Thermotherapy is a modality that can be used in office or at home by the owner. It is performed through the application of hot or cold (cryotherapy) to change the cutaneous (skin), intra-articular and core temperature of soft tissue with the intention of improving the symptoms of certain conditions. Using ice or heat on decreases pain on a muscle and joint as well as soft tissue. Each has the opposite effect on the target tissue:
Heat- causes vasodilation of the target tissue which increased blood flow to a target area. It also increases tissue distensibility and metabolic rate. Heat increases oxygen uptake and can accelerate healing. It can increase activity of destructive enzymes and increase the catabolic rate.
Cold- causes initial vasoconstriction followed by vasodilation at a certain time point (which provides a protective effect against tissue hypoxia.) Cold reduces tissue metabolism, nerve conduction rate in the area, inflammation and tissue distensibility. At joint temperatures of 30°C or lower, the activity of cartilage degrading enzymes is inhibited. The decreased metabolic rate limits further injury and aids the tissue in surviving the cellular hypoxia that occurs after injury.
Both can cause injury if overdone or impair healing if not used correctly, so how do you know when to use which one?
To understand when to use heat vs cold, it is important to know what phases of healing a damaged area goes through.
The first phase is the inflammatory phase. This phase usually lasts about 2 days following an injury. During this phase, cold can help to decrease swelling, while heat would be contraindicated since it would have the opposite effect.
The next two phases are the proliferative phase and remodeling phase. The proliferative phase is where new tissue and scar tissue are formed. The remodeling phase is the restoration of structure and function of injured tissues. Heat therapy can be used in both of these phases.
These treatments are advantageous in that they are inexpensive, simple and able to be performed at home. It is common to have these treatments performed by owners so that other modalities that may be of benefit can be focused on during in-clinic rehabilitation treatment sessions.
Want to know more about how to use thermotherapy to help your pet's injury? Contact your rehabilitation therapist or veterinarian to find out more!