Linda J. Vogelnest

Infections and some other conditions affecting the skin and subcutis of the naso-ocular region of cats—Clinical experience 1987–2003

Infections of the skin or subcutis of the naso-ocular region develop through two mechanisms. Cases with lesions but without concomitant signs of nasal disease probably result from cat scratch injuries. Under certain circumstances, such lacerations result in the introduction of saprophytic microorganisms in such large numbers that host defence mechanisms are overwhelmed. This results in localised, variably invasive, disease in an otherwise immunocompetent host. An unpredictable range of organisms can give rise to such infections including a variety of fungal and bacterial genera. Causal organisms will likely vary from one geography to another as a result of differences in soil type and related environmental factors. Accordingly, procurement of appropriate tissue specimens for culture and susceptibility testing is essential to guide therapy, as these cases require medical and sometimes surgical intervention in order to effect a favourable outcome. In contrast, patients with naso-ocular lesions and concurrent signs of nasal disease have a different pathogenesis. Primary infection of the sinonasal region likely results from the inhalation of infectious propagules, with the infection subsequently penetrating overlying bones to invade the subcutaneous space. These lesions are typically the result of cryptococcosis or aspergillosis and must be distinguished from invasive nasal malignancies. An approach to the investigation and treatment of these patients is presented together with photographs of representative cases.

Feline atopic dermatitis: a retrospective study of 45 cases (2001–2012)

BACKGROUND Atopic dermatitis (AD) is recognized as a common cause of pruritus in cats, but it remains incompletely characterized. HYPOTHESIS/OBJECTIVES The aim of the study was to evaluate cases of confirmed feline AD. ANIMALS Fourty-five cats from a dermatology referral practice (2001-2012). METHODS A retrospective case record review was carried out using strict diagnostic criteria, including exclusion of flea-bite hypersensitivity and adverse food reaction. RESULTS Disease prevalence was 12.5%, with domestic mixed (n = 24), Abyssinian (n = 6) and Devon rex (n = 3) cat breeds predisposed. Median age of onset was 2 years (62% <3 years; 22% >7 years; range 3 months to 12 years). Common presentations were severe (82%), nonseasonal (82%), waxing/waning (36%) pruritus, with alopecia/crusting/excoriations and/or erosions/ulceration (73%). Miliary dermatitis (20%) and eosinophilic granuloma complex lesions (27%) occurred. The face/head (71%), ventral abdomen (51%), neck (51%), limbs (38%), pinnae (31%), dorsum/rump (31%) and feet (16%) were frequently affected sites; lesions were restricted to the head/neck in only five cats (11%). Concurrent otitis externa (16%), superficial bacterial pyoderma (49%), Malassezia dermatitis (7%), flea-bite hypersensitivity (24%) and adverse food reaction (13%) occurred. Strong reactions on intradermal allergen testing were common (68%; 19 of 30), most frequently to pollens (61%) and/or insects (46%). Good response to ciclosporin (100%; 10 of 10), systemic glucocorticoids (55%; 22 of 40) and allergen-specific immunotherapy (57%; 13 of 23) and good/partial response to antihistamines (67%; 22 of 33) were reported. CONCLUSIONS AND CLINICAL IMPORTANCE The prevalence of feline AD was higher than previously suggested, and breed predispositions were confirmed. Severe nonseasonal pruritus was most common, with a varied spectrum of lesions affecting a range of body areas.

High allergen-specific serum immunoglobulin E levels in nonatopic West Highland white terriers.

