Effect of coat on rate of temperature increase in muscle during ultrasoundtreatment of dogs

Objective-To determine effect of coat during ultrasound treatment and to es tablish a protocol to achieve adequate thermal effects. Animals-9 healthy adult dogs. Procedure-A standardized area was treated on the semitendinosus muscle of s edated dogs. Needle thermistors were inserted in the biceps femoris muscle to depths of 5 and 10 cm and in the ultrasound gel in the treatment area. E ach dog was given 4 randomized 10-minute treatments (intensities of 0.5, 1. 0, 1.5, and 2.0 W/cm(2)). Temperatures were measured at 30-second intervals during treatment and at 1- to 2-minute intervals after treatment. Results-Baseline temperatures (mean +/- SD) were 30.6 +/- 1.8 C for coat, 3 8.2 +/- 1.2 C at a depth of 5 cm, and 39.0 +/- 0.7 C at a depth of 10 cm. A t the 5-cm depth, an increase of > 1.6 C was obtained only with the maximum intensity when coat was clipped. Treatment with maximum intensity through short and long coats yielded mean increases at a depth of 5 cm of 0.7 and 0 .4 C, respectively. Temperature at the 10-cm depth increased < 0.6 C for al l treatments. Temperatures within the coat increased approximate ly 8.3 C a nd 22.2 C for short and long coals, respectively, with intensities of 1.5 a nd 2.0 W/cm(2). Conclusions-Ultrasound treatment applied Ih rough an intact coat considerab ly warmed the coat with loss of thermal effects in underlying tissues. Inap propriate heating was apparently affected by selection of intensity, durati on, and size of treatment area. Clinical Relevance-Coat can impede successful use of ultrasound treatment o f dogs.