FC-53 Serologic allergy testing in horses with insect hypersensitivity

The usefulness of the intradermal test (IDT) and the serological allergy test (SAT) for detecting antigen-specific IgE in allergic cats has not yet been established. In this study, we compared the results of IDT with those of SAT and evaluated the clinical usefulness of the two tests for detecting possible allergens in allergic cats. IDT and SAT using eight antigens were performed on 22 cats with intense pruritus after excluding ectoparasites and performing diet elimination tests. Approximately 50% of the cats reacted to at least one allergen by either IDT or SAT, and 36.4% of the cats reacted on both IDT and SAT. In contrast, seven healthy cats did not show any reactions on IDT or SAT. The most commonly detected allergen in both tests was house dust mites (IDT, 36.4%; SAT, 40.9%). Five cats reacted to one allergen and the others reacted to more than one allergen with IDT. Three cats reacted to one allergen with SAT. The following percentage agreement between the results of the two tests was calculated: house dust mites (86.4%), cat fleas (63.6%), grass mix (86.4%), common mugwort (81.8%), cat epithelia (90.9%), ragweed (86.4%), Japanese cedar (90.9%), and plantain (81.8%). The overall mean percentage agreement was 83.5%. In summary, the present study showed good agreement between IDT and SAT for cats, and SAT may be more sensitive than IDT, but less specific for detecting sensitized allergens.
Funding: Self-funded.     

FC‐51 Comparison of intradermal test and antigen‐specific IgE test in 22 cases of feline allergic dermatitis

The usefulness of the intradermal test (IDT) and the serological allergy test (SAT) for detecting antigen‐specific IgE in allergic cats has not yet been established. In this study, we compared the results of IDT with those of SAT and evaluated the clinical usefulness of the two tests for detecting possible allergens in allergic cats. IDT and SAT using eight antigens were performed on 22 cats with intense pruritus after excluding ectoparasites and performing diet elimination tests. Approximately 50% of the cats reacted to at least one allergen by either IDT or SAT, and 36.4% of the cats reacted on both IDT and SAT. In contrast, seven healthy cats did not show any reactions on IDT or SAT. The most commonly detected allergen in both tests was house dust mites (IDT, 36.4%; SAT, 40.9%). Five cats reacted to one allergen and the others reacted to more than one allergen with IDT. Three cats reacted to one allergen with SAT. The following percentage agreement between the results of the two tests was calculated: house dust mites (86.4%), cat fleas (63.6%), grass mix (86.4%), common mugwort (81.8%), cat epithelia (90.9%), ragweed (86.4%), Japanese cedar (90.9%), and plantain (81.8%). The overall mean percentage agreement was 83.5%. In summary, the present study showed good agreement between IDT and SAT for cats, and SAT may be more sensitive than IDT, but less specific for detecting sensitized allergens. Funding: Self‐funded.     

Intradermal and serological testing for mites in healthy beagle dogs

Background – Intradermal testing (IDT) is widely used in veterinary medicine to select allergens for immunotherapy. The recommended concentration for mites is 250 protein nitrogen units (PNU)/mL. It is not known whether healthy dogs responding to this concentration have asymptomatic sensitization or irritation. Furthermore, interbatch and intersupplier variability of allergens has not been fully addressed. Hypothesis/Objectives – The incidence of positive IDTs in healthy beagles was recorded and the value of combining these results with serology to differentiate between asymptomatic sensitization and irritancy evaluated. Additionally, the interbatch and intersupplier variability of allergens was assessed. Animals – Seventeen healthy laboratory beagles with no history or clinical signs of canine atopic dermatitis were used. Methods – Intradermal tests were performed with four mite allergens from two suppliers (varying batches). An initial IDT at 250 PNU/mL was used to determine whether decreasing or increasing test concentrations were used in the subsequent titration IDTs. Additionally, two IgE ELISA tests from different manufacturers were performed. Results – Seven of 17 dogs showed IDT reactions at 250 PNU/mL. There were highly significant allergen interbatch and significant intersupplier correlations and agreement. The associations between the IDT reactions and the IgE serologies statistically identified two groups of dogs: one with positive serology and IDT reactions at 250 PNU/mL; and another with negative serology and IDT reactions. Conclusions and clinical importance – Our results suggest that dogs that have IDT reactions and positive serology are asymptomatically sensitized, while dogs that react at higher allergen concentrations, but have negative serology, do so as a result of irritant reactions.     

