COMPARISON OF TWO COARSE FRACTIONATED RADIATION PROTOCOLS FOR THE MANAGEMENT OF CANINE PITUITARY MACROTUMOR: AN OBSERVATIONAL STUDY OF 24 DOGS.

Radiotherapy is a commonly used treatment for pituitary macrotumors in dogs, but the optimum protocol has not been established. Twenty four dogs with MRI confirmed pituitary macrotumors were treated with one of two radiotherapy protocols. Twelve dogs were treated with 10 fractions of 3.8 Gy/fraction on a "Monday-Wednesday-Friday" schedule, the remaining 12 with five "once-a-week" protocols (1 × 5 Gy, followed by 4 × 8.25 Gy) to a total dose of 38 Gy. The overall median survival time for all dogs was 235 days (range 28-1,328), dogs treated with 10 fractions had a median survival time of 961 days (range 28-1,328) compared to 182 days (range 42-507) in the five-fraction group (P = 0.006). Clinical improvement was found in both groups, and no significant side effects were noted in either group. These results suggest that a "Monday-Wednesday-Friday" schedule may improve survival times, as compared to a "once-a-week" protocol. As this study was of an observational nonrandomized nature, future work is necessary to establish whether more highly fractionated protocols or different total doses will further improve outcome.

Impact of palliative-intent radiotherapy with or without chemotherapy on lameness in flat coat retrievers with localised periarticular histiocytic sarcoma - a retrospective cohort, single institution study.

Histiocytic sarcoma (HS) is a common tumour in flat coat retrievers (FCRs) often affecting periarticular tissues and joints. Palliative-intent radiotherapy, seeks to achieve local tumour control, pain relief and improve limb function. However, the effect of palliative-intent radiotherapy on analgesic levels of dogs with localised HS has not been studied. We hypothesised that palliative-intent radiotherapy could improve lameness in dogs affected by localised HS. This study aimed to assess the impact of palliative-intent radiotherapy on lameness of FCRs with localised HS. A retrospective cohort single institution study was performed. Medical records of FCR dogs with HS that received external beam radiotherapy between 2003 and 2022 were reviewed and included demographic, staging, severity of baseline lameness, therapeutic management and outcome data. Descriptive statistics, McNemar's chi-squared test, Fisher's exact test and Kaplan-Meier analysis were used for statistical analysis. Thirty-nine dogs were included with a median age of 7.2 years, 25 were male and 14 were female. HS was most commonly located in the forelimb (29 dogs, 74.3%), affecting the shoulder joint (19 dogs, 48.7%). Staging was performed in all 39 dogs with 22 (56.4%) dogs having localised HS, six (15.3%) dogs had localised HS with node metastasis and 11 (28.2%) dogs had localised HS with systemic metastasis. All dogs received palliative-intent hypo-fractionated radiation therapy, 32 (82%) dogs showed improvement in lameness. In conclusion, palliative intent radiation treatment has an analgesic effect reducing lameness or clinical signs associated with affected tumour-bearing joints.

Vinblastine/prednisolone chemotherapy leads to hematological toxicity in dogs with high-grade or metastatic mast cell tumors.

