Treatment of canine hemangiopericytomas with photodynamic therapy.

BACKGROUND AND OBJECTIVES: Canine hemangiopericytomas are a commonly occurring neoplasm with a clinical course of recurrence after surgical removal. This study sought to evaluate Photochlor (HPPH) photodynamic therapy (HPPH-PDT) as an adjuvant therapy to prevent recurrence of tumor after surgical removal. STUDY DESIGN/MATERIALS AND METHODS: Sixteen dogs with naturally occurring hemangiopericytomas were treated with surgical removal of the tumor followed by PDT using Photochlor as the photosensitizer. Photochlor was injected intravenously at a dose of 0.3 mg/kg. Forty-eight hours later the treatment consisted of surgical removal of the tumor followed by HPPH-PDT. RESULTS: Nine dogs (56%) had recurrence of tumor from 2 to 29 (median 9) months after treatment. These results are comparable or not as good as other forms of therapy. CONCLUSIONS: Photochlor photodynamic therapy applied after surgery appears to have no advantage over other forms of therapy in regards to preventing recurrence. Delayed wound healing and infections are problematic and make HPPH-PDT an undesirable addition to surgery for the treatment of this tumor type.

Clinical assessment of a chemosensitivity assay as a treatment planning tool for dogs with cancer.

This study evaluated the clinical utility of a commercially available chemosensitivity assay. In the first part of the study, tumor tissues from dogs with various malignancies were tested, and the dogs were treated with a mitoxantrone/cyclophosphamide combination protocol. Tumor response was evaluated and compared to the predicted response. Assay results were not a significant predictor of clinical response to chemotherapy or of survival time. In the second part of the study, assay results were used to direct therapy in dogs with refractory lymphoma. There was no significant correlation (p equals 0.323) between predicted response and case outcome.

Alveolar mucosal approach to the canine nasal cavity.

A nine-year-old, intact female Afghan hound was presented for evaluation of an intermittent, mucopurulent, unilateral nasal discharge with a three-year duration. Radiographs showed the ipsilateral canine tooth within the rostral nasal cavity. The tooth was removed through an alveolar mucosal rhinotomy. There has been no recurrence of the nasal discharge or complications associated with the surgical procedure during the 20-month follow-up period.

Intraosseous approach to the nasolacrimal duct for removal of a foreign body in a dog.

A Labrador retriever was evaluated because of chronic mucopurulent discharge from the left eye. A foreign body was identified in the nasolacrimal duct by use of dacryocystorhinography. Attempts to alleviate the inflammation by use of flushing and administration of antimicrobials were unsuccessful. At surgery, the infraorbital foramen was used as a landmark for a skin incision, because the nasolacrimal duct courses dorsal and parallel to the infraorbital canal. An air drill was used to remove the portion of the maxillary bone overlying the nasolacrimal duct, which exposed the intraosseous portion of the duct and allowed removal of a plant-material foreign body. The incision in the duct was allowed to heal by second intention, and the dog recovered without complications.

Regional anesthesia of the infraorbital and inferior alveolar nerves during noninvasive tooth pulp stimulation in halothane-anesthetized cats.

OBJECTIVE: To determine whether anesthesia of the infraorbital and inferior alveolar nerves abolishes reflex-evoked muscle action potentials (REMP) during tooth-pulp stimulation in halothane-anesthetized cats. ANIMALS: 8 healthy adult cats. PROCEDURE: In halothane-anesthetized cats, an anodal electrode was attached to the tooth to be stimulated and a platinum needle cathodal electrode was inserted in adjacent gingival mucosa. Cathodal and anodal electrodes were moved to the upper and lower canine, upper fourth premolar, and lower first molar teeth for stimulation; baseline REMP was recorded. A 25-gauge 1-cm needle was inserted 0.5 cm into the infraorbital canal. A 25-gauge 1-cm needle was inserted 1 cm rostral to the angular process of the ramus, and advanced 0.5 cm along the medial aspect. Chloroprocaine was injected at each site. Each tooth was stimulated every 10 minutes for 90 minutes. RESULTS: REMP was abolished within 10 minutes for all upper teeth, except for the upper canine tooth in 1 cat, and abolished within 10 minutes for lower teeth in 4 cats. In 1 cat, REMP was not abolished in the lower first molar tooth. In 3 cats, REMP was not abolished in the lower canine and first molar teeth. At 90 minutes, REMP was restored for all teeth except the lower canine tooth in 1 cat, for which REMP was restored at 120 minutes. CONCLUSIONS AND CLINICAL RELEVANCE: Regional anesthesia of the infraorbital and inferior alveolar nerves may provide dental analgesia in cats.

Treatment of canine oral squamous cell carcinomas with photodynamic therapy.

