USE OF THERAPEUTIC ULTRASOUND IN DOGS
Therapeutic ultrasound is a physiotherapy technique that aims to speed up the healing of damaged muscles, tendons, or ligaments by reducing inflammation and the amount of scar tissue laid down. This is one of the most commonly used devices in physical therapy. It uses sound waves with frequencies much higher than those audible to humans, the frequencies used as a therapeutic tool, 1 x 106, that is 1 Mega-Hertz (MHz), are not audible to any mammal.Normally, veterinary clinics and hospitals use ultrasounds for sonographic scans with the same type of wave. The difference lies in the power, frequency and time of use.
In therapy we use frequencies of 1MHz for deep treatments up to 8 cm and frequencies of 3MHz for more superficial problems. The power ranges from 0.2 to 3 watts/square centimeter.Therapeutic ultrasound is a very high frequency sound wave that when applied to tissue via a probe head, causes the molecules in its path to vibrate at a microscopic level. This has various beneficial effects including increasing the blood circulation to the area (which brings in healing cells and helps disperse natural toxins), decreases swelling, and speeds the rate of healing. Therapeutic ultrasound requires repeated visits, but the patient does not usually need sedation for this therapy.
Therapeutic ultrasound is used as a treatment modality (method) to exert thermal, mechanical, and chemical effects on the treated tissues to enhance and facilitate healing. Physical therapists have used therapeutic ultrasound on human patients since the 1940s, and veterinarians have used it on animals since the 1970’s. The sound waves of therapeutic ultrasound are produced by applying an electric current to a crystal, causing the crystal to vibrate at a specific frequency. The vibrations of the crystal within the head of the ultrasound probe create pulsed or continuous pressure waves (energy) that pass through the skin and vibrate the tissues. The ultrasound probe is applied directly against the pet’s skin using water-soluble ultrasound gel.Most people are probably more familiar with diagnostic ultrasound, which is used to look inside the body in noninvasive ways. We use diagnostic ultrasound to evaluate the heart as it beats and see the size, shape, and structure of organs in the abdomen. This is the type of ultrasound that shows pregnant women what their babies look like in the uterus.
Animals experience pain and injuries just like humans do. So, it makes sense that care and rehabilitation of animals is very similar to treatment received by humans. For example, many therapeutic modalities, like ultrasound machines, used in physical therapy for humans can be used in the treatment of animals.
Therapeutic ultrasound has been used by physical therapists as a treatment modality since the 1940’s. Around 1970, veterinarian’s discovered that the healing benefits of therapeutic ultrasound could help animals heal as well. In an animal’s case, most people may be familiar with the use of diagnostic ultrasound as a way to diagnose problems or injuries but therapeutic ultrasound can be used to facilitate enhance and facilitate healing.
The benefits of therapeutic ultrasound are the same for humans and animals alike. When using therapeutic ultrasound, sound waves pass through the skin which causes a vibration within the surrounding tissues. This vibration is heat-producing helping penetrate deep into injured tissues. The side-effects of therapeutic heat are:
- Increase in the flexibility of ligaments, tendons, scar tissue and joint capsules
- Reduction in pain and muscle spasms
- Improve the healing of injured tissue
How are Animals Treated Using Therapeutic Ultrasound?
The treatment area is prepared (shaving if necessary in order to access bare skin) and a gel is applied to the area. No sedation is used, because the animal must be able to indicate comfortability feedback as treatment is given. Therapeutic ultrasound treatments for animals last about 10-20 minutes, with a recommendation to have treatment 2-3 times a week until the injury or problem is resolved.
