Thermoregulation Solutions

DSI has developed robust continuous monitoring solutions for data acquisition and analysis in chronic temperature studies. Available industry standard wireless systems range from small to large animal species with fully implantable telemetry.

Thermoregulation is a broad area of research that focuses primarily on the organism's behavioral and autonomic responses to regulate temperature. Understanding this mechanism is important as it not only impacts core, subcutaneous and skin temperatures but also heart rate, blood pressure, neurological function, metabolism, immune response, and behavior as the body generates and dissipates heat. 

In order to understand if a drug or therapy impacts the animal’s ability to regulate temperature, it is important to understand its thermal regulatory characteristics including its thermoneutral zone.  The thermoneutral zone is defined as the range of ambient temperatures where core temperature is controlled without significant changes in metabolic heat production.  Ambient temperature, age, species and gender all play a role in affecting the animal’s thermoneutral zone.

Animal Model Considerations

Existing regulatory guidelines may mislead researchers to use environmental ambient temperatures that are detrimental for their specific animal model.  With the rise in transgenic models and variability with age, gender and weight, researchers may find the recommended range too broad or even inappropriate. Understanding the animal model’s thermoregulation is a critical first step to ensure the accuracy of data collection.

Recognize the Signs

Unlike humans, animal test subjects cannot directly say if it’s too hot or too cold, but they do exhibit certain characteristics that indicate their comfort level.  As humans, we are aware of our body’s ability to regulate temperature. We modify our external behavior to stay in the thermoneutral zone all the time by adding or shedding layers of clothing and turning the heat up in our homes.  However, the human body is also making autonomic adjustments that may not be noticeable such as a change in heart rate, blood flow to the skin, core temperature (fever) and shivering/sweating.  Animals also make these adjustments which are indicators to their ability to regulate heat. 

Study Impact of Thermoregulation

Understanding the basics of thermoregulation can help appropriately identify the difference between sick animals (by design or not) and animals outside their thermoneutral zone.  Misinterpreting data is an easy mistake if the animal is unknowingly already in a stressed state to begin with.  A translational research study found that certain cancer research is not comparable to humans when an animal model is used that is experiencing mild cold stress (still within the regulatory care guidelines). 

Monitoring core body temperature continuously with implantable telemetry is clearly the gold standard of thermoregulatory measurements. However it isn't the only parameter that should be considered.  There are many other physiologic parameters that can assist researchers in understanding the health of  an animal's thermoregulatory system and a few of them have been listed below.

Thermoregulation Indicators and Parameters


Core Body Temperature

This can be measured via telemetry by implanting a temperature telemetry device in the intraperitoneal space.  Rectal probes have been used for this measurement in the past and are best used in acute monitoring of anesthetized animals.  Core temperature may be averaged over time in most cases, but before averaging, ensure you understand the particular animal's circadian rhythm whether it be daily, weekly, or monthly so you can accurately subtract the normal rhythm to detect a true fever.


Subcutaneous Temperature

Infrared cameras can capture skin temperature gradients in some cases.  Fur from the animal may impede the measurement.  Peripheral temperature measurements can also be taken by placing a temperature telemetry device subcutaneously or via a hardwired thermistor probe in anesthetized models.


Local Temperatures

In some animal models, specific localized temperatures may be recorded such as Brown Adipose Tissue (BAT), brain, tail, or other specific organ temperatures.  A thermistor at the end of a temperature probe may be required to enable this measurement.  DSI offers telemetry products which have external thermistor probes for use in small animals.  These are commonly used in neonatal, target organ and metabolic studies looking at quick temperature changes.


Heart Rate

Heart rate can be measured to help understand an animal’s cardiac response to their environment.  Changes in heart rate may indicate an animal’s thermoregulatory behaviors.  Heart rate can be derived from an ECG or systemic blood pressure signal.  DSI can accommodate these measurements in the conscious animal model via implantable telemetry, external telemetry, minimally invasive telemetry or acutely in an anesthetized model with hardwired electrodes and pressure catheters.


Physical Motor Activity

Animals exhibit certain behaviors when they are hot or cold in the same way that human beings do.  They may burrow, groom, group together, shiver, sweat, and increase or decrease general activity.  This can be observed manually by visual observation, but a camera can also be integrated into your software system via video.  For nocturnal rodents or for animals that are easily excitable, manual observation may be impossible, so a camera solution may be worth investigating. 


Environmental Considerations


Consistent Environment

Monitoring and recording ambient temperature, pressure and humidity is important for thermoregulatory research.  Each degree of variation can change heart rate by 15-20 BPM in mice.  Humidity can also play a large factor in an animal's ability to regulate heat.


