Cyclosporine treatment of anal furunculosis in 26 dogs

Longitudinal evaluation of the cutaneous and rectal microbiota of German shepherd dogs with perianal fistulas undergoing therapy with ciclosporin and ketoconazole

BACKGROUND

Perianal fistulas are painful ulcers or sinus tracts that disproportionately affect German shepherd dogs and are proposed as a spontaneous animal model of fistulising Crohn's disease.

OBJECTIVES

To characterise the rectal and cutaneous microbiota in German shepherd dogs with perianal fistulas and to investigate longitudinal shifts with lesion resolution during immunomodulatory therapy.

ANIMALS

Eleven German shepherd dogs with perianal fistulas and 15 healthy German shepherd dogs.

MATERIALS AND METHODS

Affected dogs were evaluated and swabbed at three visits, 30 days apart, while undergoing treatment with ciclosporin and ketoconazole. Healthy German shepherd dogs were contemporaneously sampled. Sites included the rectum, perianal skin and axilla. The microbiome was evaluated following sequencing of the V4 hypervariable region of the 16S ribosomal RNA (rRNA) gene.

RESULTS

Alpha diversity was not significantly different between healthy and affected dogs at each of the three body sites (p > 0.5), yet rectal and perianal beta diversities from affected dogs differed significantly from those of healthy dogs at Day 0 (p = 0.004). Rectal and perianal relative abundance of Prevotella spp. increased and perianal Staphylococcus spp. relative abundance decreased in affected dogs over time, coincident with lesion resolution.

CONCLUSIONS AND CLINICAL RELEVANCE

Changes in lesional cutaneous and rectal microbiota occur in German shepherd dogs with perianal fistulas and shift over time with lesion resolution during immunomodulatory therapy. Further investigations of the role of cutaneous and enteric microbiota in the pathogenesis of perianal fistulas, and whether manipulation of microbial populations may ameliorate disease, are needed.

Medical Management of Canine Chronic Ulcerative Stomatitis Using Cyclosporine and Metronidazole

Canine chronic ulcerative stomatitis (CCUS) is a spontaneously occurring, painful, and often debilitating condition of the oral cavity, with a suspected immune-mediated component. The response to pharmacological treatment is generally poor, thus the need to identify more effective medical therapies for this condition. This article describes a prospective clinical trial that was designed to evaluate the efficiency of a combination of cyclosporine and metronidazole in managing CCUS. The hypothesis was that a combination of cyclosporine and metronidazole would effectively minimize clinical signs associated with CCUS. Ten client-owned dogs with a biopsy-confirmed diagnosis consistent with CCUS were prescribed cyclosporine (5 mg/kg) for 1 week, followed by the addition of metronidazole (15-20 mg/kg), both administered orally once daily. The cyclosporine dosage interval was lengthened over time. Dogs were observed for a 6-month period and evaluated using a 32-point Canine Ulcerative Stomatitis Disease Activity Index (CUSDAI). Regular cyclosporine therapeutic drug monitoring was also conducted by the measurement of whole blood cyclosporine levels and the pharmacodynamic assessment of the T-cell expression of IL-2. The results demonstrated that a combination of cyclosporine and metronidazole was effective in minimizing the clinical signs of CCUS and in reducing CUSDAI scores. Neither blood cyclosporine levels nor the T-cell expression of IL-2 predicted improvement in clinical signs and CUSDAI scores, although there was a correlation between blood drug concentrations and the suppression of T-cell IL-2 expression. The evaluation of clinical signs and CUSDAI scores appears to be the most effective means of assessing response to therapy, and therapeutic drug level monitoring does not appear to be routinely indicated.