OBJECTIVE: To determine the myelosuppressive effects/hematological toxicities, other general toxicities, and when these occur during vinblastine/prednisolone chemotherapy in dogs bearing high-grade or metastatic cutaneous/subcutaneous mast cell tumors (MCTs). METHODS: Medical records were retrospectively reviewed between November 1, 2016, and March 1, 2023. Thirty client-owned dogs with histopathologically confirmed cutaneous high-grade MCTs/metastatic subcutaneous MCTs and that subsequently completed a 12-week vinblastine/prednisolone chemotherapy protocol were included. Hematology was assessed before commencing chemotherapy and before each vinblastine treatment. The effect of each treatment upon hematological values was evaluated. Measured outcomes included the type, frequency, and severity of hematological and other more general toxicities. RESULTS: 24 of 30 dogs experienced at least 1 hematological toxicity, 6 experienced gastrointestinal toxicity, and 4 experienced lethargy. The most common toxicity was anemia (15/30 [50%]), with 93.3% (14/15 dogs) classified as Veterinary Cooperative Oncology Group-Common Terminology Criteria for Adverse Events grade I and 6.6% (1/15) classified as grade II. The second most common toxicity was neutropenia (14/30 [46.6%]), with 71.4% (10/14) classified as grade I and 28.6% (4/14) as grade III. The least common hematological toxicity was thrombocytopenia (4/30 [13%]), all grade I. Neutropenia mainly occurred during weeks 2 and 3; however, there was no significant decrease in neutrophil count relative to baseline. Neutrophil count increased and Hct decreased during weeks 6 to 12 of treatment when compared to baseline. No change in platelet count was observed. CLINICAL RELEVANCE: Vinblastine/prednisolone chemotherapy leads to hematological toxicity; however, this was mostly low-grade and did not require major intervention. Vinblastine/prednisolone chemotherapy is well tolerated in dogs bearing high-grade or metastatic MCTs.

Clinical and low-field MRI characteristics of injection site sarcoma in 19 cats.

Magnetic resonance imaging (MRI) has been recommended for staging and surgical planning in cats with injection site sarcomas (ISS). The purpose of this retrospective study was to describe low-field MRI characteristics of confirmed injection site sarcomas in a group of cats. Low-field MR images, thoracic radiographs, histopathology findings, and medical records of cats that fulfilled histological criteria of injection site sarcoma were retrieved and reviewed retrospectively. Presence or absence of tumor mineralization and pulmonary metastases were recorded from thoracic radiographs. Characteristics recorded from low-field MRI studies included tumor number, volume (ellipsoid method), intensity relative to surrounding musculature, homogeneity, regions of signal void (mineralization) or cavitation, degree and pattern of contrast enhancement, tumor margination, presence of a peripheral T2W hyperintense zone, and bone contact. A total of 19 cats met inclusion criteria. Cats with multiple tumors were more likely to have had previous excisional biopsy, and were less likely to undergo definitive surgery. All tumors were hyperintense relative to surrounding musculature on T1W and T2W images. Larger tumors were more likely to exhibit mineralization (P < 0.05). Tumor volume could not predict tumor-free margins at definitive surgery. The majority of tumors showed moderate to marked heterogeneous contrast enhancement. Infiltrative margins and the presence of a peripheral T2W hyperintense zone were more prevalent following excisional biopsy, while cavitation was more prevalent following incisional biopsy. Findings indicated that low-field MRI characteristics of injection site sarcoma may vary widely and may be affected by prior incisional or excisional biopsy.

Sarcoma Predisposition in Dogs with a Comparative View to Human Orthologous Disease.

Sarcomas are malignant tumors arising from the embryonic mesodermal cell lineage. This group of cancers covers a heterogenous set of solid tumors arising from soft tissues or bone. Many features such as histology, biological behavior and molecular characteristics are shared between sarcomas in humans and dogs, suggesting that human sarcoma research can be informative for canine disease, and that dogs with sarcomas can serve as relevant translational cancer models, to aid in the understanding of human disease and cancer biology. In the present paper, risk factors for the development of sarcoma in dogs are reviewed, with a particular focus on recent advances in clinical genetics, and on the identification of simple and complex genetic risk factors with a comparison with what has been found in human orthologous disease.

T-cell lymphoma involving the rectum of a dog.

A mediastinal mass was diagnosed in a 7-year-4-month-old neutered female mixed breed dog following a 3-week history of lethargy, hyporexia and pyrexia. Bi-cavitary imaging, needle aspirate cytology and flow cytometry confirmed WHO clinical stage IVb, intermediate to large T-cell lymphoma involving the mediastinum, liver and spleen. The dog initially responded to a multidrug chemotherapy protocol but clinical deterioration occurred 3 months later. The dog presented with anorexia, vomiting and diarrhoea, associated with marked faecal tenesmus and haematochezia, initially believed by the primary care practitioner to be related to chemotherapy toxicity. However, rectal examination revealed multiple sessile and pedunculated masses. Further diagnostic imaging, cytology and flow cytometry confirmed progressive disease, including T-cell lymphoma of the rectum. Histology and immunohistochemistry confirmed an infiltrate of intermediate-sized CD3-positive neoplastic cells that expanded the rectal mucosa. Rectal lymphoma is uncommon in dogs and previous cases have been B cell in origin. In this report we describe the clinical presentation and macro- and microscopic findings of a case of canine T-cell lymphoma involving the rectum.

