2024 Guidelines for reporting radiation therapy in veterinary medicine.

Evidence-based medicine drives patient care decision-making; thus, accurate and complete reporting in scientific publications is paramount. A checklist for complete reporting of veterinary radiation therapy was proposed in 2012 using the recommendations of the International Commission of Radiation Units and Measurements (ICRU). The purpose of this study is to review the 2012 checklist and propose updates based on changes in technology. Significant technology advancements have gained traction in veterinary medicine, including intensity-modulated radiation therapy (IMRT) and stereotactic radiation therapy (SRT), both of which have related modality-specific ICRU reporting recommendations. The 2012 checklist and proposed 2024 checklist are then used to assess the completeness of reporting in veterinary radiation oncology publications between 2015 and 2022, of which one hundred and eight publications met the inclusion criteria. Prior to the publication of the 2012 checklist (2005-2010), only nine checklist items showed a good level of completeness in reporting, and from 2015 to 2022, this increased to 16 items. Encouraging and/or requiring the use of reporting checklists at the time of manuscript submission may be responsible for this improvement in reporting. Using the 2024 checklist, which is more relevant to publications discussing IMRT and SRT treatments, only 14 of the analyzed checklist items (34%) show a good level of completeness in reporting, suggesting there is a need for updated guidelines to capture the nuances of advanced techniques. This study proposes a 2024 checklist that can be used as a guideline for future reporting of radiation therapy in veterinary medicine.

Recurrent corneal hemangiosarcoma in a cat with subsequent extension into the orbit.

A 7-year-old neutered female Domestic Short-haired cat was presented for evaluation of ulceration and severe vascularization of the left cornea. Ophthalmic examination revealed a large red irregular mass over the whole cornea in the left eye. A lamellar keratectomy was performed. Histopathology revealed a chronic lymphoplasmacytic, histocytic, neutrophilic ulcerative keratitis with fibrosis and vascularization. The tumor recurred within 3 months, and another lamellar keratectomy and sclerotomy were performed. The lesion was diagnosed histopathologically as a hemangiosarcoma with incomplete margins. The mass recurred locally 6 weeks later, and an enucleation was performed. Histopathology revealed infiltration of the limbus and connective tissue beyond the sclera. Seven weeks later, a fluctuant swelling was found in the left orbit. Computed tomography confirmed a soft tissue attenuating mass measuring 33 x 24 mm diameter in the orbit. There was no sign of metastasis. Clinical remission was achieved with combined chemotherapy with doxorubicin and radiation therapy. The patient remained in clinical remission 20 months post-chemotherapy.

McKesson® lubricating jelly and Aquasonic® ultrasound gel can be used as bolus materials for radiation therapy.

Bolus materials are commonly used for both human and veterinary radiation therapy (RT). Commercially available bolus materials often leave an air gap between the bolus and the skin which can lead to underdosing of the tumor. This prospective exploratory study evaluated the 6 MV X-ray and electron beam (6, 9, and 12 MeV) attenuating properties for two alternative bolus materials: McKesson lubricating jelly® (MLJ) and Aquasonic 100 Ultrasound gel® (AUG). The results comparing MLJ and water for 12 MeV and 9 MeV electron beams showed <3% difference, however, no other significant differences in radiation dose between water and MLJ nor AUG were seen. Findings demonstrated that both AUG and MLJ have radiation dose attenuating properties similar to water and supported use of these materials as alternative bolus materials for veterinary radiation therapy applications.

Evaluation of two different radiotherapy anaesthetic protocols for dogs: a randomized clinical crossover trial.