The Intersection of Human and Veterinary Medicine-A Possible Direction towards the Improvement of Cell Therapy Protocols in the Treatment of Perianal Fistulas

The effective treatment of perianal fistulizing Crohn's disease is still a challenge. Local administration of mesenchymal stromal cells (MSCs) is becoming a part of accepted treatment options. However, as a fledgling technique, it still can be optimized. A new trend in translational research, which is in line with "One Health" approach, bases on exploiting parallels between naturally occurring diseases affecting humans and companion animals. Canine anal furunculosis (AF) has been indicated as condition analogous to human perianal Crohn's disease (pCD). This narrative review provides the first comprehensive comparative analysis of these two diseases based on the published data. The paper also outlines the molecular mechanisms of action of MSCs which are likely to have a role in modulating the perianal fistula niche in humans, and refers them to the current knowledge on the immunomodulatory properties of canine MSCs. Generally, the pathogenesis of both diseases shares main determinants such as the presence of genetic predispositions, dysregulation of immune response and the relation to intestine microbiota. However, we also identified many aspects which should be further specified, such as determining the frequency of true fistulas formation in AF patients, elucidating the role of TNF and Th17 pathway in the pathogenesis of AF, or clarifying the role of epithelial-to-mesenchymal transition phenomenon in the formation of canine fistulae. Nevertheless, the available data support the hypothesis that the results from testing cell therapies in dogs with anal furunculosis have a significant translational value in optimizing MSC transplants procedures in pCD patients.

Dysbiosis in a canine model of human fistulizing Crohn's disease

Crohn's disease (CD) is a chronic immune-mediated inflammatory condition caused by the loss of mucosal tolerance toward the commensal microbiota. On average, 29.5% and 42.7% CD patients experience perianal complications at 10 and 20 y after diagnosis, respectively. Perianal CD (pCD) result in high disease burden, diminished quality of life, and elevated health-care costs. Overall pCD are predictors of poor long-term outcomes. Animal models of gut inflammation have failed to fully recapitulate the human manifestations of fistulizing CD. Here, we evaluated dogs with spontaneous canine anal furunculosis (CAF), a disease with clinical similarities to pCD, as a surrogate model for understanding the microbial contribution of human pCD pathophysiology. By comparing the gut microbiomes between dogs suffering from CAF (CAF dogs) and healthy dogs, we show CAF-dog microbiomes are either very dissimilar (dysbiotic) or similar (healthy-like), yet unique, to healthy dog's microbiomes. Compared to healthy or healthy-like CAF microbiomes, dysbiotic CAF microbiomes showed an increased abundance of Bacteroides vulgatus and Escherichia coli and a decreased abundance of Megamonas species and Prevotella copri. Our results mirror what have been reported in previous microbiome studies of patients with CD; particularly, CAF dogs exhibited two distinct microbiome composition: dysbiotic and healthy-like, with determinant bacterial taxa such as E. coli and P. copri that overlap what it has been found on their human counterpart. Thus, our results support the use of CAF dogs as a surrogate model to advance our understanding of microbial dynamics in pCD.

Challenges of stem cell therapies in companion animal practice

Regenerative medicine using stem cells from various sources are emerging treatment modality in several refractory diseases in veterinary medicine. It is well-known that stem cells can differentiate into specific cell types, self-renew, and regenerate. In addition, the unique immunomodulatory effects of stem cells have made stem cell transplantation a promising option for treating a wide range of disease and injuries. Recently, the medical demands for companion animals have been rapidly increasing, and certain disease conditions require alternative treatment options. In this review, we focused on stem cell application research in companion animals including experimental models, case reports and clinical trials in dogs and cats. The clinical studies and therapeutic protocols were categorized, evaluated and summarized according to the organ systems involved. The results indicate that evidence for the effectiveness of cell-based treatment in specific diseases or organ systems is not yet conclusive. Nonetheless, stem cell therapy may be a realistic treatment option in the near future, therefore, considerable efforts are needed to find optimized cell sources, cell numbers and delivery methods in order to standardize treatment methods and evaluation processes.

Management of canine perianal fistula with fluorescence light energy: preliminary findings

BACKGROUND

Canine perianal fistula (CPF) is a severe, painful, debilitating skin condition affecting the perianal skin. It often interferes with the quality of life of both dog and owner. Conventional medical treatment involves the use of immunosuppressive therapy; however, the successful resolution of lesions can be limited by poor owner compliance, adverse drug effects and dependence on costly therapies.