Effect of pituitary-dependent hypercortisolism on the survival of dogs treated with radiotherapy for pituitary macroadenomas.

BACKGROUND: Radiotherapy (RT) is an effective treatment for dogs presented with neurologic signs caused by pituitary tumors. However, its impact on the outcome of concurrent pituitary-dependent hypercortisolism (PDH) is controversial. OBJECTIVES: Determine whether dogs with PDH have longer survival after pituitary RT compared with dogs with nonhormonally active pituitary masses and to evaluate whether clinical, imaging, and RT variables affect survival. ANIMALS: Ninety-four dogs divided into 2 groups: PDH and non-PDH, based on the presence of hypercortisolism. Forty-seven dogs were allocated to the PDH group and 47 to the non-PDH group. METHODS: Retrospective cohort study in which clinical records of dogs undergoing RT for pituitary macroadenomas between 2008 and 2018 at 5 referral centers were retrospectively evaluated. RESULTS: Survival was not statistically different between PDH and non-PDH groups (median survival time [MST], 590 days; 95% confidence interval [CI], 0-830 days and 738 days; 95% CI, 373-1103 days, respectively; P = .4). A definitive RT protocol was statistically associated with longer survival compared with a palliative protocol (MST 605 vs 262 days, P = .05). The only factor statistically associated with survival from multivariate Cox proportional hazard analysis was total radiation dose (Gy) delivered (P < .01). CONCLUSIONS AND CLINICAL IMPORTANCE: No statistical difference in survival was identified between the PDH and non-PDH groups, and longer survival was associated with higher Gy delivered.

Patterns of nodal metastases, biological behaviour and prognosis of canine mast cell tumours of the pinna: A multi-institutional retrospective study.

Canine cutaneous mast cell tumours (cMCTs) of the pinna have been associated with an aggressive biological behaviour, although data remain scarce. The knowledge acquired over the past years on histologic gradings, and the value of lymph node (LN) staging, may help in better characterizing this anatomical presentation. The first aim was to describe the frequency, location, and histologic appearance of LN metastases in cMCT of the pinna. A second aim was to evaluate prognosis. Medical records of dogs with cMCT of the pinna, that underwent tumour and sentinel (SLN) or regional LN (RLN) excision, were reviewed. The influence of potential prognostic variables on time to progression (TTP) and tumour-specific survival (TSS) was investigated. Thirty-nine dogs were included: 19 (48.7%) had Kiupel high-grade (K-HG) and 20 (51.3%) had low-grade (K-LG) MCTs. Eighteen (46.1%) dogs underwent SLN mapping: the superficial cervical LN was at least one of SLN in 17 (94.4%) cases. Twenty-two (56.4%) dogs had LN metastases; the superficial cervical LN was always involved. On multivariable analysis, only K-HG was associated with increased risk of progression (p = .043) and tumour-related death (p = .021). Median TTP and TSS were 270 and 370 days in K-HG, respectively; these were not reached in dogs with K-LG tumours (p < .01). cMCTs of the pinna are often K-HG and are also associated with a higher frequency of LN metastasis; however, we confirmed the independent prognostic value of histologic grading. A multimodal treatment may lead to favourable long-term outcome. Moreover, the superficial cervical LN is most often the SLN.

Multimodal Treatment of a Canine Lingual Melanoma Using a Combination of Immunotherapy and a Tyrosine Kinase Inhibitors.

