Lomustine for the treatment of gastrointestinal mast cell tumour in a dog

An eight-year-old, male boxer dog was referred for the treatment of a large (5.5 x 5 cm), unresectable visceral mast cell tumour. The dog had a surgical resection performed one month before referral, and it had widespread metastases to the abdominal lymph nodes. The patient was treated with lomustine and prednisone and showed a rapid improvement and increased level of activity, weight gain and consistent tumour reduction. The patient remained in partial remission (defined as a greater than 50 per cent reduction in tumour volume) for seven months. Toxicity was acceptable and was limited to moderate anaemia and two episodes of neutropenia. At the completion of the seven months of therapy, the dog experienced a chemotherapy-induced sepsis, and the owners elected for euthanasia due to financial concerns. At that time, the tumour was still in partial remission. This case report suggests that a combination of lomustine and prednisone is an effective protocol for the palliation of aggressive visceral mast cell tumours.     

A Combination Chemotherapy Protocol (VELCAP-L) for Dogs with Lymphoma

Ninety-eight dogs with lymphoma treated with a 5-drug combination chemotherapy regimen (vincristine, L-asparaginase. cyclophosphamide, doxorubicin, prednisone [VELCAP-L]) were evaluated for pretreatment characteristics predictive for response and remission duration. The complete remission rate was 69%, with a median remission duration of 55 weeks. Dogs with advanced stage of disease, constitutional signs, dogs that were older, and dogs that were dyspneic were less likely to achieve remission. Once in remission, small dogs and dogs without pretreatment thrombocytopenia were likely to have longer remission duration. Toxicoses were frequent, but rarely fatal, and no predictitive factors were found for a dog developing toxicoses. VELCAP-L is an effective treatment for dogs in stage I-III lymphoma, particularly in young, small animals.     

Cutaneous neosporosis during treatment of pemphigus foliaceus in a dog

A 4-year-old, intact male rottweiler was presented with a 10-day history of papulonodular dermatitis. At the time of presentation, the dog was receiving prednisone and azathioprine to treat pemphigus foliaceus. Cutaneous neosporosis was diagnosed by immunohistochemistry on skin biopsy specimens and a high serum antibody titer to Neospora caninum by Neospora agglutination test. Electron microscopy examination of skin specimens further supported the diagnosis. Clindamycin therapy, together with withdrawal of immunosuppressive medication, resulted in prolonged clinical remission. This report documents cutaneous neosporosis in an adult dog and suggests that immunosuppressive therapy might be a predisposing factor.     

Carmustine, vincristine, and prednisone in the treatment of canine lymphosarcoma

A chemotherapeutic protocol using carmustine in combination with vincristine and prednisone was tested in dogs with multicentric malignant lymphosarcoma. Of seven dogs treated, six (85.7%) achieved complete remission. A partial response occurred in one dog. Median survival time was 224 days (mean 386 days), and median duration of remission was 183 days (mean 323 days). Marked neutropenia was observed following carmustine administration. There were no significant alterations in platelets and red blood cell counts during treatment, and no abnormalities attributable to the chemotherapy were found in serum biochemical profiles. Results of this study showed that carmustine is an effective alternative option in the treatment of canine lymphosarcoma.     

Transient hyperglycaemia in a prediabetic dog treated with prednisone and cyclosporin A

A dog with immune-mediated haemolytic anaemia developed transient hyperglycaemia and glucosuria requiring insulin therapy in association with prednisone and cyclosporin A therapy. Following short-term therapy with insulin and cyclosporin A, the dog remained on prednisone therapy but required no further insulin therapy for 12 weeks, at which time the dog became permanently diabetic. We hypothesise that prednisone and cyclosporin A contributed to insulin resistance in a prediabetic dog with suboptimal endogenous insulin concentration and that the degree of insulin resistance decreased when cyclosporin A therapy was discontinued.     

