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.

Figurate erythema in 11 Eastern European sphynx cats

BACKGROUND

In humans, figurate erythema (FE) represents a heterogenous group of dermatoses with circular or serpiginous erythematous skin lesions; FE has not been reported in cats.

OBJECTIVES

To report clinical and histological characteristics and outcomes of FE in sphynx cats from Baltic sea-bordering countries.

ANIMALS

Eleven client-owned sphynx cats with FE.

MATERIALS AND METHODS

We recruited cases meeting the following criteria: (i) a sphynx breed, (ii) FE with or without scaling, (iii) a chronic, waxing-and-waning course lasting longer than a month and (iv) an absence of other skin diseases.

RESULTS

Of 11 cats, there were seven Donskoys, one Peterbald, one Ukrainian Levkoy and two presumed Canadian sphynxes; all except one were males, and the age of onset was <12 months in eight cats. Skin lesions lasted between 1.2 and 56 months, and they consisted of erythematous plaques with a linear-to-serpiginous, annular, gyrate or iris configuration predominating on the trunk and extremities. Scaling was often seen trailing the edge of the centrifugally expanding erythema. All cats were otherwise asymptomatic or mildly pruritic. Dermatophytosis was ruled out by special stains and/or fungal cultures in eight cats. Microscopic lesions revealed focal, mild-to-moderate epidermal hyperplasia and hyperkeratosis, minimal-to-mild dysplasia and subepidermal collagen smudging. Special stains were negative for dermatophytes. The clinical remission of FE was not achieved with diet changes or medical interventions; yet, a spontaneous, transient, partial or complete improvement occurred in most cats.

CONCLUSION AND CLINICAL RELEVANCE

This is the first report of FE in sphynx cats from Eastern Europe.

Effect of glycerin on immediate cutaneous reactions of histamine (positive) and phosphate-buffered saline (negative) controls in intradermal skin testing of healthy dogs: A randomised, blinded study

BACKGROUND

Glycerinated allergen extracts contain 50% glycerin, an excellent preservative. While glycerin is a recognised irritant in humans, the utility of glycerinated extracts for intradermal testing has not been validated in dogs.

HYPOTHESIS/OBJECTIVE

To determine and compare the effects of glycerin on immediate cutaneous reactions to intradermal injections of histamine and saline in healthy dogs.

ANIMALS

Eight healthy laboratory beagles.

MATERIALS AND METHODS

The study was designed as a randomised, blinded study. Intradermal injections of histamine (positive control) and saline (negative control) in aqueous and glycerinated (50%) forms were performed on the right thorax. Global wheal scores (GWS) at 20 min were evaluated by two independent investigators blinded to the interventions.

RESULTS

There were no wheal and flare reactions observed after the intradermal injections of phenolated saline. By contrast, 50% glycerosaline injections induced erythema and induration in all dogs. Global wheal scores were significantly higher in aqueous histamine (Friedman test, p < 0.0001) and 50% glycerinated histamine (Friedman test, p = 0.0084) compared to phenolated saline controls. Interestingly, only aqueous histamine (Friedman test, p = 0.01) had significantly higher GWS than 50% glycerosaline injections, while no significant difference in GWS between 50% glycerinated histamine and 50% glycerosaline groups was observed (Friedman test, p = 0.59).

CONCLUSION AND CLINICAL RELEVANCE

This study demonstrates that intradermal injection of 50% glycerosaline induces erythema and induration skin reactions in healthy dogs that can mimic positive reactions to allergenic extracts. Further dilutions of glycerinated positive and negative control solutions need to be optimised for intradermal testing in dogs.

Use of a colorimeter is a viable method to measure melanin and erythema content in the context of laser beam attenuation by use of a class IV laser in different tissues in dogs

OBJECTIVE

Patient factors may alter laser photon attenuation, but these factors have not been adequately evaluated in live dogs. Our objective was to evaluate class IV laser beam attenuation (LBA) by canine tissues using a colorimeter to evaluate melanin and erythema indices. We hypothesized that greater melanin and erythema indices and unclipped hair would increase LBA, and these properties would vary among tissues.

ANIMALS

20 client-owned dogs.

PROCEDURES

Between October 1 and December 1, 2017, colorimeter measurements and LBA in various tissues before and after clipping overlying hair were evaluated. Data were analyzed using generalized linear mixed models. Statistical significance was set at P < .05.

RESULTS

LBA was greater in unclipped (98.6 ± 0.4%) than clipped hair (94.6 ± 0.4%). The least LBA occurred in the pinna (93%) while the greatest occurred in the caudal vertebra (100%) and caudal semitendinosis muscles (100%). Each mm of tissue thickness resulted in LBA of 11.6%. Each unit increase in melanin index resulted in a 3.3% increase in LBA. There was no association of LBA with erythema index.

CLINICAL RELEVANCE

To our knowledge, this is the first study that evaluated LBA by different tissues in live dogs using a colorimeter to evaluate melanin and erythema indices. We recommend clipping hair prior to photobiomodulation to decrease laser beam attenuation and using increased laser doses in thicker tissues and dogs with high melanin content. The colorimeter may be helpful in customizing patient treatment dosimetry. Future studies are necessary to determine therapeutic laser doses for adequate photobiomodulation effects.

