Alternating rabacfosadine and doxorubicin for treatment of naïve canine lymphoma.

The current standard of care treatment for canine lymphoma is a multi-agent, CHOP-based chemotherapy protocol. Single agent doxorubicin (DOX) is less burdensome; however, multi-agent chemotherapy protocols are often superior. The recently approved drug rabacfosadine (RAB, Tanovea) provides an attractive option for combination therapy with DOX, as both drugs demonstrate efficacy against lymphoma and possess different mechanisms of action. A previous study evaluating alternating RAB/DOX reported an overall response rate (ORR) of 84%, with a median progression-free survival time (PFS) of 194 days. The aim of this prospective trial was to evaluate the same protocol in an additional population of dogs. Fifty-nine dogs with treatment naïve lymphoma were enrolled. RAB (1.0 mg/kg IV) was alternated with DOX (30 mg/m2 IV) every 21 days for up to six total treatments (3 cycles). Response assessment and adverse event (AE) evaluation were performed every 21 days using VCOG criteria. The ORR was 93% (79% CR, 14% PR). The median time to maximal response was 21.5 days; median PFS was 199 days. T cell immunophenotype and lack of treatment response were predictive of inferior outcomes. AEs were mostly gastrointestinal. Six dogs developed presumed or confirmed pulmonary fibrosis; four were grade 5. One dog experienced grade 3 extravasation injury with RAB that resolved with supportive treatment. These data mirror those of the previously reported RAB/DOX study, and support the finding that alternating RAB/DOX is a reasonable treatment option for canine lymphoma.

Retrospective evaluation of intranasal carcinomas in cats treated with external-beam radiotherapy: 42 cases.

BACKGROUND: Little is known regarding the comparative efficacy of various irradiation strategies used to treat intranasal carcinomas (INC) in cats. OBJECTIVES: Investigate outcomes and prognostic factors associated with survival for cats with INC. ANIMALS: Forty-two cats with INC that underwent radiotherapy (RT). METHODS: Single-arm retrospective study. Medical record review for cats with INC that underwent RT at 1 of 7 veterinary RT facilities. Irradiation protocols categorized as: definitive-intent fractionated RT (FRT), definitive-intent stereotactic RT (SRT), and palliative-intent RT (PRT). Median overall survival time (OST) and disease progression-free survival (PFS; documented by advanced transverse imaging, or recurrence of symptoms) were calculated. Associations between tumor stage, RT protocol/intent, and adjunctive treatment usage and outcome were calculated. RESULTS: Cats underwent SRT (N = 18), FRT (N = 8), and PRT (N = 16). In multivariate modeling, cats received definitive-intent treatment (DRT; FRT/SRT) had significantly longer median PFS (504 days, [95% confidence interval (CI): 428-580 days] vs PRT 198 days [95% CI: 62-334 days]; p = 0.006) and median OST [721 days (95% CI: 527-915 days) vs 284 days (95% CI: 0-570 days); p = 0.001]). Cats that underwent second DRT course at time of recurrence lived significantly longer than cats that received 1 RT course (either DRT or PRT [median OST 824 days (95% CI: 237-1410 days) vs 434 days (95% CI: 277-591 days); p = .028]). CONCLUSION: In cats with INC, DRT is associated with prolonged OST and PFS as compared to PRT. If tumor progression occurs, a second course of DRT should be considered.

Rabacfosadine for naïve canine intermediate to large cell lymphoma: Efficacy and adverse event profile across three prospective clinical trials.

While current lymphoma therapies induce remission in most dogs, drug-resistant relapse is common, creating a need for novel agents. Rabacfosadine (RAB), a double prodrug of the acyclic nucleotide phosphonate 9-(2-phosphonylmethoxyethel) guanine (PMEG), preferentially targets lymphoma cells with reduced systemic toxicity compared with PMEG. Previous studies evaluating RAB administered every 21 days have suggested efficacy in both naïve and relapsed subjects; however, no large studies of RAB as a single agent have been reported in previously untreated dogs with intermediate to large cell lymphoma. The purpose of this study was to evaluate the safety and efficacy of RAB in dogs with previously untreated (excluding corticosteroids) lymphoma. Sixty-three dogs received up to five RAB treatments every 21 days (16 at 0.82 mg/kg and 47 at 1.0 mg/kg) as a 30 minutes intravenous infusion, with (n = 23) or without (n = 40) concurrent corticosteroids. Response assessment and adverse event (Ae) evaluation were performed every 21 days via Veterinary Cooperative Oncology Group (VCOG) criteria. The overall response rate was 87% (52% CR, 35% PR). The overall median progression free interval was 122 days (199 for CR, 89 for PR and 153 days for all responders). T-cell immunophenotype and corticosteroid pre-treatment were predictive of inferior outcomes on multivariate analysis. AEs were most commonly of gastrointestinal origin (hyporexia/diarrhoea) and generally resolved with supportive treatment and/or dosage adjustment. Three dogs experienced VCOG-CTCAE grade 5 delayed pulmonary fibrosis. In conclusion, RAB administered every 3 weeks is generally well tolerated and demonstrates substantial antitumour activity in dogs with previously untreated intermediate to large cell lymphoma.