HYPOTHESIS/OBJECTIVES

The present study aimed to assess the potential benefits of fluorescent light energy (FLE) on cases of CPF.

ANIMALS

Four dogs with active perianal fistulas METHODS AND MATERIALS: FLE was applied as sole management therapy once a week with two consecutive applications in the same session for each dog until clinical signs had significantly improved, with weekly assessments for a six week period. Dogs were assessed by measuring the size of lesions at the start of the study and then weekly for six weeks, using planimetry software. Owners recorded vocalization and straining frequency scores during their pet's defaecation, and perianal licking frequency on a 0-5 point scale to assess the response to therapy.

RESULTS

All dogs improved with FLE, achieving a significant reduction in vocalization, straining and licking after two weeks (P = 0.002). After five weeks of FLE therapy, lesional areas had significantly decreased (P = 0.04). Only one dog required more than seven applications. No adverse events were reported.

CONCLUSION AND CLINICAL IMPORTANCE

FLE may be a promising alternative therapy for CPF.

Ciclosporin 10 years on: indications and efficacy

Ciclosporin is a lipophilic cyclic polypeptide with powerful immunosuppressive and immunomodulatory properties that has been used in veterinary medicine for two decades. It is a calcineurin inhibitor whose principal mode of action is to inhibit T cell activation. The drug is principally absorbed from the small intestine and is metabolised in the intestine and liver by the cytochrome P450 enzyme system. Ciclosporin is known to interact with a wide range of pharmacological agents. Numerous studies have demonstrated good efficacy for the management of canine atopic dermatitis and this has been a licensed indication since 2003. In addition to the treatment of atopic dermatitis, it has been used as an aid in the management of numerous other dermatological conditions in animals including perianal fistulation, sebaceous adenitis, pododermatitis, chronic otitis externa and pemphigus foliaceus. This article reviews the mode of action, pharmacokinetics, indications for use and efficacy of ciclosporin in veterinary dermatology.

Oral cyclosporine treatment in dogs: a review of the literature

Cyclosporine is an immunomodulatory drug used to treat an increasing spectrum of diseases in dogs. Cyclosporine is a calcineurin inhibitor, ultimately exerting its inhibitory effects on T-lymphocytes by decreasing production of cytokines, such as interleukin-2. Although, in the United States, oral cyclosporine is approved in dogs only for treatment of atopic dermatitis, there are many other indications for its use. Cyclosporine is available in 2 oral formulations: the original oil-based formulation and the more commonly used ultramicronized emulsion that facilitates oral absorption. Ultramicronized cyclosporine is available as an approved animal product, and human proprietary and generic preparations are also available. Bioavailability of the different formulations in dogs is likely to vary among the preparations. Cyclosporine is associated with a large number of drug interactions that can also influence blood cyclosporine concentrations. Therapeutic drug monitoring (TDM) can be used to assist in attaining consistent plasma cyclosporine concentrations despite the effects of varying bioavailability and drug interactions. TDM can facilitate therapeutic success by guiding dose adjustments on an individualized basis, and is recommended in cases that do not respond to initial oral dosing, or during treatment of severe, life-threatening diseases for which a trial-and-error approach to dose adjustment is too risky. Pharmacodynamic assays that evaluate individual patient immune responses to cyclosporine can be used to augment information provided by TDM.

Update on immununosuppressive therapies for dogs and cats

Treatment of immune-mediated disease in dogs and cats continues to evolve as new therapies are introduced or adapted from human medicine. Glucocorticoids remain the first-line therapy for many of the immune-mediated or inflammatory diseases of cats and dogs. The focus of this article is to provide an update on some of the common immunosuppressive therapies used in small animal veterinary medicine. The goals of therapy are to induce disease remission through the inhibition of inflammation and the modulation of lymphocyte function.

