Evaluation of clinical response and prognostic factors in canine multicentric lymphoma treated with first rescue therapy

Despite an initial strong response in most dogs with multicentric lymphoma treated with chemotherapy, relapse remains common. There is no clearly superior first rescue protocol described either for resistant or relapsed canine multicentric lymphoma. The objectives of this study were to assess clinical response and outcomes for canine multicentric lymphoma treated with first rescue protocols. The secondary objective was to assess prognostic variables for dogs undergoing these protocols. This was a bi-institutional retrospective cohort study. Two hundred and sixty-five dogs were treated with first rescue chemotherapy, including anthracycline-based combination chemotherapy (CHOP-like, n = 50), nitrosourea alkylating agent-rich chemotherapy (n = 45), anthracycline-based or related compound chemotherapy (n = 34), or nitrosourea single-agent chemotherapy (n = 136). The overall median progression free survival time of first rescue protocol was 56.0 days (0-455 days). Important prognostic factors identified for first rescue protocol included the attainment of a complete response to the first rescue chemotherapy (p < .001), the use of a CHOP-like first rescue protocol (p = .009), duration of first remission (HR 0.997, p = .028), and if prednisolone was included in the first rescue protocol (HR 0.41, p = .003). Adverse events (AE) were common, with 81.1% of dogs experiencing at least one AE during first rescue chemotherapy. This study highlights the need for improved first rescue therapies to provide durable remission in canine resistant or relapsed lymphoma.

Genomic Analysis of Lymphoma Risk in Bullmastiff Dogs

Lymphoma is the most common haematological malignancy affecting dogs and has a high incidence in the Bullmastiff breed. The aim of this study was to identify risk loci predisposing this breed to the disease. The average age of lymphoma diagnosis in 55 cases was less than 6 years, similar to the median age of 64 cases from our clinical and pathology databases. When fine-scale population structure was explored using NETVIEW, cases were distributed throughout an extended pedigree. When genotyped cases (n = 49) and dogs from the control group (n = 281) were compared in a genome-wide association analysis of lymphoma risk, the most prominent associated regions were detected on CFA13 and CFA33. The top SNPs in a 5.4 Mb region on CFA13 were significant at a chromosome-wide level, and the region was fine-mapped to ~1.2 Mb (CFA13: 25.2-26.4 Mb; CanFam3.1) with four potential functional candidates, including the MYC proto-oncogene bHLH transcription factor (MYC) and a region syntenic with the human and mouse lncRNA Pvt1 oncogene (PVT1). A 380 Kb associated region at CFA33: 7.7-8.1 Mb contained the coding sequence for SUMO specific peptidase7 (SENP7) and NFK inhibitor zeta (NFKBIZ) genes. These genes have annotations related to cancer, amongst others, and both have functional links to MYC regulation. Genomic signatures identified in lymphoma cases suggest that increased risk contributed by the regions identified by GWAS may complement a complex predisposing genetic background.

Demographic risk factors for lymphoma in Australian dogs: 6201 cases

Background

Lymphoma is common in the dog. Studies of population risk factors primarily have been derived from referral institution or insurance data.

Objective

To identify and quantify the host risk factors for lymphoma in a broad population of Australian dogs.

Animals

Data on 6201 client owned dogs were retrieved from a commercial veterinary laboratory, a general practice group and 2 referral hospitals.

Methods

Data collected included breed, sex, and neuter status. A reference population of 640 105 dogs was generated from the referral hospitals and from council registration data. The risk of lymphoma by sex and neuter status was calculated as odds ratios (OR).

Results

The study identified 30 breeds at increased risk of lymphoma, 15 that have not been reported previously, and 26 breeds at decreased risk, 18 that have not been reported previously. Males were over represented compared to females with an OR of 1.1 (95% CI, 1.1–1.2; P < .001). Neutered animals were at higher risk compared to intact animals with an OR of 3.2 (95% CI, 2.9–3.5) which was found in both males (OR, 2.8; 95% CI; 2.5–3.2) and females (OR, 4.4; 95% CI, 3.5–5.1).

Conclusions and Clinical Importance

Breed, sex, and neuter status alter the risk of lymphoma in dogs. These 3 factors must be considered when evaluating lymphoma risk as potential markers of underlying differences in disease etiology. Comparison of breeds at increased and decreased risk could be advantageous when evaluating specific etiological factors.

