A complimentary tool to help aid physiotherapists
Canine & Equine Electrotherapy
What are Electrophysical agents and how are they used within Veterinary Physiotherapy?
The goal of rehabilitation is to maximise the patient's functional recovery, this can be achieved through a number of methods including; therapeutic exercise, manual techniques, mobility retraining, and the use of assistive devices. Physiotherapists need to make an informed decision regarding the aim or intention of the treatment, rather than making a decision based on the machine (Mcgowan & Goff, 2016). EPA should be chosen regarding the aim or intention of the treatment eg. stimulate tissue repair or to increase muscular strength based on a detailed and thorough assessment. A physical assessment of joints, muscle and other soft tissue structures will allow the therapist to identify the key physiological events that need to be stimulated, promoted or in some ways enhanced (Mcgowan & Goff, 2016).
Therapeutic modalities use thermal, sound, electrical and light energy to impact the physiology of the tissue. With an understanding of the impact each tool can have on different tissues they can complement and augment the treatment plan. Therapeutic tools can be effective in tissue healing, improving flexibility, and facilitating muscle strengthening. The introduction of any energy type into a tissue will instigate a physiological response in the tissue provided that sufficient energy has been employed to surpass the response threshold (Mcgowan & Goff, 2016). The physiological response which occurs through adding energy to tissue can be used to provide a therapeutic effect whether its tissue repair, muscle function or pain management (Mcgowan & Goff, 2016).
When treating the therapist should take into consideration the correct dose which is provided to the animal eg. Energy, energy density, frequency, intensity, pulsing parameters and treatment time is a critical aspect of electrotherapy. Underdosing a tissue is not dangerous it is just ineffective in reaching the optimal therapeutic outcome, overdosing can however cause serious damage to a tissue. Therefore, it is critical for a therapist to understand the correct dosage for each treatment, this starts off with the physical assessment deciding what the aim or intention will be (stimulate repair or stimulate growth); from this the therapist can decide what physiological events need to occur to stimulate, promote or enhance.
LASER THERAPY (Photobiomodulation)
Acronym for light amplification by stimulated emissions of radiation, a form of electromagnetic radiation in the visible and near visible part of the spectrum. Lasers are artificial light sources which emit radiation in the form of flowing photons. This process begins with the activation of electrons in the laser (helium-neon, gallium-arsenide, or gallium-aluminium-arsenide), when dropped from their excited state to the ground state photons are created. Photons are released through a semi reflective mirror to form a beam of light.
The interactions underlying laser therapy is the absorption of light in irradiated tissue by specific biomolecules which are known as chromophores which are found within the mitochondria. Chromophores absorb light energy and transfer it into biochemical energy. After absorption of light secondary actions result in modulation of cellular function that stimulate tissue repair mechanisms, Laser can also help with reduction of pain.
Light provides electromagnetic radiation in the form of photons, laser therapy has been incorporated into treatments to treat conditions including skin wounds, muscles tendon and ligament injuries, neurological conditions, arthritis, and pain. Due to laser stimulating cellular metabolism and growth laser can accelerate tissue repair, and cell growth on structures like tendons, ligaments and muscles. Laser therapy can also have an antiinflammatory effect on the body.
Lasers within rehabilitation are used to modulate cellular function, which is known as photobiostimulation. Low level laser modulates biological processes such a mitochondrial respiration and adenosine triphosphate (ATP) to help accelerate wound and joint healing and to also promote muscle regeneration. Low level laser has also been used to treat acute and chronic pain, neurological conditions, and provide post operative care.
Sourced from Watson ( 2016), Mcgowan & Goff (2016) & Millis & Levine (2014)
Therapeutic Ultrasound
Ultrasound energy is mechanical in nature, sound waves which vibrate at a frequency greater than 20Khz are classified as ultrasound. Therapeutic ultrasound frequencies are commonly in the MHz (millions of cycles per second), this is beyond the hearing frequency of animals. Mechanical energy delivered at MHz will generate heat in the tissue when applied with sufficient power. Coupling is required when using therapeutic ultrasound to maximise acoustic contact between the transducer and the insonated tissue.
The frequencies which are most often employed are 1 and 3 Mhz.
1 MHz is used to reach deeper tissue down to 2-5 cm- Used to reach deeper soft tissue and ligaments
3 MHz is used for the more superficial lesions reaching a depth of 0.5-2cm- Used to treat superficial muscles, tendons and wounds.
The absorption of ultrasound energy is optimal in dense collagen based tissues (ligaments, tendons, joint capsules and established scar tissue), giving the most effective treatment to these tissues.