OBJECTIVES: To describe alfentanil-propofol admixture for induction of anaesthesia for canine radiotherapy and compare it to alfentanil-atropine followed by propofol induction in terms of heart rate (HR), mean arterial pressure (MAP), recovery duration and quality. STUDY DESIGN: Prospective, masked, randomized clinical crossover trial. ANIMALS: A group of 40 client-owned dogs anaesthetized from October 2017 to June 2018. METHODS: Dogs were randomly assigned to be administered one of two protocols. For both protocols, IV preanaesthetic medication was given 30 seconds before rapid IV administration of a set volume of induction agent, with further induction agent administered as needed to permit intubation. For protocol ADMIX, the preanaesthetic medication was 0.04 mL kg-1 0.9% sodium chloride and the induction agent was 0.2 mL kg-1 propofol-alfentanil admixture. For protocol ATRO, the preanaesthetic medication was 10 µg kg-1 alfentanil with 12 µg kg-1 atropine (0.04 mL kg-1 total volume) and the induction agent was 0.2 mL kg-1 propofol. Anaesthesia was maintained with sevoflurane. Cardiorespiratory variables, agitation, hypotension, or inadequate depth of anaesthesia requiring supplemental boluses of propofol or increased vaporizer settings were recorded. Time to extubation, sternal recumbency and walking was noted. Videos were recorded for recovery quality scoring. Owner questionnaires gave feedback about recoveries at home. The other protocol was administered for the next radiotherapy session. RESULTS: The only significantly different variable between protocols was mean HR during anaesthesia, which was lower in ADMIX (p < 0.001). Hypotension was recorded in seven (17.5%) dogs in ATRO and three (7.5%) in ADMIX, with an association (p < 0.005) between ATRO and hypotension. Owners reported animals recovered 'normal' behaviour and appetite by the next morning. CONCLUSIONS AND CLINICAL RELEVANCE: Both protocols were acceptable for dogs undergoing radiotherapy, with minimal differences in anaesthetic quality, recovery duration and quality. Although MAP did not differ overall, the incidence of hypotension was higher in ATRO.

Outcome of Metastatic and Recurrent Ovarian Dysgerminoma Using Radiation Therapy and Chemotherapy in a Dog.

An 8 yr old female spayed poodle/terrier mixed-breed dog was referred for evaluation of a recurrent and metastatic ovarian dysgerminoma. A total dose of 20Gy was administered to both the mediastinal metastatic lesion and retroperitoneal recurrent dysgerminoma in five daily fractions of 4Gy. Acute side effects were mild and self-limiting. This was followed by several courses of chemotherapy using a variety of agents. Despite extensive disease, this patient was still alive at the time of publication, 524 days after presentation and 501 days following completion of radiation. This case report demonstrates tolerability and efficacy of palliative radiation and chemotherapy for this rare tumor type.

Short survival time following palliative-intent hypofractionated radiotherapy for non-resectable canine thyroid carcinoma: A retrospective analysis of 20 dogs.

Radiotherapy is the treatment of choice for non-resectable canine thyroid carcinoma. High tumor response rates and median survival times of 2 years or longer have been previously reported with conventionally fractionated and hypofractionated protocols, even in dogs with distant metastasis. The objective of this retrospective, descriptive, case series study was to evaluate the clinical outcomes of dogs with thyroid carcinoma irradiated with palliative intent using hypofractionated radiotherapy at our institution. Medical records of 20 dogs treated between 1999 and 2014 were reviewed. All dogs had macroscopic primary tumors and presented with tumor-related clinical signs. Median longest tumor diameter was 10 cm. Nineteen dogs (95%) had metastasis (7/19 lymph node; 16/19 distant metastasis). Most dogs were treated with four weekly fractions of 6.5-8 Gy. Radiotherapy was well tolerated in 17 dogs; three died of respiratory compromise before completing radiotherapy. Eleven dogs received adjuvant chemotherapy. Five dogs experienced a local tumor response including two complete and three partial responses. Overall median survival time was 170 days (range, 1-824 days; 95% CI: 58-392 days). Of potential variables examined (radiation delivery system and protocol, tumor size and location, vascular/lymphatic invasion, metastatic disease, chemotherapy, tumor response), only achievement of complete or partial response was predictive of overall survival. In contrast to previously reported cohorts, dogs with clinical signs and stage IV disease predominated in this study. Previous studies may over-estimate survival following hypofractionated radiotherapy in dogs with advanced thyroid carcinoma.

Hypofractionated radiotherapy in nine dogs with unresectable solitary lung adenocarcinoma.

Although lung lobectomy is the most common treatment option for dogs with solitary lung tumors, surgery often cannot be performed at the time of diagnosis. In this retrospective, case series study, we described the effects of hypofractionated radiotherapy for tumor mass reduction in nine dogs with solitary lung adenocarcinoma that were later considered for surgical resection, and we assessed the tolerability of the radiation protocol. Tumors were deemed unresectable by the attending veterinarian. The dose prescription was 7.0-12.0 Gy/fraction in four to seven fractions, administered weekly for a total dose of 40-50 Gy. Treatment planning prioritized normal tissue dose constraints. The median interval between the last radiotherapy session and maximum tumor size reduction was 56 (range: 26-196) days, with six and three dogs exhibiting a partial response and stable disease, respectively. Although acute and late radiation-induced toxicity to the skin and/or lungs developed in all nine dogs, it was self-limiting or improved with short-term anti-inflammatory treatment. Tumor progression after initial size reduction was confirmed in three dogs at 62, 126, and 175 days, respectively, after the last radiotherapy session. Seven of the nine dogs underwent lobectomy a median of 68 days after radiotherapy when tumors were in partial response or stable disease or at the time of progression, and five received systemic chemotherapy concurrent with or after radiotherapy. These findings suggest that hypofractionated radiotherapy for canine solitary lung adenocarcinoma is useful when the tumor is large or when surgery cannot be performed immediately after diagnosis.

