Lomustine and prednisone as a first-line treatment for dogs with multicentric lymphoma: 17 cases (2004-2005)

OBJECTIVE: To assess response rate, median duration of response, adverse effects, and prognostic factors associated with concurrent administration of lomustine and prednisone as a first-line treatment for dogs with multicentric lymphoma. DESIGN: Retrospective case series. ANIMALS: 17 dogs. PROCEDURES: Medical records were reviewed. Information obtained included signalment, physical examination findings, results of diagnostic testing, stage and substage, initial lomustine and prednisone dosages, and total number of lomustine doses administered. RESULTS: Lomustine was administered at a median starting dosage of 67 mg/m(2), PO, every 21 days until 5 doses were given or disease progression was observed. Prednisone was administered at a median starting dosage of 1.8 mg/kg/d (0.82 mg/lb/d), PO, with dosage tapered during the first month of treatment. Six dogs had a complete response, and 3 had a partial response. Mean and median durations of response were 48.8 and 39.5 days, respectively. Median survival time was 111.2 days. In multivariate analyses, female sex and higher total lomustine dose were significantly associated with a longer disease-free inter-val. Neutropenia was the dose-limiting factor, with 4 dogs developing clinically important neutropenia 1 week after administration of a dose of lomustine. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that concurrent treatment with lomustine and prednisone was well tolerated in dogs with multicentric lymphoma, but findings did not support the use of this combination for first-line treatment of affected dogs.     

Comparison of platelet count recovery with use of vincristine and prednisone or prednisone alone for treatment for severe immune-mediated thrombocytopenia in dogs

OBJECTIVE: To evaluate the effect of prednisone alone, compared with a combination of prednisone and vincristine, on platelet counts in bleeding dogs with severe primary immune-mediated thrombocytopenia (IMT). DESIGN: Prospective case study. ANIMALS: 24 dogs with severe primary IMT PROCEDURE: All dogs received immunosuppressive doses of prednisone (1.5 to 2 mg/kg [0.7 to 0.9 mg/lb] of body weight, PO, q 12 h). In addition, 12 dogs received a single dose of vincristine (0.02 mg/kg [0.01 mg/lb], IV). Platelet count, transfusion requirement, and outcome were monitored. A response was defined as an increase in platelet count to > or = 40,000/microl. Dogs in the prednisone group that failed to respond received 1 dose of vincristine on day 7. RESULTS: Dogs that received prednisone and vincristine had a significantly faster increase in platelet count to > or = 40,000 platelets/microl than dogs that received prednisone alone (mean +/- SD, 4.9 +/- 1.1 vs 6.8 +/- 4.5 days, respectively). A similarly rapid response was observed in dogs that received vincristine on day 7 after treatment with prednisone alone failed. Furthermore, duration of hospitalization was reduced in the vincristine group, compared with the prednisone group (5.4 +/- 0.3 vs 7.3 +/- 0.5 days, respectively). No adverse effects attributable to vincristine were observed in any dog. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of combined vincristine and prednisone is associated with more rapid increase in platelet numbers and shortened duration of hospitalization in dogs with IMT, compared with use of prednisone alone. Early use of vincristine seems warranted in dogs with severe primary IMT.     

Evaluation of neoadjuvant prednisone administration and surgical excision in treatment of cutaneous mast cell tumors in dogs

OBJECTIVE: To determine response rate and reduction in tumor burden and effect of dose on tumor response in dogs treated with neoadjuvant prednisone for cutaneous mast cell tumors (MCTs). DESIGN: Combined prospective clinical study and retrospective case series. ANIMALS: 49 dogs with MCT. PROCEDURES: Medical records were retrospectively reviewed for dogs with primary untreated cutaneous MCT managed with neoadjuvant prednisone administration and surgery. Tumor characteristics and response to treatment were recorded. A subset of dogs assigned to low-dose (LD) treatment with neoadjuvant prednisone (1.0 mg/kg [0.45 mg/lb], PO, q 24 h) or high-dose (HD) treatment (2.2 mg/kg [1.0 mg/lb], PO, q 24 h) was used to determine the effects of dose. RESULTS: The overall objective response rate was 70% for dogs treated with neoadjuvant prednisone; prednisone dose was not significantly associated with response. Prospectively, the median sum maximal diameter (MaxD) reduction was 45.2%, and reduction in tumor volume was 80.6%. In both treatment groups, the mean percentage MaxD reduction and tumor volume reduction were significant. The difference in response between the LD and HD groups was not significant. The LD group had mean MaxD and tumor volume reductions of 35.4% and 52.5%, respectively, compared with mean reductions of 48.8% in MaxD and 78% in tumor volume in the HD group. CONCLUSIONS AND CLINICAL RELEVANCE: Treatment with neoadjuvant prednisone appears to be useful for inducing reduction of MCTs and may facilitate resection when adequate surgical margins cannot be confidently attained because of mass location or size or both.     

