Characterization of the Pro-Inflammatory and Pruritogenic Transcriptome in Skin Lesions of the Experimental Canine Atopic Acute IgE-Mediated Late Phase Reactions Model and Correlation to Acute Skin Lesions of Human Atopic Dermatitis.

Intradermal injection of anti-immunoglobulin E (IgE) antibodies in dogs grossly and histologically resemble naturally occurring atopic dermatitis (AD). However, the activated inflammatory and pruritic pathways have not been characterized. The objectives of this study were to characterize the inflammatory transcriptome of experimental acute canine IgE-induced lesions and to determine how these correlate to the transcriptome of naturally occurring human and canine acute atopic dermatitis. Biopsies were collected at 6 and 24 h after intradermal injections of anticanine-IgE antibodies to eight healthy male castrated Beagles; healthy and saline-injected skin served as controls. We extracted total RNA from skin biopsies and analyzed transcriptome using RNA-sequencing. Gene expressions of IgE-induced biopsies were compared to that of controls from the same subject (1.5-fold change, p-adjusted value ≤ 0.05). Acute IgE-mediated lesions had a significant upregulation of pro-inflammatory (e.g., LTB, IL-1B, PTX3, CCL2, IL6, IL8, IL18), T helper-(Th)1/IFNγ signal (e.g., STAT-1, OASL, MX-1, CXCL10, IL-12A) and Th2 (e.g., IL4R, IL5, IL13, IL33 and POSTN) genes, as well as Th2 chemokines (CCL17, CCL24). Pathway analysis revealed strong significant upregulation of JAK-STAT, histamine, IL-4 and IL13 signaling. Spearman correlation coefficient for the shared DEGs between canine anti-canine-IgE and human AD samples revealed a significant moderate positive correlation for anti-canine-IgE 6-h samples (r = 0.53) and 24-h samples (r = 0.47). In conclusion, acute canine IgE-mediated skin lesions exhibit a multipolar immunological axis upregulation (Th1, Th2 and Th17) in healthy dogs, resembling acute spontaneous human AD lesions.

Microarray Gene Expression Analysis of Lesional Skin in Canine Pemphigus Foliaceus.

Canine pemphigus foliaceus (PF) is considered the most common autoimmune skin disease in dogs; the mechanism of PF disease development is currently poorly understood. Therefore, this study aimed to characterize the molecular mechanisms and altered biological pathways in the skin lesions of canine PF patients. Using an RNA microarray on formalin-fixed, paraffin-embedded samples, we analyzed the transcriptome of canine PF lesional skin (n = 7) compared to healthy skin (n = 5). Of the 800 genes analyzed, 420 differentially expressed genes (DEGs) (p < 0.05) were found. Of those, 338 genes were significantly upregulated, including pro-inflammatory and Th17-related genes. Cell type profiling found enhancement of several cell types, such as neutrophils, T-cells, and macrophages, in PF skin compared to healthy skin. Enrichment analyses of the upregulated DEGs resulted in 78 statistically significant process networks (FDR < 0.05), including the Janus kinase signal transducer and activator of transcription (JAK-STAT) and mitogen-activated protein kinase (MAPK) signaling. In conclusion, canine PF lesional immune signature resembles previously published changes in human pemphigus skin lesions. Further studies with canine PF lesional skin using next-generation sequencing (e.g., RNA sequencing, spatial transcriptomics, etc.) and the development of canine keratinocyte/skin explant PF models are needed to elucidate the pathogenesis of this debilitating disease.

Mastocytosis in the skin in dogs: A multicentric case series.

