Canine ischaemic dermatopathy: a retrospective study of 177 cases (2005–2016) Katherine A. Backel*, Charles W. Bradley*, Christine L. Cain*, Daniel O. Morris*, Kyle H. Goldschmidt† and Elizabeth A. Mauldin* *School of Veterinary Medicine, University of Pennsylvania, 3900 Spruce Street, Philadelphia, PA 19104, USA †Operations and Supply Chain Management, University of St. Thomas, 1000 LaSalle Ave, Minneapolis, MN 55403, USA Correspondence: Katherine A. Backel, 248 S. 21st Street, Second Floor, Philadelphia, PA 19103, USA. E-mail: kbackel@upenn.edu Background – Ischaemic dermatopathy encompasses a poorly understood subset of canine diseases that share similar clinical and histological features. Very little information is currently available regarding population charac- teristics, progression and outcome. Hypothesis/objectives – This study aimed to describe the clinical features and therapeutic outcomes of ischae- mia dermatopathy, excluding familial dermatomyositis, using cases diagnosed by histopathological analysis. Animals – One hundred and seventy-seven cases submitted for histopathological analysis between 2005 and 2016 met inclusion criteria, of which 93 had complete medical records available. Methods and materials – Both records and pointed surveys were used to retrieve information. Scoring sys- tems were created to subjectively evaluate clinical outcomes and likelihood of a vaccine association. Results – Of 177 cases, toy and miniature poodles, Chihuahuas, Maltese, Yorkshire terriers and Jack Russell ter- riers were significantly over-represented (P < 0.001). Of the 93 cases for which historical data were obtained, median age at skin biopsy was five years (0.42–13 years) and median body weight was 7.3 kg (range 1.32– 50.3 kg). The condition in 45 dogs (48.3%) was found likely to be associated with vaccination. Younger ages (P = 0.011) and higher body weights (P = 0.003) were positively correlated with greater likelihood of vaccination. Body weight <10 kg (P = 0.0045) and older ages (P = 0.0048) were significantly associated with worse out- comes. Conclusions and clinical importance – This study provides support for breed predispositions and identifies potential prognostic factors. Importantly, over half of the cases were considered unlikely to be vaccine-associ- ated, demonstrating the need to investigate other underlying causes of this condition. Introduction Ischaemic dermatopathy is a diagnosis that encompasses different clinical syndromes with common features and a wide range of possible aetiologies. Ischaemic diseases previously have been grouped into five subtypes: canine familial dermatomyositis (FDM), juvenile onset dermato- myositis-like disease in atypical breeds, post-rabies vac- cine panniculitis, generalized vaccine-associated ischaemic dermatopathy and generalized idiopathic ischaemic dermatopathy. 1 Whether generalized or localized, cutaneous signs include alopecia, hyper- or hypopigmentation, scaling, crusts and ulcers. Lesions are found most commonly at vaccine sites and/or generalized areas including the pinnal margin, tip of the tail, head, face and pressure points. An acral distribution also is frequently observed and charac- terized by lesions on phalanges, paw pads and claws (onychodystrophy and onychomadesis). Histological features of ischaemic dermatopathy include follicular atrophy, a cell-poor lymphocytic interface dermatitis, dermal oedema/mucin deposition, and eosino- philic tinctorial changes to the dermal collagen and vascu- lar tunics imparting a “smudged” appearance to the collagen. These changes are thought to represent a chronic oxygen-/nutrient-deficient state of the affected tissue. 1,2 Despite being recognized in the mid-1980s, very few primary publications since then have focused on nonfa- milial variants of ischaemic dermatopathy. 2–6 Although rabies vaccine-associated cases are relatively well recog- nized in clinical practice, there is a paucity of information regarding the true patient population, risk factors and clin- ical outcomes. Additionally, even less is known about idiopathic ischaemic dermatopathies in which an obvious vaccine trigger is not identified. Furthermore, optimal medical management of vaccine-associated and idio- pathic cases has not been examined closely. Pentoxi- fylline has been reported to be effective in cases of FDM and is used for other subtypes of ischaemic dermatopa- thy, despite few published supportive data. 7 Three cases of vaccine-associated disease were reported to respond well to therapy with pentoxifylline combined with vitamin E (and in two of these cases, short courses of Accepted 10 May 2019 Source of Funding: This study was self-funded. Conflicts of Interest: No conflicts of interest have been declared. © 2019 ESVD and ACVD, Veterinary Dermatology 1 Vet Dermatol 2019 DOI: 10.1111/vde.12772