Effect of prophylactic cefalexin treatment on the development of bacterial infection in acute radiation-induced dermatitis in dogs: a blinded randomized controlled prospective clinical trial.

BACKGROUND: Acute radiation-induced dermatitis (ARID) is a common sequela of radiation therapy and carries the risk of secondary bacterial skin infection. No standard of care exists for managing canine ARID and evidence-based guidelines are lacking; however, prophylactic use of antibiotics is common. HYPOTHESIS/OBJECTIVES: To evaluate the impact of prophylactic cefalexin on the prevalence and severity of bacterial infection in canine ARID. ANIMALS: Seventeen dogs treated with definitive-intent radiotherapy. METHODS: All dogs were treated with definitive-intent radiation therapy (48-57.5 gray) targeted to the skin surface. Dogs were randomized to receive either prophylactic cefalexin (22 mg/kg twice daily) beginning halfway through the prescribed radiotherapy course (cohort A) or to serve as controls (cohort B). Aerobic skin cultures and surface cytological evaluation were performed at first onset of moist desquamation and one week following completion of radiation therapy. Skin toxicity grading and owner quality of life (QoL) questionnaires were performed weekly. The rate of infection, multidrug resistance status, toxicity severity and QoL between cohorts were compared. RESULTS: Staphylococcus schleiferi and S. pseudintermedius were the most frequent bacterial agents isolated in both cohorts. There was no significant difference in prevalence of bacterial infection or overall QoL between cohorts at either time point; however, multidrug-resistant infections were significantly increased in cohort A versus cohort B. Clinician- and client-perceived severity of toxicity was significantly greater and median duration of moist desquamation was significantly longer in cohort A than cohort B. CONCLUSIONS AND CLINICAL IMPORTANCE: Prophylactic use of cefalexin for management of canine ARID is not recommended.

Hybrid surgical treatment for 2 feline cases of intrahepatic shunt.

Intrahepatic portosystemic shunt was encountered in 2 cats (10 and 5 months old) exhibiting neurological symptoms and general deterioration. Both cats were treated with coil embolization using a hybrid surgical technique combining conventional open surgery and interventional radiology techniques, achieving good postoperative outcomes (follow-up: 22 and 10 months, respectively).

Traitement chirurgical hybride pour deux cas félins de shunt intrahépatique. Un shunt portosystémique intrahépatique a été observé chez deux chats (âgés de 10 et de 5 mois) manifestant des symptômes neurologiques et une détérioration générale. Les deux chats ont été traités par une embolisation utilisant des spires à l'aide d'une technique chirurgicale hybride combinant une chirurgie ouverte conventionnelle et des techniques de radiologie d'intervention afin d'obtenir de bons résultats postopératoires (suivi : 22 et 10 mois, respectivement).(Traduit par Isabelle Vallières).

Metronomic administration of lomustine following palliative radiation therapy for appendicular osteosarcoma in dogs.

The purpose of this study was to determine if metronomic administration of lomustine following palliative radiation therapy (RT) improved length of palliation and therefore survival in dogs with appendicular osteosarcoma compared to treatment with palliative radiation alone. A search of medical records identified dogs with appendicular osteosarcoma, treated with palliative RT (2 fractions of 8 Gray in a 24 hour time frame, day 0 and day 1; or day 0, 6 hours apart). Data collected included signalment, history, clinical signs, physical examination findings, clinicopathologic abnormalities, extent of disease, response, toxicity, other therapy, survival time, and whether dogs received metronomic lomustine (ML) or not. Of 86 patients, 43 received ML while 43 did not. Median survival time (MST) was not significantly different (P = 0.84), at 184 +/- 17 days for patients which received ML, and 154 +/- 20 days for those which did not. Metronomic lomustine administration was well-tolerated, but it did not improve survival in dogs with palliatively treated osteosarcoma.