Cyclophosphamide exerts no beneficial effect over prednisone alone in the initial treatment of acute immune-mediated hemolytic anemia in dogs: a randomized controlled clinical trial

Cyclophosphamide is commonly used with prednisone in the initial treatment of severe idiopathic immune-mediated hemolytic anemia (IMHA) in dogs because retrospective reports suggest its benefit. This randomized controlled prospective clinicaltrial evaluated whether combined cyclophosphamide and prednisone therapy is more efficacious than prednisone therapy alone in the initial treatment of IMHA. Eighteen dogs with acute, severe idiopathic IMHA were randomly assigned to 1 of 2 treatment groups. The P group received prednisone therapy alone (1-2 mg/kg PO q12h), and the PC group received prednisone (1-2 mg/kg PO q12h) and cyclophosphamide (50 mg/m2 PO q24h for 4 consecutive days a week) for 4 weeks. The mortality rate in the P group was 20% (2 of 10), and in the PC group, the mortality rate was 38% (3 of 8). There was no difference in sequential CBC evaluations between the 2 groups. However, whereas dogs in the P group showed increases in reticulocyte count, reticulocytosis was suppressed in dogs in the PC group during the 1st week of therapy. Spherocytosis resolved more quickly in the P group (day 21) than in the PC group (day 28), but the time taken to achieve a negative Coombs' test result was comparable between groups. No difference was observed in the volume of packed red blood cells (pRBCs) given per transfusion between treatment groups, but more dogs in the PC group required a 2nd transfusion. The results of this limited study suggest that cyclophosphamide plus prednisone has no benefit over prednisone alone in the initial treatment of acute, severe idiopathic IMHA indogs.     

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.     

Actinomycin D as rescue therapy in dogs with relapsed or resistant lymphoma: 49 cases (1999--2006)

OBJECTIVE: To evaluate response rate and disease-free interval in dogs with relapsed or resistant lymphoma treated with actinomycin D, determine hematologic toxicoses, and identify prognostic factors associated with response to treatment. DESIGN: Retrospective case series. ANIMALS: 49 dogs with relapsed or resistant lymphoma. PROCEDURES: Medical records were reviewed for information regarding signalment, physical examination findings, results of diagnostic testing, substage, previous chemotherapy, previous treatment with prednisone, actinomycin D dosage, number of doses administered, response, disease-free interval, and results of CBCs performed after treatment. RESULTS: Actinomycin D was administered at a median dosage of 0.68 mg/m2 (range, 0.46 to 0.72 mg/m2), IV, every 3 weeks for 5 treatments or until disease progression. Twenty-six (53%) dogs received prednisone concurrently. Twenty (41%) dogs had a complete remission, and median disease-free interval in these dogs was 129 days. Thrombocytopenia was the most common hematologic toxicosis (n = 22 [45%]). Concurrent prednisone administration, a shorter duration of first remission, and an increased number of previous chemotherapy agents were significantly associated with a lower likelihood of responding to actinomycin D treatment. Concurrent prednisone administration and an increased number of previous chemotherapy agents were significantly associated with a shorter disease-free interval. CONCLUSION AND CLINICAL RELEVANCE: Results suggested that administration of actinomycin D as a single agent was effective for rescue chemotherapy of dogs with relapsed or resistant lymphoma and that treatment was well tolerated, although mild thrombocytopenia developed commonly.     

Prednisone treatment alters the serum amylase and lipase activities in normal dogs without causing pancreatitis.

In order to test the hypothesis that treatment with glucocorticoids causes pancreatitis in dogs, 18 mongrel dogs were divided into three groups of six individuals, each group receiving prednisone at different doses orally or intramuscularly for two weeks. Two groups consisting of six dogs each served as controls. Treatment for two weeks with oral prednisone at 1.2 mg/kg body weight or at 4 mg/kg body weight daily decreased the serum amylase activities, but increased the serum lipase activities. Postmortem examinations revealed microscopic evidence of mild pancreatitis in only one dog given prednisone, that clinically appeared normal. It was concluded that daily doses of 4 mg prednisone/kg body weight or less given orally or intramuscularly for two weeks do not cause pancreatitis in dogs.     