A 9-year-old female neutered Miniature Schnauzer was diagnosed with a lingual malignant melanoma on the basis of incisional biopsy and histopathology. The patient was initially given a guarded prognosis of a few months' survival as surgical treatment options were declined by the owner. In order to control the disease a combination treatment of immunotherapy and tyrosine kinase inhibitors was initiated. The mass showed a marked and sustained reduction in size, whilst preserving quality of life for the patient, with a survival at the time of writing of 15 months since diagnosis. This experience suggests that combination therapy for oral malignant melanoma using immunotherapy and tyrosine kinase inhibitors may be successful in some patients and warrants further investigation.

Comparison of the Clinical Characteristics of Histiocytic Sarcoma in Bernese Mountain Dogs and Flat-Coated Retrievers.

Histiocytic sarcoma (HS) is an aggressive malignant tumor of histiocytes, which can affect almost any organ in the body and is characterized by a broad array of tumor locations and clinical presentations. So far, no complete overview exists of the array of clinical aspects of HS in specific dog breeds in large groups. Therefore, we investigated the clinical characteristics of HS in a population of Bernese Mountain Dogs (BMD; n = 365) and Flat-Coated Retrievers (FCR; n = 289), which are two of the most affected dog breeds. Cases were selected from databases from different pathology services, and clinical information was retrospectively collected for each case. Localized HS was reported significantly more frequently in the FCR (60.6%) than in the BMD (39.2%), and disseminated HS was recorded significantly more frequently in the BMD (60.8%) than in the FCR (39.4%). Lameness was seen more often in FCR than in BMD, and the vast majority (78.1%) of LHS leading to lameness was located in the front legs in the FCR, while in the BMD, there was a more even distribution. BMD had significantly more often leukocytosis and thrombocytopenia, even corrected for the type of HS, than FCR. No significant difference in the frequency of anemia was recorded between BMD and FCR. In those dogs in which blood examination was performed, hypercalcemia was diagnosed in 15 BMD, while none of the FCR had hypercalcemia. The new information provided in this study can aid the diagnostic process and allow for prompt treatment recommendations.

Serum amyloid A and other clinicopathological variables in cats with intermediate- and large-cell lymphoma.

OBJECTIVES: Serum amyloid A (SAA) concentrations are increased in cats with lymphoma vs healthy cats; however, the association between SAA concentrations and prognosis in cats with lymphoma is unclear. The aim of this study was to evaluate if SAA concentrations were different in cats with nasal vs non-nasal lymphoma, if SAA concentrations are prognostic in patients treated with high-dose chemotherapy and if SAA concentrations are correlated with other clinicopathological variables. METHODS: Cats diagnosed with intermediate- or large-cell lymphoma between 2012 and 2022 with SAA concentration data available were included. Associations between tumour site (nasal vs non-nasal), stage, response to treatment and SAA concentration were evaluated using non-parametric statistics. Associations between SAA concentrations and stage with survival time were evaluated using Cox regression analysis. Patients with nasal tumours and those not receiving high-dose chemotherapy were excluded from the survival analyses. RESULTS: Thirty-nine cats were included. Median SAA concentrations were significantly higher in non-nasal compared with nasal lymphoma (42 µg/ml [range <0.3-797] vs <0.3 µg/ml [range <0.3-0.9]; P = 0.026). SAA concentrations did not correlate with tumour stage. Median survival time for patients with non-nasal tumour and undergoing chemotherapy was 49 days (range 2-1726). Responders had a better median survival time than non-responders (273 days [range 43-1728] vs 39 days [range 2-169]; P <0.001), whereas SAA concentrations were not associated with survival time. Lower haematocrit at presentation was associated with a reduced median survival time (P = 0.007). CONCLUSIONS AND RELEVANCE: In the population examined, no correlation between serum concentration of SAA and prognosis in patients with lymphoma was identified, while low haematocrit and lack of response to treatment were both found to be associated with survival time. SAA concentrations were elevated in patients with non-nasal lymphoma vs patients with tumours confined to the nasal cavity.

Repurposing Drugs in Small Animal Oncology.

