Stereotactic body radiation therapy for treatment of soft tissue sarcomas in 35 dogs.

OBJECTIVE: To describe response rate, tumor progression, patient survival times, prognostic factors associated with tumor progression and patient survival times, and radiation toxicoses (acute and latent) in dogs treated with curative-intent stereotactic body radiation therapy (SBRT) for soft tissue sarcomas (STS). ANIMALS: 35 client-owned dogs with STS treated with curative-intent SBRT between October 2011 and May 2017. PROCEDURES: Medical records were reviewed to identify dogs that underwent SBRT. Dogs with oral tumors, hemangiosarcoma, or histiocytic sarcoma were excluded. Data collected included patient-, STS-, and SBRT-related information, including follow-up information pertaining to tumor progression and patient survival time for ≥ 6 months, unless tumor progression or patient death occurred sooner. RESULTS: Objective measurements allowing for evaluation of tumor response were available for 28 dogs, of which 13 (46%) had either a partial (10/28 [36%]) or complete (3/28 [11%]) response. Twenty-four dogs died, and the medians for progression-free survival time, time to progression of disease, overall survival time, and disease-specific survival time were 521, 705, 713, and 1,149 days, respectively. Low histologic grade and extremity locations of STSs were positive prognostic factors for patient survival times. Acute adverse effects were limited to skin, and 1 dog underwent limb amputation because of a nonhealing wound. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that SBRT for STS was well tolerated in most dogs and provided local tumor control. Additional studies are needed to determine the best SBRT protocol for treatment of STSs in dogs.

Outcomes and adverse effects associated with stereotactic body radiation therapy in dogs with nasal tumors: 28 cases (2011-2016).

OBJECTIVE To assess outcomes, factors associated with survival time, and radiation-induced toxicoses in dogs treated for nasal tumors with curative-intent stereotactic body radiation therapy (SBRT). DESIGN Retrospective case series. ANIMALS 28 client-owned dogs. PROCEDURES By use of a 6-MV linear accelerator, dogs were treated with SBRT (3 consecutive-day fractions of 9 or 10 Gy or once with 1 fraction of 20 Gy). Data regarding adverse effects, outcomes, and survival times were obtained from the medical records. RESULTS The median survival time to death due to any cause was 388 days. Of the 24 dogs known to be dead, 14 (58%) died or were euthanized because of local disease progression. Acute radiation-induced adverse effects developed in the skin (excluding alopecia) in 26% (6/23) of dogs and in the oral cavity in 30% (7/23) of dogs. Acute ocular adverse effects included discharge in 26% (6/23) of dogs and keratoconjunctivitis sicca in 4% (1/23) of dogs. Among the 22 dogs alive at > 6 months after SBRT, 4 (18%) developed a unilateral cataract; 4 (18%) developed other complications that may have been late-onset radiation toxicoses (excluding leukotrichia and skin hyperpigmentation). CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that dogs treated with SBRT had outcomes comparable to those reported for dogs with nasal carcinomas and sarcomas that undergo conventionally fractionated radiation therapy. Administration of SBRT was associated with a comparatively lower frequency of acute radiation-induced adverse effects. For SBRT and conventionally fractionated radiation therapy, the frequencies of serious late-onset adverse effects appear similar.

Retrospective survey of owners' experiences with palliative radiation therapy for pets.

OBJECTIVE To describe animal owners' experiences with palliative radiation therapy (PRT) of pets and identify factors influencing satisfaction with their pets' treatment. DESIGN Retrospective, cross-sectional study. SAMPLE 118 owners of dogs, cats, or rabbits. PROCEDURES Medical records were searched to identify animals that underwent PRT between 2004 and 2013. Signalment, tumor-related data, and outcome information were recorded. Owners completed an electronic survey assessing satisfaction with treatment (ie, satisfaction with the decision for their pet to undergo PRT and indication that they would choose PRT for their pet again), expectations regarding PRT, and perceptions of their pets' quality of life (QOL) and signs of discomfort from acute adverse radiation effects. Additional data regarding practical aspects of treatment, pet death, communications with veterinarians, and owner demographics were collected. Variables were tested for association with measures of owner satisfaction. RESULTS 92 of 116 (79%) owners were satisfied with the decision to have their pets undergo PRT. Most (92/118 [78%]) owners reported their pet's QOL improved after PRT; these owners were significantly more likely to be satisfied than those who did not report improved QOL. Owners who perceived their pets had discomfort from adverse radiation effects (38/116 [33%]) were significantly less likely to be satisfied than owners who did not report this observation. Measures of satisfaction were not associated with patient survival time. Twenty-one of 118 (18%) owners indicated they expected PRT would cure their pet's tumor. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that short life expectancy should not deter recommendation of PRT for pets. Protocols that minimize risk of acute adverse effects may be advantageous. Veterinarians should attempt to ensure that owners understand the goals of PRT.

Clinical outcome in dogs with nasal tumors treated with intensity-modulated radiation therapy.

Intensity-modulated radiation therapy (IMRT) is a valuable tool in human radiation oncology, but information on its use in veterinary medicine is lacking. In this study, 12 dogs with nasal tumors were treated with IMRT at a median radiation dose of 54 Gy. Patient survival times and frequency and severity of side effects on ocular structures, oral mucosa, and skin were recorded. Eight dogs (67%) had resolution of clinical signs during radiation therapy. Median overall survival time was 446 d with a 50% 1-year and a 25% 2-year survival rate. Minimal grade 2 or 3 acute skin toxicity, no grade 2 or 3 late skin toxicity, and no grade 2 or 3 toxicity to oral mucosa or the eye opposite the tumor were identified in the dogs treated with IMRT in this study. The ipsilateral eye could not be routinely spared due to its proximity to the tumor.