Corticosteroid (methylprednisolone sodium succinate) pulse therapy in five dogs with autoimmune skin disease

Corticosteroid pulse therapy is the parenteral administration of suprapharmacologic doses of methylprednisolone sodium succinate for short periods. Five dogs diagnosed as having autoimmune skin disease were treated, using pulse therapy, with subsequent dramatic and rapid improvement of skin lesions. The dogs had no adverse clinical signs attributable to the treatment. All dogs had a relapse of clinical signs after a maintenance protocol (0.5 mg/kg, q 48 h) of orally administered prednisone was started. Skin lesions on 4 of 5 dogs eventually were controlled by prednisone, azathioprine, or gold therapy.     

Combination of CCNU and DTIC chemotherapy for treatment of resistant lymphoma in dogs

BACKGROUND: Pleotropic-glycoprotein (P-gp)-mediated resistance is the usual cause of relapse in dogs with lymphoma. 1-(2-chloroethyl)3-cyclohexyl-1-nitrosurea (CCNU) and 5-(3,3-dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC) are alkylating agents that are not affected by P-gp and lack cross-resistance to each other. A combination protocol offers the advantage of improved summation dose and synergistic activity. HYPOTHESIS: A combination of CCNU and DTIC that is well tolerated can be used to treat dogs with lymphoma that developed resistance or failed to respond to previously administered chemotherapy. ANIMALS: Fifty-seven dogs with lymphoma that were resistant to treatment with standard chemotherapy (L-CHOP; L-asparaginase, cyclophosphamide, doxorubicin, vincristine, prednisone). METHODS: Prospective phase I and II trials were performed. CCNU was given PO immediately before a 5-h IV infusion of DTIC. Concurrent antiemetics and prophylactic antibiotics were used. Treatments were administered every 4 weeks. RESULTS: Based on the results of 8 dogs in the phase I study, CCNU at 40 mg/m(2) PO combined with DTIC at 600 mg/m(2) IV was used to treat 57 dogs with resistant lymphoma. Thirteen (23%) dogs had a complete response (CR) for a median of 83 days and 7 (12%) had a partial response for a median of 25 days. The median L-CHOP CR duration of the dogs that did not respond to CCNU-DTIC was significantly longer than that of the dogs that did achieve remission with CCNU-DTIC (225 days versus 92 days, P= .02). The principal toxic event was neutropenia; the median neutrophil count 7 days after treatment was 1,275 cells/microL. Increases in alanine transaminase activity, possibly associated with hepatotoxicity, were detected in 7 dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: A combination of CCNU and DTIC can be an effective option to rescue dogs with resistant lymphoma.     

Bromide Therapy in Refractory Canine Idiopathic Epilepsy

On a retrospective basis, the response to adding chronic oral bromide (BR) to phenobarbital (PB) administration in 23 refractory canine idiopathic epileptics between 1986 and 1991 was studied. The mean age for an observed first seizure was 24 months (range 7 to 72) for all dogs. Thirteen (57%) dogs were males with no breed predisposition observed. All dogs were diagnosed as having idiopathic epilepsy based on normal metabolic and neurologic diagnostic evaluations. Dogs were evaluated before BR therapy for a mean time of 22 months (range 5 to 75 months). Seventeen dogs (74%) received multiple antiepileptic drugs (AEDs) before BR therapy. All animals were maintained on PB at least 4 months before the onset of BR therapy, with a mean trough serum concentration of 37.8 mcg/mL and no improvement in seizure severity or recurrence. Twelve dogs presented with generalized isolated seizures and 11 with generalized cluster seizures (two or more seizures within 24 hours) as their first seizure. The effects of BR therapy were evaluated for a mean time of 15 months (range 4 to 33), with 17 dogs (74%) followed for 12 or more months. The mean BR serum concentration for the 0 to 4 months time period was 117 mg/dL compared with 161 mg/dL for the greater than 4 months period. Overall, response to BR therapy was associated with a reduction in the total number of seizures in 83% of the dogs when compared with their respective pre-BR period. For those followed for 1 year after BR, there was a 53% reduction in the number of seizures compared with the previous 12 months. Furthermore, owners reported a decrease in seizure intensity (65% of dogs) and change to a less severe seizure type (22% of dogs) in those dogs that continued to have seizures. Seizure-free status was obtained in 26% of the dogs with protection continuing up to 31 months in one dog. No correlations could be determined between response to BR and either age of onset of the first seizure or interval from the first AED therapy to BR therapy. Adverse effects of concomitant BR and PB therapy were polydipsia (56% of dogs), polyphagia (30% of dogs), excessive sedation (30% of dogs), and generalized ataxia (17% of dogs). As a result of BR treatment, the PB dosage was reduced in eight dogs (35%). In conclusion, concomitant BR and PB was well tolerated in dogs of this study and was effective in treating refractory canine idiopathic epilepsy, regardless of prior interval of seizure activity or previous treatment. (Journal of Veterinary Internal Medicine 1993; 7:318–327. Copyright © 1993 by the American College of Veterinary Internal Medicine.)     