Long term survival of a dog with disseminated Aspergillus deflectus infection without definitive treatment

Canine disseminated fungal infection by Aspergillus species carries a guarded to grave prognosis as they often rapidly progress and are refractory to treatment with many euthanased soon after diagnosis. This case report describes a 2.5 year old female spayed German Shepherd Dog diagnosed with disseminated Aspergillus deflectus infection for which definitive treatment was declined by the owners. With only palliative management the dog survived three years and two months before succumbing to chronic kidney disease.

Malignant melanoma in 63 dogs (2001-2011): the effect of carboplatin chemotherapy on survival

AIMS

The aim of the study was to compare the effect of carboplatin chemotherapy on the survival of canine patients diagnosed with malignant melanoma after loco-regional control or as a sole therapy.

METHODS

A retrospective study of 63 dogs with oral, digital or cutaneous malignant melanoma treated with surgery and/or chemotherapy was undertaken. Dogs were grouped based on the anatomical site of melanoma development. For oral melanoma, dogs were subclassified into two groups: loco-regional control and gross disease. All patients in the digital and cutaneous groups had achieved loco-regional control with surgery. Comparisons between survival data for each group at each anatomical site were then made. Within the loco-regional control groups survival time was compared between those treated with and without chemotherapy post surgery. For the oral melanoma patients with gross disease survival was compared between those treated with chemotherapy and palliative therapy. The toxicity of carboplatin chemotherapy was evaluated overall.

RESULTS

The overall median survival times for patients with oral, digital and cutaneous melanoma were 389, 1,350 days and not reached (with a median follow-up of 776 days) respectively. Median survival time was defined as "not reached" when less than 50% of the subjects died of the disease at the end of the follow-up period, or at the time they were lost to follow-up. The addition of chemotherapy to surgery did not confer a survival benefit in the loco-regional control setting when assessing survival for each anatomical site. For oral melanoma patients with gross disease there was no difference between survival of patients treated with chemotherapy and palliative intent therapy. There was however an improvement in survival in the three dogs that responded to chemotherapy (978 days; p=0.039) compared to the eight non-responders (147 days). On univariate and multivariate analysis, anatomic location was the only variable that was significantly related to survival (p=0.0002 and p=0.009, respectively).

CONCLUSIONS

The addition of chemotherapy to local treatments for canine melanoma at oral, digital and cutaneous sites did not lead to a significant increase in survival times. Carboplatin was well tolerated and appeared to have activity against oral melanoma in a subset of patients with gross disease that responded to treatment.

CLINICAL RELEVANCE

Carboplatin with piroxicam could be considered for patients with gross disease when more traditional therapies, such as surgery or radiation therapy, are declined or are not available. In the loco-regional control setting, prospective randomised blinded studies with matched control groups are required to determine if chemotherapy has a role in the treatment of these types of cancer.

Polyostotic lymphoma with multiple pathological fractures in a six-month-old cat

A 6-month-old female neutered domestic shorthair cat was examined for pain and swelling of the distal limbs. Swelling and malalignment of both carpi, dorsiflexion of the distal metatarsals and a mild, multicentric lymphadenopathy were detected on examination. Screening blood tests revealed a biclonal gammopathy, hypercalcemia and atypical leukocytes. Survey radiographs revealed lysis and proliferative changes within the physes. Multiple pathological physeal fractures were present, including the distal radii, metacarpal and metatarsal bones. No treatment was attempted and the patient was euthanased. Histopathology revealed infiltration by monomorphic round cells within the liver, spleen, kidney and bone marrow. Immunohistochemistry revealed strong reactivity to CD20. Clonality assays revealed clonal results for the B-cell loci, consistent with B-cell lymphoma. To the authors' knowledge this is the first report of polyostotic lymphoma with multiple pathological fractures in a cat. The predominantly distal distribution of osseous lesions is rarely reported in dogs and humans.

Effect of pimobendan on the clinical outcome and survival of cats with non-taurine responsive dilated cardiomyopathy

This retrospective study was designed to assess the effect of pimobendan on the median survival time (MST) of cats with non-taurine responsive dilated cardiomyopathy (DCM). Thirty-two client-owned cats with a left ventricular internal dimension at end systole (LVIDs) >14 mm, a fractional shortening (FS) <28% and a lack of response to taurine therapy were included over a 9-year period (2001-2010). These cats were divided into pimobendan (n=16) and non-pimobendan (n=16) treatment groups. All cats received standard treatment with frusemide, taurine and benazepril or enalapril. Nine cats in the non-pimobendan group also received digoxin. The MST of the pimobendan group (49 days; range 1 to >502 days) was four times that of the non-pimobendan group (12 days; 1 to 244 days). The difference in survival between the two groups was statistically significant (P = 0.048). Hypothermia and FS <20% were associated with a poor prognosis. No adverse effects to pimobendan were noted.