Canine cutaneous mastocytosis (CM) is rare in contrast to canine mast cell tumours. In humans, CM commonly affects children and is usually indolent with possible spontaneous resolution. Systemic mastocytosis (SM) with bone marrow involvement typically affects adults, can have a poor outcome, and often includes skin lesions. 'Mastocytosis in the skin' (MIS) is the preferred term of skin lesions, if bone marrow evaluations are not available, which is often the cases in dogs. In human SM and CM, KIT mutations are often detected. The veterinary literature suggests clinical resemblances between human and canine MIS, but data is limited, and KIT mutations are rarely assessed. This retrospective study describes clinicopathological findings, treatment and outcome of 11 dogs with suspected MIS. Dogs with multiple mast cell tumours were excluded. Histopathology reports (n = 5) or slides (n = 6) were reviewed. KIT mutation analysis including exons 8, 9, 11, 14 and 17 were analysed in eight dogs. Median age at diagnosis was 4 years (range, 1-12). Typical clinical signs included multifocal to generalised nodules and papules. Histologically, skin lesions were characterised by dermal infiltration of well-differentiated mast cells. KIT mutations were detected in 3/8 dogs (exon 9: n = 2; exon 11: n = 1). One dog had mastocytaemia suggesting possible SM. Glucocorticoids were mostly successful with lesion improvement in all treated dogs (n = 8). This cohort highlights resemblances between human and canine MIS. Further studies are required to confirm these findings and establish diagnostic criteria for CM and MIS associated with SM in dogs.

Impact of apitherapy on canine, equine, and chicken lymphocytes, in vitro.

Apitherapy is a form of alternative medicine that utilizes products from the western honeybee (Apis mellifera), including honey, propolis, and honeybee venom, to improve the health status of human patients by altering host immunity. An added benefit of these products is that they are nutraceuticals and relatively inexpensive to aquire. Currently, little is known about the use of honeybee products in veterinary species, as well as their impact on host immunity. In the present in vitro study, honey, propolis, and honeybee venom were co-cultured with enriched canine, equine, and chicken peripheral blood lymphocytes (PBLs) with cell proliferation, cell viability/apoptosis, and cellular morphology evaluated. Concanavalin A (Con A) and dexamethasone were used as stimulatory and suppressive controls, respectively. Honeybee products' effects on the three veterinary species varied by product and the species. Honey stimulated the PBLs proliferation in all three species but also displayed some increased cytotoxicity. Propolis stimulated proliferation in canine and equine PBLs, however, it suppressed proliferation in the chicken PBLs. Honeybee venom was the strongest PBL stimulant for all three species and in the equine, surpassed the stimulant response of Con A and yet, enhanced PBL cell viability post culture. In summary, the results of this preliminary in vitro study show that these three honeybee products do impact lymphocyte proliferation and viability in dogs, horses, and chickens, and that more research both in vitro and in vivo will be necessary to draw conclusions regarding their future use as immune stimulants or inhibitors.

Characterisation of the pruritus responses and pruritic behaviours in an interleukin 31-induced canine model of pruritus.

BACKGROUND: Intravenous administration of interleukin (IL)-31 in healthy dogs has been used as a model to assess antipruritic drugs. However, there is no known in-depth characterisation of pruritic behaviours, and the repeatability of the IL-31-induced pruritus in the individual dogs is currently unknown. OBJECTIVES: To evaluate the immediate/delayed pruritus responses and the pruritic behaviours observed in the IL-31-induced pruritic model in healthy dogs after repeated IL-31 injections. ANIMALS: Fifteen healthy laboratory beagles. METHODS: All dogs were video-recorded for 270 min after two intravenous recombinant IL-31 injections (1.75 µg/kg) and vehicle (phosphate-buffered saline, control) injections, respectively; interventions were randomised and performed with a 2 week wash-out period. Two blinded investigators reviewed the pruritic behaviours of all video recordings. RESULTS: Both canine IL-31 (IL-31_01, IL-31_02) injections significantly increased pruritic seconds and categorical minutes ('YES'/'NO' behaviour per discrete 1 min interval) in healthy dogs compared with both vehicle groups (Vehicle_01, Vehicle_02). The second intravenous canine IL-31 (IL-31_02) administered 14 days after the first IL-31 injection induced a significant increase in pruritic seconds (p = 0.021) and not pruritic categorical minutes (p = 0.231). An increase in pruritic seconds was observed in both IL-31 groups in the first 30 min post-administration, while there was no significant difference between IL-31 and vehicle groups. CONCLUSIONS AND CLINICAL RELEVANCE: In conclusion, intravenous IL-31 reproducibly induces itch responses in dogs. Future evaluations of the canine IL-31 pruritic model should assess total pruritic behaviours in seconds rather than using a biased 'YES/NO' behaviour per 1 min scoring system.

