and cover the patient with another Conrad Thermal Blanket. This works quite well when used in a recovery cage. 

ConRad Thermal Blankets

Strict adherence a patient warming protocol is imperative to maximizing the economic benefit of your patient warming system. Measure the esophageal or rectal temperature of your patient so that you have a view of their core temperature. That which is not measured cannot be managed.

Estimating the Dollar Savings of an Effective Patient Warming System

Every veterinary facility’s cost data of intraoperative hypothermia will be different because every facility’s cost of doing business is unique. We can, however, build an estimate based on the available data. When data is available, the most conservative scenario will be utilized in this derivation.

1. Number of surgical cases per year
   Assumptions:  3 to 5 cases per day – 3 cases per day
   Cases per week – 3 cases X 5 days per week = 15 cases per week.
   Cases per year – 15 cases X 50 weeks per year = 450 cases per year
   
   
2. Incidence of Intraoperative Hypothermia
   Cornell Study – 33 to 70 percent – Average – 51.5 percent
   Science Daily – 83.6 to 96.7 percent – Average 90.2 percent
   
   
3. Economic costs based on cost drivers

1. 1. Increased Surgical Site Infections (SSIs) and impaired wound healing
      Pub MedCentral (PMC) study – increased cost of $320
      
      
   2. Increased Operating Room time
      Increased time due to increased bleeding, delayed clot formation, blood transfusions, and coagulation issues
      -Increased OR time – 30 minutes
      -Average cost of OR time - $8 per minute
      -Cost of increased OR time – 30 min X $8 per min. = $240
      
      
   3. Increased post-anesthesia recovery time
      A patient whose body temperature is 2 to 3 degrees F below normal body temperature can increase recovery time by 1.5 to 2 hours.
      Conservatively, we will use 1 hour of increased time at $175 per hour
      Cost of increased post-anesthesia recovery time - $175
      
      
   4. Extended hospitalization
      Hypothermia can increase hospital stays with the fixed costs of staffing, monitoring, lower case throughput etc.
      Extended hospital stay - $200
      
      Total cost of one case of Intraoperative Hypothermia – data used from above $320 + $240 + $175 + $200 = $935 per hypothermic case
      
      These costs do not account for decreased clinical efficiency and lost opportunity costs.
      
      
   5. Yearly cost of intraoperative hypothermia –
      The Cornell study indicated intraoperative hypothermia in an average of 51.5 percent of their cases, and the analysis in Science Daily indicated intraoperative hypothermia in an average of 90.2 percent of their cases. For our derivation, we will use a round number of 50 percent of yearly cases experiencing hypothermia.
      
      Annual cases of intraoperative hypothermia – 450 per year X .50 = 225 cases
      Annual cost of intraoperative hypothermia per year –
      225 cases X $935 per case =   $210,375
      
      
   6. Cost of a patient warming system per year
      The cost obviously depends on what you get. For our derivation let us estimate the cost of one of the most common patient warming system used; the forced air warming system. A common forced air warming system includes a warm air blower and associated disposable warming blankets.
      Average warm air blower cost - $2000
      Average disposable blanket cost - $14
      Yearly disposable blanket cost is – 450 cases X $14 = $6300 per year
      
      Cost of warming system per year - $2000 + $6300 = $8300 per year
      (if the warm air blower is amortized over 5 years, the blower cost is $400 per year, bringing the annual cost to $6700 per year)
      
      
   7. Cost of intraoperative hypothermia after patient warming system intervention
      Realistically, no patient warming system provides normothermia in 100 percent of cases. For our derivation let’s say that the introduction of a patient warming system decreases the incidence of intraoperative hypothermia to 15 percent from the previous 50 percent without a warming system.
      15 percent of 450 cases - .15 X 450 = 68 cases of intraoperative hypothermia
      
      Cost per case of intraoperative hypothermia - $935
      
      Cost of intraoperative hypothermia – 68 cases X $935 = $63,580
      
      
   8. Gross savings with the introduction of the patient warming system
      Cost of intraoperative hypothermia before introduction of patient warming system (from above) - $210,375
      Cost of intraoperative hypothermia after introduction of patient warming system (from above) - $63,580
      
      Gross savings with introduction of patient warming system
      $210,375 minus $63,580 = $146,795
      
      
   9. Net savings with introduction of patient warming system
      Gross savings - $146,795
      Annual cost of patient warming system - $8,300
      Net savings with introduction of patient warming system
      
      $146,795 minus $8,300 = $138,495
      
      
   10. Return On Investment (ROI) for a patient warming system
       Savings per month - $138,495 / 12 = $11,541.25
       Savings per week - $11,541.25 / 4 = $2,885.31

Return On Investment (ROI) – less than 3 weeks

Further Savings from Reusable Patient Warming Systems

Further savings come from lowering operating costs. A 2023 analysis found that veterinary facilities could save 66 percent on patient warming by switching from forced air warming systems using disposable blankets to a reusable active warming system. An innovative example is the HoverHeat Patient Warming System. The HoverHeat   utilizes any warm air blower that a veterinary facility may already have to provide true underbody warming. The HoverHeat will increase the warming capacity of any warm air blower by 50 to 75 percent due to its ability to warm an increased surface area, the entire underside of the patient. No disposables are necessary.