CCNU (lomustine) toxicity in dogs: a retrospective study (2002-07)

OBJECTIVE

To describe the incidence of haematological, renal, hepatic and gastrointestinal toxicities in tumour-bearing dogs receiving 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU).

DESIGN

The medical records of 206 dogs that were treated with CCNU at the Melbourne Veterinary Specialist Centre between February 2002 and December 2007 were retrospectively evaluated.

RESULTS

Of the 206 dogs treated with CCNU, 185 met the inclusion criteria for at least one class of toxicity. CCNU was used most commonly in the treatment of lymphoma, mast cell tumour, brain tumour, histiocytic tumours and epitheliotropic lymphoma. Throughout treatment, 56.9% of dogs experienced neutropenia, 34.2% experienced anaemia and 14.2% experienced thrombocytopenia. Gastrointestinal toxicosis was detected in 37.8% of dogs, the most common sign of which was vomiting (24.3%). Potential renal toxicity and elevated alanine transaminase (ALT) concentration were reported in 12.2% and 48.8% of dogs, respectively. The incidence of hepatic failure was 1.2%.

CONCLUSIONS

CCNU-associated toxicity in dogs is common, but is usually not life threatening.

Metastatic mast cell tumour in a dog presenting with spinal pain

The clinical, advanced imaging and surgical features of a case of canine extradural mast cell tumour are presented. This rare location has only been reported once before as a primary lesion, although the present case may be a metastatic lesion. Given the frequent occurrence and treatment of cutaneous mast cell tumours in dogs, the finding of spinal metastasis is an important reminder to consider metastatic neoplasia in cases of previously treated cancers presenting with spinal pain.

Pretreatment tumor prostaglandin E2 concentration and cyclooxygenase-2 expression are not associated with the response of canine naturally occurring invasive urinary bladder cancer to cyclooxygenase inhibitor therapy

The purpose of this study was to determine the extent to which pretreatment prostaglandin E2 (PGE2) concentration and cyclooxygenase-2 (cox-2) expression could be used to predict the antitumor activity of cox inhibitor treatment in naturally occurring canine transitional cell carcinoma of the urinary bladder (TCC). Snap frozen tissues (to measure PGE2) and formalin-fixed TCC samples (for cox-2 immunohistochemistry) were obtained by cystoscopy or surgery. Complete tumor staging was performed before and after one month of treatment with the cox inhibitor, piroxicam (0.3 mg/kg q24 h po). The pretreatment PGE2 concentration ranged from 57 to 1624 ng/g of TCC tissue; n=18 dogs). Cox-2 immunoreactivity was observed in all TCC samples. There was no association between PGE2 concentration, cox-2 expression, and change in tumor volume with piroxicam treatment. In conclusion, cox-2 expression or PGE2 concentration alone, or the combination of the two was not useful in predicting response to piroxicam treatment in canine TCC.

Evaluation of cisplatin combined with piroxicam for the treatment of oral malignant melanoma and oral squamous cell carcinoma in dogs

OBJECTIVE

To determine the maximum tolerated dose (MTD) of cisplatin administered with piroxicam, the antitumor activity and toxicity of cisplatin combined with piroxicam in dogs with oral malignant melanoma (OMM) and oral squamous cell carcinoma (SCC), and the effects of piroxicam on the pharmacokinetics of cisplatin in dogs with tumors.

DESIGN

Prospective nonrandomized clinical trial.

ANIMALS

25 dogs.

PROCEDURE

Dogs were treated with a combination of cisplatin (escalating dose with 6 hours of diuresis with saline [0.9% NaCI] solution) and piroxicam (0.3 mg/kg 10.14 mg/lb], PO, q 24 h). The initial cisplatin dose (50 mg/m2) was increased by 5 mg/m2 until the MTD was reached. Tumor stage and size were determined at 6-week intervals during treatment. The pharmacokinetics of cisplatin were determined in dogs receiving a combination of cisplatin and piroxicam during the clinical trial and dogs that were treated with cisplatin alone.

