Nd:YAG surgical laser effects in canine prostate tissue: temperature and damage distribution.

An in vitro model was used to predict short-term, laser-induced, thermal damage in canine prostate tissue. Canine prostate tissue samples were equipped with thermocouple probes to measure tissue temperature at 3, 6, 9 and 12 mm depths. The tissue surface was irradiated with a Nd:YAG laser in contact or non-contact mode for up to 20 s, using powers from 5 to 20 W. Prediction of thermal damage using Arrhenius theory was discussed and compared to the in vitro damage threshold, determined by histological evaluation. The threshold temperature for acute thermal tissue damage was 69 +/- 6 degrees C (means +/- SD), irrespective of exposure time. Contact mode laser application caused vaporization of tissue, leaving a crater underneath the fiber tip. The mean extent of tissue damage underneath the vaporization crater floor was 0.9 +/- 0.6 mm after 5, 10 or 20 s of contact mode laser irradiation at 10 W, whereas 20 W non-contact exposure up to 20 s causes up to 4.7 +/- 0.2 mm coagulation necrosis. It was concluded that short-term acute thermal tissue damage can be comprehensively described by a single threshold temperature.

Preliminary results of intraoperative photodynamic therapy with 5-aminolevulinic acid in dogs with prostate carcinoma.

Six client-owned dogs with prostate carcinoma were treated with a combination of (1) partial subcapsular prostatectomy using an Nd:YAG laser, (2) intraoperative photodynamic therapy using a halogen broad band lamp after local administration of a photosensitiser, and (3) systemic treatment with meloxicam. Median survival time was 41days (range 10-68days), which compared negatively with previous reports of subtotal laser prostatectomy combined with topical interleukin-2 administration, and photodynamic therapy alone. Despite treatment, the disease progressed locally, causing signs of stranguria to recur, and in the form of distant metastases. The recurrence of clinical signs due to the primary tumour despite photodynamic therapy is probably largely explained by insufficient penetration of light into the tissue. Better results may be obtained using other light sources (e.g. laser) and alternative techniques of light delivery, such as fibres or catheters allowing interstitial diffusion of light.

Thoracic bite trauma in dogs: a comparison of clinical and radiological parameters with surgical results.

OBJECTIVES: Canine bite wounds may cause severe underlying tissue trauma even with no clinically evident puncture wounds. In order to assess the ability of pre-operative diagnostic parameters to predict the extent of internal damage inflicted by a thoracic bite wound, the clinical, radiological and surgical data of 45 dogs that sustained thoracic bite trauma were recorded. METHODS: Clinical, radiographic and surgical parameters from 45 dogs of various breeds with thoracic bite trauma, were analysed (P<0.05). All dogs were treated according to a previously described protocol and had exploratory surgery including a thoracotomy. RESULTS: Mainly small-breed dogs were traumatised. Clinical and radiological data were suggestive of internal trauma but not reliable as accurate indicators for internal lesions. Only radiological evidence of lung contusion was significantly associated with the presence of surgically confirmed lung contusion (P=0.006). Dogs with postoperative wound complications had a significantly higher risk of dying than those without complications (P=0.04). CLINICAL SIGNIFICANCE: This study concludes that according to protocol an optimal management of thoracic bite wounds in small dogs includes surgical exploration of the wound and the thoracic cavity in the presence of flail or pseudo-flail chest, fractured ribs, radiological evidence of lung contusion, pneumothorax or any combination of these.

[Traumatically-induced mucocele of the frontal sinus in two dogs]. / Traumatisch bedingte Mukozoele des Sinus frontalis bei zwei Hunden.

Two young dogs were presented with an accumulation of mucus in the frontal sinus which occurred after a head injury had caused an obstruction of the nasofrontal openings. Both dogs were successfully managed by surgically reconstructing and draining the nasofrontal ducts.