Repurposing drugs in oncology consists of using off-label drugs that are licensed for various non-oncological medical conditions to treat cancer. Repurposing drugs has the advantage of using drugs that are already commercialized, with known mechanisms of action, proven safety profiles, and known toxicology, pharmacokinetics and pharmacodynamics, and posology. These drugs are usually cheaper than new anti-cancer drugs and thus more affordable, even in low-income countries. The interest in repurposed anti-cancer drugs has led to numerous in vivo and in vitro studies, with some promising results. Some randomized clinical trials have also been performed in humans, with certain drugs showing some degree of clinical efficacy, but the true clinical benefit for most of these drugs remains unknown. Repurposing drugs in veterinary oncology is a very new concept and only a few studies have been published so far. In this review, we summarize both the benefits and challenges of using repurposed anti-cancer drugs; we report and discuss the most relevant studies that have been previously published in small animal oncology, and we suggest potential drugs that could be clinically investigated for anti-cancer treatment in dogs and cats.

Expression of Phosphorylated Signal Transducer and Activator of Transcription 3 and its Prognostic Significance in Canine Anal Sac Adenocarcinoma.

Prognostication in canine anal sac adenocarcinomas (ASACs) is difficult due to conflicting evidence regarding metastatic rates and median survival times (MSTs). The transcription factor signal transducer and activator of transcription 3 (STAT3) is a prognostic predictor in several human cancers. The aim of this retrospective study was to assess STAT3 expression in ASACs and to explore its association with clinical presentation and outcome. We hypothesized that STAT3 expression would distinguish tumours with early versus late metastasis. Records from The Queen's Veterinary School Hospital, Cambridge, UK, were searched for dogs diagnosed with ASAC from 2008 to 2019. Immunohistochemical expression of phosphorylated STAT3 (pSTAT3) was assessed in primary tumours (n = 57) and metastatic lymph nodes (n = 30) and MSTs were calculated for cases with low and high pSTAT3 expression. Of the 57 cases assessed, 27 presented with primary tumours but no metastasis and 30 with both primary and local metastatic disease. Most cases (50/57) expressed nuclear pSTAT3 within neoplastic cells in both primary tumour and metastatic lymph nodes. pSTAT3 expression was predominantly observed in neoplastic cells at the edges of neoplastic lobules, suggesting a potential role in invasion. There was no significant difference in pSTAT3 expression between cases metastatic at presentation and those that did not have detectable metastasis at presentation. There was no significant difference between the MSTs in cases with high and low pSTAT3 expression. Cases that presented with metastatic disease had shorter MSTs (395 days) than those with primary tumours alone (623 days). Although pSTAT3 is variably expressed in primary and metastatic ASAC cells, pSTAT3 did not provide prognostic information for canine ASAC.

Peripheral blood cell ratios as prognostic factors in canine diffuse large B-cell lymphoma treated with CHOP protocol.

Diffuse large B-cell lymphoma (DLBCL) is the most common haematopoietic tumour in dogs and recognized as clinical model for its human counterpart. Recently, neutrophil-to-lymphocyte (NLR) and lymphocyte-to-monocyte (LMR) ratios have been shown to predict time-to-progression (TTP) and lymphoma-specific survival (LSS) in dogs with DLBCL treated with CHOP-based chemotherapy. We retrospectively evaluated in 59 dogs diagnosed with DLBCL the prognostic value of haematological parameters and derived ratios: NLR, LMR, platelet-to-lymphocyte (PLR) and platelet-to-neutrophil (PNR) ratios for TTP, LSS and associated secondary end-points (time-to-progression-rate [TTPR] and lymphoma-specific survival-rate [LSSR]) as rates at 180 and 365 days. PNR is an independent prognostic marker (p ≤ .001) for TTPR/180 and 365 days, dogs with a PNR above 0.032 were more likely to progress before 180 days (sensitivity 46.5%, specificity 87.5%, p = .004). On univariate analysis, NLR showed a prognostic significance for LSSR/180 (p = .006) and LSSR/365 (p = .009). A baseline NLR value below 7.45 was positively associated with survival at 180 days (sensitivity 52%, specificity 85.3%, p = .025). The presence of substage b, was associated with early progression and decreased survival at 180 days (p = .031). Anaemia significantly reduced LSSR at 365 days (p = .028). This is the first study evaluating PLR and PNR in canine DLBCL and demonstrates that PNR could be a predictor of early lymphoma progression. Since peripheral blood cell composition can be affected by several non-oncological causes, the development of larger multicenter studies with homogeneous inclusion criteria could help to better determine the true predictive values of blood cell ratios in dogs' DLBCL treated with CHOP chemotherapy.