Indirect computed tomography lymphangiography with aqueous contrast for evaluation of sentinel lymph nodes in dogs with tumors of the head.

Sentinel lymph node evaluation is widely used in human medicine to evaluate the first lymph node(s) to which a tumor drains. Sentinel lymph node biopsy allows avoidance of extensive lymphadenectomies in cases where the sentinel lymph node is negative for metastasis, thereby reducing patient morbidity. It has been shown that regional lymph nodes are not always the sentinel lymph node, thus identification and sampling of sentinel lymph nodes allows for more accurate staging, which is critical for treatment and prognostication in dogs with cancer. The objective of this prospective, pilot study was to determine if indirect computed tomography (CT) lymphangiography with aqueous contrast agent would successfully allow identification of sentinel lymph nodes in dogs with masses on the head. Eighteen dogs underwent CT lymphangiography. The sentinel lymph node was successfully identified within 3 min of contrast injection in 16 dogs (89%). Compression of lymphatic vessels from endotracheal tube ties and/or the patient's own body weight delayed or prevented identification of sentinel lymph nodes in two dogs (11%). Computed tomography lymphangiography with aqueous contrast can be used successfully to rapidly identify sentinel lymph nodes in dogs with masses on the head.

Vaccine-associated feline sarcoma: current perspectives.

Feline injection site sarcomas (FISS; also known as vaccine-associated sarcomas) have been recognized for >20 years. Although uncommon, these tumors are iatrogenic, and vaccination against rabies and feline leukemia virus is perhaps the most common inciting cause. The exact etiopathogenesis is unknown, but it is widely accepted that inflammation induced by vaccines or other injections likely plays a critical role in tumor development. Injection site sarcomas are extremely locally invasive. Multimodal therapy, incorporating combinations of surgery, radiation therapy, and sometimes chemotherapy or immunotherapy, is recommended. However, tumor recurrences are common even with aggressive treatment, and many cats with FISS ultimately succumb to this devastating disease. While vaccination protocols play an important role in the management and control of infectious disease, veterinarians must be diligent in following established vaccination guidelines to minimize individual patient risk of FISS development. Early tumor detection and client education are also vital in the successful treatment of FISS.

Outcomes of dogs undergoing limb amputation, owner satisfaction with limb amputation procedures, and owner perceptions regarding postsurgical adaptation: 64 cases (2005-2012).

OBJECTIVE: To evaluate outcomes of dogs and owner satisfaction and perception of their dogs' adaptation following amputation of a thoracic or pelvic limb. DESIGN: Retrospective case series. ANIMALS: 64 client-owned dogs. Procedures-Medical records of dogs that underwent limb amputation at a veterinary teaching hospital between 2005 and 2012 were reviewed. Signalment, body weight, and body condition scores at the time of amputation, dates of amputation and discharge from the hospital, whether a thoracic or pelvic limb was amputated, and reason for amputation were recorded. Histologic diagnosis and date of death were recorded if applicable. Owners were interviewed by telephone about their experience and interpretation of the dog's adaptation after surgery. Associations between perioperative variables and postoperative quality of life scores were investigated. RESULTS: 58 of 64 (91%) owners perceived no change in their dog's attitude after amputation; 56 (88%) reported complete or nearly complete return to preamputation quality of life, 50 (78%) indicated the dog's recovery and adaptation were better than expected, and 47 (73%) reported no change in the dog's recreational activities. Body condition scores and body weight at the time of amputation were negatively correlated with quality of life scores after surgery. Taking all factors into account, most (55/64 [86%]) respondents reported they would make the same decision regarding amputation again, and 4 (6%) indicated they would not; 5 (8%) were unsure. CONCLUSIONS AND CLINICAL RELEVANCE: This information may aid veterinarians in educating clients about adaptation potential of dogs following limb amputation and the need for postoperative weight control in such patients.

An integrated widefield imaging and spectroscopy system for contrast-enhanced, image-guided resection of tumors.