Causes of death or reasons for euthanasia in military working dogs: 927 cases (1993-1996)

OBJECTIVE: To determine causes of death or reasons for euthanasia in a population of military working dogs. DESIGN: Retrospective study. ANIMALS: 927 military working dogs. PROCEDURE: Records of all military working dogs that died during the period from 1993 to 1996 were evaluated for cause of death or reason for euthanasia by review of necropsy and histopathology reports, death certificates, and daily clinical treatment sheets. A single primary cause of death or euthanasia was determined. RESULTS: Although sexually intact male dogs were more numerous in the study population, castrated male dogs typically lived longer than spayed females or sexually intact males. Leading causes of death or euthanasia (76.3% of all dogs) were appendicular degenerative joint disease, neoplasia, spinal cord disease, nonspecific geriatric decline, and gastric dilatation-volvulus. Compared with German Shepherd Dogs, Belgian Shepherd Dogs were at increased risk for death attributable to neoplasia, behavior, and respiratory tract disease. German Shepherd Dogs had nearly twice the risk for death associated with spinal cord diseases, compared with Belgian Shepherd Dogs. CONCLUSIONS AND CLINICAL RELEVANCE: For most military working dogs, death or euthanasia results from a few diseases commonly associated with advanced age. Some breed differences in risk for these diseases may exist, which clinicians should consider in the procurement and long-term management of these dogs.     

Influence of drug treatment on survival of dogs with immune-mediated hemolytic anemia: 88 cases (1989-1999)

OBJECTIVE: To evaluate association of various treatments for immune-mediated hemolytic anemia with survival to discharge in dogs. DESIGN: Retrospective cross-sectional analysis. ANIMALS: 88 dogs with idiopathic immune-mediated hemolytic anemia. PROCEDURE: Medical records of dogs with immune-mediated hemolytic anemia treated between August 1989 and August 1999 were examined. Survival to discharge, PCV at referral, autoagglutination, and drug treatment and dosage were recorded. RESULTS: Treatments included administration of prednisone, dexamethasone, azathioprine, danazol, cyclosporine, cyclophosphamide, bovine hemoglobin solution, and human immunoglobulin. Overall mortality rate was 50.5%. Significant associations with death were not detected for use of azathioprine, cyclosporine, danazol, or human immunoglobulin. A significant difference in mortality rate was not detected between use of multiple immunosuppressive drug treatments and use of single immunosuppressive drugs. Use of cyclophosphamide and bovine hemoglobin solution were associated with significant increases in relative risk of death CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that use of cyclophosphamide and bovine hemoglobin solution in treatment of idiopathic immune-mediated hemolytic anemia may be associated with increased risk of death.     

Hematologic and serum biochemical effects of long-term administration of anti-inflammatory doses of prednisone in dogs.