The use of ciclosporin A in veterinary dermatology

Ciclosporin A (CsA) has potent immunosuppressive and immunomodulatory activity that has been exploited in human medicine to prevent the rejection of transplanted organs and to manage atopic dermatitis and psoriasis. Over the past decade, CsA has been employed more frequently in veterinary dermatology and its value in the management of several canine and feline dermatoses is now well established. CsA inhibits calcineurin phosphatase, suppressing T cell activation and the synthesis of T cell cytokines consequently impairing the activity of B cells, antigen-presenting cells, mast cells, basophils and eosinophils. The pharmacokinetics of CsA are similar in humans, dogs and cats and the drug has a wide safety margin in dogs, cats and rabbits. Adverse effects, principally transient vomiting and soft faeces/diarrhoea, may be seen shortly after instituting treatment but often resolve despite continuing treatment. Gingival hyperplasia and cutaneous effects such as hirsutism may occur after prolonged treatment.

Cyclosporine A affects the in vitro expression of T cell activation-related molecules and cytokines in dogs

Cyclosporine is a powerful immunosuppressive drug that is being used with increasing frequency to treat a wide range of immune-mediated diseases in the dog. To date, ideal dosing protocols that will achieve immunosuppression with cyclosporine in dogs remain unclear, and standard methods that can measure effectiveness of immunosuppression have not been established. The aim of our study was to evaluate the effects of in vitro cyclosporine exposure on a panel of molecules expressed by activated T cells to ascertain their potential as biomarkers of immunosuppression in dogs. Blood was drawn from six healthy dogs, and peripheral blood mononuclear cells (PBMC) were isolated and activated. Half of the cells were incubated with 200 ng/mL cyclosporine prior to activation, and the other half were not exposed to cyclosporine. Samples were analyzed using flow cytometry, and the expression of intracellular cytokines IL-2, IL-4, and IFN-γ was evaluated after 6, 12, and 24h of drug exposure. Each cytokine exhibited a time-dependent suppression profile, and all but two samples activated in the presence of cyclosporine showed lower cytokine expression than untreated controls. We also evaluated the expression of the surface T cell activation molecules CD25 and CD95 by flow cytometry after 36 h of drug exposure. Expression of these surface molecules decreased significantly when activated in the presence of cyclosporine. Our results suggest that suppressed expression of the markers related to T cell activation could potentially be utilized as an indicator of the efficacy of cyclosporine therapy in dogs.

Grapefruit juice, lyophilized grapefruit juice, and powdered whole grapefruit inhibit cytochrome P450-mediated triazolam hydroxylation by beagle dog liver microsomes

Coadministration of grapefruit juice (GFJ) has been proposed to enhance the systemic availability and decrease the required dose of drugs such as cyclosporine that are extensively metabolized in the intestine and liver. Although GFJ inhibits human cytochrome P450 (CYP) 3A, effects on dog CYP have not yet been reported. Consequently, we determined whether GFJ inhibits triazolam hydroxylation by Beagle dog liver microsomes (DLM) using human liver microsomes (HLM) as positive control. Results were compared with the effects of lyophilized GFJ and commercially-available powdered grapefruit capsules, which may be more convenient dosage forms. GFJ inhibited alpha-hydroxytriazolam formation in both DLM and HLM with similar IC(50) (inhibitor concentration producing a 50% decrease in reaction velocity) values of 0.56% and 0.52% (v/v), respectively. Lyophilized GFJ and powdered grapefruit also inhibited DLM alpha-hydroxytriazolam formation with IC(50) values of 0.76 and 1.2 mg/mL, respectively. Consistent with mechanism-based enzyme inhibition, preincubation of DLM with any of the grapefruit products for 20 min resulted in significant enhancement of inhibition of triazolam alpha-hydroxylation by 8-20%. The results indicate that 16 g of lyophilized GFJ or 23 g of powdered grapefruit would be equivalent to dosing 100 mL of GFJ. In vivo pharmacokinetic interaction studies are needed to confirm these in vitro findings.

