Diascopy and histopathological evaluation of nonblanching erythematous dermatoses in dogs.

BACKGROUND: Diascopy is a point-of-care diagnostic test used to differentiate skin erythema due to vascular dilation from haemorrhage. In the veterinary literature, only a handful of diseases have been described to be associated with a negative (nonblanching) diascopy result, and histological investigation of haemorrhage has been inconsistent. OBJECTIVES: Retrospective study to undertake a histopathological investigation of canine, nonblanching erythematous dermatoses for the presence or absence of haemorrhage and vascular changes. MATERIALS AND METHODS: Skin biopsies from dogs presented with moderate-to-severe nonblanching erythema were evaluated histologically. Additionally, clinical data about each patient were analysed. RESULTS: Twenty cases were identified with nonblanching erythema. Diagnoses included vasculopathy (n = 6), canine eosinophilic dermatitis (n = 3), cutaneous epitheliotropic T-cell lymphoma (n = 2), and one case each of sterile granuloma and pyogranuloma syndrome, German shepherd dog pyoderma, multiple mast cell tumours, haemangiosarcoma, exfoliative cutaneous lupus erythematosus, canine leishmaniosis with sebaceous adenitis, sebaceous adenitis with concurrent dermatophytosis, calcinosis cutis and canine atopic dermatitis with insect-bite reaction. One or more vascular changes were present in all 20 cases and included perivascular oedema, endothelial swelling and neutrophilic infiltration of vessel walls. Haemorrhage was identified in 17 of 20 cases (85%). Three cases without dermal haemorrhage were calcinosis cutis, sebaceous adenitis with dermatophytosis and canine atopic dermatitis with insect-bite reaction. CONCLUSIONS AND CLINICAL RELEVANCE: Negative diascopy was associated with haemorrhage and vascular pathological findings in the majority of cases, yet not all. Haemorrhage was identified histologically in all diseases previously reported as nonblanching as well as in a few additional diseases.

Intervention with impact: Reduced isolation of methicillin-resistant Staphylococcus pseudintermedius from dogs following the introduction of antimicrobial prescribing legislation in Germany.

BACKGROUND: Legislation was introduced in Germany in 2018, requiring bacterial culture and antimicrobial susceptibility testing before the prescription of fluoroquinolones and third-generation cephalosporins to dogs. We hypothesised that, following this intervention, the number of clinical samples testing positive for methicillin-resistant Staphylococcus pseudintermedius (MRSP) would reduce. METHODS: Reports of S. pseudintermedius isolated from canine clinical samples by three German veterinary diagnostic microbiology laboratories during the 38 months before the introduction of the legislation and the 46 months after were compared. Bacterial identification was performed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, and antimicrobial susceptibility testing followed recognised recommendations but with changes during the study period. RESULTS: Among a total of 120,571 S. pseudintermedius isolates, MRSP accounted for 7.1% overall. Following the legislative intervention, monthly submissions yielding S. pseudintermedius increased at all three laboratories. The MRSP percentage was lower in the period after the intervention in two of the three laboratories (p < 0.001); in the third laboratory, there was no change between periods, but a year-on-year reduction in MRSP percentages occurred after the intervention (p = 0.0004). LIMITATIONS: Changing susceptibility testing methods limited the direct comparison of resistance patterns among laboratories. CONCLUSION: The reduction in MRSP in canine clinical samples following the introduction of this legislation suggests a positive impact of compulsory laboratory testing on reducing antimicrobial resistance.

Mycobacterium setense isolated from a cat with atypical mycobacterial panniculitis.

Atypical mycobacterial panniculitis was diagnosed in a cat. Mycobacterium setense was identified as causative agent by 16 S rRNA gene sequence analysis. This a gram-positive rod-shaped acid-fast bacterium belonging to Mycobacterium fortuitum group was never reported before in diseased animals. Resistance to doxycycline and clarithromycin was detected. During treatment with pradofloxacin, additional resistance to fluoroquinolones developed which was due to a mutation in the gyrase gene gyrA (S90W exchange). Despite of antimicrobial treatment for 33 months the patient did not fully recover. Species identification and susceptibility testing for choosing adequate antimicrobial treatment is recommended in cases of feline mycobacterial panniculitis.

Is "milk crust" a transient form of golden retriever ichthyosis?