Evaluation of Erythema Severity in Dermatoscopic Images of Canine Skin: Erythema Index Assessment and Image Sampling Reliability

The regular monitoring of erythema, one of the most important skin lesions in atopic (allergic) dogs, is essential for successful anti-allergic therapy. The smartphone-based dermatoscopy enables a convenient way to acquire quality images of erythematous skin. However, the image sampling to evaluate erythema severity is still done manually, introducing result variability. In this study, we investigated the correlation between the most popular erythema indices (EIs) and dermatologists’ erythema perception, and we measured intra- and inter-rater variability of the currently-used manual image-sampling methods (ISMs). We showed that the EI_BRG, based on all three RGB (red, green, and blue) channels, performed the best with an average Spearman coefficient of 0.75 and a typical absolute disagreement of less than 14% with the erythema assessed by clinicians. On the other hand, two image-sampling methods, based on either selecting specific pixels or small skin areas, performed similarly well. They achieved high intra- and inter-rater reliability with the intraclass correlation coefficient (ICC) and Krippendorff’s alpha well above 0.90. These results indicated that smartphone-based dermatoscopy could be a convenient and precise way to evaluate skin erythema severity. However, better outlined, or even automated ISMs, are likely to improve the intra- and inter-rater reliability in severe erythematous cases.

Epidemiology and pathological progression of erythematous lip lesions in captive sun bears (Helarctos malayanus)

This study investigates the occurrence of erythematous lip lesions in a captive sun bear population in Cambodia, including the progression of cheilitis to squamous cell carcinoma, and the presence of Ursid gammaherpesvirus 1. Visual assessment conducted in 2015 and 2016 recorded the prevalence and severity of lesions. Opportunistic sampling for disease testing was conducted on a subset of 39 sun bears, with histopathological examination of lip and tongue biopsies and PCR testing of oral swabs and tissue biopsies collected during health examinations. Lip lesions were similarly prevalent in 2015 (66.0%) and 2016 (68.3%). Degradation of lip lesion severity was seen between 2015 and 2016, and the odds of having lip lesions, having more severe lip lesions, and having lip lesion degradation over time, all increased with age. Cheilitis was found in all lip lesion biopsies, with histological confirmation of squamous cell carcinoma in 64.5% of cases. Single biopsies frequently showed progression from dysplasia to neoplasia. Eighteen of 31 sun bears (58.1%) had at least one sample positive for Ursid gammaherpesvirus 1. The virus was detected in sun bears with and without lip lesions, however due to case selection being strongly biased towards those showing lip lesions it was not possible to test for association between Ursid gammaherpesvirus 1 and lip squamous cell carcinoma. Given gammaherpesviruses can play a role in cancer development under certain conditions in other species, we believe further investigation into Ursid gammaherpesvirus 1 as one of a number of possible co-factors in the progression of lip lesions to squamous cell carcinoma is warranted. This study highlights the progressively neoplastic nature of this lip lesion syndrome in sun bears which has consequences for captive and re-release management. Similarly, the detection of Ursid gammaherpesvirus 1 should be considered in pre-release risk analyses, at least until data is available on the prevalence of the virus in wild sun bears.

Accuracy of an Affordable Smartphone-Based Teledermoscopy System for Color Measurements in Canine Skin

Quality smartphone cameras and affordable dermatoscopes have enabled teledermoscopy to become a popular medical and veterinary tool for analyzing skin lesions such as melanoma and erythema. However, smartphones acquire images in an unknown RGB color space, which prevents a standardized colorimetric skin analysis. In this work, we supplemented a typical veterinary teledermoscopy system with a conventional color calibration procedure, and we studied two mid-priced smartphones in evaluating native and erythematous canine skin color. In a laboratory setting with the ColorChecker, the teledermoscopy system reached CIELAB-based color differences ΔE of 1.8-6.6 (CIE76) and 1.1-4.5 (CIE94). Intra- and inter-smartphone variability resulted in the color differences (CIE76) of 0.1, and 2.0-3.9, depending on the selected color range. Preliminary clinical measurements showed that canine skin is less red and yellow (lower a* and b* for ΔE of 10.7) than standard Caucasian human skin. Estimating the severity of skin erythema with an erythema index led to errors between 0.5-3%. After constructing a color calibration model for each smartphone, we expedited clinical measurements without losing colorimetric accuracy by introducing a simple image normalization on a white standard. To conclude, the calibrated teledermoscopy system is fast and accurate enough for various colorimetric applications in veterinary dermatology.

Evaluation of the number of colony forming units on the skin of dogs after clipping the hair with two sizes of clipper blades

OBJECTIVE

To evaluate erythema and number of CFUs on the skin of dogs with hair clipped by use of 2 sizes of clipper blades.

ANIMALS

67 client-owned dogs receiving an epidural.