Characterization of the serum and skin inflammatory profile in canine pemphigus foliaceus using multiplex assay and quantitative real-time polymerase chain reaction (qRT-PCR).

Canine pemphigus foliaceus (PF) is a common autoimmune skin disease characterized by autoantibodies binding to epithelial adhesion molecules resulting inflammatory response. The immune network of cytokine and chemokine abnormalities that characterize the immune response in canine PF are poorly explored. This study evaluated serum and lesional skin cytokine and chemokine profiles of dogs diagnosed with PF compared to healthy control dogs. Serum samples obtained from 11 PF dogs and 16 healthy control dogs were analyzed using commercially available canine multiplex assay for 13 biomarkers (Canine Milliplex assay). Eight lesional skin samples from seven PF dogs and five healthy site-matched samples from five healthy dogs were evaluated for 20 immune markers using quantitative real-time PCR. Immunomodulating medications were suspended for at least four weeks in all dogs before obtaining serum and skin samples. PF patients showed significantly higher serum concentrations of tumor necrosis factor-α, interleukin (IL)- 6, IL-8, IL-18, CCL2, KC-like, and granulocyte-macrophages colony-stimulating factor when compared to healthy controls (Mann-Whitney U test; p < 0.05 for all). Lesional PF skin exhibited significant expression and upregulation of pro-inflammatory/T helper (Th1) 1 markers IL-1ß, MX1, GZMB, OAS1, and IFN-γ as well as Th2 cytokines IL-13, IL-33, TSLP, IL-31 and Th17/22 markers IL-17A and IL-22 (Mann-Whitney U test; p < 0.05 for all). Taken together, the findings from this study describe the role of numerous cytokines and chemokines associated with immune response in the skin and serum of canine PF patients. Further larger-sample proteomics and RNA-sequencing transcriptomics studies are needed to understand the immune pathogenesis of canine PF skin lesions.

Tolerability and the effect on skin Staphylococcus pseudintermedius density of repeated diluted sodium hypochlorite (bleach) baths at 0.005% in healthy dogs.

BACKGROUND: Dilute sodium hypochlorite (bleach) baths at 0.005% concentration twice weekly have been shown to markedly reduce the severity of atopic dermatitis in children, yet no tolerability and efficacy data are available for this treatment in dogs. OBJECTIVES: To determine the local tolerability and the longitudinal effect on the density of Staphylococcus pseudintermedius of repeated diluted bleach baths on healthy dog skin. ANIMALS: Four healthy hound cross-bred dogs. METHODS: Bleach baths (0.005%; twice weekly for 15 min) were applied to four healthy hound cross-bred dogs over four weeks (eight baths). Local tolerability was assessed for axillae, abdomen and legs by an investigator before, immediately after and 24 h after each bath. The longitudinal effect on density of S. pseudintermedius from axillae and groin was analysed through quantitative PCR before treatment [at Day (D)-7 and -3], during treatment on D4, D11 and D25, and on D30. RESULTS: There was no erythema or scaling after the baths in any dog. Copy numbers of S. pseudintermedius in axillae, groin and both (axillae and groin together) were not significantly different at any time point during the study. CONCLUSIONS AND CLINICAL RELEVANCE: Repeated 0.005% hypochlorite bleach baths over four weeks were safe and well-tolerated in healthy dogs without significant changes in the density of S. pseudintermedius.