Administration métronomique de lomustine après radiothérapie palliative pour le traitement des ostéosarcomes appendiculaires chez le chien. L'objectif de cette étude était de déterminer si l'administration métronomique de lomustine après radiothérapie palliative (RT) améliore la durée de palliation, et par conséquent la durée de vie, des chiens atteints d'ostéosarcome appendiculaire, en comparaison avec la radiothérapie seule. Les dossiers médicaux des chiens atteints d'ostéosarcome appendiculaire traités par radiothérapie palliative (2 fractions de 8 Gray dans un intervalle de 24 heures, jour 0 et jour 1; ou jour 0, à 6 heures d'intervalle) ont été identifiés et évalués. Les données collectées incluaient l'anamnèse, les commémoratifs, les anomalies de l'examen clinique et des analyses de laboratoires, les résultats du bilan d'extension, la réponse au(x) traitement(s), le développement de toxicités, d'éventuelles autres thérapies prodiguées, la durée de vie et si les chiens avaient été traités avec de la lomustine ou non. Sur 86 patients, 43 ont reçu de la lomustine tandis que 43 n'en ont pas reçu. La médiane de survie (MST) n'était pas significativement différente (P = 0.84), 184 +/− 17 jours pour les patients traités avec de la lomustine, et 154 +/− 20 jours pour ceux n'ayant pas reçu de lomustine. L'administration métronomique de lomustine était bien tolérée mais ne prodigua pas d'amélioration de la durée de vie lors de la prise en charge palliative des chiens atteints d'ostéosarcome.(Traduit par les auteurs).

A NOVEL, REMOVABLE, CERROBEND, BEAM-BLOCKING DEVICE FOR RADIATION THERAPY OF THE CANINE HEAD AND NECK: PILOT STUDY.

Radiation therapy of the head and neck can result in mucositis and other acute affects in the oral cavity. This prospective pilot study evaluated a novel, intraoral, beam-blocking device for use during imaging and therapeutic procedures. The beam-blocking device was made from a metal alloy inserted into a coated frozen dessert mold (Popsicle® Mold, Cost Plus World Market, Oakland, CA). The device was designed so that it could be inserted into an outer shell, which in turn allowed it to be placed or removed depending on the need due to beam configuration. A Farmer type ionization chamber and virtual water phantom were used to assess effects of field size on transmission. Six large breed cadaver dogs, donated by the owner after death, were recruited for the study. Delivered dose at the dorsal and ventral surfaces of the device, with and without the alloy block in place, were measured using radiochromic film. It was determined that transmission was field size dependent with larger field sizes leading to decreased attenuation of the beam, likely secondary to scatter. The mean and median transmission on the ventral surface without the beam-blocking device was 0.94 [range 0.94-0.96]. The mean and median transmission with the beam-blocking device was 0.52 [range 0.50-0.57]. The mean and median increase in dose due to backscatter on the dorsal surface of the beam-blocking device was 0.04 [range 0.02-0.04]. Findings indicated that this novel device can help attenuate radiation dose ventral to the block in dogs, with minimal backscatter.

Perianal neuroendocrine tumor with suspected lymph node metastasis causing colonic compression and subsequent megacolon.

An 8-year-old spayed female domestic shorthair cat was presented with a 4- to 5-month history of a progressively growing mass above her anus and an inability to defecate for 3 to 4 wk. External perianal and internal regional masses were subsequently identified and diagnosed as tumors of neuroendocrine origin through surgical excision and histopathologic evaluation. The cat was treated with 2 courses of chemotherapy and radiation therapy.

Tumeur neuroendocrinienne périanale avec une métastase suspectée des ganglions lymphatiques causant une compression du côlon et un mégacôlon subséquent. Une chatte commune domestique stérilisée âgée de 8 ans a été présentée avec une anamnèse de 4 ou 5 mois d'une masse à croissance progressive au-dessus de l'anus et l'incapacité de déféquer depuis 3 ou 4 semaines. Les masses périanales externes et régionales internes ont été subséquemment identifiées et diagnostiquées comme des tumeurs d'origine neuro-endocrinienne suite à l'excision chirurgicale et une évaluation histopathologique. La chatte a été traitée à l'aide de deux séries de traitement et d'une radiothérapie.(Traduit par Isabelle Vallières).

Comparison of adaptive radiotherapy techniques for external radiation therapy of canine bladder cancer.