Human and canine atopic dermatitis (AD) share an association with IgE specific to environmental allergens, but few studies have evaluated serum allergen-specific IgE in nonatopic dogs. This study compared serum allergen-specific IgE levels in 30 atopic and 18 nonatopic West Highland white terriers. Atopic dermatitis was confirmed using standard criteria. Nonatopic dogs were over 5 years of age and had no clinical signs or history of AD. Serum allergen-specific IgE levels were measured with Allercept(®) IgE ELISAs using a 48-allergen Australian panel. Positive reactions were defined as ≥150 ELISA absorbance units. Intradermal tests were performed in 16 atopic dogs, either at the time of or at various times prior to serum collection. In atopic dogs, the most common positive ELISA and intradermal test results were to Dermatophagoides farinae (11 of 30 dogs), but there were no statistically significant correlations between results from the two methods for any allergen. In nonatopic dogs, multiple high-positive ELISA reactions were reported to 45 of 48 allergens, most commonly D. farinae and Tyrophagus putrescentiae (17 of 18 dogs each). Positive ELISA results in nonatopic dogs were statistically significantly higher than those in atopic dogs for 44 of 48 allergens, including two allergens (D. farinae and Dermatophagoides pteronyssinus) commonly regarded as significant in canine AD. In conclusion, positive allergen-specific IgE ELISAs were not specific for canine AD, and high allergen-specific IgE levels were seen in nonatopic dogs. The clinical significance of this and whether it characterizes a protective phenotype is unclear.

Papillomavirus-associated multicentric squamous cell carcinoma in situ in a cat: an unusually extensive and progressive case with subsequent metastasis

BACKGROUND Multicentric squamous cell carcinoma in situ (MSCCIS) is an uncommon cutaneous disease of middle-aged to older cats, with some cases being linked to papillomavirus infection. The disease course is usually benign. Initial eruption of multifocal, pigmented, hyperkeratotic plaques is typical, with gradual progression to thickly crusted ulcerative lesions. ANIMAL A 5-year-old male neutered Devon rex cat in apparent good health was initially presented with a 16 month history of over 40 nonpruritic dorsally distributed hyperpigmented patches. Lesions progressed gradually over 2 years to larger, more pigmented, crusted plaques and ulcerated nodules. At 7 years of age the cat developed neurological signs and systemic illness and was euthanized. METHODS AND RESULTS Initial skin histopathology revealed discrete regions of epidermal and follicular epithelial hyperplasia, with moderate numbers of apoptotic keratinocytes, and mild focal epithelial dysplasia. A diagnosis of erythema multiforme was considered; feline herpesvirus-1 immunohistochemistry was negative. Repeat histopathology 22 months after initial presentation confirmed MSCCIS with foci of invasive squamous cell carcinoma (SCC). Postmortem examination 1 month later revealed SCC within the thoracic wall, lungs and vessels of the thoracic spinal cord and heart base, presumed to be metastases from skin lesions. Fluorescent in situ hybridization of initial and later histopathology samples was positive for Felis domesticus papillomavirus type 2. Immunoreactivity of p16 was prominent within early and late cutaneous lesions and internal SCCs. CONCLUSIONS This case represents an unusual presentation of papillomavirus-associated MSCCIS with extensive lesions, atypical initial histopathology and progression to SCC with distant metastases.

IgE Responsiveness to Dermatophagoides farinae in West Highland White Terrier Dogs Is Associated with Region on CFA35

Immunoglobulin E (IgE)-mediated hypersensitivity against environmental allergens, commonly including Dermatophagoides farinae, is associated with atopic diseases in both humans and dogs. We have recently identified a family of clinically healthy West Highland white terriers (WHWTs) with high-serum D. farinae-IgE levels. In this study, we investigated the genetic mechanism controlling IgE responsiveness in dogs by performing a genome-wide association study (GWAS) using the Affymetrix V2 Dog SNP array in 31 high-IgE and 24 low-IgE responder WHWTs. A gene-dropping simulation method, using SIB-PAIR software, showed significant allelic association between serum D. farinae-specific IgE levels and a 2.3-Mb area on CFA35 (best empirical P = 1 × 10(-5)). A nearby candidate gene, CD83, encodes a protein which has important immunological functions in antigen presentation and regulation of humoral immune responses. We sequenced this gene in 2 high-IgE responders and 2 low-IgE responders and identified an intronic polymorphic repeat sequence with a predicted functional effect, but the association was insufficient to explain the GWAS association signal in this population (P = 1 × 10(-3)). Further studies are necessary to investigate the significance of these findings for IgE responsiveness and atopic disease in the dog.

