Photodynamic therapy for the treatment of intranasal tumors in 3 dogs and 1 cat

Three dogs and 1 cat with intranasal tumors were treated with pyropheophorbide-a-hexyl ether-based photodynamic therapy (PDT). PDT was well tolerated by all the animals, and no adverse effects from photosensitizer injection, such as cutaneous photosensitization, were observed. Facial swelling was observed in all animals after each PDT treatment but resolved spontaneously within 72 hours after treatment. All animals had a decrease in severity of epistaxis, frequency of sneezing, and amount of nasal discharge after PDT. Clinical signs were controlled for variable time, although long-term responses were comparable with radiation therapy in 2 animals. This small case series demonstrates another application for PDT in veterinary medicine. On the basis of these findings. further studies are warranted to define the role of PDT in the management of intranasal tumors in dogs and cats.     

OSTEOSARCOMA OF THE PATELLA WITH PULMONARY METASTASES IN A DOG

A 6-year-old neutered male Rottweiler was examined for a progressive right pelvic limb lameness. In radiographs of the right stifle, there was an osteolytic lesion with irregular new bone formation along the cranial aspect of the patella consistent with an aggressive bone lesion. In thoracic radiographs, there were multiple soft tissue nodular opacities throughout the lung fields, consistent with pulmonary metastases. Microscopically, fine needle aspirate samples from the right patella contained pleomorphic spindle cells with cytologic features of osteosarcoma. The presence of pulmonary metastases at the time of initial diagnosis in the dog described herein suggests that osteosarcoma of the patella has the potential for similar aggressive biologic behavior as that seen in dogs with appendicular osteosarcoma.     

Preclinical study in cats of the pro-photosensitizer 5-aminolevulinic acid

OBJECTIVE: To determine whether feline cells were able to convert 5-aminolevulinic acid (ALA) to protoporphyrin IX (PpIX) in vivo and in vitro, whether i.v. administration of ALA to healthy cats resulted in adverse effects, and whether PpIX accumulated in a squamous cell carcinoma (SCC) of a cat. ANIMALS: 4 healthy adult cats and 1 adult cat with a cutaneous SCC. PROCEDURE: In vitro production of PpIX was determined by incubating Crandell feline kidney cells with ALA. Effects of ALA administration and in vivo production of PpIX were determined by administering ALA (100, 200, or 400 mg/kg of body weight) to healthy cats and collecting skin biopsy specimens for up to 24 hours after drug administration. Blood samples were collected for CBC and serum biochemical analyses, and necropsies were performed. Accumulation of PpIX in a SCC was determined by treating a cat with a facial SCC with ALA and collecting specimens of the tumor and adjacent grossly normal skin. RESULTS: Incubation of ALA with feline cells resulted in time- and dose-dependent cytoplasmic accumulation of PpIX in vitro. After i.v. ALA administration, PpIX was detected in all tissues examined, with the highest fluorescence intensity in epithelia and in squamous cell carcinoma. The tumor-to-skin fluorescence intensity ratio was 5. All cats developed hepatotoxicoses. CONCLUSIONS AND CLINICAL RELEVANCE: Results from this limited number of cats suggest that ALA may be a useful photosensitizer in cats, but that doses > 100 mg/kg, i.v., may not be safe.     

Clinical outcome and associated diseases in dogs with leukocytosis and neutrophilia: 118 cases (1996-1998)

OBJECTIVE: To describe diseases, prognosis, and clinical outcomes associated with leukocytosis and neutrophilia in dogs. DESIGN: Retrospective study. ANIMALS: 118 dogs with leukocytosis and neutrophilia. PROCEDURE: Medical records from 1996 to 1998 were examined for dogs with WBC > or = 50,000 cells/microliter and neutrophilia > or = 50%. Signalment, absolute and differential WBC counts, body temperature, clinical or pathologic diagnosis, duration and cost of hospitalization, and survival time were reviewed. RESULTS: Mean age was 7.7 years, WBC count was 65,795 cells/microliter, and absolute neutrophil count was 53,798 cells/microliter. Mean duration of hospitalization was 7.4 days and cost of hospitalization was $2,028.00. Forty (34%) dogs were febrile, and 73 (62%) dogs died. Overall median survival time was 17 days. Dogs with neoplasia or fever were more likely to die than dogs that were hospitalized or had systemic or local infections. CLINICAL IMPLICATIONS: Leukocytosis and neutrophilia were associated with high mortality rate and have prognostic value. Given the mean duration and cost of hospitalization, frank discussion with an owner at first recognition of leukocytosis and neutrophilia may be warranted.     