Daily bladder variations make it difficult to utilize standard radiotherapy as a primary treatment option for muscle-invasive bladder cancer. Our purpose was to develop a model comparing dose distributions of image-guided and adaptive radiotherapy (ART) techniques for canine bladder cancer. Images were obtained retrospectively from cone-beam computed tomography (CBCT) scans used for daily positioning of four dogs undergoing fractionated image-guided radiotherapy (IGRT). Four different treatment plans were modeled for each dog, and dosimetric data were compared. Two plans were developed using planning target volumes based on planning computed tomography (CT) bladder volume. These plans then used bony anatomy or soft tissue anatomy for daily positioning and dosimetric modeling. The third plan type was a hybrid IGRT and ART technique utilizing a library of premade anisotropic planning target volumes using bladder wall motion data and selection of a "plan-of-the-day" determined from positioning CBCT bladder volumes. The fourth plan was an ART technique that constructed a new planning target volume each day based on daily bladder volume as determined by pretreatment CBCT. Dose volume histograms were generated for each plan type and dose distribution for the bladder and rectum were compared between plan types. Irradiated rectal volume decreased and irradiated bladder volume increased as plan conformality increased. ART provided the greatest rectal sparing, with lowest irradiated rectal volume (P < 0.001), and largest bladder volume receiving 95% of the prescription dose (P < 0.001). In our model, adaptive radiotherapy techniques for canine bladder cancer showed significant reduction in rectal volume irradiated when compared to nonadaptive techniques, while maintaining appropriate bladder coverage.

Chemotherapy and radiation therapy in 4 dogs with muscle-invasive transitional cell carcinoma of the urinary tract.

Four dogs with T(2)N(0)M(0) transitional cell carcinoma of the lower urinary tract underwent multimodal treatment consisting of neoadjuvant chemotherapy, external-beam radiotherapy, and adjuvant chemotherapy. No significant toxicity was documented. All dogs showed clinical improvement and reduction of tumor volume based on computed tomography (CT).

RésuméChimiothérapie et radiothérapie comme traitement pour carcinomes à cellules transitionnelles urothéliaux avec infiltration du muscle dans 4 chiens. Quatre chiens avec des carcinomes à cellules transitionnelles du bas tractus urinaire (TNM) ont été traités avec une approche multimodale consistent en chimiothérapie néodjuvante, radiothérapie externe et chimiothérapie adjuvante. Nous n'avons pas observé une toxicité signifiante. Tous les chiens ont répondu à ce traitement multimodale, défini comme amélioration des symptômes cliniques et réduction des dimensions de la tumeur, indiqué au scanner.(Traduit par Julia Buchholz).

Retrospective study and review of ocular radiation side effects following external-beam Cobalt-60 radiation therapy in 37 dogs and 12 cats.

This retrospective study evaluated the ocular side effects of cancer-bearing dogs and cats treated with external-beam Cobalt-60 (Co-60) radiation in which one or both orbit(s) were included in the radiation field. A total of 37 dogs and 12 cats presented to the Ontario Veterinary College during the 10-year study period (1999-2009) were evaluated. The radiation protocols ranged from a maximum of 60 Gray (Gy) in 24 fractions for curative intent to a minimum of 8 Gy in 1 fraction for palliative treatment. The main ocular side effect reported in both dogs and cats was conjunctivitis (79% and 55%, respectively). Other common ocular side effects included eyelid lesions in dogs (44%), ulcerative keratitis in cats (36%), and keratoconjunctivitis sicca in both dogs and cats (44% and 27%, respectively). The high incidence of ocular side effects in both patient populations indicates a need for regular ophthalmic examinations as a component of routine follow-up for radiation therapy involving the orbit. Radiation damage to ocular tissues is also reviewed.