Vesicular cutaneous lupus erythematosus in a Border Collie in New Zealand

A 3-year-old Border Collie was initially presented for a small ulcerative lesion on the left axilla. The lesion failed to respond to conservative treatment with antibiotics, and the dog was re-presented one week later with ulcerative lesions involving the inguinal and axillary areas bilaterally. Histology of a biopsy of these lesions revealed a lymphocytic ulcerative interface dermatitis. Apoptosis and degeneration of basaloid cells was evident, with clefting along the dermo–epidermal junction. Vesicular cutaneous lupus erythematosus was diagnosed. The dog was treated with prednisone and azathioprine, resulting in complete remission of signs. However, recurrence occurred when drugs were tapered, necessitating ongoing treatment. Vesicular cutaneous lupus erythematosus has been described in North America in Rough-coated Collies and Shetland Sheepdogs. However, in Australasia, it is most commonly observed in Border Collies.     

Suspected polymyxin B-induced pemphigus vulgaris in a dog

A case of pemphigus vulgaris (PV), putatively induced by topical application of polymyxin B ear drops, is described. A 3-year-old, female Tosa Inu, presented with acute onset swelling, blistering and ulceration of the pinnae, nostrils, lips and oral mucous membranes. The dog was depressed, febrile and anorexic. For 7 days prior to the onset of the acute ulcerative disease, polymyxin B ear drops had been applied to both ears to treat an ear infection. Skin and mucosal biopsies showed suprabasilar cleft formation and acantholysis, indicative of PV. The polymyxin B ear drops were discontinued and the dog was treated with intravenous fluids, systemic and topical antibacterial therapy, and immunosuppressive therapy comprising prednisone and azathioprine. Complete remission was noted after 2 weeks, and the immunosuppressive therapy was discontinued one month later. No clinical signs of PV recurred over a 1 year follow-up period. As PV does not usually resolve spontaneously, or enter long-term remission, it was considered that the condition was most likely drug induced due to the aural application of polymyxin B.     

Biclonal gammopathy associated with immunoglobulin A in a dog with multiple myeloma

A 10-year-old neutered male Airedale Terrier was evaluated for inappetance, weight loss, and lameness. Multiple myeloma was diagnosed based on bone marrow plasmacytosis, multiple lytic bone lesions, and hyperglobulinemia with a clonal gammopathy on serum protein electrophoresis. Splenic plasmacytosis, and retinal lesions consistent with hyperviscosity syndrome also were found. Temporary responses to 2 different chemotherapy protocols (melphalan and prednisone, and cyclophosphamide and prednisone) were seen, with remission of clinical signs and a decrease in the biclonal gammopathy but no resolution of the splenic mass. Eventual return of clinical signs led to euthanasia at 175 days postdiagnosis. Necropsy examination confirmed multiple myeloma involving bone marrow and spleen, and glomerulonephritis. An immunoglobulin-A (IgA) gammopathy was demonstrated by immunoelectrophoresis; biclonality was ascertained by immunofixation electrophoresis. The clonal components consisted of intact Ig with a heavy chain of the a class and a light chain of undetermined class. To our knowledge, this is the first report of undimerized biclonal gammopathy in a dog caused by a single heavy chain class involving IgA.     

Acute pancreatitis in two dogs given azathioprine and prednisone

Acute pancreatitis was diagnosed in 2 dogs given azathioprine and prednisone. Prednisone and azathioprine had been given as immunosuppressive therapy for pemphigus foliaceus in dog 1 and for polymyositis in dog 2. Azathioprine was discontinued in both dogs. In dog 1, prednisone was reinstituted on day 6 of hospitalization. Prednisone was continued throughout the period of hospitalization in dog 2. Both dogs recovered without complication. Glucocorticoid therapy has been associated with the development of pancreatitis. In human beings, a common side effect of azathioprine is the development of drug-induced pancreatitis. Definitive identification of azathioprine as the cause of pancreatitis in these dogs was not possible; the owners refused to permit retreatment with the drug. Therefore, the synergistic action between these 2 drugs could not be ruled out as the cause of pancreatitis.     

Type I idiopathic non-erosive immune-mediated polyarthritis in a mixed-breed dog

A young adult dog was presented with an acute onset of stiffness, weakness, marked muscle atrophy and rapid weight loss. The dog was inappetent, lethargic, and had grossly visible distension of multiple joints. Synovial fluid analysis, routine bloodwork, and radiography confirmed immune-mediated polyarthritis; the dog responded favorably to treatment with prednisone and analgesics.     

