Putative drug-related pemphigus foliaceus in four dogs

Pharmacology of drugs used in autoimmune dermatopathies in cats and dogs: A narrative review

Immunosuppressive drugs are the mainstay of treatment for many feline and canine autoimmune skin diseases, either as monotherapy or in combination with other drugs. Treatment with these drugs is often lifelong and may have long-term consequences on the affected animal's overall quality-of-life. Clinicians need to understand the pharmacology of immunosuppressants in planning and executing the treatment regimen for the best possible clinical outcome, as well as reducing the risk of adverse effects. This review paper will focus on the mechanism of action, pharmacokinetics and pharmacodynamics, clinical uses and adverse effects of immunosuppressive drugs used to treat autoimmune dermatoses in cats and dogs. These include glucocorticoids, ciclosporin A, azathioprine, chlorambucil, mycophenolate mofetil, oclacitinib and Bruton's tyrosine kinase inhibitors.

A case report of the beneficial effect of oclacitinib in a dog with pemphigus vulgaris

Pemphigus vulgaris is a rare immune-mediated skin disorder of the dog, usually treated with immunosuppressive medications such as oral glucocorticoids, azathioprine or ciclosporin. Herein we report the successful treatment of pemphigus vulgaris in a dog, using oclacitinib and a topical product containing fucidic acid (0.5 % w/w) and betamethasone valerate.

Combination therapy with azathioprine, cyclosporine and ketoconazole in a dog with concurrent pemphigus foliaceus and hyperadrenocorticism - Case report

A 10-year-old, spayed female Shih Tzu dog presented with a history of progressive erythema and multiple crusts developing 85 days previously. The dog had been diagnosed with hyperadrenocorticism (HAC) 55 days prior to presentation and was treated with oral trilostane (2.86 mg/kg, once daily) that was discontinued due to a poor response. In addition to generalised alopecia, erythematous plaques and crusts were noted on the trunk, head and footpads. Lesional impression smears revealed numerous acantholytic cells and non-degenerated neutrophils. Histopathological findings demonstrated subcorneal pustules with acantholytic cells and intact neutrophils. On the basis of these findings, we diagnosed pemphigus foliaceus (PF) with concurrent HAC. We wished to avoid glucocorticoids and, therefore, prescribed oral, once-daily azathioprine (2 mg/kg), modified cyclosporine (7 mg/kg) and ketoconazole (5 mg/kg). By day 71 post-treatment, the erythematous crusts had almost disappeared and the alopecia had improved considerably. However, by the subsequent follow-up examination on day 99, the clinical signs had reappeared due to the tapering of cyclosporine. To the best of our knowledge, this is the first case report describing concurrent PF and HAC in a dog. Combination therapy with azathioprine, modified cyclosporine and ketoconazole was effective, and should be considered for dogs diagnosed with concurrent autoimmune diseases and HAC.

CTLA4 overexpressing adipose tissue-derived mesenchymal stem cell therapy in a dog with steroid-refractory pemphigus foliaceus

Background

Canine pemphigus foliaceus is an autoimmune antibody-mediated skin disease characterized by acantholysis. The objective of this case report is to present the successful management of steroid refractory pemphigus foliaceus with cytotoxic T-lymphocyte antigen 4 (CTLA4)-overexpressing adipose tissue mesenchymal stem cells (ATMSCs).

Case presentation

A 10-year-old, 12.3-kg, castrated male Shih Tzu presented with severe pruritus and anorexia. The diagnosis of pemphigus foliaceus was made based on its history, physical examination, and histopathology results of a skin biopsy. Treatment with prednisolone and combination therapy of other immunosuppressive drugs had failed; therefore, immunosuppressive gene, CTLA4 overexpressing ATMSCs (CTLA4-ATMSCs) and/or naive ATMSCs administration was performed with the consent of the owner. ATMSCs were administered 21 times over a period of 20 months with intervals of 2 to 8 week. Prednisolone was gradually tapered concurrently and no relapse of the clinical signs was observed. After the termination of CTLA4-ATMSCs and/or naive ATMSCs treatment, the skin lesions had improved and could be managed with a low dose of prednisolone for 12 months.

