Psoriasis manifests as chronic dermatitis and arthritis (PsA) in people. Psoriasis with concurrent PsA is characterized by erythematous, silvery, scaly plaques, especially on the extremities, and concurrent arthritis with enthesitis, tenosynovitis, and dactylitis. To date, no such disease has spontaneously occurred in domestic animals. This case report aims to describe the clinical, radiographic, and histologic appearance of a psoriasis-like dermatitis and psoriatic-like arthritis in a dog. A 4-year-old female spayed pug mix presented for the evaluation of chronic history of hyperkeratotic footpads and deforming arthritis. After ruling out other differential diagnoses and based on the similarity of clinical, radiographic, and histologic findings to human psoriasis and PsA, a tentative diagnosis of psoriasis-like disease was made. Treatment was begun to control pain (tramadol, gabapentin, and carprofen) and psoriatic dermatitis (clobetasol propionate 0.05%, calcipotriene 0.005%, and urea 40% ointment twice daily). Dramatic positive response to treatment was achieved confirming the tentative diagnosis. This case may provide preliminary evidence for the existence of a psoriasis-like condition in dogs and may elucidate treatment options in otherwise refractory cases of chronic dermatitis and polyarthropathy in dogs.
Psoriasis is a very common and frustrating disease in people that can have both cutaneous and bone manifestations. Interestingly there has been no report, so far, of spontaneously occurring psoriasis-like disease in domestic animals. The reasons for this difference are not known. In this report we describe the first case of a psoriasis-like disease in a dog that presented with both cutaneous and bone signs. The dog of this case report had not responded to treatments prescribed for the various conditions known in veterinary medicine attempting to make her fit in what is known in animals. Thus she had been unsuccessfully managed for a long time as it did not fit in any previously described diseases of dogs. To the dog’s benefit, a human dermatologist happens to be available for assessment and a diagnosis of psoriasis-like disease was made as the changes found in this dog appeared to be classic for how the disease presents in people. The purpose of this report is to make practitioners aware that although this psoriasis-like condition may be very rare in dogs, it can develop and it seems to respond to the same treatments reported in human medicine.
A 4-year-old female spayed pug mix weighing 8.7 kg presented for a two-year history of chronic, hyperplastic, crusting, parakeratotic pododermatitis, intermittent episodes of lethargy and minimal weight bearing on all four limbs. The dog had ability to ambulate but was reluctant to do so especially on hard surfaces. There was soft tissue swelling associated with multiple digits of every foot. The dog had been adopted at age 2 with the above symptoms already present; thus the exact age of onset of clinical signs was not known.
When presented to the referring veterinarian (rDVM) at 2 years old, the original diagnosis was interdigital pododermatitis and cellulitis on all four limbs with almost all digits involved. Clinical differentials by rDVM included necrolytic migratory erythema (NME), pemphigus foliaceus, and chronic footpad hyperkeratosis, but the joint changes and soft tissue swelling did not fit any of these differentials. Radiographs confirmed soft tissue swelling and revealed periosteal proliferations suggesting chronic periosteitis. Blood work did not reveal any abnormalities. Oral enrofloxacin and cephalexin were begun as well as debridement, flush, topical antibiotic ointment, and bandaging of the footpads. Pain was controlled with metacam liquid. At the one-month recheck, there was no response to treatment and worsening in condition had occurred despite oral antibiotics. Therapy was changed to tetracycline, prednisone, and niacinamide as well as cold laser therapy. Skin biopsy was performed and showed severe hyperplastic parakeratotic hyperkeratosis with infiltration of lymphocytes and plasma cells and a smaller population of neutrophils, mast cells, and macrophages.
The dog was then referred to a local dermatologist who performed a toe amputation for additional biopsy and culture and sensitivity. Biopsy showed marked acanthosis with formation of papillae, parakeratosis, and multiple pustules and parakeratotic microabscesses and crust formation. The crust was composed by necrotic cellular debris and neutrophils. No acantholysis and no primary etiologic agents were detected. In the biopsy a moderate amount of chronic active neutrophilic, superficial perivascular pododermatitis was present. Bacterial culture showed scant growth of
On presentation to UF Dermatology at the veterinary school, the patient was quiet, alert, and responsive but reluctant to ambulate. Her cardiothoracic auscultation and physical exam parameters were within normal limits. Dermatologic examination revealed severe hyperkeratosis on footpads (Figure
Photograph before treatment of worst affected digit, featuring soft tissue swelling, proliferative arthritis, and hyperkeratosis.