Eleven dogs with naturally occurring oral squamous cell carcinomas were treated with photodynamic therapy (PDT) using Photochlor (HPPH) as the photosensitizer. The largest length of the tumours measured in a two-dimensional plane ranged from 0.9 to 6.8 cm. Seven of the tumours invaded underlying bone as determined by radiograph appearance. Photochlor was injected intravenously at a dose of 0.3 mg kg(-1). Forty-eight hours later the tumours were treated. Tumours with a surface to base depth of greater than 1 cm were surgically reduced to less than 1 cm. Irradiation with 665 nm light with an energy density of 100 J cm(-2) was administered. Eight dogs were considered cured with no tumour recurrence for at least 17 months after treatment. Local treatment of oral squamous cell carcinomas with PDT appears to give results similar to those obtained with surgical removal of large portions of the mandible or maxilla. The cosmetic results with PDT are superior to those of radical surgical removal. The new sensitizer, Photochlor, appears effective for oral squamous carcinomas with results similar to those reported for other sensitizers.

Clinical evaluation of a modified circumcostal gastropexy in dogs.

A modified circumcostal gastropexy was performed in 5 Greyhounds. A 3-cm-long tunnel was created between the seromuscular and submuscosal layers of the pyloric antrum. A 6- to 7-cm-long segment of the cartilaginous portion of the 10th or 11th rib was dissected free of surrounding tissues and transected; the proximal portion of the rib was inserted through the seromuscular tunnel. The transected ends of the rib were overlapped approximately 1.5 cm and sutured in apposition in a side-by-side manner. Mean time for completion of the gastropexy was 11.5 minutes. Persistence of the surgically created gastric adhesion was verified by laparoscopy and ultrasonography 6 and 18 months after surgery. Positive-contrast radiography confirmed normal anatomic position of the stomach. Important complications associated with the procedure were not detected. Results for these 5 dogs indicated that modified circumcostal gastropexy could be performed rapidly, was safe, and created long-lasting gastric fixation.

Infantile desmoid-type fibromatosis in an Akita puppy.

A 10-week-old Akita puppy was evaluated for a reported umbilical hernia. Repair of the hernia had been attempted three times prior to referral. A defect in the ventral abdominal wall with an associated soft-tissue mass was identified on abdominal radiographs. Exploratory surgery was performed; the mass was resected and the abdominal wall defect was repaired. Histopathological evaluation of the mass was consistent with infantile desmoid-type fibromatosis.

Regional anesthesia of the infraorbital and inferior alveolar nerves during noninvasive tooth pulp stimulation in halothane-anesthetized dogs.

OBJECTIVE: To document that regional anesthesia of the infraorbital and inferior alveolar nerves would abolish reflex-evoked muscle action potentials (REMP) in the digastricus muscle during noninvasive stimulation of tooth pulp in halothane-anesthetized dogs. DESIGN: Prospective study. ANIMALS: 9 healthy female dogs between 2 and 6 years old. PROCEDURE: Dogs were anesthetized using halothane. An alligator clip anodal electrode was attached to the tooth to be stimulated, and a platinum needle cathodal electrode was inserted in adjacent gingival mucosa. The cathodal and anodal electrodes were moved to the left upper and lower canine, fourth premolar, and first molar teeth for sequential stimulation. Baseline recording of REMP was made for each tooth. Catheters were inserted percutaneously in the infraorbital and mandibular canals. Saline (0.9% NaCl) solution was injected at each catheterized site in 3 control dogs, and chloroprocaine hydrochloride was injected at each catheterized site in 6 test dogs. Each tooth was stimulated every 10 minutes for 90 minutes (test dogs) or every 10 minutes for 30 minutes and at 90 minutes (control dogs), and REMP was recorded. RESULTS: REMP was abolished within 10 minutes in all test dogs, except during stimulation of the lower first molar in 1 dog. In 4 dogs, duration of blockade was less than 90 minutes. The REMP was not restored within 90 minutes for the upper teeth in 1 dog and within 2 hours for all teeth in another dog. At 24 hours, REMP was restored for all teeth except the lower left canine in 1 dog. The REMP was restored for the lower left canine in that dog at 96 hours. The REMP was not abolished at any time in control dogs. CLINICAL IMPLICATIONS: Regional anesthesia of the infraorbital and inferior alveolar nerves may effectively provide analgesia for dental procedures in dogs.

Evaluation of percutaneous gastrostomy as a technique for permanent gastropexy.