BACKGROUND: A recessive inherited form of lamellar ichthyosis is well recognized in golden retrievers. In this breed, young puppies demonstrate a self-limiting scaling disorder which is commonly recognized by breeders, who use the term "milk crust" to describe this syndrome. HYPOTHESIS/OBJECTIVES: To determine whether "milk crust" is a new keratinization disorder or a self-limiting form of golden retriever ichthyosis. ANIMALS: A total of 179 golden retriever dogs (21 dams and 158 puppies) were examined. METHODS: Dermatological examination and assessment of the patatin-like phospholipase-1 (PNPLA1) genotype by PCR testing of buccal mucosal swabs. Skin biopsies from one affected puppy were evaluated for histopathological abnormalities. RESULTS: Forty-five of 158 (28%) puppies exhibited scaling at 8 weeks of age; 113 of 158 (72%) were dermatologically normal. Of 144 analysed samples, 40 of 144 (28%) puppies demonstrated a homozygous mutation of the PNPLA1 genotype [of which, 36 of 40 (90%) had signs of scaling], 77 of 144 (53%) demonstrated a heterozygous mutation and 27 of 144 (19%) were a normal wild-type. In six of 17 (35%) dams, a homozygous mutation of the PNPLA1 genotype was found, eight of 17 (47%) demonstrated a heterozygous mutation and three of 17 (18%) were normal wild-type. Dams with a homozygous mutation were clinically unaffected. A 1 year follow-up revealed that 23 of 28 (82%) puppies affected with this syndrome failed to develop typical signs of ichthyosis. In five of 28 (18%) dogs there was persistence of mild scaling. CONCLUSIONS AND CLINICAL IMPORTANCE: We hypothesize that the clinical syndrome termed "milk crust" could represent a transient form of golden retriever ichthyosis. Remission is not fully linked to PNPLA1 genotype, suggesting that unknown factors may contribute to the clinical disease.

Response of feline eosinophilic plaques and lip ulcers to amoxicillin trihydrate-clavulanate potassium therapy: a randomized, double-blind placebo-controlled prospective study.

In this study, we evaluated the treatment of feline eosinophilic plaques and lip ulcers with amoxicillin trihydrate-potassium clavulanate (Clavamox(®); Pfizer Animal Health). Nineteen cats with clinical and cytological findings consistent with eosinophilic plaques and/or lip ulcers were enrolled. Lesions were photographed and their areas measured in square centimetres before and after 21 days of therapy with either flavoured amoxicillin-clavulanate suspension or flavoured placebo suspension. Sixteen cats completed the study, with nine plaque lesions (four treatment and five placebo) and eight lip ulcer lesions (four treatment and four placebo) included in the analysis. All lesions were shown to have infection, with bacterial phagocytosis present on cytological examination. Coagulase-positive staphylococci were the most commonly isolated bacteria. The amoxicillin-clavulanate-treated eosinophilic plaque group had a statistically significant 96.2% reduction in mean lesion size (-7.60 cm(2), P = 0.0078) and an 80% reduction in mean percentage of microscopic fields demonstrating evidence of bacterial infection (P < 0.0001), whereas the placebo group did not. The amoxicillin-clavulanate-treated lip ulcer group had a 42.6% decrease in mean lesion size (-0.25 cm(2), P = 0.4125) and the placebo group a 36.6% increase (+0.49 cm(2), P = 0.1575), although neither change was statistically significant. The amoxicillin-clavulanate-treated lip ulcer group had a statistically significant 65.0% reduction in mean percentage of microscopic fields demonstrating evidence of bacterial infection (P < 0.0001), while no significant reduction was observed in the placebo group. A suspension of amoxicillin trihydrate-potassium clavulanate is an effective monotherapy for the treatment of feline eosinophilic plaques.

Susceptibility of Pseudomonas isolates from the ears and skin of dogs to enrofloxacin, marbofloxacin, and ciprofloxacin.

The purpose of this study was to compare susceptibilities of ear and skin Pseudomonas spp. isolates to enrofloxacin, marbofloxacin, and ciprofloxacin. Specimens were obtained from dogs examined in a veterinary dermatology referral hospital. Susceptibilities of ear isolates to enrofloxacin, marbofloxacin, and ciprofloxacin were 46.9%, 66.7%, and 75.0%, respectively. Susceptibilities of skin isolates to the same drugs were 76.2%, 81.0%, and 80.0%, respectively. Ear isolates were significantly less susceptible to enrofloxacin than to ciprofloxacin (P=0.021), and ear isolates were significantly less susceptible to enrofloxacin than were skin isolates (P=0.034). When fluoroquinolone resistance was present, ear isolates were significantly less susceptible to enrofloxacin than to ciprofloxacin (P<0.001) and marbofloxacin (P=0.014).

Feline pyoderma therapy.

Feline pyoderma is a disease entity more prevalent than previously described. Diagnosis is made by finding bacteria in the presence of inflammatory cells or bacterial phagocytosis on routine cytological examination. Diseases leading to secondary bacterial pyoderma include allergic and inflammatory skin diseases, parasitosis, feline chin acne, and others. Lesions of feline pyoderma are variable and include crusted and eroded papules, pustules, furuncles, eroded to ulcerated plaques with variable exudation and crusting, and linear to nodular ulcerative granulomatous lesions. Three cases of feline pyoderma responsive to antimicrobial therapy are discussed: case 1, a 10.5-year-old male neutered domestic short hair with eosinophilic lip ulcer, case 2, a 7-year-old male neutered domestic short hair with multiple cutaneous eosinophilic plaques, and case 3, an 8-month-old male neutered domestic short hair cat with Pseudomonas dermatitis, vasculitis, and panniculitis. Antibiotic selection for treatment of feline pyoderma should be based on cytological examination, and culture and sensitivity in unresponsive cases.