Results of routine hematologic and serum biochemical analyses from 12 healthy adult male dogs that were given prednisone (0.55 mg/kg of body weight, PO, q 12 h) for 35 days were compared with those of a control group of 6 dogs that were given gelatin capsules. Analyses were performed at 2-week intervals during and after prednisone administration. Lymphocyte and eosinophil counts were significantly (P less than 0.005) decreased after 2 and 4 weeks of prednisone treatment, compared with controls. Two weeks after treatment, eosinophil counts in prednisone-treated dogs were similar to those of control dogs, whereas lymphocyte counts remained low 4 weeks after treatment in treated dogs (1,869 +/- 145 cells/microliters), compared with that in control dogs (3,662 +/- 548 cells/microliters). Neutrophil and monocyte counts did not significantly change during glucocorticoid administration. Mean platelet volume significantly (P less than 0.001) decreased after 4 weeks of prednisone treatment, but returned to pretreatment values by 2 weeks after treatment. Four weeks of prednisone treatment did not cause significant increased activity in serum alanine transaminase, total alkaline phosphatase or the steroid-induced isoenzyme of alkaline phosphatase. Significant increases in serum albumin (P less than 0.001) and total protein (P less than 0.05) concentrations were detected after 4 weeks of treatment, but mean values were not significantly different from those of controls 2 weeks after treatment ended. Results of our study indicate that eosinophil and lymphocyte counts are the most sensitive indicators of long-term glucocorticoid administration at anti-inflammatory dosages of 1.1 mg/kg daily.     

Role of platelet activating factor in development of thrombocytopenia and neutropenia in dogs with endotoxemia

OBJECTIVE: To determine the role of platelet activating factor (PAF) in lipopolysaccharide (LPS)-induced thrombocytopenia and neutropenia in dogs. ANIMALS: 42 dogs. PROCEDURES: Blood samples were obtained from dogs given LPS (40 microg/kg of body weight; n = 16), PAF (1 microg/kg; 6), PAF (5 microg/kg/h for 90 minutes; 4), or physiologic saline (0.9% NaCl) solution (0.1 ml/kg/h for 90 minutes; 3) IV to monitor changes in blood cell counts, using automated counters and blood smears stained with Giemsa. Blood samples were also obtained from dogs given LPS (40 microg/kg) that had (n = 5) or had not (6) been treated beforehand with TCV-309, a potent PAF antagonist. Concentration of PAF in blood was determined by use of 125I-radioimmunoassay in dogs given LPS at 1 mg/kg (n = 3) and 40 microg/kg (9). RESULTS: Thrombocytopenia and neutropenia were found in all dogs except those given saline solution. The LPS-induced thrombocytopenia was significantly suppressed by prior treatment with TCV-309. The PAF concentrations increased markedly 1 hour after injection of 1 mg/kg of LPS and increased slightly but significantly 10 minutes after injection of 40 microg/kg of LPS. CONCLUSION AND CLINICAL RELEVANCE: PAF plays an important role in the development of LPS-induced thrombocytopenia and neutropenia in dogs. Control of PAF production, PAF-induced effects, or both may be important in the treatment of dogs with gram-negative bacterial infections and associated thrombocytopenia and neutropenia.     

A retrospective study of canine and feline cutaneous vasculitis

Twenty-one cases of cutaneous vasculitis in small animals (dogs and cats) were reviewed, and cases were divided by clinical signs into five groups. An attempt was made to correlate clinical types of vasculitis with histological inflammatory patterns, response to therapeutic drugs and prognosis. Greater than 50% of the cases were idiopathic, whereas five were induced by rabies vaccine, two were associated with hypersensitivity to beef, one was associated with lymphosarcoma and two were associated with the administration of oral drugs (ivermectin and itraconazole). Only the cases of rabies vaccine-induced vasculitis in dogs had a consistent histological inflammatory pattern (mononuclear/nonleukocytoclastic) and were responsive to combination therapy with prednisone and pentoxifylline, or to prednisone alone. Most cases with neutrophilic or neutrophilic/eosinophilic inflammatory patterns histologically did not respond to pentoxifylline, but responded to sulfone/sulfonamide drugs, prednisone, or a combination of the two.     

The effects of prednisone and azathioprine on circulating immunoglobulin levels and lymphocyte subpopulations in normal dogs.