OBJECTIVE: This study was designed to evaluate right-sided percutaneous endoscopic gastrostomy (PEG) as a method for creation of a permanent gastropexy. STUDY DESIGN: Percutaneous endoscopic gastrostomy adhesions were evaluated by gross examination and by mechanical testing and the results were compared with those obtained by conventional incisional gastropexy. ANIMALS OR SAMPLE POPULATION: Fourteen mixed-breed dogs. METHODS: Incisional gastropexies were performed on the dogs of group one (N = 7) and PEG tubes were placed in the dogs of group 2 (N = 7). All skin sutures (group 1) and PEG tubes (group 2) were removed on day 14. The animals were maintained for an additional 44 days before euthanasia and immediate necropsy. Gastropexy adhesions were evaluated and collected for biomechanical evaluation using a materials testing machine. RESULTS: The duration of the procedure for group 2 was less (32.86 min +/- 7.65) than for group 1 (56.29 min +/- 8.28). The number of complications was not significantly different between group 1 and group 2 (P = .103). Gastroperitoneal adhesions were present in 7 of 7 dogs in group 1 and 4 of 7 dogs in group 2. The adhesion lengths and widths were significantly lager in dogs in group 1 compared with those in group 2. The adhesions present in group 1 dogs sustained significantly greater tensile loads to failure (61.98 +/- 14.65 N), compared with the adhesions present in group 2 dogs (22.31 +/- 26.87 N). CONCLUSIONS: Right-sided PEG inconsistently formed a weak gastropexy and the procedure was associated with a trend toward greater morbidity than incisional gastropexy. CLINICAL RELEVANCE: Right-sided PEG is not recommended as a means of prophylactic gastropexy.

Comparison of the degree of abdominal adhesion formation associated with chromic catgut and polypropylene suture materials.

OBJECTIVE: To evaluate the histologic pattern and biomechanical properties of adhesions caused by chromic catgut and polypropylene sutures, using an enteropexy model. DESIGN: Enteropexies were created in dogs, using chromic catgut and polypropylene suture. The adhesions associated with the enteropexies were examined histologically and mechanically. ANIMALS: 6 mixed-breed dogs weighing 16 to 20 kg. PROCEDURE: 72 enteropexies were created between the jejunum and abdominal wall. 36 sites were sutured with chromic catgut and 36 were sutured with polypropylene. 3 dogs were euthanatized after 1 week. The remaining dogs were euthanatized after 1 month. Samples of the enteropexy sites were obtained for histologic examination. The remaining sites were mechanically distracted until failure of the enteropexy site or adjacent tissue occurred. RESULTS: Histologic examination of the enteropexy sites did not reveal substantial differences in the degree of inflammation between the 2 suture types at 1 week or 1 month. The degree of inflammation decreased and the maturity of fibrous tissue formed at the enteropexy sites increased for all specimens over time. No statistically significant difference in breaking strength was observed between suture types at 1 week or 1 month. CONCLUSION: In dogs, the formation and strength of intentionally created abdominal adhesions are not increased by use of chromic catgut. CLINICAL RELEVANCE: Selection of chromic catgut suture for use in surgical procedures where adhesions are desired is unwarranted.

Effects of three occlusive dressing materials on healing of full-thickness skin wounds in dogs.

The effects of 3 occlusive dressing materials and a standard, nonadherent dressing material on healing of full-thickness skin defects were evaluated in dogs. Two wounds measuring 2 x 2 cm were created bilaterally (4 wounds/dog) on the dorsolateral aspect of the trunk of 12 Beagles. Wound treatments were evenly distributed between 4 sites, using a Latin square design. Treatments evaluated were: equine amnion (group A), biosynthetic hydrogel dressing (group B), transparent polyethylene sheeting (group T), and a semi-occlusive rayon/polyethylene, nonadherent dressing (group C). Rates of contraction and epithelialization of group-A wounds were significantly greater than those of wounds of groups C, B, and T. On days 14, 21, and 28, mean percentage of wound contraction and mean percentage of total wound healed in group A exceeded those wounds in groups C, B, and T. On day 28, wounds in group A were significantly smaller than wounds in groups B and T, but were not significantly smaller than wounds in group C. All wounds in group A achieved 100% healing during the 28-day study period. Mean time for complete healing of group-A wounds was 21 days. The percentages of wounds completely healed by day 28 for groups B, C, and T were 25, 67, and 25%, respectively. Results indicate that use of equine amnion as an occlusive biological dressing on full-thickness wounds in dogs increases rate of healing.

Androgen receptors in the pelvic diaphragm muscles of dogs with and without perineal hernia.