Conclusion

CTLA4-ATMSCs or naive ATMSCs transplantation may be beneficial as adjunctive therapy to initiate and maintain the remission of skin lesions caused by pemphigus foliaceus in veterinary medicine.

Fipronil-amitraz-S-methoprene-triggered pemphigus foliaceus in 21 dogs: clinical, histological and immunological characteristics

BACKGROUND

A recently launched topical ectoparasiticide containing fipronil, amitraz and S-methoprene has been associated with the development of an acantholytic pustular dermatitis similar to that of Promeris-triggered pemphigus foliaceus (PF).

HYPOTHESIS/OBJECTIVES

Our objectives were to describe the clinical, histological and immunological features of this PF-like cutaneous adverse drug reaction.

ANIMALS

Twenty-one dogs with a probable or definitive diagnosis of PF-like cutaneous adverse drug reaction were identified between May 2012 and February 2013.

MATERIAL AND METHODS

Histology, direct and indirect immunofluorescence were employed to address the study objectives.

RESULTS

Most dogs were middle-aged or older (median, 9 years) and of large size (median, 23 kg). In six dogs (29%), the PF-like lesions remained confined to the site of application, while 15 dogs (71%) exhibited lesions at distant sites. One or two applications of the ectoparasiticide were sufficient to trigger PF-like lesions in seven (33%) and six (29%) dogs, respectively. Systemic signs were reported in nine dogs (43%), all with lesions extending to sites distant from application areas. Tissue-bound antikeratinocyte IgG was detected in the lesional epidermis of eight of 19 (42%) cases by direct immunofluorescence, while serum antikeratinocyte IgG was detected in 10 of 14 (71%) cases by indirect immunofluorescence. Autoantibodies were found to target canine desmocollin-1 in 11 of 14 dogs (79%), but not canine desmoglein-1, by indirect immunofluorescence on transfected cells. These immunological findings were similar in cases with localized and distant disease.

CONCLUSIONS AND CLINICAL IMPORTANCE

This new topical ectoparasiticide containing fipronil, amitraz and S-methoprene is capable of triggering the development of an acantholytic pustular dermatosis that is a clinical, histological and immunological close match for Promeris-triggered PF and naturally occurring autoimmune PF in dogs.

Drug hypersensitivity reactions targeting the skin in dogs and cats

Adverse drug reactions (ADRs) can be dose dependent or idiosyncratic. Most idiosyncratic reactions are believed to be immune-mediated; such drug hypersensitivities and allergies are unpredictable. Cutaneous reactions are the most common presentation of drug allergies. In veterinary medicine it can be difficult to assess the true prevalence of adverse drug reactions, although reports available suggest that they occur quite commonly. There are multiple theories that attempt to explain how drug allergies occur, because the pathogenesis is not yet well understood. These include the (pro)-hapten hypothesis, the Danger Theory, the pi concept, and the viral reactivation theory. Cutaneous drug allergies in veterinary medicine can have a variety of clinical manifestations, ranging from pruritus to often fatal toxic epidermal necrolysis. Diagnosis can be challenging, as the reactions are highly pleomorphic and may be mistaken for other dermatologic diseases. One must rely heavily on history and physical examination to rule out other possibilities. Dechallenge of the drug, histopathology, and other diagnostic tests can help to confirm the diagnosis. New diagnostic tools are beginning to be used, such as antibody or cellular testing, and may be used more in the future. There is much yet to learn about drug allergies, which makes future research vitally important. Treatment of drug allergies involves supportive care, and additional treatments, such as immunosuppressive medications, depend on the manifestation of the disease. Of utmost importance is to avoid the use of the incriminating drug in future treatment of the patient, as subsequent reactions can be worse, and ultimately can prove fatal.