This study investigates serum immunoglobulin (SIg) levels and lymphocyte subpopulations in normal dogs in response to putative immunosuppressive doses of prednisone and/or azathioprine. The objectives were to quantify SIg levels and lymphocyte subpopulations, including Thy-1+, CD4+, CD8+ and B cells, in normal dogs both before and after the administration of prednisone and/or azathioprine at 2 mg/kg, PO, each. Eighteen beagles were divided into 3 groups of 6 dogs each. Blood samples for radial immunodiffusion assay of IgG, IgM and IgA, complete blood count (CBC)and flow cytometry were collected prior to the administration of any drugs and again after 14 d of azathioprine, prednisone or azathioprine and prednisone. Peripheral blood mononuclear cells were isolated using density centrifugation and were incubated with monoclonal antibodies reacting with CD4+, CD8+, Thy-1+ and membrane immunoglobulin. Lymphocyte subsets were quantified using flow cytometry. Azathioprine-treated dogs had no significant changes in SIg levels or lymphocyte subpopulations. Prednisone-treated dogs had significant (P < 0.05) decreases in all SIg levels, all lymphocyte subpopulations and erythrocyte numbers, and had an increase in neutrophil counts. Prednisone and azathioprine-treated dogs had significant (P < 0.05) decreases in serum IgG levels and Thy-1+ and CD8+ lymphocyte subpopulations, with an increase in the CD4:CD8. These dogs also had a significant decrease in erythrocyte number and a significant increase in the monocyte count. These findings suggest that azathioprine and prednisone in combination or prednisone alone may be useful for the treatment of T cell-mediated diseases since decreased circulating T cell levels were demonstrated following treatment. The combination of drugs or azathioprine alone may not be appropriate for treatment of acute or autoantibody-mediated immune disease, because SIg levels were minimally affected by treatment.     

Acquired amegakaryocytic thrombocytopenia--four cases and a literature review

Acquired amegakaryocytic thrombocytopenla was diagnosed in four dogs. Initial platelet counts in all four dogs were less than 50,000 x 10(9)/litre and initial bone marrow examinations revealed megakaryocytic hypoplasia with minimal changes in the erythroid and myeloid cell lines. Two dogs had evidence of idiopathic immune-mediated disease and two dogs had evidence of associated infectious disease. One dog had a positive antibody titre to Borrella burgdorferi, and one dog had positive titres to both Ehrlichia canis and B. burgdorferi. Treatment consisted of prednisone and cyclophosphamide for the dogs with presumptive immune-mediated disease, and prednisone and tetracycline for the dogs with positive antibody titres to the Infectious organisms. Both dogs with evidence of associated infectious disease responded to treatment. A postmortem examination did not reveal the underlying aetiology in the two dogs with presumptive idiopathic immune-mediated disease.     

Visual outcome in a group of dogs with ocular blastomycosis treated with systemic antifungals and systemic corticosteroids

OBJECTIVE: To evaluate the success of the use of systemic corticosteroids and antifungal medications in the treatment of dogs with ocular lesions associated with systemic blastomycosis. DESIGN: Retrospective study. ANIMALS STUDIED: Medical records of 25 dogs diagnosed with blastomycosis, via either cytology or histopathology, at the Purdue University Veterinary Teaching Hospital between 1 January 2000 and 1 January 2005, were reviewed. PROCEDURE: Data collected from the medical records included signalment, presence and progression of ocular lesions, antifungal drugs administered, oral and topical corticosteroid administration, length of follow-up, response to treatment, and visual outcome. RESULTS: Of the 25 cases reviewed, 12 dogs (19 eyes) with follow-up information were found to have lesions consistent with ocular blastomycosis. Length of follow-up in the 12 cases ranged from 1 month to 31 months with a mean of 9 months. Antifungal therapy for all cases consisted of oral itraconazole (5 mg/kg every 24 h) initially. In seven cases, the antifungal drug administered was changed from itraconazole to oral fluconazole. Two of these also received intravenous amphotericin B, and two received additional treatment with itraconazole. All 12 dogs also received oral prednisone. The dose of oral prednisone utilized ranged from 0.2 mg/kg/day to 1.4 mg/kg/day with a mean of 0.7 mg/kg/day; the duration of oral prednisone administration ranged from 2 weeks to 8.5 months with a mean of 3 months. Topical prednisolone was a component of the treatment of 16 of the 19 eyes. Duration of topical prednisolone treatment ranged from 1 month to 30 months with a mean of 5 months. Lesions not located in the eyes exhibited a positive response to treatment in 11 (92%) of the 12 dogs. Overall, 14/19 (74%) affected eyes were visual at the time of their final recheck. All eyes with mild or moderate lesions and 5/10 (50%) severely affected eyes were visual at their last recorded recheck examination. CONCLUSIONS: The administration of systemic corticosteroids did not appear to adversely affect the survival rate and might have played a role in preservation of vision in a majority of dogs in this group with ocular blastomycosis.