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.

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.

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.