Étude rétrospective et examen des effets secondaires de la radiation oculaire après une radiothérapie externe au cobalt-60 chez 37 chiens et 12 chats. Cette étude rétrospective a évalué les effets secondaires oculaires chez des chiens et des chats atteints du cancer traités avec une radiation externe au cobalt-60 (Co-60) lorsque l'une ou l'autre des orbites étaient incluses dans le champ de radiation. Un total de 37 chiens et de 12 chats présentés à l'Ontario Veterinary College durant la période d'étude de 10 ans (1999­2009) ont été évalués. Les protocoles de radiation s'échelonnaient de 60 Gray (Gy) en 24 fractions pour un traitement curatif à un minimum de 8 Gy en 1 fraction pour un traitement palliatif. Le principal effet secondaire oculaire signalé chez les chiens et les chats était la conjonctivite (79 % et 55 %, respectivement). D'autres effets secondaires communs étaient des lésions des paupières chez les chiens (44 %), une kératite ulcérative chez les chats (36 %) et une kératoconjonctivite sèche chez les chiens et les chats (44 % et 27 %, respectivement). L'incidence élevée d'effets secondaires oculaires dans les deux populations de patients signale le besoin d'examens ophtalmologiques réguliers comme élément d'un suivi de routine pour la radiothérapie touchant l'orbite. Les dommages de la radiation aux tissus oculaires sont également examinés.(Traduit par Isabelle Vallières).

Commissioning a small-field biological irradiator using point, 2D, and 3D dosimetry techniques.

PURPOSE: To commission a small-field biological irradiator, the XRad225Cx from Precision x-Ray, Inc., for research use. The system produces a 225 kVp x-ray beam and is equipped with collimating cones that produce both square and circular radiation fields ranging in size from 1 to 40 mm. This work incorporates point, 2D, and 3D measurements to determine output factors (OF), percent-depth-dose (PDD) and dose profiles at multiple depths. METHODS: Three independent dosimetry systems were used: ion-chambers (a farmer chamber and a micro-ionisation chamber), 2D EBT2 radiochromic film, and a novel 3D dosimetry system (DLOS∕PRESAGE®). Reference point dose rates and output factors were determined from in-air ionization chamber measurements for fields down to ∼13 mm using the formalism of TG61. PDD, profiles, and output factors at three separate depths (0, 0.5, and 2 cm), were determined for all field sizes from EBT2 film measurements in solid water. Several film PDD curves required a scaling correction, reflecting the challenge of accurate film alignment in very small fields. PDDs, profiles, and output factors were also determined with the 3D DLOS∕PRESAGE® system which generated isotropic 0.2 mm data, in scan times of 20 min. RESULTS: Surface output factors determined by ion-chamber were observed to gradually drop by ∼9% when the field size was reduced from 40 to 13 mm. More dramatic drops were observed for the smallest fields as determined by EBT∼18% and ∼42% for the 2.5 mm and 1 mm fields, respectively. PRESAGE® and film output factors agreed well for fields <20 mm (where 3D data were available) with mean deviation of 2.2% (range 1%-4%). PDD values at 2 cm depth varied from ∼72% for the 40 mm field, down to ∼55% for the 1 mm field. EBT and PRESAGE® PDDs agreed within ∼3% in the typical therapy region (1-4 cm). At deeper depths the EBT curves were slightly steeper (2.5% at 5 cm). These results indicate good overall consistency between ion-chamber, EBT2 and PRESAGE® measured OFs, PDDs, and profiles. CONCLUSIONS: The combination of independent 2D and 3D measurements was found to be valuable to ensure accurate and comprehensive commissioning. Film measurements were time consuming and challenging due to the difficulty of film alignment in small fields. PRESAGE® 3D measurements were comprehensive and efficient, because alignment errors are negligible, and all parameters for multiple fields could be obtained from a single dosimeter and scan. However, achieving accurate superficial data (within 4 mm) is not yet feasible due to optical surface artifacts.

Treatment of an amelanotic melanoma using radiation therapy in a lesser Madagascar hedgehog tenrec (Echinops telfairi).

A 15-yr-old, male lesser Madagascar hedgehog tenrec (Echinops telfairi) presented with a mass caudal to the right ear. Cytology suggested a sarcoma. Surgical removal was attempted. Histology was consistent with a soft tissue sarcoma. The mass recurred within 331 days post operation. Radiation therapy was initiated. Computed tomography was used for staging in conjunction with three-dimensional computerized treatment planning software to permit accurate lesion localization and to optimize normal tissue sparing. A total dose of 6,480 cGy was administered in 24 fractions over 46 days. Transient hind limb paresis developed during the course of the radiation therapy, but resolved after 7 days with prednisone treatment. Minimal acute radiation toxicity was observed. The mass responded with at least a 90% reduction in volume following radiation treatment. The animal survived 266 days from the initiation of treatment. On necropsy, a small mass and granulation tissue were found at the site of the initial neoplasm, indicating good regional control of the tumor; however, extensive metastases to the spleen and liver were present. Immunohistochemically, the original, recurrent, and metastatic populations were strongly positive for HMB 45 and weakly positive for S-100, and the final diagnosis was metastatic amelanotic melanoma.