Comparison of intradermal and serum testing for allergen-specific IgE using a Fcepsilon RIalpha-based assay in atopic dogs in the UK

Atopic dermatitis in dogs is a common allergic skin disease that affects substantial numbers of dogs in the UK. The purpose of this study was to compare the results of an intradermal test (IDT) and an in vitro test in a large cohort of dogs. Dogs were intradermal tested with Greer allergens (Greer Labs Inc, Lenoir, NC, USA) using standard techniques. At the same time blood samples were drawn and submitted for evaluation by ELISA using the ALLERCEPT Definitive Allergen Panels for allergen-specific IgE, a commercial assay that uses a biotinylated recombinant extracellular domain of the high affinity Fc-epsilon receptor alpha chain protein (Fcepsilon RIalpha). The allergens used in the two tests included grass, tree and weed pollens, moulds, flea saliva/whole flea extract and house dust mite species. The optical density readings from the ELISA for each allergen were compared with the results of the IDT for 265 dogs. The prevalence of positive reactions in the ELISA was equal to or greater than the results of the IDT in the case of almost all of the allergens, but two notable exceptions were the house dust mites Dermatophagoides farinae and Dermatophagoides pteronyssinus. These two allergens were the most common positive reactions by IDT (prevalence D. farinae 78.9%, D. pteronyssinus 66.4%). The results of the two tests were significantly different (McNemar's test, P<0.05) for 16 of the 22 allergens. The sensitivities of the ELISA compared to the IDT (where there were more than 3 dogs with positive reactions in both tests) varied between 19.3 and 77.1% (D. pteronyssinus 19.3% and D. farinae 67.9%) and the specificities varied between 64.2 and 96.6% (D. pteronyssinus 96.6% and D. farinae 89.3%).     

Pilot investigation of a model for canine atopic dermatitis: environmental house dust mite challenge of high-IgE-producing beagles, mite hypersensitive dogs with atopic dermatitis and normal dogs

Although canine atopic dermatitis (cAD) is common, few models are available. The aim of this study was to evaluate high-IgE beagles epicutaneously sensitized to house dust mite (HDM) as a possible model for cAD. Six high-IgE beagles were environmentally challenged with HDM using various doses and protocols. Similar challenge protocols were used in positive and negative control dogs: three dogs with naturally occurring cAD and positive intradermal skin test (IDT) to HDM and three normal dogs without history of skin disease and negative IDT to HDM. All high-IgE beagles and all atopic dogs developed severe cutaneous lesions and pruritus after challenge. Lesions were erythematous papules and macules in contact areas such as face, ears, ventral abdomen, groin, axillae and feet. They were first visible after 6 h and increased in severity over time. No normal dog developed pruritus or lesions. Biopsies of representative lesions in the high-IgE beagles were taken for histopathology and immunohistochemistry. There was superficial perivascular dermatitis with mononuclear infiltrates and spongiosis. Lymphocytes and eosinophils accumulated in small epidermal micro-abscesses with hyperplasia of epidermal IgE-bearing dendritic cells. These findings suggest that this colony of high-IgE beagles develops a dermatitis that clinically, histopathologically and immunologically resembles the naturally occurring canine disease. It is also concluded that this modality of challenge is not irritating to normal dogs but induces flare-ups in hypersensitive atopic dogs.     

Results of intradermal tests in horses without atopy and horses with chronic obstructive pulmonary disease