Reusable warming systems reduce overhead costs by eliminating the need to constantly purchase and manage inventory of disposable supplies. This reduces supply costs, inventory management time and labor costs.

Utilizing reusable thermal retention blankets, like the ConRad Thermal Blankets, with your reusable system can further augment patient warming. The utilization of reusable  ConRad Thermal Blankets have been shown to significantly decrease costs of patient warming as well as laundry costs.

Putting Numbers into Practice for Your Veterinary Facility

Let’s get personal. That which is not measured cannot be managed. To determine the cost of intraoperative hypothermia in your facility, insert your numbers into the derivation I used. I will outline it for you below.

• Number of surgical cases per year
• Current incidence of intraoperative hypothermia
• Your costs based on cost drivers
  • Cost of surgical site infections and impaired wound healing
  • Cost of increased operating room time
  • Cost of increased post-anesthesia recovery time
  • Cost of extended hospitalization
• Yearly cost of intraoperative hypothermia
• Cost of a patient warming system
• Cost of intraoperative hypothermia with a patient warming system
• Gross savings
• Net savings
• Return on investment (ROI)

Conclusion

An effective patient warming system in veterinary surgery is more than a comfort measure. It is a powerful business investment. Drawing on veterinary practice insights and economic data, it is clear that:

• Hypothermia in the perioperative period increases recovery time, complications, monitoring, staff cost and risk.
• Warming systems reduce incidence of hypothermia, speed recovery, reduce complications and thereby produce real dollar savings.
• In realistic veterinary practice models, net savings can range from tens to hundreds of thousands of dollars annually, depending on case mix, incidence reduction and cost per case.
• The cost of warming equipment is minimal compared to the cost of complications and lost efficiency.
• Beyond direct savings, effective patient warming improved case throughput, client satisfaction, lower risk, and enhanced standard of care.

For veterinary surgical practices aiming to optimize efficiency, control costs and improve outcomes, implementing a dedicated warming system and patient warming protocol should be a high-priority strategic investment.

References

1. Fiedler MA. “Maintaining intraoperative normothermia: a meta-analysis of outcomes with costs.” AANA Journal. 1999;67(4):‡. PubMed
2. Mahoney C.B., Odom J. “The Economics of Patient Warming.” Outpatient Surgery Magazine. Oct 2007. Aorn.org
3. Smith A. “Patient Warming’s Preventative Benefits.” Outpatient Surgery Magazine. May 2021. Aorn.org
4. Zhang et al. “Value of active warming devices for intraoperative hypothermia prevention – a meta-analysis and cost-benefit analysis.” Int J Environ Res Public Health. 2021;18(21):11360. PubMed
5. BMC Surgery. “Strategies for perioperative hypothermia management: advances in warming techniques and clinical implications.” 2024. BioMed Central
6. “Warm up to ways of preventing hypothermia.” Veterinary Practice News. (Veterinary context) Veterinary Practice News
7. Cornell University College of Veterinary Medicine. “Investigation of perioperative inadvertent hypothermia in cats and dogs and effect of implementing a thermal care bundle.” (Research project) vet.cornell.edu
8. “Intraoperative Hypothermia and Effective Temperature Management to Improve Patient Outcomes.” Medline White Paper.
9. Mahoney C.B., Odom J. Maintaining intraoperative normothermia: a meta-analysis of outcomes with costs. AANA Journal. 1999;67(2):155-164. PubMed
10. Value of Active Warming Devices for Intraoperative Hypothermia Prevention — A Meta-Analysis and Cost-Benefit Analysis. Int J Environ Res Public Health. 2021;18(21):11360. MDPI
11. “Warm up to ways of preventing hypothermia” Veterinary Practice News. Veterinary Practice News
12. “Hypothermia in the Veterinary Operating Room” Today’s Veterinary Practice. Today's Veterinary Practice
13. Incidence of perioperative hypothermia in a high-quality high-volume spay/neuter setting. Rodriguez‐Diaz J, Hayes G, et al. 2023. abvp.com
14. Incidence of surgical site infection in dogs undergoing soft tissue surgery: risk factors and economic impact. PMC. PMC
15. Other cost/economic references (Outpatient Surgery Magazine “The Economics of Patient Warming”)