Eosinophilic granuloma of the nasal skin in a dog

A recurrent mass removed surgically from the dorsocaudal aspect of the planum nasale in a 12-year-old dog was identified histologically as eosinophilic granuloma. The dog was treated orally with prednisone for 15 days, and the granuloma has not recurred.     

Multiple papillomavirus-associated epidermal hamartomas and squamous cell carcinomas in situ in a dog following chronic treatment with prednisone and cyclosporine

A 4-year-old, spayed female toy fox terrier developed multiple epidermal hamartomas and squamous cell carcinomas in situ following chronic immunosuppressive therapy with prednisone and cyclosporine for management of an immune-mediated nonregenerative anaemia. Immunohistochemical staining was positive for papillomavirus antigen within both benign (n = 19) and malignant (n = 8) cutaneous lesions that developed during a 3-year period of observation, with positive staining most often seen in keratinocytes in the granular cell layer. Treatment of the papillomavirus infection with interferon-alpha was discontinued after 2 weeks because of diarrhoea and a further increase in liver enzymes. The cutaneous lesions of this dog persisted and new lesions developed during the year following discontinuation of both cyclosporine and prednisone. This is the first reported case of papillomavirus-associated squamous cell carcinoma in situ developing in a dog following chronic administration of cyclosporine and prednisone.     

Azathioprine therapy for acquired myasthenia gravis in five dogs.

Five dogs with acquired myasthenia gravis (MG), verified via positive serum acetylcholine (ACh) receptor antibody concentrations, were treated with a drug protocol including azathioprine (AZA). Four of the five dogs were concurrently treated with pyridostigmine. Azathioprine was used as the sole immunosuppressive agent in four dogs. One dog was temporarily treated with a combination of an immunosuppressive dose of prednisone and AZA, then maintained on AZA as the sole immunosuppressive drug. Three patients experienced complete remission of clinical signs within three months of therapy. In the four dogs for which follow-up serum ACh receptor antibody concentrations were available, initial versus final concentrations decreased substantially (81%), coincident with clinical improvement. One dog died suddenly due to a suspected myasthenic crisis before attaining the target dose of AZA. Two of the four surviving dogs were euthanized approximately one and seven years after diagnosis. One of these two dogs was euthanized because of a rib osteosarcoma, and the other dog was euthanized because of paraparesis of undetermined cause. The remaining two dogs were alive and doing well at the time of final follow-up evaluation, approximately six months and one year after diagnosis. The use of AZA as a therapeutic agent for acquired canine MG has not been investigated. The cases presented in this report suggest a potentially important role for AZA in the treatment of acquired MG in dogs.     

Response of Canine Mast Cell Tumors to Treatment With Oral Prednisone

Twenty-five dogs with naturally occurring mast cell tumors were treated with daily oral prednisone (1 mg/kg) for 28 days. Five dogs (20%) had reduction in tumor volume and were considered responders. Four of these underwent partial remission and one underwent complete remission. Survival times for the five responders were 3, 5, 6, 7.5, and greater than 28 months, respectively. We therefore conclude that prednisone is effective in some canine mast cell tumors. Further studies are indicated to determine the most effective dose of prednisone, the appropriate duration of treatment, and the efficacy in more benign mast cell tumors, and in combination with other forms of therapy.     

Treatment of basophilic leukemia in a dog.

Basophilic leukemia in a 6-year-old dog was characterized by marked splenomegaly, anemia, and leukocytosis in which 89% of the circulating leukocytes were basophilis. After an attempt at busulfan therapy, the dog was treated with hydroxyurea and was maintained on this drug for 2 months. After withdrawl of hydroxyurea, the dog remained in remission and was still in remission at the time of writing (8 months later).     

