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  • Author or Editor: Daniel O. Morris x
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Abstract

Objective—To determine the functionality of canine anti- Malassezia IgE via the passive transfer of immediate hypersensitivity localized to the skin (ie, cutaneous anaphylaxis) from atopic dogs with dermatitis attributable to overgrowth of Malassezia pachydermatis ( Malassezia dermatitis [MD]) to healthy recipient dogs by use of the Prausnitz-Küstner (P-K) technique.

Animals—7 clinically normal dogs, 32 atopic dogs with MD, serum from 11 atopic dogs with MD, and 3 healthy dogs without prior sensitization to M pachydermatis.

Procedure—Serum from atopic dogs with MD was used for P-K tests in 3 clinically normal recipient dogs. Serial dilutions of untreated, heat-inactivated, IgE-absorbed, and bovine serum albumin (BSA)- absorbed (control) aliquots of serum were injected ID in triplicate for dermal sensitization. Twenty-four, 48, and 72 hours later, a crude extract of M pachydermatis was injected ID into the sites used for sensitization injections, and immediate hypersensitivity reactions were graded on a 4-point scale.

Results—Untreated serum caused P-K reactivity beginning 24 hours after passive sensitization and persisting through 72 hours (titers, 1:32 to 1:64). Heat inactivation and IgE-absorption of serum eliminated P-K reactivity, whereas treatment of serum with BSA did not.

Conclusions and Clinical Relevance—Analysis of P-K test results supports the passive transfer of cutaneous anaphylaxis by anti-Malassezia IgE and indicates it is functional in type-1 hypersensitivity reactions of atopic dogs with MD. Reduction or blockade of anti-Malassezia IgE in atopic dogs with MD may provide better clinical control of the disease. (Am J Vet Res 2003;64:262–266)

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in American Journal of Veterinary Research

Abstract

Objective—To characterize skin lesions and causative infections in diabetic dogs and evaluate other potential causes of dermatologic disorders, including concurrent endocrinopathies, allergic skin disease, and long-term corticosteroid administration.

Design—Retrospective study.

Animals—45 dogs with diabetes mellitus (DM) that were examined by dermatologists.

Procedure—Medical records were reviewed for signalment; allergic conditions prior to development of DM; prior corticosteroid administration; and results of dermatologic examinations, ear and skin cytologic examinations, skin scrapings for parasites, bacteriologic and fungal culturing of ear and skin specimens, histologic examinations, and endocrine testing.

Results—Bacterial skin infection was the most common dermatologic disorder (n = 38 [84%]), followed by otitis (26 [58%]) and Malassezia-induced dermatitis (19 [42%]). Twenty-two (49%) dogs had pruritic skin disease consistent with allergic dermatitis, which preceded diagnosis of DM. Prior corticosteroid administration was reported in 21 (47%) dogs. Concurrent hyperadrenocorticism was diagnosed in 13 (29%) dogs, and concurrent hypothyroidism was diagnosed in 5 (11%) dogs. Iatrogenic hyperadrenocorticism was diagnosed in 1 additional dog. Only 10 (22%) dogs did not have a documented concurrent endocrinopathy or allergic disease that could have caused the dermatitis.

Conclusions and Clinical Relevance—Bacterial and yeast-induced dermatitis and otitis develop in dogs with DM. Many diabetic dogs with dermatologic problems have a preexisting allergic condition, history of prior corticosteroid administration, or concurrent endocrinopathy that may be a more likely cause of dermatologic problems than DM alone. (J Am Vet Med Assoc 2001:219: 203–208)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To define clinical differences between coagulase-positive and coagulase-negative Staphylococcus schleiferi infections in dogs and to identify risk factors for the isolation of oxacillin-resistant S schleiferi.

Design—Retrospective case series.

Animals—225 dogs (yielding 225 S schleiferi isolates).

Procedures—Information obtained from affected dogs' medical records included isolate body site source, antimicrobial treatments, and primary disease. For each dog, the S schleiferi isolate was characterized and antimicrobial susceptibility data were recorded. Risk factors for infection based on coagulase status and for S schleiferi oxacillin resistance were investigated.

Results—Allergic dermatitis was the most common underlying disease (111/225 dogs). Ears (102 [45%]) and skin (95 [42%]) were sources of most of the 225 isolates. Isolate coagulase status was not significantly associated with any patient-level factors. Of the 225 isolates, 129 (57%) were oxacillin resistant. Coagulase-negative isolates were more likely to be oxacillin resistant than were coagulase-positive isolates (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.1 to 3.0). Administration of penicillin-based or first-generation cephalosporin drugs (OR, 3.0; 95% CI, 1.8 to 5.9) and third-generation cephalosporins (OR, 3.7; 95% CI, 1.1 to 12.3) within 30 days prior to culture were risk factors for oxacillin resistance.