Establishment of an Intradermal Canine IL-31-Induced Pruritus Model to Evaluate Therapeutic Candidates in Atopic Dermatitis.

Pruritic models in healthy dogs utilizing intravenous administration of interleukin 31 (IL-31) bypass the "natural" itch sensation in AD, which is initiated by pruriceptive primary afferent neurons in the skin. This study aimed to evaluate the immediate/delayed pruritus responses and the pruritic behaviors observed in an intradermal IL-31-induced pruritic model of healthy dogs and the anti-pruritic effect of oclacitinib on said model. In Phase 1, all the dogs were randomized and video-recorded for 300 min after intradermal canine recombinant IL-31 injections (1.75 µg/kg) and vehicle (phosphate-buffered saline) injections. In Phase 2, all the dogs received oral oclacitinib (0.4-0.6 mg/kg, twice daily for 4 consecutive days and once daily on day 5), with the intradermal IL-31 injection performed on day 5. Two blinded investigators reviewed the pruritic behaviors in all the video recordings. Intradermal IL-31 administration to healthy dogs caused a significant increase in the total (p = 0.0052) and local (p = 0.0003) seconds of pruritic behavior compared to the vehicle control. Oral oclacitinib administration significantly reduced the total (p = 0.0011) and local (p = 0.0156) intradermal IL-31-induced pruritic seconds; there was no significant difference in pruritic seconds between the vehicle and oclacitinib within the IL-31 groups. Significant delayed pruritic responses at 150-300 min after IL-31 injections were observed, and intradermal IL-31 failed to induce acute itch (first 30 min). Intradermal injection of IL-31 induces delayed itch responses in dogs that are diminished by the effect of oclacitinib, an oral JAK inhibitor.

Effect of glycerin on immediate cutaneous reactions of histamine (positive) and phosphate-buffered saline (negative) controls in intradermal skin testing of healthy dogs: A randomised, blinded study.

BACKGROUND: Glycerinated allergen extracts contain 50% glycerin, an excellent preservative. While glycerin is a recognised irritant in humans, the utility of glycerinated extracts for intradermal testing has not been validated in dogs. HYPOTHESIS/OBJECTIVE: To determine and compare the effects of glycerin on immediate cutaneous reactions to intradermal injections of histamine and saline in healthy dogs. ANIMALS: Eight healthy laboratory beagles. MATERIALS AND METHODS: The study was designed as a randomised, blinded study. Intradermal injections of histamine (positive control) and saline (negative control) in aqueous and glycerinated (50%) forms were performed on the right thorax. Global wheal scores (GWS) at 20 min were evaluated by two independent investigators blinded to the interventions. RESULTS: There were no wheal and flare reactions observed after the intradermal injections of phenolated saline. By contrast, 50% glycerosaline injections induced erythema and induration in all dogs. Global wheal scores were significantly higher in aqueous histamine (Friedman test, p < 0.0001) and 50% glycerinated histamine (Friedman test, p = 0.0084) compared to phenolated saline controls. Interestingly, only aqueous histamine (Friedman test, p = 0.01) had significantly higher GWS than 50% glycerosaline injections, while no significant difference in GWS between 50% glycerinated histamine and 50% glycerosaline groups was observed (Friedman test, p = 0.59). CONCLUSION AND CLINICAL RELEVANCE: This study demonstrates that intradermal injection of 50% glycerosaline induces erythema and induration skin reactions in healthy dogs that can mimic positive reactions to allergenic extracts. Further dilutions of glycerinated positive and negative control solutions need to be optimised for intradermal testing in dogs.

Comparison of whole blood concentrations of oral human generic modified ciclosporin capsules with microemulsified ciclosporin capsules approved for canine atopic dermatitis following a single oral administration to healthy dogs.