OBJECTIVE: To compare results of intradermal tests (IDT), conducted using environmental allergens, in horses without atopy and horses with chronic obstructive pulmonary disease (COPD). ANIMALS: 38 horses (22 horses without atopy and 16 horses with COPD). PROCEDURE: All horses were examined (physical examination, hematologic examination, serum biochemical analyses, examination of bronchoalveolar lavage fluid). An IDT was conducted, using a full panel of 73 allergens consisting of grasses, weeds, trees, molds, and insects. Results of the IDT were evaluated 30 minutes and 4, 6, and 24 hours after injection of allergens. Horses without atopy were euthanatized, and gross and histologic changes of lung parenchyma were assessed. RESULTS: Horses without atopy had a greater number of positive immediate and late-phase reactions than did horses with COPD. Horses with COPD did not have a significantly greater number of positive reactions than horses without atopy at any time period for any allergen group (grasses, weeds, trees, molds, and insects). CONCLUSIONS AND CLINICAL RELEVANCE: Positive results of IDT document allergen-specific hypersensitivity but do not necessarily distinguish clinically relevant reactions from subclinical reactivity in horses with COPD. Interpreting the clinical relevance of results of IDT requires a thorough knowledge of the medical history, physical examination findings, and environment of each animal.     

Results of intradermal testing for the investigation of atopic dermatitis and recurrent urticaria in 50 horses in the south of England

Atopic dermatitis (AD) and recurrent urticaria (RU) are common immune‐mediated conditions of horses and ponies associated with high morbidity. Effective pharmacological treatment options are limited but identification of the causal allergens allows avoidance strategies and immunotherapy regimens to be employed. Intradermal testing (IDT) is the most widely accepted means of identifying the relevant allergens but there are no published reports of this technique being used in the UK for the investigation of dermatological disease. This study presents the results of testing with a varied panel of allergens in 50 horses with dermatological disease living in the south of England. Intradermal testing was performed in horses presented to The Liphook Equine Hospital for further investigation of AD or RU between June 2002 and March 2009. Allergen selection was based upon availability, results of previous studies, pollen charts and the likelihood of allergens being prevalent in the stable or pasture environment in the south of England. Injection sites were evaluated at 1 h (immediate phase), 4 h (late phase) and 24 h (delayed phase) and skin responses compared to the response generated by the positive control (histamine) at 1 h. Total numbers of positive reactions and numbers of positive reactions to specific allergens were similar in horses with atopic dermatitis and those with urticaria (P = 0.39). There was a statistically significant difference in the number of reactions observed at different time points, with more positive reactions occurring at 1 h than 24 h (P<0.001), and at 4 h than 24 h (P<0.001). Reading the test at 24 h rarely provides additional information. Reaction patterns were similar to those of previous studies performed in other countries with large numbers of positive reactions reported to mites, dusts and insects. Positive reactions were also common to allergens not previously identified as irritants or common allergens in equids; nettle, daisy, dandelion, horse chestnut, cat, cattle, sheep and pigeon. These allergens may be important causes of allergic dermatitis in equids in the UK; however, further studies should be performed in both normal horses and horses with allergic dermatitis to investigate irritant thresholds and validate these findings. Intradermal testing may be shortened from the conventional 24 h to 4 h without significantly affecting the results of the test.     

Investigation on the effects of ciclosporin (Atopica) on intradermal test reactivity and allergen‐specific immunoglobulin (IgE) serology in atopic dogs

The ability to use ciclosporin (Atopica^®: Novartis Animal Health, Greensboro, NC, USA) prior to intradermal testing (IDT) would help avoid exacerbation of clinical disease that can be associated with drug withdrawal. This study evaluated the effects of 30 days of administration of ciclosporin at a dose of 5 mg/kg once daily on IDT reactivity (immediate phase reactions) in a group of dogs with atopic dermatitis (AD) with initial positive IDT reactions. 16 dogs diagnosed with AD were included in the study. Eight dogs (group A) were treated with ciclosporin orally at 5 mg/kg once daily for 30 days. Eight dogs (group P) were treated with a placebo orally once daily for 30 days. IDT was performed at day 0 and day 30 on all dogs enrolled using a standardized panel of 45 aqueous allergens (Greer Laboratories, Lenoir, NC, USA) appropriate to our geographical region. IDT reactivity was assessed by both subjective and objective methods at 15 min post‐intradermal injection. Serum for allergen‐specific immunoglobulin (IgE) serology was obtained at day 0 and day 30. The study was designed as a double‐blinded, placebo‐controlled, cross‐over study. Data were analysed using a split‐plot analysis of variance with the grouping factor of treatment and the repeat factor of time (SAS System for Windows). At week 4, ciclosporin did not have a statistically significant effect on IDT reactivity or serology results. It therefore appears that, no withdrawal is recommended to evaluate immediate phase reactions.     