Determination of threshold concentrations of multiple allergenic extracts for equine intradermal testing using normal horses in three seasons.

Forty-one normal horses were evaluated for reactivity to intradermally injected aqueous allergens to determine allergen threshold concentrations (TC), with potential relevance to equine intradermal testing (IDT). Horses were tested three times over 1 year to assess seasonal variation in reactivity, using three to five serial dilutions of 27 allergens each time. Injection sites were evaluated after 15 min, 1 h, 4 h and 24 h. The highest allergen concentration at which < 10% of horses demonstrated positive reactivity (subjective score of > or = 2, scale of 0 to 4) at 15 min was considered the TC. The TC was determined for nine pollens (2000 to > 6000 PNU mL(-1)), four moulds (4000 to > 6000 PNU mL(-1)), seven insects (ant, horse fly 125 PNU mL(-1); house fly, cockroach 250 PNU mL(-1); moth 60 PNU mL(-1); mosquito 1000 PNU mL(-1); Culicoides nebeculosis 1 : 5000 w v(-1)) and three of four storage mites (1 : 10,000 w v(-1)). The TC was not determined due to excessive reactivity at the lowest concentrations tested for dust mites (Dermatophagoides farinae [< 1 : 12,000 w v(-1)], D. pteronyssinus [< 1 : 30,000 w v(-1)]), and Acarus siro (< 1 : 10,000 w v(-1)). Minor variation in the TC for specific allergens occurred in different seasons. Progressive sensitization with repeat testing occurred for grain mill dust mix. Positive reactivity at 1 h and 4 h occurred in > 10% of horses for nine of 19 allergens (pollens, mosquito, storage mites) at their determined TC. Positive reactivity was rare at 24 h. This study in normal horses suggests that appropriate testing concentrations of allergens for equine IDT in atopic horses may be > or = 1000 PNU mL(-1) for pollens and moulds, 60 to 250 PNU mL(-1) for most insects and < 1 : 12,000 w v(-1) for dust mites; and that reactions at 1-4 h may be insignificant.

Storage mite contamination of commercial dry dog food in south‐eastern Australia

OBJECTIVE To evaluate contamination of unopened and opened stored sources of commercial dry dog food by viable storage mites. DESIGN Prospective laboratory and field study. MATERIAL AND METHODS Samples were collected from nine brands of previously unopened bags (new bags) of dry food and 20 field sources of stored dry food in homes in Sydney and Canberra, Australia. All samples were initially examined for the presence of mites using a stereo-binocular microscope and then placed in separate filter-paper-sealed containers. Field samples were incubated at an average temperature of 29°C and 78% relative humidity (RH) for 5 weeks and then at average 26°C/83% RH for 8 weeks. Paired new-bag samples were stored under room conditions (average 23°C/47% RH) and controlled incubator conditions (average 26°C/80% RH) for 6 weeks. All samples were thoroughly examined for mites, mite eggs and visible mould once weekly using a stereo-binocular microscope. RESULTS Storage mites were not visualised in any of the field samples or in new-bag samples stored at room temperature. Storage mites, identified as Tyrophagus putrescentiae, were visualised in increasing numbers in seven of nine new-bag samples after incubation, with first mites and then eggs evident after 3 weeks of incubation. CONCLUSIONS We confirmed the presence of viable storage mites in a range of previously unopened commercial dry dog foods in Australia and confirmed the possibility of heavy storage mite contamination for dry food stored under conditions of moderate temperature and high humidity. These findings have relevance to storage mite and/or dust mite sensitivity in canine atopic dermatitis.