PROCEDURES

Hair was clipped with a No. 10 blade (approx hair length, 1.5 mm) on one half and a No. 40 blade (approx hair length, 0.25 mm) on the other half of each epidural site. Skin was surgically scrubbed with 2% chlorhexidine gluconate and 70% isopropyl alcohol. Samples were obtained immediately after clipping, after skin was scrubbed, and again 24 hours after clipping. Number of CFUs for both sides of the clipped areas, types of microorganisms, and growth on MacConkey agar were evaluated every 24 hours for 72 hours. Colonies were evaluated for bacterial morphology and Gram stain characteristics. Sites were evaluated 24 hours after clipping for evidence of erythema.

RESULTS

24 hours after hair was clipped, there was a significantly higher incidence of erythema and higher number of Micrococcaceae bacteria for the side clipped with the No. 40 blade than the side clipped with the No. 10 blade. Number of CFUs did not differ significantly between size of clipper blades.

CONCLUSIONS AND CLINICAL RELEVANCE

Clipping hair with a No. 40 blade resulted in a significant increase in the incidence of erythema and higher number of Micrococcaceae bacteria, compared with results for clipping with a No. 10 blade. These results supported use of a No. 10 clipper blade to prevent erythema and reduce variation in the skin microbiome.

Characterization of platelet-activating factor-induced cutaneous edema and erythema in dogs

OBJECTIVE To characterize platelet-activating factor (PAF)-induced edema and erythema in the skin of dogs and compare those reactions with histamine-induced cutaneous reactions. ANIMALS 6 healthy Beagles. PROCEDURES Experiments were performed at ≥ 2-week intervals. Each dog received ID injections (5 μg/site) of PAF C16, PAF C18, lyso-PAF, and histamine. Edema (mean diameter) and erythema scores (none, mild, moderate, or severe) were assessed 30 minutes after the injections. Dogs received ID injections of PAF and histamine each with various concentrations of WEB 2086 (PAF receptor antagonist) or underwent ID testing with PAF and histamine before and 3 hours after oral administration of cetirizine hydrochloride or prednisolone (at 2 doses each). RESULTS ID injections of PAF C16 and PAF C18, but not lyso-PAF, induced comparable levels of edema and erythema. The PAF-induced edema and erythema peaked at 30 minutes and lasted for 6 hours after the injection; histamine-induced edema and erythema peaked at 30 minutes and lasted for 3 hours after the injection. Edema sizes and erythema scores were significantly smaller and lower, respectively, for PAF than for histamine. The WEB 2086 inhibited PAF-induced but not histamine-induced edema and erythema. Cetirizine slightly, but significantly, repressed PAF-induced edema and erythema as well as histamine-induced cutaneous reactions. Prednisolone suppressed both PAF-induced and histamine-induced edema and erythema. CONCLUSIONS AND CLINICAL RELEVANCE In canine skin, the duration of PAF-induced inflammation was longer than that of histamine-induced inflammation. The PAF- and histamine-induced cutaneous reactions were effectively suppressed by oral administration of prednisolone. The importance of PAF in dogs with anaphylaxis and allergic disorders warrants further investigation.

Determination of a safe and effective ultraviolet B radiant dose in budgerigars (Melopsittacus undulatus): a pilot study

The object of this study was to establish a minimum dose of ultraviolet B (UVB) radiation capable of producing an erythemal reaction in budgerigars (Melopsittacus undulatus), to determine a threshold dose of UVB for vitamin D photoconversion, and to investigate the use of safer UVB wavelengths. In each of 5 experiments of this study, 20 birds were divided into a control group (n = 10) and a UVB irradiated group (n = 10). Light sources that provide broadband UVB wavelengths (280-315 nm) and narrowband UVB (310-320 nm) were used. Varied doses of UVB radiation were administered to budgerigars by altering exposure time and irradiance. Safety was determined by observing body weight and incidence of photokeratitis and photodermatitis. Efficacy was evaluated by measuring changes in serum 25-hydroxycholecalciferol levels. Serum corticosterone was measured in 1 experiment to monitor stress levels. The results demonstrated that exposure to 180 mJ/cm2 broadband UVB induced vitamin D photoconversion, decreased body weights, and increased serum corticosterone levels. At these wavelengths, UVB-induced lesions were observed. A broadband UVB of 150 to 300 mJ/cm2 was determined as the minimum erythema dose, and the threshold dose for vitamin D photoconversion was calculated to be in the range of 113-225 mJ/cm2. No erythemal lesions or vitamin D photoconversion took place after exposure to up to 1730 mJ/cm2 narrowband UVB radiation. A minimum erythema dose and a threshold dose for vitamin D conversion need to be determined for each species if phototherapy is to be considered as a safe and effective therapeutic or husbandry tool.

