Thermotherapy is the therapeutic use of heat and is a widely used conservative treatment for soft tissue injury. The superficial application of heat has been proposed to aid in the relief of pain and muscle spasm, promote healing, and reduce joint stiffness and muscle contracture.1–3 Heat has been proposed as a treatment for soft tissue injuries that have already entered the healing phase or in situations of chronic pain.4–8 The use of supplemental heat during the acute phase of injury can cause increased production of metabolic waste products and propagate the inflammatory response, especially if there is impaired venous or lymphatic return; therefore, heat therapy is not currently recommended during the acute phase of injury.4,5
It has been well established that blood flow to the skin will increase as a result of application of heat.9–11 Increased blood flow occurs by vasodilation and increased metabolic rate of the warmed tissue.9 Increased blood flow and cellular metabolism enhance healing and enable removal of metabolic waste products at a higher rate.2,3 In nonacute painful disorders, increased blood flow may accelerate the removal of chemical stimuli, thereby resulting in decreased pain.
Relief of pain is thought to occur via direct reduction of the painful stimulus and alteration of metabolic activity of neural receptors.4,12 Increasing the extensibility of contracted musculotendinous units secondary to injury and pain, resulting in relaxation, is 1 mechanism by which heat can be beneficial in the treatment for pain.2 Increasing the temperature of a musculotendinous unit results in lengthening, tension reduction, and increased range of motion.4,13,14 By reducing muscle rigidity, heat is believed to aid in reduction of injury associated with strenuous activity, assist with physical therapy exercises, and reduce pain associated with affected muscle groups.4, 8
Application of heat for the treatment of soft tissue injury or chronic pain in dogs is largely empirical, with no evidence-based research on the topic. The purpose of the study reported here was to accurately measure temperature change associated with the use of a commonly used method of heat application at varying tissue depths in healthy dogs. We hypothesized that increases in tissue temperature would be directly proportional to the duration of warm compress application.
Cumulative equivalent minutes at 43°C
Brymill, Ellington, Conn.
Digi-Sense, Cole-Parmer, Vernon Hills, Ill.
Rubbermaid, Atlanta, Ga.
Mueller Sport Care, Prairie du Sac, Wis.
1. Barnes WS, Larson MR. Effects of localized hyper- and hypothermia on maximal isometric grip strength. Am J Phys Med 1985; 64: 305–314.
4. Nanneman D. Thermal modalities: heat and cold. A review of physiologic effects with clinical applications. AAOHN J 1991; 39: 70–75.
6. Chapman BL, Liebert RB, Lininger MR, et al. An introduction to physical therapy modalities. Adolesc Med State Art Rev 2007; 18: 11–23, vii–viii.
8. Chou R, Huffman LH. Nonpharmacologic therapies for acute and chronic low back pain: a review of the evidence for an American Pain Society/American College of Physicians clinical practice guideline. Ann Intern Med 2007; 147: 492–504.
9. Minson CT, Berry LT, Joyner MJ. Nitric oxide and neurally mediated regulation of skin blood flow during local heating. J Appl Physiol 2001; 91: 1619–1626.
10. Petrofsky J, Bains G, Prowse M, et al. Dry heat, moist heat and body fat: are heating modalities really effective in people who are overweight? J Med Eng Technol 2009; 33: 361–369.
11. Lohman EB III, Bains GS, Lohman T, et al. A comparison of the effect of a variety of thermal and vibratory modalities on skin temperature and blood flow in healthy volunteers. Med Sci Monit 2011; 17:MT72–MT81.
12. Kelly R, Beehn C, Hansford A, et al. Effect of fluidotherapy on superficial radial nerve conduction and skin temperature. J Orthop Sports Phys Ther 2005; 35: 16–23.
13. Cosgray NA, Lawrance SE, Mestrich JD, et al. Effect of heat modalities on hamstring length: a comparison of pneumatherm, moist heat pack, and a control. J Orthop Sports Phys Ther 2004; 34: 377–384.
14. Funk D, Swank AM, Adams KJ, et al. Efficacy of moist heat pack application over static stretching on hamstring flexibility. J Strength Cond Res 2001; 15: 123–126.
15. Millard RP, Towle-Millard HA, Rankin DC, et al. Effect of cold compress application on tissue temperature in healthy dogs. Am J Vet Res 2013; 74: 443–447.
16. Borrell RM, Parker R, Henley EJ, et al. Comparison of in vivo temperatures produced by hydrotherapy, paraffin wax treatment, and fluidotherapy. Phys Ther 1980; 60: 1273–1276.
17. Petrofsky JS, Bains G, Raju C, et al. The effect of the moisture content of a local heat source on the blood flow response of the skin. Arch Dermatol Res 2009; 301: 581–585.
18. Petrofsky JS, Laymon M. Heat transfer to deep tissue: the effect of body fat and heating modality. J Med Eng Technol 2009; 33: 337–348.
19. Trowbridge CA, Draper DO, Feland JB, et al. Paraspinal musculature and skin temperature changes: comparing the Thermacare HeatWrap, the Johnson & Johnson Back Plaster, and the ABC Warme-Pflaster. J Orthop Sports Phys Ther 2004; 34: 549–558.
21. Yarmolenko PS, Moon EJ, Landon C, et al. Thresholds for thermal damage to normal tissues: an update. Int J Hyperthermia 2011; 27: 320–343.
22. Goldstein LS, Dewhirst MW, Repacholi M, et al. Summary, conclusions and recommendations: adverse temperature levels in the human body. Int J Hyperthermia 2003; 19: 373–384.
23. Dewhirst MW, Viglianti BL, Lora-Michiels M, et al. Basic principles of thermal dosimetry and thermal thresholds for tissue damage from hyperthermia. Int J Hyperthermia 2003; 19: 267–294.
24. Guedes AG, Papich MG, Rude EP, et al. Pharmacokinetics and physiological effects of intravenous hydromorphone in conscious dogs. J Vet Pharmacol Ther 2008; 31: 334–343.