BACKGROUND: There have been no comparative bioavailability studies between the microemulsified ciclosporin formulation, approved for the treatment of canine atopic dermatitis (cAD), and the generic modified formulation of ciclosporin for humans. OBJECTIVES: To compare whole blood ciclosporin concentrations of oral generic modified ciclosporin (Treatment A; Teva Pharmaceuticals) and ciclosporin brand Atopica (Treatment B; Elanco Animal Health) in healthy dogs at 1 and 1.5 h following a single oral administration. METHODS: Whole blood concentrations were evaluated at 1 and 1.5 h post-oral administration of treatments A and B in a randomised, blinded, cross-over study with an 8-day wash-out, after a single administration at 4.4-5.3 mg/kg/day in eight healthy, male-castrated research beagle dogs. Ciclosporin blood concentrations were measured through the Auburn University Clinical Pharmacology Laboratory. RESULTS: Ciclosporin blood concentrations were below the detection limit before the start of treatment for both groups. Blood ciclosporin concentrations for Treatment A (median 1192 ng/ml) were significantly higher at 1 h post-oral administration than those for Treatment B (median 499 ng/ml; p = 0.001). However, no significant differences (p = 0.75) in ciclosporin values were observed at 1.5 h post-administration between treatments A (median 945 ng/ml) and B (median 809 ng/ml). CONCLUSIONS AND CLINICAL RELEVANCE: Generic modified ciclosporin achieved higher blood concentrations at 1 h post-administration than Atopica after a single oral administration in healthy dogs; no difference was noted at 1.5 h. Further clinical studies using generic modified ciclosporin in client-owned dogs affected with cAD are advocated to confirm its therapeutic efficacy.

A self-limited acute febrile sterile neutrophilic dermatosis (Sweet's-like syndrome) in a dog featuring target skin lesions with strong upregulation of interleukin-8 and T-helper 1 pathway.

In this report, we provide a case of self-limiting canine acute febrile sterile neutrophilic dermatosis in which the clinical signs featured typical target skin lesions with strong upregulation of T-helper 1 markers and interleukin-8, a potent neutrophil chemoattractant. Further, large case series are needed to characterize canine sterile neutrophilic dermatosis.

Dans cet article, nous présentons un cas de dermatose neutrophilique fébrile stérile aiguë canine spontanément résolutive dans laquelle les signes cliniques comportaient des lésions cutanées cibles typiques avec une forte régulation à la hausse des marqueurs T-helper 1 et de l'interleukine-8, un puissant chimioattractant des neutrophiles. D'autres grandes séries de cas sont nécessaires pour caractériser la dermatose neutrophile stérile canine.

En este artículo exponemos un caso de dermatosis neutrofílica estéril febril aguda canina autolimitante en la que los signos clínicos fueron lesiones cutáneas típicas en forma de diana con una intensa elevación de los marcadores T-helper 1 y de interleucina-8, un potente quimiotáctico de neutrófilos. Se necesitan series de casos más grandes para caracterizar la dermatosis neutrofílica estéril canina.

Neste relato, nós apresentamos um caso de dermatose neutrofílica estéril canina aguda febril em que os sinais clínicos típicos foram lesões cutâneas em alvo com forte ativação de marcadores T-helper 1 e interleucina-8, um potente quimioatrativo de neutrófilos. São necessários mais estudos com uma grande série de casos para caracterizar a dermatose neutrofílica estéril canina.

Transcriptome analysis of selected cytokine and chemokines in the eosinophilic plaques of cats with atopic skin syndrome.