Immunopathogenesis of keratoconjunctivitis sicca in the dog

Keratoconjunctivitis sicca (KCS), more commonly known as dry eye, is an inflammatory condition of the ocular surface caused by a pathologic reduction in the aqueous component of the tear film. It is seen commonly in the dog and defined as a Schirmer tear test with a reading of less than 10 mm in one minute. While KCS may be caused by neurological disease or drug toxicity, most cases are immune-mediated. Whereas the immunological basis of autoimmune KCS has been extensively investigated in humans and experimental rodent models, little research has been undertaken in the dog. It is hoped that this review spurs further research into the etiopathogenic factors in canine KCS.

Focal metatarsal sinus tracts in a Weimaraner successfully managed with ciclosporin

Focal metatarsal sinus tracts ('fistulation') are, to the authors knowledge, reported for the first time in a Weimaraner. The six-year-old, entire male had a five-month history of two symmetrical, well-demarcated sinuses on the plantar aspect of each metatarsus. The area surrounding each pair of sinuses was slightly fluctuant and a serosanguineous discharge could be expressed. Cytological examination of the discharge was characteristic of pyogranulomatous inflammation. Bacterial culture showed the material to be sterile. Examination of a skin biopsy revealed a severe inflammatory reaction involving the dermal collagen, with an infiltrate of neutrophils, macrophages, lymphocytes, plasma cells and multi-nucleated giant cells, with some micro-pustule formation. Treatment with ciclosporin induced total remission. Reduction of the dose of ciclosporin resulted in recurrence of the physical signs with further remission on re-introduction of the original dosage. This is the first report of the use of ciclosporin to control this condition.

Evaluation of Azathioprine on Lesion Severity and Lymphocyte Blastogenesis in Dogs With Perianal Fistulas

Fourteen dogs with perianal fistulas were entered into a prospective clinical study to investigate the effects of long-term azathioprine on clinical outcome and to determine if the clinical results correlated with lymphocyte blastogenesis tests. Complete remission of perianal fistulas was seen in eight (57%) of 14 dogs; partial remission occurred in one (7%) dog; and no response was detected in five (36%) dogs. The results of lymphocyte blastogenesis assays did not correlate with therapeutic response.

Preoperative Immunosuppressive Therapy and Surgery as a Treatment for Anal Furunculosis

OBJECTIVES

To evaluate the efficacy of combining preoperative immunosuppressive therapy with surgical excision for treatment of anal furunculosis (AF) in dogs.

STUDY DESIGN

Retrospective study.

ANIMALS

Dogs (n=25) with stages 1-4 AF.

METHODS

Preoperative immunosuppressive therapy was either cyclosporine A (CyA) alone or in combination with ketoconazole (Group 1; n=18), or azathioprine combined with prednisolone (Group 2; n=7). Surgical excision of residual draining tracts, cryptectomy, and anal sacculectomy were performed. Only dogs with postoperative clinical follow-up exceeding 9 months were retained for the study.

RESULTS

Both immunosuppressive protocols were effective in reducing progression of AF. Subsequent draining tracts excision, cryptectomy, and anal sacculectomy were bilateral (12 dogs) or unilateral (13 dogs of which 4 had bilateral anal sacculectomy). Postoperative recovery was uneventful, except for 2 dogs that had wound breakdown. Recurrence was not observed in any of the dogs that had bilateral surgical excision and or in 9 dogs that had unilateral excision.

CONCLUSION

Preoperative immunosuppressive therapy, combined with bilateral surgical resection of affected tissue consistently, resulted in resolution of AF. Four dogs that had recurrence had unilateral excision despite initial bilateral involvement, suggesting that all diseased tissue should be excised.

CLINICAL RELEVANCE

These preliminary results suggest that immunosuppressive therapy before surgical excision for AF yields minimizes recurrence in dogs.