Appropriate Calibrations

DSI’s implantable telemetry is typically calibrated over the normal core body temperatures of 33-41 degrees Celsius. If you are challenging an animal's ability to regulate temperature in a hypothermia or related study, several things must be considered including the calibration of the device you are using.  Pressure is also temperature dependent and is calibrated at body temperature.  If you want to use pressure in a temperature challenge environment ensure you understand the limitations before purchasing. DSI would be happy to answer your questions if you'd like more information on the limitations of products or if you'd like to request custom calibrations.


All measurement equipment needs to be regularly calibrated to be sure it doesn't drift over time.  Check the accuracy, precision and resolution of your equipment before designing the study to see what changes you can realistically measure.  To calibrate equipment yourself you should have a standard reference thermometer that is at least 10 times more sensitive as the signal you are calibrating.  Take the time to understand how often your equipment needs to be calibrated and keep a schedule to ensure the best results.

Implantable Telemetry Systems

Temperature is included in almost every DSI telemetry platform. Listed below are all the DSI implantable telemetry options for continuous monitoring.


Mouse and Small Animal Platforms

All rodent platforms operate on the same hardware system.

System Components
PhysioTel HD Small Animal Telemetry Setup 

Hybrid Digital (HD) Small Animal Platform

This platform is the future of DSI small animal devices.  It has easy to use features such as: 

  • Better battery life monitoring
  • Automatic entry of calibration values
  • Digital serial number trace ability 

Choose your temperature and activity implant:


Implant

Minimum Animal
Weight

Pressure

Biopotential
(ECG, EEG, EMG, etc)

Warrantied Battery Life

HD-S21

>175g

2 Channels

1 Channel

2 months

HD-S11

>175g

1 Channel

1 Channel

2 months

HD-X11

>19g

1 Channel

1 Channel

1 month


PhysioTel Small Animal Platform

These products have such wide use in the field of research they set the standard for implantable telemetry as it is known today.  DSI is the industry leader in miniaturized implantable telemetry devices and is known for product reliability with over 1000+ peer reviewed publications using this technology. These products will always work with DSI software, but for customers who prefer a different platform some have been integrated into other programs.  Contact DSI if you have other software you'd like to integrate with these products.


Choose your temperature and activity implant:


Implant

Minimum Animal Weight

Pressure

Biopotential

(ECG, EEG, EMG, etc)

Warrantied Battery Life

TA-F40

>175g

12 Months

TA-F50*

>175g

3.5 Months*

F40-TT**

>175g

4 Months

C50-PT

>175g

1 Channel

2 Months

CTA-F40

>175g

1 Channel

6 Months

F40-EET

>175g

2 Channels

3 Months

4ET^

>200g

4 Channels

3 Months^

TA-F10

>17g

6 Months

ETA-F10

>17g

1 Channel

2 Months

ETA-F20

>20g

1 Channel

4 Months

F20-EET

>20g

2 Channels

6 Weeks

^has a replaceable battery and comes in two frequencies for pair housing

*transmits the signal further to accommodate a larger cage size

**has two external thermistor probes


Large Animal Platforms

PhysioTel Digital Large Animal Platform

This platform is the future of DSI large animal devices.  It has easy to use features such as: 

  • Battery life saving features help extend the usable life of the device
  • Social housing capability
  • Automatic entry of calibration values removes independent calibration data storage
  • Digital serial number traceability ensures the data will come from the right animal every time
  • Improved signal fidelity with digital data, high frequency catheters and intravenous solid tip leads

Choose your temperature and activity implant:


Implant

Minimum Animal Weight

Pressure

Biopotential
(ECG, EEG, EMG, etc)

Warrantied Battery Life

L00

>2.5kg

5 Months

L11

>2.5kg

1 Channel

1 Channel

4 Months

L21

>2.5kg

2 Channels

1 Channel

3 Months


System Components
  • Transciever: TRX
  • Acquisition Hardware: CLC
  • Environmental Reference: APR-1
  • Ethernet to Serial Converter: E2S-1
  • Computer and Monitor
  • Software: Ponemah
  • PhysioTel Digital Telemetry Implant
           PhysioTel Digital Primate Example Setup 
PhysioTel Large Animal Platform

These products have such wide use in the field of research they set the standard for implantable telemetry as it is known today.  DSI is the industry leader in miniaturized implantable telemetry devices and is known for product reliability with over 1000+ peer reviewed publications using this technology.