Conclusions and Clinical Relevance—Results suggested that coagulase-negative and coagulase-positive S schleiferi are potential pathogens in dogs and are often oxacillin resistant. Recent patient treatments with penicillin or cephalosporin were risk factors for oxacillin resistance. In clinical cases, full speciation of all Staphylococcus isolates should be performed and microbial treatments should be selected on the basis of results of susceptibility testing.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare clinical information obtained from medical records of cats with methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S aureus (MSSA) infections, evaluate antibiograms of MRSA and MSSA for multiple-drug resistance (MDR), and characterize the strain type and staphylococcal chromosome cassette (SCC)mec type of each MRSA.

Sample Population—70 S aureus isolates obtained from 46 cats.

Procedures—Clinical information obtained from medical records, including signalment, clinical signs, histologic examination of affected tissues, and outcomes, was compared between the 2 groups. Composite antibiograms of MRSA and MSSA were compared statistically. The MRSA strains were characterized by use of pulsed-field gel electrophoresis and SCCmec typing.

Results—No statistical differences in signalment or subjective differences in clinical signs or outcomes were detected between groups with MRSA or MSSA infection. Significant differences in antimicrobial resistance were detected, with MRSA having complete resistance to fluoroquinolone and macrolide antimicrobials, whereas MSSA maintained a high frequency of susceptibility. Seven pulsed-field patterns were observed in 15 MRSA strains; all but 1 were highly related. All MRSA isolates contained a type II SCCmec element.

Conclusions and Clinical Relevance—Because MDR cannot be predicted in staphylococcal infections in cats on the basis of clinical signalment, culture and susceptibility testing are recommended whenever initial empirical treatment is unsuccessful. Molecular characterization of MRSA strains suggests that there has been reverse-zoonotic transmission from humans.

Impact for Human Medicine—The SCCmec type II element is typically associated with nosocomial MRSA infections of people. Cats may serve as reservoirs for MRSA infections in humans.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To assess the degree of biological similarity (on the basis of genotype determined via pulsed-field gel electrophoresis [PFGE]) between isolates of 2 Staphylococcus schleiferi subspecies (S schleiferi subsp coagulans and S schleiferi subsp schleiferi) in clinical samples obtained from dogs.

Sample Population—161 S schleiferi isolates from 160 canine patients.

Procedures—A commercial microbiology identification system was used to identify each isolate as S schleiferi. Isolates underwent slide and tube coagulase testing and antimicrobial susceptibility testing. A mecA PCR assay and a latex agglutination test for penicillin-binding protein 2a (PBP2a) were also performed on each isolate. Clonal clusters with a similarity cutoff value of 80% were identified via PFGE.

Results—Of the 161 isolates, 61 (38%), 79 (49%), and 21 (13%) were obtained from cutaneous sites, ears, and other sites, respectively; 110 (68%) were coagulase negative, and 51 (32%) were coagulase positive. Among the coagulase-negative and coagulase-positive isolates, 65% (71/110) and 39% (20/51) were oxacillin resistant, respectively. All oxacillin-resistant isolates yielded positive results via mecA PCR assay and PBP2a latex agglutination testing. Via PFGE, 15 major clusters and 108 individual pulsed-field profiles were identified. Oxacillin-resistant and oxacillin-susceptible isolates clustered separately. Clonal clusters were heterogeneous and contained representatives of both subspecies.

Conclusions and Clinical Relevance—Coagulase-positive and coagulase-negative isolates were not genotypically distinct and may represent a single S schleiferi sp with variable coagulase production, rather than 2 biologically distinct subspecies. Further studies are needed to characterize clinical or epidemiological differences associated with infections with coagulase-positive and coagulase-negative S schleiferi in dogs.

Full access
in American Journal of Veterinary Research

Abstract

Objective–To investigate the potential cell-mediated immune response of atopic dogs to the yeast Malassezia pachydermatis and to correlate it with the type-1 hypersensitivity (humoral) response of the same population of dogs.

Animals–16 clinically normal dogs, 15 atopic dogs with Malassezia dermatitis, 5 atopic dogs with Malassezia otitis, and 7 atopic control (ie, without Malassezia dermatitis or otitis) dogs.

Procedure–A crude extract of M pachydermatis was extracted for use as an intradermal allergy testing reagent and for stimulation of isolated peripheral blood mononuclear cells in vitro. Flow cytometry was also used to assess cell surface antigenic determinants (CD3, CD4, CD8, CD14, CD21, CD45RA, surface immunoglobulin) on peripheral blood mononuclear cells.

Results–Atopic dogs with cytologic evidence of Malassezia dermatitis had an increased lymphocyte blastogenic response to crude M pachydermatis extract, compared with clinically normal dogs and dogs with Malassezia otitis. Atopic control dogs did not differ significantly in their responses from atopic dogs with Malassezia dermatitis or otitis. A significant correlation was not found between the lymphocyte blastogenic response and the type-1 hypersensitivity response to M pachydermatis within any of the groups.