Matrix metalloproteinase mRNA expression in canine anal furunculosis lesions

Although the aetiology of anal furunculosis (AF) in dogs is poorly understood, there is evidence for an underlying immune dysfunction. This is illustrated by the presence of a T helper type 1 cytokine mRNA profile in AF lesions and the clinical response to ciclosporin therapy. Expression of MMPs 2, 9 and 13 were evaluated in AF lesional biopsies by real-time quantitative RT-PCR. There was significantly increased expression of both MMP-9 and MMP-13 mRNA in AF biopsies compared to controls (p<0.001) but no significant difference in MMP-2 mRNA expression. Since MMP-9 and MMP-13 are primarily produced by macrophages, these data suggest that ulceration could be the result of aberrant activation of this cell type in the tissues. It is feasible that such pathological macrophage activity occurs in response to interferon-gamma secreted by T helper type 1 cells. This could explain why the lesions resolve following treatment with the immunosuppressive drug ciclosporin.

Evaluation of the Effect of Two Dose Rates of Cyclosporine on the Severity of Perianal Fistulae Lesions and Associated Clinical Signs in Dogs

OBJECTIVE

To investigate the effect of cyclosporine (2 or 5 mg/kg every 24 hours) on perianal fistulae (PAF) lesions.

STUDY DESIGN

Blinded randomized, prospective trial.

ANIMALS

Dogs (n = 20) with perianal fistulae.

METHODS

Dogs were randomly assigned to administration of either 2 mg/kg (n = 10) or 5 mg/kg (n=10) of cyclosporine orally every 24 hours for 8 weeks. Lesion surface area was measured, lesion severity was graded using a visual analog scale, and the presence and severity of clinical signs recorded every 2 weeks.

RESULTS

Lesion variables were significantly reduced in both groups after 8 weeks and owners also reported a reduction in clinical sign severity. The 5 mg/kg dose rate significantly accelerated lesion resolution compared with 2 mg/kg. In the 2 mg/kg group, 20% of dogs had complete resolution of clinical signs and 10% had resolution of lesions. In the 5 mg/kg group, 40% of dogs had complete resolution of clinical signs and 60% had resolution of lesions.

CONCLUSIONS

A dose rate of 5 mg/kg every 24 hours was more effective at reducing the surface area and severity of PAF lesions than 2 mg/kg every 24 hours but less effective at resolving PAF lesions than previous studies using dose rates > or =5 mg/kg every 12 hours.

CLINICAL RELEVANCE

Cyclosporine at 5 mg/kg every 24 hours may be useful for the palliation of PAF lesions.

The role of surgery in the management of canine anal furunculosis. A review of the literature and a retrospective evaluation of treatment by surgical resection in 51 dogs

AIMS

To retrospectively evaluate the outcome of surgical management of anal furunculosis (AF) in 51 dogs. To compare the outcome of surgery with those of current medical protocols by way of a review of the literature.

METHODS

Dogs referred for treatment of AF (n=51) were treated by en bloc surgical resection of diseased tissue and primary wound closure. This technique was combined with bilateral anal sacculectomy in all cases in which the anal sacs had not been previously removed. Immunomodulatory therapies were not used, with the exception of post-operative metronidazole antibiosis for 7-10 days. Follow-up was performed by the author using a telephone questionnaire.

RESULTS

Forty-eight dogs were eligible for post-operative follow-up 1.5 to 36 (mean 17.4, median 18) months after surgery. Lesion recurrence, faecal incontinence and stricture formation occurred in 2%, 4% and 13% of dogs, respectively. The percentage of dogs considered by their owners to have an acceptable level of faecal continence and an improved quality of life was 94%.

CONCLUSIONS AND CLINICAL RELEVANCE

The aetiopathogenesis of canine AF remains unclear. Whilst recent advances in medical management by the use of various immunomodulatory medications (such as cyclosporine) hold promise, this approach has yet to be refined with respect to affordability, long-term efficacy and morbidity. With meticulous surgical dissection and reconstruction techniques (anoplasty), excellent success rates can be achieved following a single surgical procedure with minimal complications. Surgery remains a viable treatment option, alone or in combination with immunomodulatory medications, until a more thorough understanding of this debilitating disease is achieved.