Contraindications for Therapeutic Ultrasound for Animals
Therapeutic plans in veterinary rehabilitation generally involve a combination of manual therapies (joint mobilizations and soft tissue mobilizations), physical modalities (laser, therapeutic ultrasound, e-stim, shockwave), and therapeutic exercises. The modalities are generally used to prepare the tissues for the manual therapies and therapeutic exercises. Physical modalities should never be the sole therapeutic method applied to any patient. Therapeutic parameters for each modality are chosen based upon the acuity of the injury, so the therapist must be well versed on the definitions of the acute, subacute, and chronic phases of healing. Therapeutic ultrasound works on a frequency of 1 MHz (megahertz) or 3 MHz via a reverse piezoelectric effect. This is the conversion of electricity to sound waves and takes place within the piezoelectric crystal housed in the transducer (sound head). Therapeutic ultrasound can create thermal and non-thermal effects, with the latter causing tissue modulation instead of heat. Tissue heating caused by therapeutic ultrasound causes increased collagen extensibility and blood flow, decreased muscle spasm, and creates a mild inflammatory effect. Non-thermal effects of therapeutic ultrasound cause enhanced tissue repair via stimulation of fibroblasts, increased protein synthesis, blood flow and glycosaminoglycans synthesis, facilitated inflammation, and improved cartilage healing. Indications for therapeutic ultrasound include muscle spasm, muscle pain secondary to IVDD, tendinopathy, delayed wound healing, and muscle strain injuries. Setting variables for therapeutic ultrasound include duty cycle, frequency, intensity, and treatment duration. Duty cycle refers to the ratio of on time to off time and can be either continuous or pulsed. Continuous treatment causes tissue heating. Pulsed duty cycle can range from 10% to 90%, with increased potential for tissue heating at higher levels.
Frequency, measured in megahertz (MHz), determines the depth of penetration of the sound waves. One MHz penetrates to 5 centimeters and 3 MHz penetrates to 1 to 2 centimeters. Intensity is measured in watts per square centimeter and is generally set between 0.1 and 2.0 W/cm2. Treatment duration is determined by the size of the transducer head and the size of the area to be treated. Transducer heads come in sizes from 1 cm2 to 10 cm2, and the general rule is to treat for 2.5 minutes per treatment area equal to the head diameter. This means that if the patient has a treatment area of 20 cm2 and the therapist has a 5 cm2 treatment head, the treatment will take 10 minutes.
There are precautions that the therapist must take when using a therapeutic ultrasound device. The crystal in the transducer head is very fragile. The head must maintain contact with fluid at all times when the unit is turned on. If the head is allowed to remain in dry air while turned on, the crystal will be damaged. As the potential for tissue heating exists, the transducer head must be kept in motion at all times during the therapy session. Fur can attenuate the sound waves preventing transmission to the deeper tissues and creating heat at the surface. To prevent this, the fur must be clipped or at least soaked in water or gel. Contraindications for use of therapeutic ultrasound include therapy over open physes, over fractures, or over a pregnant uterus. There are few clinical studies looking at the use of therapeutic ultrasound in veterinary practice. One study demonstrated healing of partial gastrocnemius muscle avulsions in dogs using therapeutic ultrasound, with follow up of 6 to 12 months.
The reason therapeutic ultrasound is a popular modality is because it is non-invasive in addition to being effective in treating pain and swelling. However, ultrasound therapy is contraindicated for use on animals that have orthotic implants (such as hip replacements), bone plates (for fracture repair), pregnancy or over growth plates in young animals.
Common Uses of Therapeutic Ultrasound for Animals
Veterinarians use ultrasound to treat most tendon and muscle injuries in addition to problems that result in a decrease in range of motion.
In rehabilitation, the intention of treatment for animals is the same as humans too; decreasing pain, increasing function and maintaining quality of life. Using non-invasive therapeutic modalities, like ultrasound therapy, help animals heal from muscular injuries that may be causing them pain and inhibiting their function, making it a perfect choice for veterinary practices.
Therapeutic Ultrasound Procedure in Dogs
Therapeutic ultrasound is not painful and in most calm animals can be undertaken without the need for sedation, indeed many patients find the therapy pleasantly warming. However, there does need to be good contact between the head of the ultrasound probe and the skin, which means that in most cases fur needs to be clipped away.
The clinician applies a water-based ultrasound gel over the area, which improves the conduction of the ultrasound waves into the deeper tissues. The probe is applied for 10 – 20 minutes at a time, usually with the probe moving in gentle stroking sweeps or a small circular movements over the affected area.