Pemphigus foliaceus-like drug reaction in a 3-month-old crossbreed dog treated for juvenile cellulitis

Two weeks after administration of routine vaccinations, a 3-month-old, male crossbreed dog developed cutaneous lesions that were clinically and histopathologically consistent with a diagnosis of juvenile cellulitis. The patient was treated with systemic antibacterial, antibacterial ophthalmic ointment and nonsteroidal anti-inflammatory drugs. Within 1 week, new skin lesions that were clinically, histopathologically and immunohistochemically consistent with pemphigus foliaceus developed. The latter completely resolved following drug withdrawal, suggesting a pemphigus foliaceus-like drug reaction. However, the initial lesions persisted and required glucocorticoid therapy to effect resolution. To the authors' knowledge, this is the first reported case of a puppy developing juvenile cellulitis followed by a pemphigus foliaceus-like reaction shortly thereafter, in response to drug therapy.

A review of autoimmune skin diseases in domestic animals: I - superficial pemphigus

In humans, the pemphigus denomination encompasses a group of autoimmune blistering skin diseases with intraepidermal separation resulting from cell-cell detachment by acantholysis. Entities are classified based on the level of blistering in the epidermis, and both superficial (pemphigus foliaceus, IgA pemphigus) and deep (pemphigus vulgaris, pemphigus vegetans and paraneoplastic pemphigus) variants are recognized. In domestic animals, subsets of pemphigus have been recognized since the mid-1970s, and the disease classification resembles that used for human patients. This article reviews up-to-date knowledge on the epidemiology, clinical signs, histopathology, immunopathology and treatment outcome of superficial pemphigus in domestic animals. Detailed information on canine, feline, equine and caprine pemphigus foliaceus, canine and feline pemphigus erythematosus and canine panepidermal pustular pemphigus is provided.

Pemphigus Foliaceus in 91 Dogs

A retrospective study of 91 dogs with pemphigus foliaceus was performed. Clinical signs of the disease included crusts (n=79), pustules (n=36), and alopecia (n=33). Lesions were most common on the trunk (n=53), inner pinnae (n=46), face (n=37), and foot pads (n=32). Cytological evaluation revealed acantholytic keratinocytes in 37 of 48 dogs. Results of combination treatment with prednisolone and azathioprine were comparable to results with prednisolone therapy alone. More than half of the dogs achieved remission with appropriate therapy, and another 25% significantly improved.

Pemphigus foliaceus in the horse: a retrospective study of 20 cases

Twenty horses with pemphigus foliaceus were seen over a period of 15 years in a veterinary medical teaching hospital. Breeds seen were seven quarterhorses, five thoroughbreds, three cross-bred horses, two Arabians and one of each of the following: standardbred, Tennessee walker and warmblood. There was no breed, age or sex predisposition. Nine were mares, ten were geldings and one was a stallion. Ages ranged from 2.5 months to 25 years, with a mean of 8.6 years. Sixteen (80%) of the pemphigus foliaceus horses first exhibited signs between September and February. There was a statistically significant more common occurrence of pemphigus foliaceus during those months. Signs in the four other horses were first noted in March, May or June. Three of those horses were < 13 months of age. Oedema (14/20) and crusts (13/20) were the most common lesions. Pain was present in 9/20 horses, pruritus in 7/20 and pyrexia in 7/20. Follow-up was available for 13 horses. Five of these horses were euthanased. In three horses the reason for euthanasia was laminitis secondary to treatment. Four horses remained lesion-free after medication was discontinued. Two horses required maintenance medication and are doing well at the time of writing.

Prolonged remission after immunosuppressive therapy in six dogs with pemphigus foliaceus

Limited information is available on the long-term outcome of treatment of pemphigus foliaceus in dogs. The purpose of this study is to report that a prolonged remission can occur after discontinuation of immunosuppressive regimens in some animals with this disease. Six dogs were diagnosed with pemphigus foliaceus based on suggestive clinical signs and histopathology. These patients were treated either with immunosuppressive doses of oral glucocorticoids or with a combination of oral glucocorticoids and azathioprine. After clinical signs underwent complete remission, which occurred 1.5-5 months after immunosuppression was initiated, the drugs were tapered progressively and eventually withdrawn. The total duration of immunosuppressive therapy varied between 3 and 22 months. Skin lesions of pemphigus foliaceus did not recur for 1.5-6 years after treatment was stopped. These observations suggest that, in some dogs with pemphigus foliaceus, immunosuppression can lead to long-term remission of skin lesions, and that discontinuation of treatment is not necessarily followed by a recurrence of clinical signs.