Cardiac troponins as indicators of acute myocardial damage in dogs.

Cardiac troponin I (cTnI) and T (cTnT) have a high sequence homology across phyla and are sensitive and specific markers of myocardial damage. The purpose of this study was to evaluate the Cardiac Reader, a human point-of-care system for the determination of cTnT and myoglobin, and the Abbott Axsym System for the determination of cTnI and creatine kinase isoenzyme MB (CK-MB) in healthy dogs and in dogs at risk for acute myocardial damage because of gastric dilatation-volvulus (GDV) and blunt chest trauma (BCT). In healthy dogs (n = 56), cTnI was below detection limits (<0.1 microg/L) in 35 of 56 dogs (reference range 0-0.7 microg/L), and cTnT was not measurable (<0.05 ng/mL) in all but 1 dog. At presentation, cTnI, CK-MB, myoglobin, and lactic acid were all significantly higher in dogs with GDV (n = 28) and BCT (n = 8) than in control dogs (P < .001), but cTnT was significantly higher only in dogs with BCT (P = .033). Increased cTnI or cTnT values were found in 26 of 28 (highest values 1.1-369 microg/L) and 16 of 28 dogs (0.1-1.7 ng/mL) with GDV, and in 6 of 8 (2.3-82.4 microg/L) and 3 of 8 dogs (0.1-0.29 ng/mL) with BCT, respectively. In dogs suffering from GDV, cTnI and cTnT increased further within the first 48 hours (P < .001). Increased cardiac troponins suggestive of myocardial damage occurred in 93% of dogs with GDV and 75% with BCT. cTnI appeared more sensitive, but cTnT may be a negative prognostic indicator in GDV. Both systems tested seemed applicable for the measurement of canine cardiac troponins, with the Cardiac Reader particularly suitable for use in emergency settings.

Outcome following surgical removal of nonvisceral soft tissue sarcomas in cats: 42 cases (1992-2000).

OBJECTIVE: To identify factors associated with outcome of cats with nonvisceral soft tissue sarcomas treated with surgery alone. DESIGN: Retrospective study. ANIMALS: 42 cats. PROCEDURE: Medical records were reviewed for clinically relevant data, and histologic samples were examined. Follow-up information was obtained by means of physical examination or through telephone conversations with referring veterinarians and owners. The Kaplan-Meier method was used to construct survival curves. RESULTS: Median survival time was 608 days (range, 85 to 2,291 days), although 24 cats were still alive at the time of the study. Tumor size (ie, diameter) and histologic type were significantly associated with survival time. Median survival time was significantly longer in cats with tumors that were < 2 cm in diameter, compared with cats in which tumors were > 2 cm. Median survival times for cats with a fibrosarcoma or nerve sheath tumor were significantly longer than median time for cats with a malignant fibrous histiocytoma. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that tumor size and type are significantly associated with survival time in cats with nonvisceral soft tissue tumors.

Efficacy of cobalt-60 radiation therapy for the treatment of nasal cavity nonkeratinizing squamous cell carcinoma in the dog.

The purposes of this study were to evaluate the efficacy of cobalt-60 radiotherapy in the treatment of nonkeratinizing squamous cell carcinoma of the nasal cavity in dogs and to compare this treatment group to historical controls. Six dogs with histopathologically confirmed nasal cavity nonkeratinizing squamous cell carcinoma were treated with cobalt-60 radiotherapy to a total dose of either 63 Gy or 54 Gy. Overall survival times ranged from 30 days to 330 days, with a median survival time of 165 days. Nasal cavity nonkeratinizing squamous cell carcinoma in the dog is an aggressive tumor that responds poorly to radiotherapy.

Evaluation of the in vitro cytotoxicity of mitoxantrone following repeated freeze-thaw cycles.

Mitoxantrone, an antineoplastic anthracycline antibiotic with a wide range of veterinary applications, was developed as a less cardiotoxic alternative to doxorubicin, a related compound in this family of chemotherapy agents. Mitoxantrone has not gained widespread acceptance in the veterinary community, primarily due to its cost and single-dose packaging in a volume that exceeds the needs of the majority of veterinary cancer patients. The in vitro cytotoxicity of mitoxantrone following repeated freeze-thaw cycles was evaluated to determine whether long-term storage at -20 degrees C resulted in decreased efficacy. The drug was frozen between treatment cycles to minimize the risk of bacterial contamination because it is supplied as a preservative-free solution. Results indicated mitoxantrone maintained its cytotoxicity against cancer cells in culture following multiple freeze-thaw cycles spanning at least 12 months.

MOPP chemotherapy for treatment of resistant lymphoma in dogs: a retrospective study of 117 cases (1989-2000).

The purpose of this retrospective study was to evaluate the efficacy and toxicity of the MOPP chemotherapy protocol (mechlorethamine, vincristine, procarbazine, and prednisone) as a rescue regimen in dogs with lymphoma. One hundred seventeen dogs that had resistance to previously administered chemotherapy were evaluated. Before treatment with MOPP, all dogs received a median of 6 chemotherapy drugs for a median duration of 213 days. Thirty-one percent (36 of 117) had a complete response (CR) to MOPP for a median of 63 days, and 34% (40 of 117) had a partial response (PR) for a median of 47 days. Sixteen percent (19 of 117) had stable disease (SD) for a median of 33 days. Predictors for response to MOPP were not identified. Gastrointestinal (GI) toxicity occurred in 28% (33 of 117) of the dogs, and 13% (15 dogs) required hospitalization. Five dogs developed septicemia, and 2 died as a result. MOPP was an effective treatment for dogs with resistant lymphoma and was well tolerated by the majority of affected dogs.