Suspected toxic shock-like syndrome in a dog with closed-cervix pyometra

Several cases of toxic shock-like syndrome (TSLS) have been reported in dogs but no inciting cause has been identified. TSLS associated with a closed-cervix pyometra was suspected in the reported bitch. The dog was evaluated for the complaint of generalized dermatopathy (erythema and oedema) and systemic signs with multiorganic involvement (depression, fever, immature neutrophilia, hypoalbuminaemia, renal disease, vomiting and diarrhoea). Histological features consistent with TSLS included superficial dermatitis with epidermal neutrophilic exocytosis and necrotic keratinocytes. The tentative diagnosis of TSLS was based on case history, clinical presentation, laboratory and histopathological findings, and the resolution of all clinical signs following surgical removal of the localized bacterial infection.

A randomized comparative clinical trial of recombinant canine interferon-gamma (KT-100) in atopic dogs using antihistamine as control

Recombinant canine interferon-gamma (KT-100) or topical antihistamine (diphenhydramine: DH) was administered to dogs with atopic dermatitis (AD) for 4 weeks and their efficacies were compared using pruritus, excoriation, erythema and alopecia as evaluation criteria. Clinical studies on 92 atopic dogs (KT-100 group: 63, DH group: 29) were conducted at 18 animal hospitals in Japan. KT-100 was administered subcutaneously once a day three times a week on alternating days for 4 weeks. DH was administered topically twice daily for 4 weeks. The efficacy rates of the KT-100 group on day 28 were 72.1% for pruritus, 73.8% for excoriation, 75.4% for erythema and 60.7% for alopecia, which were significantly higher than those of the DH group (20.7% for pruritus, 27.6% for excoriation, 24.1% for erythema and 24.1% for alopecia).

Prospective open pilot study on the use of ciclosporin for feline allergic skin disease

OBJECTIVES

To evaluate the efficacy of ciclosporin in cats with allergic skin disease.

METHODS

Ten cats with signs of allergic skin disease were administered ciclosporin daily at a dose of 3.6 to 8.3 mg/kg for one month. None of these cats had previously responded to a hypoallergenic diet trial, and all animals had previously been treated with endectoparasiticidal drugs, with no improvement two weeks before entering the trial. On days 0 and 30, owners assessed pruritus with a visual analogue scale, and veterinarians evaluated cutaneous lesions.

RESULTS

All the cats had pruritus and erythema, five had alopecia, two had an eosinophilic plaque, one had miliary dermatitis and two had both alopecia and an eosinophilic plaque. Good or excellent improvement was observed in 40 per cent of cats for pruritus, 57 per cent of cats for alopecia and 60 per cent of cats for erythema. A significant decrease in mean scores was observed for pruritus only, while for erythema and alopecia, it was close to being significant (P < 0.052).

CLINICAL SIGNIFICANCE

Ciclosporin may be helpful in symptomatically treating signs of feline allergic skin disease. However, it is important to remember that ciclosporin is not licensed for use in cats.

Radiation sources providing increased UVA/UVB ratios induce photoprotection dependent on the UVA dose in hairless mice

In studies involving mice in which doses of UVA (320-400 nm) and UVB (290-320 nm) radiation were administered alone or combined sequentially, we observed a protective effect of UVA against UVB-induced erythema/edema and systemic suppression of contact hypersensitivity. The UVA immunoprotection was mediated by the induction of the stress enzyme heme oxygenase-1 (HO-1) in the skin, protection of the cutaneous Th1 cytokines interferon-gamma (IFN-gamma) and IL-12 and inhibition of the UVB-induced expression of the Th2 cytokine IL-10. In this study, we seek evidence for an immunological waveband interaction when UVA and UVB are administered concurrently to hairless mice as occurs during sunlight exposure in humans. A series of spectra providing varying ratios of UVA/UVB were developed, with the UVA ratio increased to approximately 3.5 times the UVA component in solar simulated UV (SSUV). We report that progressively increasing the UVA component of the radiation while maintaining a constant UVB dose resulted in a reduction of both the erythema/edema reaction and the degree of systemic immunosuppression, as measured as contact hypersensitivity. The UVA-enhanced immunoprotection was abrogated in mice treated with a specific HO enzyme inhibitor. UVA-enhanced radiation also upregulated the expression of cutaneous IFN-gamma and IL-12 and inhibited expression of both IL-6 and IL-10, compared with the activity of SSUV. The results were consistent with the previously characterized mechanisms of photoprotection by the UVA waveband alone and suggest that the UVA component of solar UV may have beneficial properties for humans.

Immunohistochemical demonstration of connexin-related epithelization defects in a lamb caused by (erythro)keratodermia variabilis

The distribution of four important connexins (Cx 26, 30, 31, 43) in the skin of a neonatal lamb with (erythro)keratodermia (EKV) was demonstrated using immunohistochemistry, including a very sensitive visualization system. The reaction staining for Cx 26, 30 and 31 was negative to weak in all skin structures, and only Cx 43 displayed weak to moderate positive reactions, although not uniformly distributed throughout the important systems (e.g. epidermis, hair follicle sheaths). Thus, the study proves for the first time that connexin defects are associated with the development of EKV in domesticated mammals, as they are in humans.