Intravenous Human Immunoglobulin for the Treatment of Immune-Mediated Hemolytic Anemia in 13 Dogs

Intravenous immunoglobulin (IVGG) was administered to 13 of 37 dogs with immune-mediated hemolytic anemia. All dogs received concurrent prednisone therapy, 14 dogs also received cyclophosphamide; and a single dog each received cyclosporine, azathioprines, and danazol. Dogs that responded to prednisone therapy without IVGG generally did so within 7 days (mean ± standard deviation = 5.6 ± 2.9 days). Intravenous immunoglobulin was administered after 10.4 ± 6.6 days of prednisone therapy as an intravenous infusion of 0.5 g/kg (range 0.25 to 0.73 g/kg). Eleven dogs received a single treatment, 2 dogs each received 2 treatments. No relevant adverse effects were noted. Eleven dogs had an increase in PCV of at least 4% 2.2 ±1.5 days after IVGG infusion. In 10 of these dogs, the PCV continued to increase until the time of hospital discharge. One responder died 1 hour after the increase in PCV, 1 dog was euthanized within 24 hours of IVGG administration, and 1 dog had no response over a period of 13 days. Results of this study suggest that IVGG therapy may be of value in dogs with immune-mediated hemolytic anemia that do not respond within 7 days of appropriate corticosteroid therapy.     

Effect of an anti-inflammatory dose of prednisone on thyroid hormone monitoring in hypothyroid dogs

It is not uncommon for a hypothyroid dog to be receiving concurrent corticosteroids. As hypothyroid dogs receiving thyroid supplement need periodic monitoring, knowledge of whether prednisone alters thyroid hormone concentrations would be useful to determine whether testing can or should be done while the dog is receiving therapy and whether dose adjustments are appropriate. In this study, the effect of short-term anti-inflammatory prednisone was determined in dogs with naturally occurring hypothyroidism. Eight adult dogs were given prednisone (1.0 mg/kg, orally) daily for 7 days and then on alternate days for 14 days. Serum total thyroxine (T(4) ), free T(4) (fT(4) ), and thyroid-stimulating hormone (TSH) were measured on days 7, 21 and 28 and compared with baseline data. Total T(4) concentrations were significantly decreased after 7 days of anti-inflammatory prednisone, but were not significantly altered from baseline on days 21 or 28. Free T(4) and TSH concentrations were not significantly altered from baseline at any point during the study. Two dogs had decreased total T(4) concentrations on day 7, which may have resulted in an alteration in thyroid supplementation. Results showed that administration of prednisone at a dosage of 1 mg/kg, orally, once daily for 7 days decreased total T(4) , while fT(4) was unchanged, suggesting that fT(4) may be less affected by daily prednisone administration. Anti-inflammatory doses of prednisone administered every other day did not interfere with thyroid hormone monitoring.     

Cisplatin chemotherapy for metastatic squamous cell carcinoma in two dogs

Cisplatin was used successfully to treat 2 dogs with metastatic squamous cell carcinoma. One dog was observed to have a complete remission and died of unrelated causes 23 months later. The other dog had a partial remission of the tumor, but relapsed and was euthanatized 4 1/2 months after the beginning of treatment. Both dogs tolerated the treatment well.     

Acute myelomonocytic leukemia in a dog

Cytochemical stains and morphologic characteristics were essential in making the correct diagnosis in a dog with acute myelomonocytic leukemia, which initially was diagnosed as lymphoblastic leukemia. Response to a treatment regimen of cytosine arabinoside, thioguanine, vincristine, and doxorubicin, besides accomplishing complete remission, helped revise the initial diagnosis to acute myelomonocytic leukemia. After remission was achieved, the dog died of a fulminating viral infection.     

Secondary hypoadrenocorticism associated with craniocerebral trauma in a dog

An 11-month-old, neutered female miniature schnauzer presented with a severe head injury. The dog was treated for the acute effects of craniocerebral trauma and was hospitalized for just over a week. Several weeks later, she became weak and lethargic. A diagnosis of hypoadrenocorticism was confirmed with an adrenocorticotropin hormone (ACTH) stimulation test. An endogenous ACTH assay confirmed secondary hypoadrenocorticism. The dog was tested for hypopituitarism with canine thyroid-stimulating hormone and thyroxine serum assays and an insulin-like growth factor assay. These tests could not confirm panhypopituitarism in this dog. The hypoadrenocorticism was treated with prednisone, and the dog remains controlled adequately three years later.