Choose your temperature and activity implant:


Implant

Animal Model

Pressure

Biopotential

(ECG, EEG, EMG, etc)

Warrantied Battery Life

TA-D70

>2.5kg

11 Months

CTA-D70

>2.5kg

1 Channel

4 Months

D70-PCT

>2.5kg

1 Channel

1 Channel

3.5 Months

D70-PCTP

>2.5kg

2 Channels

1 Channel

2.5 Months

D70-CCTP

>2.5kg

1 Channel

2 Channels

2.5 Months

D70-PCTR*

>2.5kg

1 Channel

1 Channel*

2.5 Months

*This transmitter also has leads that measure respiratory impedance

System Components

  • Reciever: RMC-1
  • Acquisition Hardware: DEM
  • Environmental Reference: APR-1
  • Computer and Monitor
  • Software: Dataquest ART or Ponemah
  • PhysioTel Large Animal Telemetry Implant
 
PhysioTel Large Animal Single Housed Telemetry 

DSI's new bibliography search tool may help you find publications known to use DSI technology.  It is searchable by keyword with "thermoregulation" yielding 80+ hits.  Easily export the references to a computer. These particular publications and posters are considered useful for researchers in the field of thermoregulation and have been included as key references.

General Best Practices
  • Gordon, C. J. "Thermal physiology of laboratory mice: Defining thermoneutrality." Journal of Thermal Biology (2012).
  • Swoap, Steven J., J. Michael Overton, and Graham Garber. "Effect of ambient temperature on cardiovascular parameters in rats and mice: a comparative approach." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 287.2 (2004): R391-R396. 
  • POSTER: Setser, J. J. 2009. "Comparison of rectal, transponder, and telemetry thermometry for collection of body temperatures in rats, dogs and monkeys."
Rodent References
  • Colbourne, Frederick, Garnette R. Sutherland, and Roland N. Auer. "An automated system for regulating brain temperature in awake and freely moving rodents." Journal of neuroscience methods 67.2 (1996): 185-190.
  • DeBow, Suzanne, and Frederick Colbourne. "Brain temperature measurement and regulation in awake and freely moving rodents." Methods 30.2 (2003): 167-171.
  • Leon, Lisa R., et al. "Biotelemetry transmitter implantation in rodents: impact on growth and circadian rhythms." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 286.5 (2004): R967-R974.
  • Hasegawa, Hiroshi, et al. "Alteration in dopamine metabolism in the thermoregulatory center of exercising rats." Neuroscience letters 289.3 (2000): 161-164.
  • Sakurada, Sotaro, et al. "Autonomic and behavioural thermoregulation in starved rats." The Journal of Physiology 526.2 (2000): 417-424.
  • Eliason, Heather L., and James E. Fewell. "Thermoregulatory control during pregnancy and lactation in rats." Journal of Applied Physiology 83.3 (1997): 837-844.
  • POSTER: Grippo, AJ. Allen, SM. Chandler, DL. Dave, P. McDaniel, V. McNeal, N. 2010. "A Comparison of two radiotelemetry transmitters for the recording of behavioral and electrocardiographic data in prairie voles (Microtus Ochrogaster)"
  • POSTER: Bracq. E, Maurin. A, Champeroux. P, Richard. S. "Measurement of tail skin temperature in ovariectomised rats: A model of hot flushes."
Mouse References