[Another indication for (erythro)keratodermia variabilis in livestock in the case of a neonatal lamb]

From skin biopsies of a neonatal lamb a congenital skin disease (erythro)keratodermia variabilis was diagnosed which especially showed besides an erythema formation a hyperkeratosis at some wound areas of the body. Despite of a sudden induced intensive therapy the lamb died. At the dissection of the carcass there were no further postmortem-findings which refer to another organic disease than the one of the skin. This case report is the second description of (erythro)keratodermia variabilis in domestic mammals, which is caused by an autosomal dominant inherited horning defect in humans.

Clinical response of captive common wombats (Vombatus ursinus) infected with Sarcoptes scabiei var. wombati

Seven common wombats (Vombatus ursinus) were exposed and two of these were re-exposed to Sarcoptes scabiei var. wombati (Acari: Sarcoptidae). For wombats exposed for the first time, five exposed to 5,000 mites on their shoulder developed moderate to severe parakeratotic mange after 11 wk compared with two given 1,000 mites that developed mild clinical signs of mange after 11 wk. For re-exposed wombats, one of two given 5,000 mites developed mild parakeratotic mange and the other developed severe parakeratotic mange. Initial signs of mange were erythema followed by parakeratosis, alopecia, excoriation and fissuring of parakeratotic crust and skin. Erythema usually became apparent within 14 days after exposure (DAE) or within 24 hrs of re-exposure. Parakeratosis was visible 14-21 DAE and alopecia first occurred 35-77 DAE. Clinical signs increased in severity over time and lesions spread slowly from the site of exposure. Mangy wombats scratched excessively, lost weight, and exhibited a significant neutrophilia compared with control wombats. Treatment of mange with three injections of ivermectin, 300 micrograms/kg, 10 days apart led to complete resolution of clinical signs. However mites were not entirely eliminated until wombats received a second regime of treatment.

Chronic moderate heat dermatitis (erythema ab igne) in five dogs, three cats and one silvered langur

Erythema ab igne, an old and rare disease in the human literature, is an erythematous, often pigmented, reticular, macular dermatosis that occurs at the site of repeated exposure to moderate heat. We identified lesions consistent with erythema ab igne in five dogs, three cats and one silvered langur (Trachypithecus cristatus[Raffles, 1821]). In dogs and cats, the cutaneous lesion distribution typically reflected chronic exposure to moderate heat during lateral or sternal recumbency. The silvered langur developed cutaneous lesions on the dorsal neck from exposure to a heat lamp. Principal clinical lesions consisted of irregular areas of alopecia (7/9) and erythema (7/9), sometimes with hyperpigmentation (3/9). Principal histological features consisted of karyomegaly (9/9) and keratinocyte atypia (4/9), scattered apoptotic or vacuolated basal cells and/or apoptotic keratinocytes (6/9), mild mixed mononuclear interstitial or interface dermatitis (9/9) with adnexal atrophy (8/9), and a variable number of wavy eosinophilic elastic fibres (9/9). The presence of these cutaneous lesions in an animal indicates that the environment should be evaluated for exposure to chronic moderate heat, and the heat source should be eliminated or modified to prevent further exposure and progression of lesions.

Evaluation of skin erythema by use of chromametry and image analysis of digital photographs after intradermal administration of histamine in dogs

OBJECTIVE

To investigate whether the degree of erythema during an induced erythematous reaction, the histamine skin test reaction, can be assessed objectively by use of chromametry and image analysis of digital photographs.

ANIMALS

9 pet dogs (6 Golden Retrievers and 3 yellow Labrador Retrievers).

PROCEDURE

Histamine phosphate was injected intradermally, and erythema of the wheal reaction was evaluated during the hour that followed. This was done by use of clinical scores, chromametry, and image analysis of digital photographs. Method reproducibility was tested for visual evaluation of printouts of digital photographs and for image analysis of the same photographs.

RESULTS

The coefficient of variation of the technically derived erythema values was < 10%. The reproducibility of image analysis was high and the range of agreement between observers narrow. Using chromametry, it was not possible to differentiate between various degrees of erythema intensity as visually perceived. In contrast, use of image analysis of digital photographs enabled discrimination of slight erythema from moderate and marked erythema. The dynamics of reaction measured by chromametry followed the clinical observation.

CONCLUSIONS AND CLINICAL RELEVANCE

Chromametric values are comparable to those obtained by visual inspection. As the result of standardized conditions, chromametry is preferred over digital photography.

Use of chromametry and digital photography for objective measurement of skin color in clinically normal dogs

OBJECTIVE

To evaluate whether skin erythema in clinically normal dogs can be quantified by use of chromametry and image analysis of digital photographs.

ANIMALS

9 German Shepherd Dogs and 10 mixed-breed dogs.

PROCEDURE

Hair was clipped at 7 sites on the body. Skin erythema was evaluated at the axillary region, right and left lateral aspect of thorax, right and left loin area (ie, part of the back between the thorax and pelvis), right and left groin area (ie, the junctional region between the abdomen and thigh), metatarsal digital pad, and on the nose. Replicate measurements were done by use of chromametry and image analysis of digital photographs, using erythema values in accordance with the Committee International d'Eclairage (CIE)-Lab color system.