Comparison of subjective and objective intradermal allergy test scoring methods in dogs with atopic dermatitis

An intradermal allergy test (IDT) is an important diagnostic tool for identifying offending allergens in canine atopic dermatitis. No standardized method of scoring an IDT has been described. The purpose of this study was to determine whether there is a correlation between a conventional, subjective IDT scoring method based on perceived wheal diameter, erythema, and turgor (0-4+) and an objective scoring method based on measuring wheal diameter alone. Thirty-four atopic dogs were skin tested with 68 different allergens. All skin tests were performed according to standard procedures, and any IDT score ≥2+ was considered clinically significant. When the subjective IDT scores were compared with the objective IDT scores in all dogs, there was a moderate level of correlation overall (r=0.457; P <0.0001). The highest level of agreement between subjective and objective scores was noted with the reactions assigned subjective scores of "0" and "2+." Overall, there was a slight level of agreement between subjective and objective scores based on clinical significance (i.e., subjective scores ≥2+; κ=0.20; P <0.0001). In conclusion, the authors believe that the objective scoring method used in this study may provide a point of reference for inexperienced individuals (dermatology residents, veterinarians, technicians) when learning to grade an IDT.     

Results of intradermal tests in horses without atopy and horses with atopic dermatitis or recurrent urticaria.

OBJECTIVE: To compare results of intradermal tests (IDT) for environmental allergens at 30 minutes and 4, 6, and 24 hours after injection in horses without atopy and horses with atopic dermatitis (AD) or recurrent urticaria (RU). ANIMALS: 22 horses without atopy, 10 horses with RU, and 7 horses with AD. PROCEDURE: In all horses, medical history was obtained, and results of physical examination, hematologic examination, serum biochemical analyses, examination of bronchoalveolar lavage fluid, and IDT with 73 allergens were examined. RESULTS: Horses with AD or RU had a significantly greater mean number of positive reactions for IDT, compared with horses without atopy. Horses with AD had a significantly greater number of positive reactions than horses without atopy in every allergen group at all time periods, except for molds at 4 and 24 hours. Horses with RU had a significantly greater number of positive reactions than horses without atopy in every allergen group, except for molds at 30 minutes and 4 and 6 hours, trees at 4 and 6 hours, and grasses at 4 hours. CONCLUSIONS AND CLINICAL RELEVANCE: A significantly greater number of positive reactions for IDT in horses with AD or RU, compared with horses without atopy, provides evidence of type-I IgE-mediated hypersensitivity for these diseases. Evaluation of results of IDT performed in horses with AD or RU is useful in determining specific allergens for the formulation of immunotherapy along with providing identification of allergens that could be useful when creating avoidance strategies.     

准噶尔双峰驼驼乳理化指标分析

试验旨在系统地分析不同的季节、泌乳阶段、产地和奶站驼乳理化指标的差异。收集了某公司2015年收购生驼乳质量检测数据18 372条,通过四分位数检验法确定了各指标的变化范围,对处理后的数据进行最小二乘方差分析。结果显示,不同的产地、奶站、泌乳阶段和季节驼乳的相对密度、脂肪、非脂乳固体、乳蛋白、乳糖、冰点、灰分有极显著差异（P<0.01）。因此,双峰驼繁殖和分娩具有较强的周期性和季节性,导致在一年内的不同季节和月份驼乳的产量和理化指标有较大的区别,同时驼乳生产企业可以通过此类分析获知不同的产地、奶站、泌乳阶段和季节的驼乳质量情况,驼乳产品的质量取决于生驼乳的理化指标和卫生状况。     

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.     