Levator ani and coccygeus muscle estrogen and androgen receptors were measured in 6, healthy, > or = 5-year-old, noncastrated, male Beagles (controls) and in 24 dogs with perineal hernia. Estrogen and androgen receptor analyses were performed on levator ani and coccygeus muscle specimens obtained from control dogs at the time of castration; contralateral levator ani and coccygeus muscle specimens were assayed 2 months after castration. During herniorrhaphy of dogs with perineal hernia, levator ani (non-castrated, n = 12; castrated, n = 7) and/or coccygeus (noncastrated, n = 5; castrated, n = 4) muscle biopsy specimens were obtained for estrogen and androgen receptor analyses. For estrogen and androgen receptor assays, each muscle biopsy specimen was homogenized in Tris-EDTA-glycerol buffer, and centrifuged at 30,000 x g; extracts were used for binding with ligands: [3H]methyltrienolone (3HR1881) for androgen receptors, and [3H]estradiol-17 beta for estrogen receptors. Extracts were incubated overnight at 0 to 4 C. Nonspecific binding was estimated, using 100-fold concentration of cold ligands. Bound and free hormones were separated, using hydroxylapatite batch assay. Receptor numbers for each tissue were calculated as femtomoles (fmol) per milligram of protein. Quantified data were compared between precastration and postcastration controls, using a paired t-test. One-way ANOVA and Bonferroni post-hoc test were used to compare values for precastration controls, postcastration controls, castrated dogs with perineal hernia, and noncastrated dogs with perineal hernia. Significance was set at P < 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of an ultrasonic Doppler flow detector for determining tissue viability in a dog.

An 8-month-old sexually intact female Boxer was examined because of an almost complete disarticulation of the right thoracic limb at the level of the proximal phalanges. Viability of the tissue distal to the injury was considered questionable. An ultrasonic Doppler flow detector was used to determine that circulation to the portion of the digits distal to the injury had been preserved on the palmar aspect of the foot. Orthopedic repair of the fractures of the third and fourth digits and primary skin closure of the wound was performed. Infection and instability at the fracture sites resulted in pseudoarthrosis and a valgus deformity of the digits distal to the injury. The ultrasonic Doppler flow detector provided a simple noninvasive method for determining tissue viability in the severely traumatized foot of this dog.

Transcutaneous oxygen monitoring for predicting skin viability in dogs.

Transcutaneous oxygen (PO2-TC) monitoring is commonly used in human medicine for evaluating skin viability. The application of transcutaneous monitoring for evaluating skin viability in dogs was investigated. The changes in PO2-TC values were measured from 16 avascular skin flaps created along the lateral hemithoraces of 4 dogs. Transcutaneous oxygen values were serially recorded from the vascular base and avascular apex of each flap for 12 hours after surgery. A single transcutaneous measurement was obtained from each flap base and apex 24 hours after surgery. Serial arterial blood gas analyses were obtained to compare central oxygen values with PO2-TC values. Full-thickness skin biopsy specimens were harvested from the base and apex of each flap 24 hours after surgery. The flaps were observed for 4 days and then excised for histologic examination. A subjective grading scale was used to assess histologic changes. Throughout the 12-hour period and at 24 hours, a statistically significant difference was found between the PO2-TC values for apices and bases of the flaps. The mean PO2-TC for all bases was 90.9 mm of Hg +/- 3.3 SEM, and the mean PO2-TC for all apices was 21.2 mm of Hg +/- 1.8 SEM. The mean regional perfusion index (apex PO2-TC/base PO2-TC) was 0.23 +/- 0.02. The subjective numbers assigned to the biopsy specimens were statistically evaluated by using a paired Student's t test and a Wilcoxon signed-rank test. A significant difference was found between the numbers for the collective bases and apices with both tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of skin viability in dogs, using transcutaneous carbon dioxide and sensor current monitoring.

Transcutaneous oxygen monitoring is commonly used in human beings to assess skin viability. Little attention has been directed toward the use of transcutaneous carbon dioxide (PCO2-TC) monitoring for the same purpose. The application of PCO2-TC monitoring for evaluating skin viability in dogs was investigated. The changes in PCO2-TC and local power reference (LPR) values were measured from 16 skin flaps created along the lateral hemithoraces of 4 dogs. Transcutaneous PCO2 and LPR values were serially recorded from the base and apex of each flap for 12 hours. A single measurement was obtained from each flap base and apex 24 hours after surgery. Arterial blood gas analyses were obtained to compare central PCO2 values with peripheral skin PCO2 values. The flaps were observed for 4 days and then harvested for histologic examination. Full-thickness skin biopsy specimens were obtained 24 hours after surgery and when the flaps were harvested to evaluate the viability of the apex and base of the flaps. A subjective grade was assigned to all skin biopsy specimens during histologic examination. For all measurements, a significant difference was found between the PCO2-TC values for apices and bases of the flaps. The mean PCO2-TC for all bases was 52.66 mm of Hg +/- 2.24 (SEM), and the mean PCO2-TC for all apices was 106.4 mm of Hg +/- 2.44. The regional carbon dioxide index (apex PCO2-TC/base PCO2-TC) was 2.02. A significant difference was not found between the LPR values for bases and apices.(ABSTRACT TRUNCATED AT 250 WORDS)

Perineal hernia in a cougar.

An 8-week-old female cougar with a history of acute perineal swelling was determined to have a perineal hernia. The hernia was repaired with the conventional suture technique. This case represents an unusual perineal hernia, which may have been congenital.