Evaluation of weight loss in canine cancer bearing patients undergoing radiation therapy.

Critical weight loss, as defined by ≥5% decrease in body weight, has been associated with increased morbidity and mortality in human patients with cancers of the head and neck. Weight loss has anecdotally been reported to occur frequently in veterinary patients undergoing radiation therapy and is hypothesized to be more severe in patients with cancers of the head and neck, along with those hospitalized during radiation therapy. The primary objective of this retrospective study was to evaluate the occurrence of critical weight loss in canine cancer bearing patients undergoing either definitive or palliative radiation protocols and to determine if weight changes were associated with radiation toxicity, tumour location or patient hospitalization status. Data from 47 dogs who underwent definitive and 43 dogs who underwent palliative radiation protocols at the University of Tennessee were included for analysis. Dogs were categorized based on tumour location (head/neck or other), hospitalization status (boarded or non-boarded) and radiation toxicity score. Weight recorded at the start of treatment, midway through treatment and at the final treatment was used for analysis. No significant differences were found in regard to weight change over time, location or hospitalization status when evaluated for both protocols. Overall, 5/90 dogs (5.5%) lost 5% or more of their body weight during therapy, and 7/90 dogs (7.7%) gained 5% or more of their body weight. The results of the current study suggest that critical weight loss occurs in a small percentage of canine patients undergoing radiation therapy, contrary to what is often anecdotally reported.

Assessment of irradiated socket healing in the rabbit's mandible: Experimental study.

As bone healing is altered after external radiation therapy, its evaluation is mandatory and lacks in clinical practice. The aim of the pilot study was to validate micro computed tomography (microCT) as a simple and reliable technique for assessing irradiated bone healing in the rabbit's mandible and compare with histologic findings. Nineteen rabbits (female New Zealand white) were used. The radiation protocol consisted of 5 sessions delivering 8.5 Gy each. MicroCT was performed at D0, D7, D14, D28 and D42 for the control group and D0, D28 and D42 for the irradiated group. A modified Perry's score was determined on histologic samples, and comparison between microCT and histological findings was performed. The main differences between irradiated and non-irradiated rabbits were observed at Day 28 and 42. There was a strong correlation between imaging and histologic findings. Radiation decreases bone quality and bone mineral density. As the correlation was strong between microCT and histologic findings, micro imaging could be considered as a simple and reliable technique to assess bone healing after radiation therapy and allows an easy comparison between samples, without invasive procedures. Great attention should be kept on the parameters and on the region of interest. The development of in-vivo microCT enlarges the perspectives of microCT use in experimental studies, avoiding invasive procedures, and preserving animal lives and well-being, and furthermore lead to clinical applications.

Efficacy of frameless stereotactic radiotherapy for the treatment of presumptive canine intracranial gliomas: A retrospective analysis (2014-2017).

The use of conventional multi-fractionated radiotherapy for the treatment of glial tumours is well documented in the literature. Recently, stereotactic radiotherapy (SRT) has become more widely available allowing for hypo-fractionated protocols; however, its usefulness in the treatment of canine intracranial gliomas is largely undetermined. We conducted a retrospective analysis, including 21 dogs diagnosed with presumptive intracranial gliomas treated with one or more courses of three fractions of 8 to 10 Gy CyberKnife SRT. The objective of this study was to evaluate the efficacy, safety and prognostic factors associated with the use of SRT for the treatment of canine intracranial gliomas. Overall MST for all dogs was 636 days (d). Dogs treated with one course of the described SRT protocol had a MST of 258 days while those treated with >1 course had a MST of 865 days (P = .0077 log rank, 0.0139 Wilcoxon). Dogs treated with one course of SRT who received adjuvant chemotherapy had a MST of >658 days and lived significantly longer than those who did not receive chemotherapy (MST, 230 days) (P = .0414 log rank, 0.0453 Wilcoxon). The most common adverse event included presumptive transient demyelination in 3/21 dogs, which was treated successfully with corticosteroids in all patients. This study provides evidence that SRT is effective in prolonging survival in dogs with intracranial gliomas, and may provide similar results to conventional fractionated protocols, while decreasing the number of hospital visits and anaesthetic episodes. Additionally, it appears that patients can be safely treated with multiple rounds of SRT resulting in improved survival times.