RESULTS

Repeatability was high for both techniques. Within-dog variation was lower than between-dog variation. Between-dog variation was high for both groups of dogs. Interregional variation was significant in German Shepherd Dogs and mixed-breed dogs. Erythema values revealed symmetry between the right and left lateral aspects of the thorax and loin and groin areas.

CONCLUSIONS AND CLINICAL RELEVANCE

Precise objective methods are available for skin erythema quantification. Chromametric and photographic erythema values had a high within-dog reproducibility. Between-dog variability was high for German Shepherd Dogs and mixed-breed dogs as was regional variation, indicating differences in color among dogs.

Suspected necrolytic migratory erythema associated with chronic hepatopathy in a cat

A cat presenting with generalised hypotrichosis and crusts on the feet and tail was found to have an unusual chronic hepatopathy. There was also evidence of a chronic small intestinal disease which went undiagnosed. Necrolytic migratory erythema was suspected based on clinical findings and dermatohistopathology, and an association with the chronic hepatopathy was suggested. This is the first report of such an association in a cat. Serum zinc, amino acids and essential fatty acids were analysed, and medical treatment was given with equivocal efficacy.

Experimental studies with Stronglyloides papillosus in goats

Unusual clinical and pathological observations in the field in goats and sheep suffering from Strongyloides papillosus infection prompted experimental work on this parasite. Goats were infected percutaneously with either single or multiple, low or high levels of S. papillosus. Young goats up to 12 months of age were found to be the most susceptible. Some animals, however, showed substantial resistance to infective doses. Clinical signs included transient diarrhoea, misshapen, elongated faecal pellets terminally, dehydration, anorexia, cachexia, gnashing of teeth, foaming at the mouth, anaemia and nervous signs such as ataxia, a wide-based stance, stupor and nystagmus. A 'pushing syndrome' was seen in 22% of the animals. The pathological changes are described and included enteritis, status spongiosus in the brain, hepatosis leading to rupture of the liver, nephrosis, pulmonary oedema, interstitial pneumonia and pneumonia. About 6% of the goats died acutely from fatal hepatic rupture. The development of an acquired immunity was determined. The immunity elicited an allergic skin reaction at the application site of larvae or injection sites of larval metabolites. This immunity, however, could be breached by large doses of larvae. The most profound clinicopathological changes induced by the parasites were an anaemia (most pronounced in the young goats) and hypophosphataemia. Trace element analyses provided evidence of Cu, Mn and possibly Se deficiencies in some goats.

Therapy of difficult cases of canine pyoderma with marbofloxacin: a report of 39 dogs

Thirty-nine dogs with severe and/or recurrent lesions of pyoderma were treated with marbofloxacin at an average dosage of 2.12 mg/kg bodyweight, once daily, for time periods varing from 10 to 213 days. Forty-seven strains of bacteria, isolated from 34 cultures, were tested for sensitivity to various antibiotics. At day 0, no resistance to marbofloxacin was found, but one refractory case, a strain of Staphylococcus intermedius resistant to marbofloxacin, was cultured at day 28. Thirty-three dogs (84.6 per cent) showed an excellent response (cure), one (2.6 per cent) a clear improvement and one (2.6 per cent) a smaller improvement, while the remaining four dogs showed no response after 11 to 60 days. Fifteen dogs (45.5 per cent) relapsed over the follow-up period of three to 191 days, but none of the dogs in the study exhibited any adverse effects.

Methods for exposure of laboratory animals to ultraviolet radiation

Two different sources of ultraviolet B (UVB) radiation, an electronically controlled UVB exposure unit, containing FS40 tubes, and a hand-held Kromayer lamp, were evaluated for actual irradiance in W/m2 and spectra (physical dosimetry and biological dosimetry (skin effects in rodents)). The technical studies of the FS40 sources demonstrated that the flux intensity of the lamps could be changed electronically, without affecting the spectrum. Thus it was possible to standardize UVB exposure electronically. The biologically effective doses of these sources were analysed in RIV-Tox Wistar rats and BALB/c mice. After low doses of UVB radiation, histopathological changes such as acanthosis, hyperkeratosis and dermal inflammation were observed in the skin without the presence of major side effects such as erythema and oedema. After higher doses of UVB radiation erythema and oedema were clearly visible. Quantitative studies showed that the minimal erythema dose, as a biological parameter, correlated well to the emission in J/m2. In addition, biological parameters such as acanthosis and inflammation in the skin correlated well to the actual exposure in J/m2 and were sensitive biomarkers for UVB-induced skin toxicity. Thus, in addition to minimal erythemal doses, acanthosis and inflammation may also be applied as biologically relevant doses for studies of the biological effects of UVB radiation.

Characteristics of spontaneous erythema appeared in hairless rats

The hairless rat (WBN/Kob-Ht), a dominant mutant rat derived from the Wistar strain, rarely develops spontaneous erythema of a progressive nature on its skin. Erythema was first observed at 8 weeks of age and the incidence at 20 weeks of age was about 4% in both males and females. Histopathologically, erythema was characterised by dermatitis induced by an immunological reaction. Areas of erythema in the skin were decreased by treatment with dexamethasone (1 mg/kg) or ciclosporin (25 or 50 mg/kg). These results suggested that erythema on the hairless rat could be used as an animal model of spontaneous dermatitis.