Conclusions and Clinical Relevance–Cell-mediated and humoral reactivities to M pachydermatis contribute to the pathogenesis of atopic dermatitis in dogs but are not directly correlated. Modification of the dysregulated immune response toward M pachydermatis may assist in the reduction of pathologic changes associated with an atopic dermatitis phenotype in dogs. (Am J Vet Res 2002;63:358–362)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the outcome of otitis media in dogs after video-otoscopic lavage of the tympanic bulla and long-term antimicrobial drug treatment.

Design—Retrospective study.

Animals—44 dogs with otitis media treated in an academic referral practice.

Procedure—Medical records were reviewed for signalment, duration of ear canal disease, previous medical treatments, dermatologic diagnosis, results of cytologic examination and microbial culture of ear canal exudate, findings during video-otoscopy, medical treatment, days to resolution, and maintenance treatments prescribed. Four independent variables (age, duration of ear canal disease prior to referral, use of corticosteroids in treatment regimens, and infection with Pseudomonas aeruginosa) were evaluated statistically for potential influence on time to resolution.

Results—Mean ± SD (range) duration of ear canal disease prior to referral was 24.9 ± 21.6 (3 to 84) months. Otitis media in 36 dogs resolved after lavage of the tympanic bulla and medical management; mean ± SD (range) time to resolution was 117 ± 86.7 (30 to 360) days. Time to resolution was not significantly influenced by any variable evaluated. Three dogs were lost to follow-up, and 4 dogs eventually required surgical intervention. Seven of 36 dogs in which otitis had resolved relapsed; 4 required additional lavage procedures.

Conclusions and Clinical Relevance—Results indicate that lavage of the tympanic bulla combined with medical management is an effective and viable option for treatment of otitis media in dogs. (J Am Vet Med Assoc 2004;225:548–553)

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in Journal of the American Veterinary Medical Association

Abstract

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. (J Am Vet Med Assoc 2004;224:1312–1316)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To ascertain whether Malassezia organisms can be detected via cytologic examination and fungal culture of samples from the skin surface of psittacine birds and determine whether the number of those organisms differs between unaffected psittacines and those that have chronic feather-destructive behavior or differs by body region.

Design—Prospective study.

Animals—50 unaffected psittacines and 53 psittacines that had feather-destructive behavior.

Procedure—Samples were collected by use of acetate tape strips from the skin of the head, neck, proventer, propatagium, inguinal region, and preen gland area of each bird; 0.5-cm2 sample areas were examined microscopically for yeast, and samples were also incubated on Sabouraud dextrose agar. Polymerase chain reaction assays specific for Malassezia spp, saprophytic fungi, and Candida albicans were performed on DNA prepared from cultured colonies; nested PCR evaluation for Malassezia pachydermatis was then performed.

Results—Microscopically, 63 of 618 (10%) tape-strip samples contained yeast. Thirty cultured colonies were assessed via PCR assays, and all yielded negative results for Malassezia spp; C albicans was identified in 2 colony samples. The numbers of yeast identified microscopically in psittacines with feather-destructive behavior and in unaffected birds did not differ significantly, and numbers did not differ by body region.

Conclusions and Clinical Relevance—Yeast were identified infrequently via cytologic examination of samples from the skin surface of unaffected psittacine birds or those that had chronic feather-destructive behavior. If yeast are identified on the skin of birds with feather-destructive behaviors, fungal culture of skin samples should be performed to identify the organism.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To survey 2 populations of psittacines to characterize Staphylococcus spp isolated from commensal cutaneous microflora.

Design—Prospective cross-sectional study.

Animals—107 psittacine birds from a sanctuary and 73 psittacine birds in private households or a pet store.

Procedures—Gram-positive, catalase-positive cocci isolated from mucosal and seborrheic sites were speciated, and pulsed-field gel electrophoresis was performed on coagulase-positive isolates. A bird was classified as having positive results when at least 1 sample site yielded positive results for at least 1 staphylococcal species.

Results—89 of 180 (49.4%) birds had positive results for staphylococci at the carriage sites sampled. Privately owned birds were twice as likely to have positive results for staphylococci as were sanctuary birds (71% vs 35%). Coagulase-positive staphylococci were significantly more common in the sanctuary birds (47% vs 1%). Staphylococcus intermedius was significantly more common in the sanctuary birds (46% vs 2%). Staphylococcus hominis subsp hominis and Staphylococcus epidermidis, coagulase-negative staphylococci associated with humans, were significantly more common in pet birds. Cockatoos were twice as likely to have positive results for staphylococci as were other genera.

Conclusions and Clinical Relevance—Results suggested that staphylococcal colonization in captive psittacines was less common than in other species studied. Staphylococci isolated from a pet psittacine may reflect that of the humans and other animals with which the bird lives in close proximity; however, further studies are needed to evaluate the effects exposure to humans may have on the microflora of these birds.

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in Journal of the American Veterinary Medical Association