  • Duffy, P. H., R. J. Feuers, and R. W. Hart. "Effect of age and torpor on the circadian rhythms of body temperature, activity, and body weight in the mouse (Peromyscus leucopus)." Progress in clinical and biological research 227 (1987): 111.
  • Kramer, Klaas, et al. "Effect of conditioning on the increase of heart rate and body temperature provoked by handling in the mouse." ATLA. Alternatives to laboratory animals 32 (2004): 177-181.
  • Mitchell, Gary F., Andreas Jeron, and Gideon Koren. "Measurement of heart rate and QT interval in the conscious mouse." American Journal of Physiology-Heart and Circulatory Physiology 274.3 (1998): H747-H751.
  • Slade, R. A. L. P. H., WILLIAM P. Watkinson, and GARY E. Hatch. "Mouse strain differences in ozone dosimetry and body temperature changes." American Journal of Physiology-Lung Cellular and Molecular Physiology 272.1 (1997): L73-L77.
  • POSTER: Meijer. 2000.  "Implantation of a radio-telemetry transmitter in the mouse: some practical considerations."
Guinea Pig References
  • Provan, Gayle, et al. "Development of a surgical approach for telemetering guinea pigs as a model for screening QT interval effects." Journal of pharmacological and toxicological methods 52.2 (2005): 223-228.
  • Stemkens-Sevens, Sylvia, et al. "The use of radiotelemetry to assess the time needed to acclimatize guineapigs following several hours of ground transport." Laboratory animals 43.1 (2009): 78-84.
  • POSTER: Betat, A. M. 2004. "Influence of hypokalemia on drug induced qt prolongation in the conscious telemetered guinea pig."
  • Crisanti, K. C. 1999. "Aminophylline alters the core temperature response to acute hypoxemia in newborn and order guinea pigs." Journal of Physiology 46 (1999)
  • POSTER: Mumford. "The impact of anesthetic, surgery and saline administration on guinea pig spontaneous cage activity."
Ferret References
  • POSTER: Main, Brad.  2011.  "Ferrets-A Small Alternative to Dogs in Cardiovascular Pharmacology Studies."
Rabbit References
  • Lawrence, William S., et al. "The physiologic responses of Dutch belted rabbits infected with inhalational anthrax." Comparative medicine 59.3 (2009): 257.
  • POSTER: Bynum, K.S. 2008. "Validation of the Rabbit Telemetry Model for Cardiovascular Safety Pharmacology studies.
Dog References
  • Gauvin, David V., et al. "Electrocardiogram, hemodynamics, and core body temperatures of the normal freely moving laboratory beagle dog by remote radiotelemetry." Journal of pharmacological and toxicological methods 53.2 (2006): 128-139.
  • Kearney, Kenneth, et al. "Evaluation of respiratory function in freely moving Beagle dogs using implanted impedance technology." Journal of pharmacological and toxicological methods 62.2 (2010): 119-126.
  • POSTER: Kishimoto, T. "Inter-facility differences in electrocardiographic and hemodynamic parameters in anesthetized dogs."
  • POSTER: Stewart, L. A. 2000. "Comparison of telemetric thermometry and manual rectal temperature recordings in the beagle dog."
Non-Human Primate References
  • Speece, Ty, et al. "Validation of the jacketed, external telemetry JET™ system for monitoring ECGs in non-human primates." Journal of Pharmacological and Toxicological Methods 58.2 (2008): 154.
  • Baird, T. J., et al. "Simultaneous assessment of ECGs using intracardiac and subcutaneous leads under various environmental conditions in non-human primates." Journal of Pharmacological and Toxicological Methods 56.2 (2007): e33.
  • Perret, M., and F. Aujard. "Daily hypothermia and torpor in a tropical primate: synchronization by 24-h light-dark cycle." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 281.6 (2001): R1925-R1933.
  • POSTER: Crosby, N. 2008. "Identification of Behavior and Position-related artifacts in nonhuman primate telemetry using a time-synchronized video telemetry system."  *if interested in this article see ILF!
  • POSTER: Willens, S. 2009.  "Body temperature analysis in three species of nonhuman primates after exposure to aerosolized bacillus anthracis."
Pig References
  • Jørgensen, Henry, and Peter Kappel Theil. "Use of telemetry technique in research with pigs." Use of telemetry technique in research with pigs: 6-6.
  • de Jong12, Ingrid C., et al. "Mixing induces long-term hyperthermia in growing pigs." CHRONIC STRESS PARAMETERS IN PIGS 69 (1999): 109.
  • Theil, Peter Kappel, et al. "Relation between oxygen consumption and heart rate in four breeds of pigs measured in short-and long-term changes of environmental temperature." Energy metabolism in animals. Proceedings of the 15th symposium on energy metabolism in animals, Snekkersten, Denmark, 11-16 September 2000.. Wageningen Pers, 2001.
  • Jørgensen, Henry, et al. "Surgical techniques for quantitative nutrient digestion and absorption studies in the pig." Livestock Science 133.1 (2010): 57-60.
  • Skytte, Christina, and A. Makin. "Measurement of cardiovascular effects in minipigs using telemetry." Journal of Pharmacological and Toxicological Methods 58.2 (2008): 172.
  • Mesangeau. "Six month telemetric study shows development of cardiovascular autonomic neuropathy in diabetic miniature pigs." Cardiovascular Research 45 (2000).
  • Dauncey. "Radiotelemetry of deep body temperature from one piglet within a group." Journal of Physiology 371 (1986)

Classic Studies:  

  • Animal Care and Husbandry
  • Brown Adipose Tissue
  • Calorimeter studies
  • Circadian Patterns
  • Torpor
  • Hibernation
  • Immunology and vaccine development
  • Inflammation
  • Fever

   
  Related Studies:  

  • Aging and Senescence
  • Allergies
  • Behavior
  • Burn care
  • Cardiology
  • Environmental Changes
  • Exercise Physiology
  • Organ targeted drugs
  • Metabolism
  • Neonatal and pediatric care
  • Neurology
  • Obesity
  • Reproduction and Women’s health
  • Respiratory function