Cutaneous syndrome possibly caused by heartworm infestation in a dog

A 9-year old German Shepherd bitch was presented with a recent onset of seborrhoea oleosa, hyperpigmentation, erythema, pruritus and alopecia along the neck, thorax, ventrum and the dorsal area of the carpus. The skin changes were believed to be caused by Dirofilaria immitis infection. A combination of topical and parenteral anti-heartworm therapy led to the resolution of the lesions.

Zinc-responsive dermatosis in northern-breed dogs: 17 cases (1990-1996)

OBJECTIVE

To determine the response rate of zinc-responsive dermatosis to zinc supplementation, the optimal dosage of zinc required for resolution of lesions, the rate of recurrence of lesions, and to develop recommendations for maintenance dosages of zinc to be administered to dogs with this type of zinc-responsive dermatosis.

DESIGN

Retrospective case series.

ANIMALS

17 northern-breed dogs with a diagnosis of zinc-responsive dermatosis.

PROCEDURE

Histologic evaluation of skin biopsy specimens and review of medical records. Additional information was obtained from veterinarians and owners via a telephone questionnaire.

RESULTS

In 12 of 17 dogs, lesions were unilateral initially, then became symmetrical as the disease progressed. Pyoderma was evident in 5 of 17 dogs, whereas 10 were pruritic. Most lesions initially developed between September and April, and 12 of 17 dogs developed lesions in February, October, and November. Initial dosages of zinc supplement ranged from 0.8 to 4.6 mg/kg of body weight/d (0.36 to 2.09 mg/lb/d). Effective/ maintenance dosages ranged from 0.5 mg/kg (0.23 mg/lb), twice weekly, to 8.0 mg/kg/d (3.6 mg/lb/d). Fifteen of 17 dogs had complete resolution of lesions after zinc supplementation. Lesions recurred in 9 of 16 dogs. Approximately half of the recurrent lesions were a result of a missed dose or a decrease in dosage or frequency of zinc supplementation.

CLINICAL IMPLICATIONS

An initial dosage of zinc supplement of 1.0 mg of elemental zinc/kg (0.45 mg of elemental zinc/lb), PO, every 24 hours is recommended. Treatment should be continued for 1 month to determine response to treatment, and the daily dosage should be increased by 50% if the initial dosage is not effective. Dogs are prone to recurrence of lesions if a dose of zinc is missed or the dosage or frequency is decreased.

Characterization of dermatologic changes in geriatric rhesus macaques

Nonhuman primates are frequently used for aging studies. We observed a high prevalence of skin disease among a group of geriatric rhesus monkeys (mean age = 25 years; n = 9) used in aging behavioral studies. Gross and histopathologic changes in the skin of these geriatric rhesus were compared with skin from control adult monkeys (mean age = 10; n = 4) and sun-exposed monkeys (mean age = 11; n = 4) to characterize age-related skin changes. Biopsy specimens were taken from four specified skin locations (lateral to bridge of nose, ventral midline, dorsal midline, perineal area) and from additional areas where skin lesions were present. Samples were routinely processed and evaluated by light microscopy. Blood samples were collected and tested for estrogen, thyroid-stimulating hormone, triiodothyronine thyroxine, and cortisol levels. The axilla was swabbed and samples were obtained for bacterial culturing. All nine of the geriatric monkeys had notable dermal lesions, while one of the control monkeys and one of the sun-exposed monkeys had abnormal findings. Major gross findings included increased areas of erythematous skin, wrinkling, focal skin scaling, thinning of hair, foot calluses, and exudative lesions. Histologic skin changes included subacute dermatitis, acanthotic dermatitis, and a lesion resembling an early solar lentigo in the sun-exposed animal. These changes were not associated with hormonal abnormalities or bacterial pathogens. Histologic changes are compatible with nonspecific skin changes observed in elderly humans. This study establishes a baseline of dermatologic changes of the aging rhesus macaque.

Pathological and microbiological findings from incidents of unusual mortality of the common frog (Rana temporaria)

In 1992 we began an investigation into incidents of unusual and mass mortalities of the common frog (Rana temporaria) in Britain which were being reported unsolicited to us in increasing numbers by members of the public. Investigations conducted at ten sites of unusual mortality resulted in two main disease syndromes being found: one characterized by skin ulceration and one characterized by systemic haemorrhages. However, frogs also were found with lesions common to both of these syndromes and microscopic skin lesions common to both syndromes were seen. The bacterium Aeromonas hydrophila, which has been described previously as causing similar lesions, was isolated significantly more frequently from haemorrhagic frogs than from those with skin ulceration only. However, as many of the latter were euthanased, this may have been due to differences in post mortem bacterial invasion. An iridovirus-like particle has been identified on electron microscopical examination of skin lesions from frogs with each syndrome and iridovirus-like inclusions have been detected in the livers of frogs with systemic haemorrhages. Also, an adenovirus-like particle has been cultured from one haemorrhagic frog. A poxvirus-like particle described previously from diseased frogs has now been found also in control animals and has been identified as a melanosome. Both the prevalence of the iridovirus-like particle and its association with lesions indicate that it may be implicated in the aetiology of the disease syndromes observed. Specifically, we hypothesize that primary iridovirus infection, with or without secondary infection with opportunistic pathogens such as A. hydrophila, may cause natural outbreaks of 'red-leg', a disease considered previously to be due to bacterial infection only.