The therapy is repeated two to three times a week, until the desired improvement in the movement of the joint or muscle is achieved. Therapeutic ultrasound should only be undertaken under the direction of a veterinarian, thus referral from the vet to the physiotherapist is necessary.
Effects on tissues:
The main effect of ultrasound on tissues is anti-inflammatory. Usually it is used on tendons, joints or inflamed muscles, achieving excellent results for both acute and chronic injuries, although the power must be adjusted.
Rehabilitation also seeks an analgesic effect, normally when we reduce inflammation in one structure we reduce the pressure on the nociceptors, which are the body’s receptors for sending pain signals. By reducing the pressure on these receptors, we reduce their stimulation therefore decreasing the intensity of these signals until they disappear. If there is no pain signal, there is no perception of pain.
When there is fibrosis in the different soft tissues: muscles, tendons or ligaments, first we can apply continuous ultrasounds followed by pulsating ultrasounds at full power in order to achieve a good anti-fibrotic effect.
Another classic application of ultrasounds is on muscle spasms, with the ultrasound we can reduce and even eliminate them.
The continuous ultrasounds generate heat through vibration of the molecules and both the continuous and pulsating increase the membrane’s permeability, which together with the mobilization of the molecules promotes the anti-inflammatory effect.
Application:
Ultrasounds are applied by moving the head during the course of the treatment, either in small circles or in a straight line in the direction of the tissues being treated. If done in any other way, especially if in any way besides the continuous manner, we can damage the tissues and cause significant burns.
A contact medium must be used, either contact gel or direct immersion (sub-aquatic ultrasounds). It is important to take into account the animal’s fur, the hair makes the transmission of the ultrasound difficult and it recommended that the dog is shaved before applying the ultrasound session).
Approximate time between 5 and 15 minutes
Power between 0.2 and 3 Watts / cm2
There are different head measures according to different needs.
Directions:
Ultrasounds can be used in any disease found in dogs that causes pain in the joints or soft tissue, such as tendinitis, bursitis, arthritis, contusions or significant hematomas .
Efficacy of Therapeutic Ultrasound in Dogs
Used in the human field for rehabilitation as well as the treatment of sports injuries, therapeutic ultrasound is a respected physiotherapy method. It has the major advantages of being drug-free and comfortable enough to use without sedation. Whilst it will not produce miracles, when used correctly it is unlikely to worsen a condition and highly likely to benefit it.
It is important only take the advice of a vet, as to whether therapeutic ultrasound is appropriate for your dog or not. There are some contraindications where the effects of this type of ultrasound are either not known or there is a chance of complications. The conditions for which it is not advised include:
Pregnancy: The effects of prolonged exposure to therapeutic ultrasound during pregnancy are not known, therefore any risk is best avoided
Cancer: The increased blood supply to an area could encourage the spread of cancer cells to other parts of the body.
Metal Orthopedic Implants: The pins, plates, or screws used to repair a fractured bone may heat up under prolonged exposure to therapeutic ultrasound. This will cause discomfort and pain, and is undesirable.
Therapeutic Ultrasound Recovery in Dogs
A dog that needs therapeutic ultrasound will likely be under the care of a vet or veterinary physiotherapist. Whilst the treatment itself has minimum short-term impact on the patient, it’s likely they will need to adhere to a specific exercise or physiotherapy regime as part of the recuperation process.
How swiftly the patient sees a benefit depends largely on the nature of a problem. For example, clinicians passing a therapeutic ultrasound probe over the incision from a routine ovariohysterectomy find even a single treatment speeds up wound healing. Whereas a joint that has seized up as a result of an old injury may could take multiple weeks of therapy to show a satisfactory improvement.
DR. AMIT,CANINE SPECIALIST,PUNE
REFERENCE-ON REQUEST
https://www.pashudhanpraharee.com/therapeutic-ultrasound-in-veterinary-practice/
https://veteriankey.com/therapeutic-ultrasound/