Feline superficial pyoderma: a retrospective study of 52 cases (2001–2011)

BACKGROUND Superficial pyoderma is traditionally considered rare in cats but may be more prevalent than previously reported. OBJECTIVES To better characterize superficial pyoderma in cats. ANIMALS Fifty-two cats from a dermatology referral population over a 10 year period. METHODS This study was retrospective. Cases were included if neutrophils and intracellular bacteria were reported from surface cytology of skin lesions. Medical records were reviewed for signalment, historical and clinical data, cytology results, primary skin diagnoses and treatment details. RESULTS Disease prevalence was 20%, with no breed or sex predispositions. The estimated median age of onset was 2 years, affecting 54% of cats by 3 years and 23% after 9 years. Fewer cases presented during winter (15%) compared with other seasons. Skin lesions were typically multifocal, affecting the face (62%), neck (37%), limbs (33%) and ventral abdomen (29%) most commonly. Crusting (83%), alopecia (67%), ulceration/erosion (54%) and erythema (46%) were common lesion types. Pruritus was reported in 92% of cats. Underlying hypersensitivities (confirmed in 60%; suspected in 19%), and atopic dermatitis specifically (confirmed in 48%), were the most frequent primary dermatoses. Cats were treated with a variety of systemic and/or topical antimicrobials. The overall apparent response was considered good in 61% and poor in 27% of cats. Recurrence was confirmed or suspected in 42% of cats. CONCLUSIONS AND CLINICAL IMPORTANCE Feline superficial pyoderma was more prevalent in this study population than previously reported. Young cats with hypersensitivities and older cats were more commonly affected, and a variety of lesion types and distributions occurred.

AN UNDESCRIBED DEMODEX SP. AND DEMODICOSIS IN A CAPTIVE KOALA (PHASCOLARCTOS CINEREUS)

Abstract A 12-yr-old male koala (Phascolarctos cinereus) in a zoo collection developed bilateral, noninflammatory, periocular alopecia. Deep periocular skin scrapings yielded multiple adult, nymphal, and larval mites of a previously undescribed Demodex species. Skin biopsies from affected areas revealed multiple mites in superficial keratin and within hair follicles, associated with a mild intramural lymphocytic folliculitis. Treatment with daily oral ivermectin was safe and effective. Although Demodex sp. are previously reported from skin scrapings in another koala with periocular alopecia, this is the first confirmed case of koala demodicosis.

Canine superficial bacterial pyoderma: evaluation of skin surface sampling methods and antimicrobial susceptibility of causal Staphylococcus isolates

OBJECTIVE To evaluate three easily performed methods of skin surface sampling for bacterial culture of Staphylococcus isolates obtained from dogs with superficial bacterial pyoderma (SBP) presenting to two veterinary teaching hospitals in Sydney, Australia, and to determine the antimicrobial susceptibility of isolates. DESIGN Prospective study of 27 dogs with SBP. Cytologically confirmed SBP lesions were sampled for bacterial culture using a dry cotton swab, a saline-moistened cotton swab and a skin surface scraping. Isolates were identified by standard discriminatory phenotypic and biochemical analyses, and confirmed using matrix-assisted laser desorption ionisation time of flight mass spectrometry (MALDI-TOF MS). Susceptibilities to 14 antimicrobials were determined by disk diffusion and by detection of the mecA gene using PCR. Sampling methods were compared according to bacterial yield, antibiograms and bacterial phenotypic analysis. Location of causative bacteria was evaluated via 8-mm punch skin biopsies using haematoxylin and eosin, Gram-Twort and Giemsa staining, and fluorescence in situ hybridisation (FISH). RESULTS Staphylococcus sp. were isolated from lesions in all dogs, either S. pseudintermedius (24 dogs) or S. schleiferi (3 dogs). Susceptibility was highest to cephalexin (96%) and amoxycillin clavulanate (96%). Methicillin resistance assessed by mecA real-time PCR and phenotypic oxacillin resistance was found in one dog (4.3%). Routine histology and FISH revealed bacteria within superficial stratum corneum. CONCLUSION Staphylococcal isolates from canine SBP demonstrated high susceptibility to common empirical antimicrobials. Histological techniques confirmed presence of bacteria at superficial sites, likely to be accessed by the sampling techniques. The three techniques afforded similar results and may be equally suitable for obtaining samples for culture.