Influence of asparaginase on a combination chemotherapy protocol for canine multicentric lymphoma

Combination chemotherapy is superior to single-agent chemotherapy for treating canine lymphoma, but the effect of each drug on efficacy remains unknown. By comparing 34 dogs treated with a modified cyclophosphamide, vincristine, prednisone (COP) chemotherapy protocol and 42 dogs given asparaginase in the induction phase of the same protocol, the effect of asparaginase on the chemotherapeutic protocol was determined. Both groups were compared based on clinical response at 2 weeks and 6 weeks, and on the progression-free interval. Asparaginase did not significantly increase the likelihood of a clinical remission or prolong the initial progression-free interval in the dogs studied.     

Concurrence between clinical and pathologic diagnoses in a veterinary medical teaching hospital: 623 cases (1989 and 1999)

OBJECTIVE: To determine whether there was a decline in the percentage of dogs undergoing necropsies and whether there was substantial agreement or disagreement between clinical and pathologic diagnoses. DESIGN: Retrospective study. ANIMALS: 623 dogs. PROCEDURE: Medical records of hospitalized dogs that died or were euthanatized and necropsied at a veterinary teaching hospital in 1989 and 1999 were reviewed. Clinical and pathologic diagnoses were recorded and compared. RESULTS: There was a significant decline in the necropsy rate of hospitalized dogs that died or were euthanatized in 1999, compared with 1989. In both 1989 and 1999, there was disagreement between the clinical and pathologic diagnoses in approximately a third of the cases. CONCLUSIONS AND CLINICAL RELEVANCE: Despite improved diagnostic methods, the accuracy of diagnosis did not improve significantly in 1999, compared with 1989. Necropsy is the best method to assess overall diagnostic accuracy. Increased availability of teaching funds may promote efforts to have necropsies performed in veterinary teaching hospitals.     

Neodymium:Yttrium-aluminum-Garnet (Nd:YAG) laser ablation of an obstructive urethral polyp in a dog

A miniature schnauzer presented for evaluation of a persistent lower urinary tract obstruction. Further examination revealed that the dog had developed an obstructive, inflammatory polyp secondary to a long-standing urinary tract infection. The polyp was located within the proximal urethra and interfered with normal voiding. The polyp was visualized using flexible endoscopy and then was successfully ablated using the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. The Nd:YAG laser is a potentially useful tool for treating various lesions of the lower urinary tract.     

Phototoxic effects of 635-nm light on canine transitional cell carcinoma cells incubated with 5-aminolevulinic acid

OBJECTIVE: To determine whether transitional cell carcinoma (TCC) cells incubated in media containing 5-aminolevulinic acid (ALA) would produce sufficient protoporphyrin IX (PpIX) to cause lethal phototoxic effects when exposed to 635-nm light. SAMPLE POPULATION: Canine TCC cells (K9TCC). PROCEDURE: Cultured K9TCC cells were exposed to graded doses of ALA, and PpIX concentrations were determined. Cells then were exposed to various doses of 635-nm light from a diode laser, and cell viability was assayed. RESULTS: Production of PpIX was dependent on time and dose of ALA. The K9TCC cells incubated with ALA produced sufficient PpIX to cause lethal phototoxic effects when exposed to 635-nm light. Phototoxic effects were dependent on time and dose of ALA. Increasing laser power density and energy density decreased cell survival. CONCLUSIONS AND CLINICAL RELEVANCE: ALA is an effective photosensitizer for in vitro photodynamic treatment of K9TCC cells. Further studies are warranted to assess the safety and efficacy of ALA as a photosensitizer for use in treating dogs with TCC. Impact for Human Medicine-On the basis of this study, dogs with TCC may be useful in the development of protocols for ALA-based photodynamic therapy of humans affected with muscle-invasive bladder cancer.