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Dive into the research topics where R. A. W. Rosychuk is active.

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Featured researches published by R. A. W. Rosychuk.


Veterinary Dermatology | 2010

Breed and site predispositions of dogs with atopic dermatitis: a comparison of five locations in three continents.

K. Jaeger; Monika Linek; Helen T. Power; Sonya V. Bettenay; S. Zabel; R. A. W. Rosychuk; Ralf S. Mueller

The objectives of this multicentre study were to analyse and compare breed predispositions and lesion distributions of 552 dogs diagnosed with atopic dermatitis from five different dermatologic referral centres located in Australia, Germany (2) and the United States (2). Breeds were compared with the canine population in the respective locations. Breed predispositions varied from geographical site, although golden retrievers and German shepherd dogs were predisposed in three of five practices. Lesions were present most commonly on the paws (62%), ventrum (51%), ears (48%) and face (39%). Various breeds had specific site predilections. Based on this study, breed predispositions can vary greatly both between continents and also between different locations on the same continent. In addition, some breeds showed predispositions for certain body sites which also varied in some instances with the geographical location.


Journal of The American Animal Hospital Association | 2003

A retrospective study regarding the treatment of lupoid onychodystrophy in 30 dogs and literature review.

Ralf S. Mueller; R. A. W. Rosychuk; Leonard D. Jonas

The treatment records of 30 dogs with lupoid onychodystrophy were evaluated retrospectively. Dogs were treated with fatty acid supplementation (n=18), doxycycline and niacinamide (n=12), tetracycline and niacinamide (n=10), pentoxifylline (n=6), prednisolone (n=5), azathioprine (n=1), clofazimine (n=1), or with combinations thereof. An excellent response was seen in almost half of the patients treated with tetra- or doxycycline in combination with niacinamide. Six of the dogs were maintained successfully on fatty acid supplementation. Spontaneous remissions and recurrences made evaluation of success rates difficult and emphasized the varied and often unclear etiology and natural course of the syndrome.


Journal of The American Animal Hospital Association | 2012

Corynebacterium spp. in dogs and cats with otitis externa and/or media: a retrospective study.

Kerstin Henneveld; R. A. W. Rosychuk; Francisco Olea-Popelka; Doreene R. Hyatt; Sonja Zabel

The role of Corynebacterium spp. in the pathogenesis of canine and feline otitis externa/media and their appropriate antimicrobial therapy are unclear. The objectives of this study were to (1) better establish the pathogenicity of Corynebacterium spp. in otitis utilizing reported criteria and by assessing clinical response to antibiotic therapy and (2) to determine the antimicrobial susceptibility patterns of Corynebacterium spp. associated with otitis. The study was retrospective, targeting cultures positive for Corynebacterium spp. Corynebacterium spp. were part of mixed microbial populations in 79/81 cultures. Corynebacterium spp. pathogenicity was highly questionable because of their almost invariable presence with other microbes and the observation that Corynebacterium spp. usually disappear from the ear with resolution of other infections, even when the Corynebacterium spp. are resistant to the prescribed antibiotic(s). However, 2/81 cultures came from two canine ears wherein Corynebacterium spp. may have been pathogenic. Antimicrobial sensitivities for Corynebacterium spp. were available for 54 isolates. Most isolates were susceptible to chloramphenicol (53/54), amikacin (50/54), tetracycline (50/54), gentamicin (46/54), and enrofloxacin (32/54). Among those antibiotics available in otic products, gentamicin and enrofloxacin would be rational choices for the empirical, topical therapy of Corynebacterium spp.


Veterinary Dermatology | 2015

Comparison of the stability and pharmacokinetics in dogs of modified ciclosporin capsules stored at −20°C and room temperature

Jeremy C. Bachtel; Jennifer S. Pendergraft; R. A. W. Rosychuk; Daniel L. Gustafson; Ryan J. Hansen; Paul J. Lunghofer

BACKGROUND Placement of ciclosporin (Atopica(®); Novartis Animal Health, Greensboro, NC, USA) capsules in a freezer prior to administration may reduce the incidence of vomiting in dogs. However, its impact on ciclosporin stability and pharmacokinetics is unknown. HYPOTHESIS/OBJECTIVES The purpose of this study was to evaluate the stability of Atopica(®) capsules and pharmacokinetics of ciclosporin in dogs after storage at -20°C in comparison with storage of capsules at 15-25°C. We hypothesized that there would be no difference in stability or pharmacokinetic parameters between freezer-stored and room-temperature Atopica(®) capsules. ANIMALS Eight healthy research beagle dogs received one 5.0 mg/kg oral dose each of freezer-stored and room-temperature Atopica(®) capsules with a 1 week washout period between. METHODS Ciclosporin concentrations of all available Atopica(®) capsule strengths were assessed for stability after -20°C storage at five time points over 30 days and at room temperature (15-25°C). A blinded, randomized cross-over study was also performed to compare blood concentrations of ciclosporin after capsule storage for 28 days at -20 versus 15-25°C. Blood samples were obtained over a 24 h period after administration. Capsule and whole-blood ciclosporin concentrations were assessed via high-performance liquid chromatography-tandem mass spectrometry. RESULTS There was no significant difference in stability between freezer-stored and room-temperature Atopica(®) capsules at any time point. In the cross-over study, there were no significant differences in pharmacokinetic parameters assessed. CONCLUSIONS AND CLINICAL IMPORTANCE Placing Atopica(®) capsules in a -20°C freezer for 28 days does not affect stability or absorption in the dog.


Journal of Small Animal Practice | 2004

Effect of omega‐3 fatty acids on canine atopic dermatitis

Ralf S. Mueller; Kathryn V. Fieseler; M. J. Fettman; S. Zabel; R. A. W. Rosychuk; Gregory K. Ogilvie; T. L. Greenwalt


Veterinary Dermatology | 2005

Intradermal testing with the storage mite Tyrophagus putrescentiae in normal dogs and dogs with atopic dermatitis in Colorado

Ralf S. Mueller; Kathryn V. Fieseler; R. A. W. Rosychuk; Tracey Greenwalt


American Journal of Veterinary Research | 1992

Investigation of antibodies to extractable nuclear antigens in dogs.

S.D. White; R. A. W. Rosychuk; Peter H. Schur


American Journal of Veterinary Research | 2002

Influence of long-term treatment with tetracycline and niacinamide on antibody production in dogs with discoid lupus erythematosus

Ralf S. Mueller; Kathryn V. Fieseler; Sonya V. Bettenay; R. A. W. Rosychuk


Veterinary Dermatology | 2002

A retrospective study regarding the treatment of idiopathic onychomadesis (lupoid onychodystrophy) in 30 dogs

Ralf S. Mueller; R. A. W. Rosychuk; L. D. Jonas


Veterinary Dermatology | 2002

Putrescentiae and Lepidoglyphus destructor in normal dogs and dogs with atopic dermatitis

Ralf S. Mueller; Kathryn V. Fieseler; R. A. W. Rosychuk; T. L. Greenwalt

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S. Zabel

Colorado State University

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T. L. Greenwalt

Colorado State University

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M. J. Fettman

Colorado State University

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