BACKGROUND: Previous evaluations of cytokine and chemokine gene expressions [messenger (m)RNA] in the skin of allergic cats were mostly unsuccessful in detecting the T-helper 2 (Th2) pathway, which is associated with the major effector cytokines interleukin (IL)-4, IL-5 and IL-13. HYPOTHESIS/OBJECTIVE: To evaluate differences in the mRNA expression in eosinophilic plaques of cats diagnosed with feline atopic skin syndrome (FASS) compared to healthy controls. ANIMALS: Four client-owned cats with FASS with eosinophilic plaques and five healthy control cats. MATERIALS AND METHODS: Gene expressions (mRNA) of 14 cytokines and chemokines from eosinophilic plaque skin of cats with FASS and site-matched skin samples from healthy controls were analysed using quantitative reverse-transcription PCR analysis. RESULTS: Eosinophilic plaques were characterized by upregulation of Th2 cytokines IL-4 (p ≤ 0.01), IL-5 (p ≤ 0.01) and IL-13 (p ≤ 0.01) and Th2-attracting chemokine CCL17 (p ≤ 0.05). Moreover, there was higher expression of S100 calcium-binding protein A 8 (p ≤ 0.01) as well as C-X-C Motif chemokine ligand 10 (CXCL10; p ≤ 0.01), IL-10 (p ≤ 0.05) and the Th17 cytokine IL-17A (p ≤ 0.01) in lesional skin compared to healthy samples. There was no difference in gene expressions of IL-12A, IL-31, IL-33, thymic stromal lymphopoietin (TSLP), tumour necrosis factor-α (TNF-α) or CCL5. CONCLUSIONS AND CLINICAL RELEVANCE: Results demonstrate that eosinophilic plaques feature dominant Th2 and IL-17A inflammatory responses in the skin. Further larger-sample transcriptome studies are needed to advance our understanding of the pathogenesis of different skin lesions in FASS.

Hyperkeratotic erythema multiforme variant in 17 dogs.

BACKGROUND: A new canine subgroup defined as 'old-dog' or 'hyperkeratotic' erythema multiforme (HKEM) with marked hyperkeratosis and parakeratosis has been proposed without any detailed description of larger case series. OBJECTIVES: We report herein the signalment, clinical signs, treatment outcome, and histopathological and immunological findings in 17 dogs with HKEM. ANIMALS: Inclusion criteria were the presence of (i) scaly skin lesions with or without crusting; and (ii) microscopic lesions typical of EM (i.e. a panepidermal cytotoxic lymphocytic dermatitis with or without basal keratinocyte apoptosis); and (iii) microscopic ortho- and/or parakeratotic hyperkeratosis affecting the interfollicular epidermis. MATERIALS AND METHODS: Clinical questionnaires and skin biopsies were reviewed. Polymerase chain reactions for epidermotropic viruses and direct immunofluorescence were performed. RESULTS: Various breeds were affected with an over-representation of males in their mid-to-late adulthood (median age 9 years). Generalised skin lesions included multifocal-to-coalescing, linear and annular macules and plaques with erythema and adherent firm crusting. Microscopic lesions were specific for EM and featured prominent superficial epidermal apoptosis with lymphocytic satellitosis and parakeratosis. No drug triggers were identified. Polymerase chain reactions for canine herpesvirus polymerase gene, canine parvovirus and canine distemper virus were negative in all HKEM and canine erosive EM (15 dogs) biopsies. Lesions failed to respond to oral and/or topical antimicrobials. Complete remission of signs was achieved in 9 of 17 dogs (53%) using immunosuppressive regimens. CONCLUSIONS AND CLINICAL RELEVANCE: Hyperkeratotic erythema multiforme (HKEM) is a chronic, persistent and clinically distinctive erythema multiforme (EM) variant that differs from 'classic' vesiculobullous erosive-to-ulcerative EM in dogs.

Topical Imiquimod Therapy for Localized Solar Dermatitis in a Dog.

