CCAT Therapeutic Modalities and Application 2 — Questions and Answers
Question 1: Which tissue type responds best to ultrasound frequencies in the 3 MHz range compared to 1 MHz?
- Deep muscle at 5 cm depth
- Superficial tissues within 2 cm (Correct answer)
- Cortical bone
- Articular cartilage
Correct answer: Superficial tissues within 2 cm
3 MHz ultrasound is absorbed more rapidly and is most effective for superficial tissues within 1–2 cm depth.
Question 2: When using transcutaneous electrical nerve stimulation (TENS) for pain control in dogs, which fiber type is targeted by high-frequency, low-intensity settings?
- C fibers (slow pain)
- A-delta fibers (fast pain)
- A-beta fibers (touch/pressure) (Correct answer)
- Motor efferent fibers
Correct answer: A-beta fibers (touch/pressure)
High-frequency TENS activates large-diameter A-beta fibers, which activate spinal gate control mechanisms to inhibit pain transmission.
Question 3: A dog recovering from tibial plateau leveling osteotomy (TPLO) shows limb disuse 8 weeks post-op. Which underwater treadmill parameter adjustment most directly offloads the surgical limb?
- Increasing belt speed
- Raising water level to shoulder height (Correct answer)
- Decreasing session duration
- Lowering water temperature to 18°C
Correct answer: Raising water level to shoulder height
Higher water levels provide greater buoyancy, reducing weight-bearing load on the affected limb.
Question 4: Phonophoresis uses therapeutic ultrasound to enhance delivery of topical agents. Which mechanism primarily facilitates transdermal drug penetration?
- Thermal vasodilation opening pores
- Acoustic streaming and cavitation disrupting lipid bilayers (Correct answer)
- Piezoelectric charge attracting ionic drugs
- Radiation pressure compressing the stratum corneum
Correct answer: Acoustic streaming and cavitation disrupting lipid bilayers
Acoustic streaming and cavitation alter skin barrier permeability, enhancing topical drug absorption during phonophoresis.
Question 5: In class IV laser therapy, the Arndt-Schulz law describes the dose-response relationship. What happens when photobiomodulation dose exceeds the therapeutic window?
- Accelerated tissue repair begins
- No effect or inhibitory effects occur (Correct answer)
- Analgesic effect is maximized
- Collagen synthesis doubles
Correct answer: No effect or inhibitory effects occur
Exceeding the therapeutic window can inhibit or reverse biostimulatory effects according to the Arndt-Schulz law.
Question 6: Which contraindication is shared by both therapeutic ultrasound AND electrical stimulation modalities?
- Acute inflammation
- Application over active epiphyseal growth plates (Correct answer)
- Muscle atrophy
- Chronic osteoarthritis
Correct answer: Application over active epiphyseal growth plates
Both modalities are contraindicated over open growth plates due to risk of disrupting normal bone development in immature animals.
Question 7: A cat with degenerative joint disease is treated with cold laser. Which chromophore in mitochondria is the primary target of near-infrared wavelengths (800–1000 nm)?
- Hemoglobin
- Melanin
- Cytochrome c oxidase (Correct answer)
- Myoglobin
Correct answer: Cytochrome c oxidase
Cytochrome c oxidase in the mitochondrial respiratory chain is the primary photoacceptor for near-infrared laser wavelengths.
CCAT Therapeutic Modalities and Application 2
Which tissue type responds best to ultrasound frequencies in the 3 MHz range compared to 1 MHz?