A possible role of coarse fractionated radiotherapy in the management of gingival squamous cell carcinoma in dogs: A retrospective study of 21 cases from two referral centers in the UK.

Surgery with or without the addition of radiotherapy is the treatment of choice for canine oral squamous cell carcinoma (SCC). Fractionated radiotherapy alone is also effective in the long-term control of the disease, however coarse fractionated radiotherapy (CF-RT) for gingival SCC has not been extensively reported. The aim of this study was to describe side effects, clinical response, and median survival time (MST) of dogs with gingival SCC treated with CF-RT in the palliative and adjuvant setting. Twenty-one cases from two referral centres in the UK treated with CF-RT for gingival SCC between July 2013 and June 2019 were retrospectively evaluated. Of the 21 dogs, 11 developed mild acute adverse effects. Oral mucositis was the most common radiation induced toxicity. Three dogs developed chronic severe adverse effects (oro-nasal fistula, bone necrosis and gum recession). Overall clinical response rate was 77% in dogs receiving palliative treatment with MST of 365 days (60-1,095 days). MST was not reached for dogs treated in the adjuvant setting with a mean of 466 days (121-730 days). In cases of advanced gross disease CF-RT might have a role in short term palliation of clinical signs. However, it carries a significant risk of late toxicity for cases with unexpectedly long survival times and further investigations are required to identify an optimal CF-RT protocol. Randomized controlled trials are needed to confirm the role of CF-RT as adjuvant treatment of incompletely resected gingival SCC.

Outcomes of adjunctive radiation therapy for the treatment of mast cell tumors in dogs and assessment of toxicity: A multicenter observational study of 300 dogs.

BACKGROUND: Radiation therapy is commonly used as an adjunct to incomplete surgical excision in dogs with mast cell tumors (MCT), but the optimal dose and fractionation regimen have yet to be determined. HYPOTHESIS: We assessed outcomes (time to local recurrence, patient survival and toxicity) of a large population of dogs with MCT that received adjunctive radiation therapy. ANIMALS: Three hundred dogs with 302 MCT treated using adjunctive radiation therapy. METHODS: Retrospective observational study. Clinical records of 4 veterinary radiation centers were reviewed. RESULTS: Local recurrence rates were similar regardless of radiation protocol with 6.6% of patients developing recurrent cutaneous MCT at a median of 526 days. Local recurrence rate was similar between high and low-risk MCT. Mast cell tumor related death was reported in 19% of all dogs, with 13% of dogs with low-risk MCT dying of their disease compared to 29% of dogs with high-risk MCT. No SC MCT (SCMCT) recurred after radiation therapy and only 7% of dogs with SCMCT were reported to have died of their disease. Mild late toxicity was common in both protocols and severe late toxicity occurred in 1.9% of dogs many years after treatment. CONCLUSIONS AND CLINICAL IMPORTANCE: Our study supports the use of adjunctive radiation for the long-term control of incompletely or narrowly excised cutaneous and SCMCT in dogs. More moderate dose and fractionation protocols may be appropriate in the adjunctive treatment of low-risk MCT in dogs. Large multicenter prospective studies are required to establish the optimal dose and fractionation for MCT of different risk categories.

Canine lymphoma and vector-borne diseases: Molecular and serological evaluation of a possible complicity.