Radiographs of forelimbs before treatment, showing proliferative joint disease in the interphalangeal joint, ankylosis, dactylitis, and enthesitis.
NME is frequently linked to liver changes; thus, in the attempt to further pursue NME, ultrasound was performed but findings were unremarkable. Pancreatic Lipase Immunoreactivity (PLI) and Trypsin-Like Immunoreactivity (TLI) were discussed as diagnostic options to further investigate other possible cases of NME but not pursued at first visit in light of the complete absence of clinical signs to support this differential diagnosis.
Upon further examination of the confluence of clinical signs, biopsy results, and radiographic changes noted and in consultation with a human dermatologist, it was determined that plaque psoriasis with psoriatic arthritis, although neither was ever previously documented in canines, could actually provide a comprehensive explanation for the condition of this dog. Thus, a tentative diagnosis of psoriatic-like disease was made and it was decided to attempt first line of defense therapy for psoriasis as it would be done in human medicine.
Treatment was begun based on a presumptive diagnosis of psoriatic-like arthritis and consisted of tramadol (25 mg q6-8hr PRN for pain), gabapentin (100 mg q8hr for pain), and carprofen (25 mg q24hr for pain, arthritis, and inflammation). To control the dermatologic symptoms clobetasol propionate 0.05% ointment (topical steroid), calcipotriene 0.005% ointment (topical Vitamin D), and urea 40% ointment (topical keratolytic) were prescribed to be used twice daily, with one of the daily administrations to be performed under occlusion. To properly perform occlusion therapy, Pawz dog boots (Figure
Occlusion therapy with Pawz dog boots.
Psoriasis is a chronic inflammatory skin and joint disease affecting 2-3% of humans [
This case report aims to describe the clinical, radiographic, and histologic appearance of a psoriasis-like dermatitis and corresponding psoriatic-like arthritis in a dog. Dermatologic manifestations of psoriasis in humans can usually be diagnosed by visible appearance of the patient [
Following the above criteria for clinical diagnosis of human psoriatic patients, this case report describes a dog with similar presentation to psoriasis vulgaris with PsA. Dermatologically, she had distinct, erythematous, scaly plaques located on her footpads or distal extremities. Concurrent with the psoriasis-like dermatitis, she also exhibited asymmetric arthritis of distal interphalangeal joints, dactylitis, and enthesitis and had radiographic evidence of soft tissue swelling, proliferative arthritis, and ankylosis. Her histological appearance was also similar to psoriatic patients. In human patients, histologic samples show hyperkeratosis, parakeratosis, Munro microabscesses (neutrophilic infiltrate), dilation of capillaries engorged with erythrocytes and leukocytes, tortuous blood vessels, and perivascular polymorphonuclear leukocytic infiltrate [
Treatment of psoriasis in human dermatology consists of topical agents, occlusion therapy, phototherapy, oral systemic agents, injectable biological therapies, and often a varying combination of treatment options. Topical agents are considered first line treatment, and the addition of escalated treatments depends on the added benefits of mitigating the disease process weighed against the increasing side effects or invasiveness. Topical agents include Vitamin D analogues, corticosteroids, keratolytics, and retinoids; the combination of Vitamin D analogues and corticosteroids show the greatest efficacy in terms of multiple topical therapies [
In this case study, treatment with combined topical therapy of Vitamin D analogue, corticosteroid, and keratolytic was both therapeutic and diagnostic. Psoriasis had not been previously described in dogs, but based on the similarities of clinical appearance and radiographic and histologic findings, first line psoriatic treatment was attempted. Therapy under occlusion was recommended as it has been shown to greatly increase the response in psoriatic patients [
Response to treatment further supported the psoriatic-like dermatitis diagnosis as this dog had failed to respond to any other previous therapy. Future therapy with immune-modulating antimetabolites, such as methotrexate, was considered to address the joint disease but the owner elected to not pursue it as the quality of life of this dog was sufficiently controlled with the initial plan. Although this condition is extremely rare in dogs, it is important to consider the possibility for cases in which both joint and skin involvement is reported. In this case the consultation with a human dermatologist was crucial to provide proper treatment plan for this case which had not found relief with previous therapies that had attempted to treat diseases known in veterinary medicine.
The authors declared no potential conflict of interests with respect to the research, authorship, and/or publication of this paper.
The authors would like to thank Dr. Suero for his contribution with this clinical case.