The thermal effect of ultrasound is a major indication, it increases tissue temperature which can increase collagen extensibility, blood flow, pain threshold, enzyme activity, mild inflammation reaction and changes in nerve conduction. Heating alters the tissues viscoelastic properties of the collagen and collagen modelling molecular bonding. Therapeutic ultrasound also offers a non-thermal effect when applied in a pulsed setting. Low-intensity pulsed ultrasound (LIPUS) is a type of ultrasound that emits pulsed waves and delivers at a low intensity. It has minimal heat impacts while retaining acoustic energy transfer to the target tissue, allowing it to deliver noninvasive physical stimulation for therapeutic applications. In both animal and clinical investigations, LIPUS has been shown to speed the healing of acute fractures, nonunions, and delayed unions.
Sourced from Watson ( 2016), Mcgowan & Goff (2016) & Millis & Levine (2014),
Jiang et al., (2019)
TENS (transcutaneous electrical nerve stimulation)
TENS delivers low and high level stimulation to the peripheral nerves with the primary inter to increase activity in the CNS opioid system or to encourage closers of the pain gate at the spinal cord level. TENS can be a treatment option for chronic and acute pain.
TENS intensity ranges from 0-80 mA but some machines can go up to 100 mA. TEN machines deliver discrete pulses of electrical energy at a level of 1-2 pulses per second or 200-250 pps. For effectiveness the tens machine should cover a range from 2 to 150 pulses per second. TENS use short durational pulses to achieve effective results due to sensory nerves having a relatively low threshold and they respond to rapid change of electrical state; therefore stimulation for less than a millisecond is sufficient enough to depolarize the sensory nerve.
TENs machines usually offer a dual channel output, allowing the therapist to simultaneously excite the sensory neurons.
Transcutaneous electrical nerve stimulation aims to stimulate the sensory nerve and active specific natural pain relief mechanisms, which involves activation of the A beta sensory fibers. Activation of A beta sensory fibers reduces the transmission of noxious stimulus from the C fibers through the spinal cord. A beta responds to higher pulse stimulation in the range of 80-130 hz pulses per second. Higher frequency is used to treat acute pain presentation, and results in a low level carry-over effect with treatment.
Stimulation of the A delta fibers responding to lower frequencies of 2-6 Hz will activate the opioid mechanism and provide pain relief due to the release of endogenous opiates in the spinal cord, thus releasing the activation of noxious sensory pathways. Therefore Low level frequency is used for chronic cases, and offers a longer carry-over effect and is employed with periods of stimulation at intervals of 2-3 hours.
Both peripheral nerve types can be stimulated at the same time by employing a burst mode, where the higher frequency output is interrupted at the rate of about 2-3 bursts per second. This happens by the machine delivering pulses at 100 hz which activate the A beta fibers delivering pain gate way mechanism, but by virtue the rate of the burst will excite the A delta fibers which will stimulate the opioid mechanism. This type of tens stimulation can cause muscle twitching and is less comfortable than high or low frequency.
Electrical stimulation NMES & TENS
Electrical stimulation therapy is an effective tool in increasing muscle strength, reeducating muscles, increasing range of motion, correcting structure, improving muscle tone, enhancing function, controlling pain, accelerating wound healing, reducing edemas, reducing muscle spasms, and enhancing transdermal administration of medication (iontophoresis). TENs has widely been used to identify stimulators that modify pain and NMES has been identified with muscle reeducation, preventing muscle atrophy and enhancing joint movement.
There are three currents which are commonly used in electrical therapy
Continuous- flows for 1 second or longer
Alternating- changes the direction of flow
Pulsed- Unidirectional flow of charges
NMES (Neuromuscular electrical stimulation)
A form of clinical electrotherapy used to treat a variety of physiological disorders or injuries. NMES electrically administers currents through leads to electrodes which are placed on the skin, they are generated by a stimulator and the main function is to depolarise the motor nerve and produce a contraction within the skeletal muscle.
Neuromuscular electrical stimulators recruit type II fibers first (fast twitch) then type I (slow twitch), this is the opposite in a volitional contraction. To increase muscle tone the frequency of the NMES machine needs to be increased, this results in the existing motor units firing at a fast pace.
Neuromuscular electrical stimulation also induces capillary proliferation resulting in increased blood flow. Due to blood flow increasing around type II muscle fibers, proliferation stimulated endothelial cells. NMES should therefore be applied at intensities that produce muscle contraction to stimulate microvascular perfusion within skeletal muscles.
Sourced from Watson ( 2016), Mcgowan & Goff (2016) & Millis & Levine (2014),
Jiang et al., (2019)