UNLABELLED: Tumor recurrence following surgery is a common and unresolved medical problem of great importance since surgery is the most widely used treatment for solid-mass tumors worldwide. A contributing factor to tumor recurrence is the presence of residual tumor remaining at or near the surgical site following surgery. GOAL: The primary objective of this study was to develop and evaluate an image-guided surgery system based on a near-infrared, handheld excitation source and spectrograph in combination with a widefield video imaging system. METHODS: This system was designed to detect the fluorescence of near-infrared contrast agents and, in particular, indocyanine green (ICG). The imaging system was evaluated for its optical performance and ability to detect the presence of ICG in tumors in an ectopic murine tumor model as well as in spontaneous tumors arising in canines. RESULTS: In both settings, an intravenous ICG infusion provided tumor contrast. In both the murine models and surgical specimens from canines, ICG preferentially accumulated in tumor tissue compared to surrounding normal tissue. The resulting contrast was sufficient to distinguish neoplasia from normal tissue; in the canine surgical specimens, the contrast was sufficient to permit identification of neoplasia on the marginal surface of the specimen. CONCLUSION: These results demonstrate a unique concept in image-guided surgery by combining local excitation and spectroscopy with widefield imaging. SIGNIFICANCE: The ability to readily detect ICG in canines with spontaneous tumors in a clinical setting exemplifies the potential for further clinical translation; the promising results of detecting neoplasia on the marginal specimen surface underscore the clinical utility.

Ulnar osteosarcoma in dogs: 30 cases (1992-2008).

OBJECTIVE: To examine the biological behavior of ulnar osteosarcoma and evaluate predictors of survival time in dogs. DESIGN: Retrospective case series. ANIMALS: 30 dogs with primary ulnar osteosarcoma. PROCEDURES: Medical records were reviewed. Variables recorded and examined to identify predictors of survival time were signalment, tumor location in the ulna, tumor length, serum alkaline phosphatase activity, surgery type, completeness of excision, tumor stage, tumor grade, histologic subtype, development of metastases, and use of chemotherapy. RESULTS: 30 cases were identified from 9 institutions. Eleven dogs were treated with partial ulnar ostectomy and 14 with amputation; in 5 dogs, a resection was not performed. Twenty-two dogs received chemotherapy. Median disease-free interval and survival time were 437 and 463 days, respectively. Negative prognostic factors for survival time determined via univariate analyses were histologic subtype and development of lung metastases. Telangiectatic or telangiectatic-mixed subtype (n = 5) was the only negative prognostic factor identified via multivariate analysis (median survival time, 208 days). Dogs with telangiectatic subtype were 6.99 times as likely to die of the disease. CONCLUSIONS AND CLINICAL RELEVANCE: The prognosis for ulnar osteosarcoma in this population was no worse and may have been better than the prognosis for dogs with osteosarcoma involving other appendicular sites. Partial ulnar ostectomy was associated with a low complication rate and good to excellent function and did not compromise survival time. Telangiectatic or telangiectatic-mixed histologic subtype was a negative prognostic factor for survival time. The efficacy of chemotherapy requires further evaluation.

Assessment of plasma uracil-to-dihydrouracil concentration ratio as an indicator of dihydropyrimidine dehydrogenase activity in clinically normal dogs and dogs with neoplasia or renal insufficiency.

OBJECTIVE: To determine and compare the ratio of uracil (U) to dihydrouracil (UH(2)) concentrations in plasma as an indicator of dihydropyrimidine dehydrogenase activity in clinically normal dogs and dogs with neoplasia or renal insufficiency. ANIMALS: 101 client- and shelter-owned dogs. PROCEDURES: Study dogs included 74 clinically normal dogs, 17 dogs with neoplasia, and 10 dogs with renal insufficiency. For each dog, a blood sample was collected into an EDTA-containing tube; plasma U and UH(2) concentrations were determined via UV high-performance liquid chromatography, and the U:UH(2) concentration ratio was calculated. Data were compared among dogs grouped on the basis of sex, clinical group assignment, reproductive status (sexually intact, spayed, or castrated), and age. RESULTS: Mean ± SEM U:UH(2) concentration ratio for all dogs was 1.55 ± 0.08 (median, 1.38; range, 0.4 to 7.14). In 14 (13.9%) dogs, the U:UH(2) concentration ratio was considered abnormal (ie, > 2). Overall, mean ratio for sexually intact dogs was significantly higher than that for neutered dogs; a similar difference was apparent among males but not females. Dogs with ratios > 2 and dogs with ratios ≤ 2 did not differ significantly with regard to sex, clinical group, reproductive status, or age. CONCLUSIONS AND CLINICAL RELEVANCE: Determination of the U:UH(2) concentration ratio was easy to perform. Ratios were variable among dogs, possibly suggesting differences in dihydropyrimidine dehydrogenase activity. However, studies correlating U:UH(2) concentration ratio and fluoropyrimidine antimetabolite drug tolerability are required to further evaluate the test's validity and its appropriate use in dogs.

Lymphosarcoma associated with Heterobilharzia americana infection in a dog.