Clinical and histologic characterization of cutaneous reactions to stings of the imported fire ant (Solenopsis invicta) in dogs

Four adult dogs received experimentally controlled stings in the dorsolateral abdominal skin by imported fire ants (Solenopsis invicta). The sites were examined grossly 15 minutes and at 1, 2, 3, 4, 5, 6, 24, 48, and 72 hours and histologically 15 minutes and 6, 24, 48, and 72 hours after stinging. The initial gross lesions at 15 minutes were swelling and erythema, and the microscopic changes were vascular congestion and superficial dermal edema. By 6 hours, the lesions consisted of bright erythematous pruritic papules characterized microscopically by a band of full thickness dermal necrosis and inflammation. By 24 hours and continuing to the end of the study at 72 hours, the sites appeared completely normal grossly. Biopsies taken 24, 48, and 72 hours after stings contained microscopic changes similar to those present at 6 hours after stings. These histologic changes are unlike those described for human beings stung by imported fire ants. In human beings, fire ant stings are characterized histologically by an initial superficial vesicle that evolves into a sterile pustule.

A double-blind comparison of olive oil and a combination of evening primrose oil and fish oil in the management of canine atopy

A randomised double-blind parallel study lasting eight weeks was used to assess the effects of olive oil in a group of atopic dogs whose clinical signs were well controlled by dietary supplementation with a combination of evening primrose oil and fish oil. Nine of the 11 dogs which continued to receive this combination were considered unchanged at the conclusion of the study, whereas eight of the 10 dogs switched to olive oil had deteriorated. The mean plasma concentration of dihomogammalinolenic acid, a precursor of potentially antiinflammatory mediators, was significantly reduced (P < 0.05) in the olive oil-treated group at the end of the study. There were no significant differences between the mean plasma linoleic, eicosapentaenoic and arachidonic acid concentrations in the two groups. These findings suggest that olive oil is not an effective therapeutic agent in the control of canine atopy.

Experimental 3-nitro-4-hydroxyphenylarsonic acid toxicosis in pigs

Five times the recommended dose of 3-nitro-4-hydroxyphenylarsonic acid (187.5 mg kg-1) induces a pathognomonic clinical syndrome in pigs. The main clinical features are not continually present but are inducible only by exercise. From day 11 on the experimental diet a nervous syndrome was inducible. This manifested as muscle tremors and clonic convulsive episodes. Paraparesis developed by day 22 and paraplegia by day 33. Liver arsenic levels plateaued at 5.4 +/- 1.3 mg kg-1. The experiment confirms field observations that 3-nitro produces a characteristic toxicological syndrome, which is distinct from that of arsanilic acid. It also confirms that 3-nitro has a higher absolute toxicity than arsanilic acid in pigs as well as a lower margin of safety.

Production of ultraviolet-light-induced skin erythema in the hairless rat: a comparison with the haired rat in screening for anti-inflammatory drugs

The onset of this erythema in response to different times of exposure corresponds closely to that in the haired animal. Orally administered phenylbutazone (30 mg/kg) or subcutaneously administered fluocinolone acetonide (10 mg/kg) have an equivalent antierythemic effect on haired and hairless animals. The hairless rat may therefore be an attractive alternative to its haired counterpart in this model since, prior to irradiation, it requires no depilation--which itself may affect subsequent erythema production.

Chronic dermatosis and cutaneous squamous cell carcinoma in the beagle dog

Chronic dermatosis developed in sparsely-haired, lightly pigmented, ventral body skin in 397 of 1 680 beagle dogs by the time the dogs were 5 1/2 years old. Twenty-six of 55 other beagles had developed by 12 years of age. Squamous cells carcinomas developed in the sites of dermatosis in eight of the 397 younger and five of the 26 older beagles. The lesions resembled solar keratosis (solar dermatosis, actinic dermatosis or senile keratosis) in man. They developed under circumstances suggesting that solar radiation is involved in the pathogenesis, as it is in man.

Ataxia, depression, and dermatitis associated with the use of dichlorvos-impregnated collars in the laboratory cat

Ataxia and depression developed in 21 of 50 (42%) laboratory cats wearing flea collars impregnated with 2,2-dichlorovinyl dimethyl phosphate (dichlorvos or DDVP) in a warm dry environment. Five (10%) of the cats died. Whole blood cholinesterase (ChE) activity was significantly (P smaller than 0.001) reduced in all cats and cervical dermatitis occurred in 37 (74%) of them.