Idiosyncratic toxicity associated with potentiated sulfonamides in the dog

Idiosyncratic toxicity to potentiated sulfonamides occurs in both humans and dogs, with considerable clinical similarities. The syndrome in dogs can consist of fever, arthropathy, blood dyscrasias (neutropenia, thrombocytopenia, or hemolytic anemia), hepatopathy consisting of cholestasis or necrosis, skin eruptions, uveitis, or keratoconjunctivitis sicca. Other manifestations seen less commonly include protein-losing nephropathy, meningitis, pancreatitis, pneumonitis, or facial nerve palsy. The pathogenesis of these reactions is not completely understood, but may be due to a T-cell-mediated response to proteins haptenated by oxidative sulfonamide metabolites. Our laboratory is working on tests to characterize dogs with possible idiosyncratic sulfonamide reactions, to include ELISA for anti-drug antibodies, immunoblotting for antibodies directed against liver proteins, flow cytometry for drug-dependent anti-platelet antibodies, and in vitro cytotoxicity assays. The management of idiosyncratic sulfonamide toxicity involves client education to identify clinical signs early and allow rapid drug discontinuation, supportive care to include possibly ascorbate and glutathione precursors, and avoidance of subsequent re-exposure. It is important to realize that only antimicrobial sulfonamides, such as sulfamethoxazole, sulfadiazine, and sulfadimethoxine, share this clinical syndrome. There is no evidence for cross-reactivity with drugs that have different underlying structures but share a sulfonamide moiety, such as acetazolamide, furosemide, glipizide, or hydrochlorthiazide.

Outcome and complications associated with treatment of pemphigus foliaceus in dogs: 43 cases (1994-2000)

OBJECTIVE

To identify factors affecting prognosis, outcome, and complications associated with pemphigus foliaceus in dogs.

DESIGN

Retrospective study.

ANIMALS

43 dogs with pemphigus foliaceus.

PROCEDURE

Medical records were reviewed for signalment, age at diagnosis, duration to diagnosis, body area affected, initial immunosuppressive regimens and concurrent use of antimicrobials and sucralfate or histamine receptor 2 blocking agent, adverse effects of treatment, duration of treatment, number of visits for follow-up care, cause of death, and credentials of the veterinarians responsible for continued care.

RESULTS

The case fatality rate was 60.5%. Factors significantly correlated with survival time included concurrent use of antimicrobials during initiation of immunosuppressive treatment and a lower number of adverse effects to treatment. Treatment times lasting more than 10 months from diagnosis correlated significantly with survival.

CONCLUSIONS AND CLINICAL RELEVANCE

Treatment with or prophylactic use of antimicrobials may be warranted during initial immunosuppressive treatment. The inverse correlation between survival time and number of adverse treatment effects was not unexpected because it was reflective of the owners' decision to euthanatize their dogs and of corticosteroid-related secondary diseases. Survival beyond the tenth month of treatment predicted long-term survival, which suggests that dogs require careful management during the early months of treatment.

Feline pemphigus foliaceus: a retrospective analysis of 57 cases

Fifty-seven cases of feline pemphigus foliaceus were identified from biopsy specimens submitted to University of Pennsylvania School of Veterinary Medicine's Laboratory of Pathology and Toxicology by veterinary dermatologists from 1991 to 2002. Age at onset ranged from less than 1 year to 17 years; median 5 years. Eighty per cent of cats were reported to have been pruritic. At the time of biopsy, the distribution of lesions varied, but included some combination of face/head, paws, dorsum or ventrum and consisted of crusts, erosions, scale and alopecia. The histological features of 208 biopsy specimens were reviewed and included the following. Acantholytic cells were found in large numbers in both intact and degenerating pustules in most cases. Mast cells were found in the dermal infiltrate more often than reported previously. Seventeen cases were receiving corticosteroids at the time of biopsy; reducing the percentage of diagnostic biopsies per case. Forty-four cases were followed for 1-54 months (median 9 months). Triamcinolone was more successful at inducing remission without significant adverse effects than prednisone or prednisone in combination with chlorambucil. Only 4/44 cats died from their disease or therapy during the study period.