RESULTS

11 dogs with OMM and 9 dogs with SCC were included in the clinical trial. The MTD of cisplatin when administered in combination with piroxicam was 50 mg/m2. Tumor remission occurred in 5 of 9 dogs with SCC and 2 of 11 dogs with OMM. The most common abnormality observed was renal toxicosis. Clearance of cisplatin in dogs that were treated with cisplatin alone was not significantly different from that in dogs treated with a combination of cisplatin and piroxicam.

CONCLUSIONS AND CLINICAL RELEVANCE

Cisplatin administered in combination with piroxicam had antitumor activity against OMM and SCC. The level of toxicity was acceptable, although renal function must be monitored carefully.

Effects of the cyclooxygenase inhibitor, piroxicam, on tumor response, apoptosis, and angiogenesis in a canine model of human invasive urinary bladder cancer

The mechanisms by which cyclooxygenase inhibitors exert antitumor effects are not completely defined but are postulated to involve antiangiogenic effects and induction of apoptosis. In this study, we determined the effects of the cox inhibitor, piroxicam, on tumor response, apoptotic index, proliferative index, cyclooxygenase-2 expression, prostaglandin E(2) concentration, tumor microvessel density, and urine basic fibroblast growth factor and vascular endothelial growth factor concentrations in pet dogs with naturally occurring invasive transitional cell carcinoma of the urinary bladder. Piroxicam caused reduction in tumor volume in 12 of 18 dogs, and this was strongly associated with induction of apoptosis (Fisher's exact test P < 0.015) and reduction in urine basic fibroblast growth factor concentration.

Canine anal sac adenocarcinomas: clinical presentation and response to therapy

A retrospective study of 43 dogs with anal sac adenocarcinoma (ASAC) was performed to characterize the clinical presentation and response to treatment. Clinical signs at presentation varied considerably, with signs related either to sublumbar nodal metastasis (tenesmus or constipation) or hypercalcemia (polyuria-polydipsia and anorexia) being the most frequent findings. At the time of presentation, 23 (53%) dogs had hypercalcemia and 34 (79%) had metastases, with the regional lymph nodes (31 dogs, 72%) being the most common site of metastasis. A variety of chemotherapeutic agents were administered, with partial remission (PR) recorded in 4 of 13 (31%) dogs treated with cisplatin and in 1 of 3 (33%) dogs treated with carboplatin. The median survival for all dogs was 6 months (range, 2 days-41 months). There was no statistical association between the presence of hypercalcemia and survival, although the power of the study to detect an increase in survival of 3 months was low (.33). We conclude that platinum chemotherapy has antitumor activity in canine apocrine gland carcinoma and that further study of these agents is warranted.

Ultrasonographic and cytopathological diagnosis of exocrine pancreatic carcinoma in the dog and cat

This study describes the ultrasonographic and cytopathological characteristics of malignant neoplasms of the exocrine pancreas and their value in making an antemortem diagnosis. The medical records of eight dogs and five cats were reviewed. The clinical presentations were variable and at times mimicked pancreatitis. Overall, cytopathology of ultrasound or fluoroscopic-guided biopsies or fine-needle aspirates, or impressions from surgical biopsies were helpful in establishing the diagnosis in 10 of 12 animals where it was performed. Histopathology of ultrasound or fluoroscopic-guided biopsies provided a diagnosis in five of six cases where it was performed.

Mitotane (o,p'-DDD) resistance in a dog with pituitary-dependent hyperadrenocorticism and phaeochromocytoma

A dog was presented with a 2 year history of polyuria and polydipsia due to pituitary-dependent hyperadrenocorticism. A low-dose dexamethasone suppression test and measurement of plasma ACTH concentration confirmed the diagnosis. Treatment was instituted with mitotane at 44 mg/kg/day and then 88 mg/kg/d without complete resolution of signs. The dog collapsed with signs consistent with liver disease and was euthanased. Necropsy revealed a phaeochromocytoma of the left adrenal medulla with extensive metastases to the liver. A chromophobe adenoma of the pars intermedia of the pituitary was found.

Idiopathic eosinophilic meningoencephalitis in rottweiler dogs: three cases (1992-1997)

We report three cases of eosinophilic meningitis in young male Rottweiler type dogs in New Zealand. No cause for the disease was identified. There were variable clinical signs referable to central nervous system dysfunction, and a variable response to treatment.