Lymphoma is the most common haematological malignancy in dogs and its aetiology is largely unknown. The presence of canine vector-borne agents (CVBD) in lymphoma tissues has been described and its causative effects questioned. We intended to evaluate the presence and extent of Leishmania infantum, Ehrlichia canis, Anaplasma phagocytophilum and Bartonella henselae infection in dogs with lymphoma. Sixty-one dogs, living in the Lisbon metropolitan area, with a diagnosis of lymphoma were enrolled. Immunofluorescence assays were used to detect serum IgG's. The presence of DNA from CVBD agents in tumour tissue was assessed by PCR. All dogs tested negative for B. henselae, A. phagocytophilum and E. canis by both serology and PCR. Regarding L. infantum, 8.2% (n = 5) of the dogs had a positive serologic result. L. infantum DNA was detected in two samples of diffuse large B-cell lymphoma (DLBCL). These results show an increased, but not significant, seropositivity (8.2% vs 7.9%) and molecular detection (3.3% vs 1.2%) for L. infantum in dogs with lymphoma, when compared to the reported canine population in the same geographical area. We could not identify an association between lymphoma and E. canis, A. phagocytophilum, B. henselae or Leishmania infantum infection in the studied population. Nevertheless, further studies, following dogs trough their CVBD disease evolution, are worthwhile and may help clarify a possible role of CVBD agents in lymphomagenesis.

Clinical response and survival time of cats with carcinoma of the nasal cavity treated with palliative coarse fractionated radiotherapy.

OBJECTIVES: Carcinoma is the second most common tumour of the nasal cavity in cats. Few studies assessing the response and survival of cats with carcinoma of the nasal cavity treated with palliative coarse fractionated radiotherapy have been published. METHODS: Twenty-eight cats were diagnosed with histologically confirmed carcinoma of the nasal cavity. All patients treated with a coarse fractionated radiotherapy protocol were retrospectively reviewed. RESULTS: Improvement of the clinical signs were reported in 24 cases; median survival time (MST) was 342 days; and cats with Adams modified stage IV and facial deformity had a significantly reduced MST of 152 days (P = 0.0013) and 67 days (P = 0.0002), respectively. Severe radiotherapy-related clinical signs were not reported and alopecia and leukotrichia were the most common side effects reported in ten cases. CONCLUSIONS AND RELEVANCE: Coarse fractionated radiotherapy treatment for carcinoma of the nasal cavity in cats is effective in relieving clinical signs. Long survival times can be achieved, in particular in cases with a less advanced stage of the tumour.

Effect of radiotherapy on freedom from seizures in dogs with brain tumors.

BACKGROUND: Seizures are a common presenting sign in dogs with brain tumors. HYPOTHESIS/OBJECTIVES: To investigate the effect of radiotherapy on freedom from brain tumor-associated seizures and survival time in dogs. ANIMALS: Thirty-two client-owned dogs with brain tumor-associated seizures; 18 received medical treatment and radiotherapy, 14 received medical treatment alone. METHODS: Multicenter retrospective study. Baseline characteristics (seizure semiology, magnetic resonance imaging [MRI] characteristics, and treatment) and duration of seizure freedom were recorded for the 2 treatment groups. Duration of seizure freedom between groups was compared (log-rank test) using Cox's proportional hazard analysis, with baseline characteristics entered as covariates. RESULTS: The duration of seizure freedom and survival time were significantly longer in the radiotherapy group (P < .001), with a mean of 24 months (95% confidence interval [CI], 14.3-33.8) versus 1.7 months in the control group (95% CI, 0.5-2.9) and a mean of 34.6 months (95% CI: 25.2-44.1) versus 6.2 months in the control group (95% CI, 2.6-9.7) respectively. Baseline characteristics were not associated with duration of seizure freedom after the start of treatment. In the radiotherapy group, 5 dogs were euthanized during the study period because of causes other than seizures. In the control group, recurrence of seizures was observed before death in all dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: A longer period of seizure freedom and longer survival time was observed in dogs with brain tumors after radiotherapy compared to medical treatment only. The pathophysiological mechanisms of epileptogenesis and the effect of radiation therapy on seizure control are unclear to date. Further prospective studies are needed.