Hepatic T-cell lymphosarcoma with involvement of regional lymph nodes and concurrent schistosomiasis were diagnosed in an 11-year-old male neutered mixed-breed dog with a history of chronic weight loss, inappetence, vomiting, and diarrhea. Trematode ova present in the hepatic parenchyma and mesenteric node were surrounded by sheets of neoplastic lymphocytes while those in the intestinal wall were surrounded by large numbers of non-neoplastic lymphocytes. Immunohistochemistry revealed that both the neoplastic and hyperplastic populations were T lymphocytes. The ova were identified by fecal saline sedimentation as Heterobilharzia spp., and fecal ova shedding resolved after praziquantel anthelmintic treatment. The lymphoma progressed despite chemotherapy, and the dog was euthanized after developing neurologic signs and a necropsy was performed. A monomorphic population of neoplastic T cells expanded and replaced normal architecture in the liver and spleen, surrounded nerve roots within the cauda equina, and infiltrated the meninges of the brain. The presence of schistosome ova embedded within neoplastic T-cell infiltrates suggests that, as previously reported in human schistosomiasis, heterobilharziasis may be associated with neoplasia.

Fibrosarcoma adjacent to the site of microchip implantation in a cat.

A 14-year-old spayed female domestic shorthair cat presented with an interscapular mass. A computed tomography scan, biopsy, and histological examination revealed a fibrosarcoma adjacent to a pet identification microchip. Because the cat was previously vaccinated at this site, it is not possible to establish definitive causation of the fibrosarcoma, but this is the first report of a tumor in the vicinity of a microchip in a cat. Microchip-associated tumors have been reported in rodents and dogs. Veterinarians should be aware that because inflammation may predispose felines to tumor formation, separation and observation of vaccination and implantation sites are indicated. Adherence to American Association of Feline Practitioners (AAFP) vaccination guidelines and monitoring of microchip implantation sites are recommended.

Mammary gland tumors in male dogs.

BACKGROUND: Reports of mammary-gland tumors in male dogs are lacking. OBJECTIVE: To describe the clinical characteristics of mammary-gland tumors in male dogs. ANIMALS: Eight male dogs diagnosed with mammary-gland tumors. METHODS: Retrospective study. Medical databases from 3 institutions were searched. Medical records were abstracted, and owners and referring veterinarians contacted for follow-up information. Tissues were reviewed for histologic type, and immunohistochemical staining for estrogen and progesterone receptors (ER, PR) was performed. RESULTS: Eight dogs with histologically confirmed mammary-gland tumors were included in this retrospective study. Median age at diagnosis was 11.5 years. Four dogs were sexually intact; 4 were neutered. All were purebred. Mammary-gland tumors were incidental findings in 7 of 8 dogs. All dogs were treated with only surgical excision. All but 1 dog had benign epithelial tumors. The dog with the malignant tumor was the only dog to develop possible local recurrence but de novo tumor development cannot be excluded. No dog had evidence of metastatic disease at diagnosis. Based on institutional population data, it was determined that female dogs are 62 times more likely to develop mammary-gland tumors than male dogs (P < .001). Estrogen-receptor expression was strong in the majority of tumors; progesterone-receptor expression, although present in all tumors, was less intense. CONCLUSIONS/CLINICAL IMPORTANCE: This study suggests that mammary-gland tumors in male dogs are rare, usually benign, and surgery alone can provide long-term control in most dogs.

Combination chemotherapy with L-asparaginase, lomustine, and prednisone for relapsed or refractory canine lymphoma.

BACKGROUND: Canine lymphoma (LSA) is responsive to initial treatment, however, it then becomes resistant to drugs in the initial protocol. New rescue protocols are needed. HYPOTHESIS: A combination of L-asparaginase, lomustine, and prednisone will be well tolerated and efficacious as a rescue therapy for dogs with LSA. ANIMALS: Thirty-one client owned dogs with cytologically confirmed multicentric LSA who were refractory or whose disease had relapsed after a CHOP (cyclophosphamide/doxorubicin/vincristine/prednisone)-based chemotherapy protocol. METHODS: Prospective clinical trial. Lomustine (target dose, 70 mg/m2) was administered orally at 3-week intervals for a total of 5 doses or until disease progression. L-asparaginase (400 U/kg) was administered subcutaneously concurrently with the first 2 lomustine treatments. Prednisone was administered at a tapering dose for the duration of the protocol. RESULTS: Overall response rate for dogs treated with this protocol was 87% (27/31), with 52% (16/31) of dogs achieving a complete response. Median time to response was 21 days. Median time to progression was 63 days (111 days for dogs achieving a complete response and 42 days for dogs achieving a partial response). There were no significant differences in response rates and times to progression between dogs who had received L-asparaginase before beginning this rescue protocol and those who had not. Toxicoses were mild and self-limiting in 29 of 31 cases. CONCLUSIONS AND CLINICAL IMPORTANCE: This is a well-tolerated rescue therapy for relapsing LSA in dogs. Response rates and remission durations compare favorably to other rescue protocols. Therefore, this protocol is a viable rescue option.