Chronic sun exposure in dogs can result in clinical changes in the skin referred to as solar or actinic dermatitis. A 5-year-old, neutered male, American Bulldog presented with localized unilateral erythematous macules, plaques, alopecia, comedones and hemorrhagic bullae involving the non-pigmented skin on left lateral ventral flank area. The presence of hyperplastic epidermis with keratinocyte dysplasia, superficial dermal elastosis, and multiple follicular cysts with occasional rupture (furunculosis) on histology, together with history and characteristic skin lesions was consistent solar dermatitis/actinic keratosis. Skin scrapings were negative and treatment for secondary pyoderma was initiated with oral clindamycin for 8 weeks. After 2 months of antibiotic therapy, the hemorrhagic bullae resolved; however, erythematous solar/actinic skin lesions with induration and comedones persisted. Topical application of imiquimod 5% cream 3 times weekly for 8 weeks resulted in the resolution of erythema, but some of the non-inflamed comedones remained. Staining for elastin and Ki67 revealed keratinocyte hyperplasia in hair follicle infundibulums and alterations in the elastic fibers around follicles, which may lead to closure and formation of follicular cysts. Imiquimod has been long suggested as a treatment option for solar dermatitis, but this is the first known case report detailing its efficacy in dogs.

A Retrospective Evaluation of the Steroid-Sparing Effect of Oral Modified Ciclosporin for Treatment of Canine Pemphigus Foliaceus.

The efficacy of ciclosporin as an adjuvant immunosuppressant administered with glucocorticoids (GCs) for induction of canine PF remission is unknown. This study is a retrospective review of medical records from 2015 to 2020 to evaluate the therapeutic outcomes of 11 PF dogs treated with oral modified ciclosporin and GCs. Concurrent GCs were given with ciclosporin to all PF dogs. Nine dogs (9/11) achieved complete remission (CR); five dogs received ciclosporin at a mean dose of 6.2 mg/kg/day; and four dogs received a combination of ciclosporin and ketoconazole at a mean dose of 3 mg/kg/day, respectively. Two dogs (2/11) showed only 25% or poor response, with the development of new PF lesions during treatment. The mean duration of ciclosporin therapy for nine dogs to achieve CR was 65 days (median 57 days, range 24-119 days). Slow tapering of oral GCs while continuing ciclosporin at the same dose and frequency in nine dogs with CR led to recurrence of PF lesions in four dogs, whereas, in five dogs, oral glucocorticoids were discontinued without a PF flare. Oral modified ciclosporin combined with GCs achieved CR in 9 out of 11 PF dogs during the induction phase in this study.

Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.

A retrospective evaluation of the steroid sparing effects of oral mycophenolate mofetil (MMF) as an adjunct immunosuppressant for the treatment of canine pemphigus foliaceus.

BACKGROUND: Oral mycophenolate mofetil (MMF) currently is considered a low-risk steroid-sparing therapeutic option for the management of canine pemphigus foliaceus (PF). OBJECTIVES: This retrospective study evaluates the therapeutic outcomes of dogs with PF treated with the combination of oral MMF and glucocorticoid (GC). Clinical outcomes and adverse side effects are reported. ANIMALS: Eleven dogs diagnosed with PF. MATERIALS AND METHODS: Retrospective review of medical records from dogs presented with PF to the dermatology service of a veterinary teaching hospital between 2015 and 2020. RESULTS: Eleven dogs were identified which had received concurrent GCs and MMF. The MMF dose range was 19.8-45 mg/kg/day. Only two dogs (two of 11) treated with a mean MMF dosage of 39 mg/kg/day along with oral prednisone or dexamethasone achieved complete remission (CR). Partial remission (PR) was achieved in four of 11 dogs who received either prednisone, prednisolone or dexamethasone along with MMF (mean dosage 26 mg/kg/day). Four dogs (four of 11) showed poor response to MMF given at 28.5 mg/kg/day along with prednisone or dexamethasone. In one dog (one of 11) MMF was discontinued due to severe GI upset; transient vomiting and diarrhea was observed in four of 11 dogs. The median duration of MMF therapy in conjunction with GC for all groups was 70.5 days. Tapering of oral GCs while continuing MMF administration at the same dosage and frequency led to recurrence of lesions in all PF patients. CONCLUSION: Oral MMF combined with GC achieved CR in two of 11 PF dogs included in this study. Further research of MMF efficacy in PF may need to be performed.