Laser treatment is used for pain management, inflammation control and tissue healing. The physiological effects include accelerated
cell division via mitochondrial stimulation, increased leukocyte phagocytosis, stimulation of fibroblast production, enhanced
synthesis of ATP and angiogenesis. Lasers are divided into four classes based on their power.
Most therapeutic or "cold" lasers are in Class 3 with power ranging from 1 milliwatt to 500 milliwatts. "Hot" lasers, which
are commonly used in surgery, fall into Class 4 with more than 500 milliwatts of power. Laser therapy is measured in joules
(the energy delivered by 1 watt of laser energy in 1 second). Most therapeutic regimens call for 1 to 8 joules of energy.
The penetration depth is determined by the laser's wavelength. Higher power simply delivers this energy to the same depth
at a faster rate.
Hot and cold therapies
Thermotherapy is generally used to reduce pain from arthritis and muscle spasms, and to prepare tissues for exercise or stretching.
Heat can be applied by hot packs, infrared light, hydrotherapy and therapeutic ultrasonography. Thermotherapy can result in
vasodilation with secondary increased local circulation, a decrease in pain, relaxed muscle tone, reduced muscle spasm, and
an increase in tissue extensibility, cellular metabolism and local tissue oxygenation. It should not be used in patients with
impaired thermal sensation, recent hemorrhage, malignancy or acute inflammation.
Applied via ice bath/massage/pack, vapocoolant gel or circulating ice compression units, cryotherapy is commonly used in the
acute period after injury or surgery. The benefits include vasoconstriction, reduced cellular metabolism, decreased nerve
conduction velocity (leading to analgesia), reduction of edema and decreased muscle spasm. Use caution when applying cold
therapy to patients with decreased sensation, cold hypersensitivity, or the potential for reflex vasodilation (the "Hunting
Reflex"), a profound vasodilation caused by extended exposure to cold.
This modality involves the application of sound waves directly to the skin to produce a vibration in the underlying tissue.
The intensity can be adjusted from 1 MHz to 3 MHz, depending on the desired effects, which could include deep local heating,
an increase in blood flow and breakdown of scar tissue. This modality can be used in veterinary rehabilitation to treat a
number of conditions, including joint swelling, muscle spasms, strain lesions and biciptial tenosynovitis.
Similar to diagnostic ultrasonography, therapeutic ultrasonography converts electricity to sound waves by a piezoelectric
effect in the transducer head. Ultrasound waves are attenuated by the tissues they pass through. Bone attenuates the waves
the most, followed by cartilage, tendon, skin, blood vessel, muscle, fat and, finally, blood. This variation must be taken
into account when determining the treatment intensity for a tissue or lesion that sits deep in any of these tissues. There
are many variables that can be applied to therapeutic ultrasonography, including duty cycle, frequency, intensity and treatment
duration. Generally, treatment time will equal about five minutes for a space that is twice the size of the transducer head.
Making use of modalities
There are many physical modalities available to veterinary rehabilitation therapists that can add tremendous benefit to patients.
However, it's important to remember that purchasing the best equipment does not necessarily guarantee great results. When
used together, meticulous diagnostic techniques, excellent manual techniques and creative problem-solving skills make all
Dr. Van Dyke is the founder and CEO of the Canine Rehabilitation Institute in Wellington, Fla., with locations in Fort Collins, Colo.,
and Annapolis Junction, Md.