Canine atopic dermatitis: a retrospective study of 169 cases examined at the University of California, Davis, 1992-1998. Part II. Response to hyposensitization

One hundred and sixty-nine dogs were diagnosed with atopic dermatitis, and treated with hyposensitization for at least 1 year based on the results of either intradermal skin tests (IDST) or enzyme-linked immunosorbant serum assays (ELISA). Excellent (i.e. hyposensitization alone controlled clinical signs), good (> 50% improvement), moderate (< 50% improvement) and no (clinical signs were unchanged) responses were seen in 19.5, 32.5, 20.1 and 27.8%, respectively. Age of onset, age when treatment was initiated or the duration of clinical signs had no influence on response to hyposensitization. Dogs having concurrent flea allergy dermatitis were statistically more likely to respond better than dogs with concurrent food allergies. Although not statistically significant, there were trends for Golden Retriever and male dogs to respond better than other breeds and female dogs, respectively. Dogs having more than 21 positive reactions in allergy tests and treated with more than 21 allergens had lower response scores, and a longer time course before achieving beneficial response. Lower response scores were seen in dogs having positive reactions to cultivated plants, grasses, trees or insects. There was no difference in response to hyposensitization whether based on IDST or ELISA results.     

Analysis of Physicochemical Indexes of Junggar Bactrian Camel Milk

This study was aimed to systematically analyze the difference of camel milk physicochemical index of different seasons,stage of lactation,production sites and milk station.Collected 18 372 testing data about raw camel milk quality which were purchased by a company in 2015.The range of each index was determined by the four point test method,SAS 8.1 least squares analysis of variance were performed on the processed data.The results showed that different area,milk stations,stage of lactation and season effect of camel milk had extremely significant influence (P<0.01) on the relative density,fat,non fat milk solid,milk protein,lactose,freezing point and ash.Therefore,the reproduction and childbirth of Bactrian camel had strong periodicity and seasonality,lead to a larger difference in camel milk yield and physicochemical index of different seasons and months within a year,at the same time,camel milk producers could learn about the quality of camel milk situation of different production sites,milk station,stage of lactation and season using such analysis methods,the quality of camel milk product was determines by the physical and chemical indicators and health conditions of the raw camel milk.     

Evaluation of an in vitro sulphidoleukotriene release test for diagnosis of insect bite hypersensitivity in horses

REASONS FOR PERFORMING STUDY: Insect bite hypersensitivity (IBH) is an IgE-mediated allergic dermatitis caused by bites of Culicoides and Simulium species, and improved means of diagnosis are required. OBJECTIVES: The cellular antigen simulation test (CAST) with C. nubeculosus and S. vittatum extracts was assessed in a population of IBH-affected and healthy horses. Variations in test results over a one year period and possible cross-reactivity between different insect extracts was studied. METHODS: A total of 314 mature horses were studied using the CAST. Influence of severity of clinical signs, gender and age were evaluated, and 32 horses were tested repeatedly over one year. The kappa reliability test was used to assess agreement of the test results with different insect extracts. RESULTS: Horses with IBH had significantly higher sLT release than controls with C. nubeculosus and S. vittatum. The highest diagnostic sensitivity and specificity levels were attained when using adult C. nubeculosus extracts with the CAST (78% and 97%, respectively), suggesting that most horses with IBH are sensitised against Culicoides allergens. A proportion of IBH-affected horses was found to be sensitised to allergens of Simulium spp. in addition to those of C. nubeculosus. The CAST with C. nubeculosus had positive and negative predictive values > or = 80% for a true prevalence of IBH of 12-52%. In the follow-up study, the proportion of IBH-affected horses with a positive test result ranged from 90% in November to 68% in March. Severity of clinical signs or age did not influence test results significantly. However, IBH-affected males achieved significantly more positive test results than IBH-affected females. CONCLUSIONS: The CAST with adult C. nubeculosus has high specificity and good sensitivity for diagnosis of IBH. Horses with IBH are mainly sensitised to Culicoides allergens, and some horses are additionally also sensitised to allergens in Simulium spp. POTENTIAL RELEVANCE: The CAST is likely to be a useful test for diagnosis of IBH, even allowing the identification of IBH-affected but asymptomatic horses. This test may also help in further characterisation of allergens involved in this condition.     

Familial allergic rhinitis in cattle

A group of Angus X Holstein cattle were determined to have allergic rhinitis. Clinical signs included nasal discharge, tearing, sneezing, and nasal pruritus. The diagnosis was made on the basis of intradermal skin testing of affected and clinically normal cattle. The affected cattle had positive test results to various tree, grass, weed, and mold allergens. The clinical signs and seasonal occurrence were similar to those features for allergic rhinitis in man. Breeding data indicated an inherited mode of transmission, although only females were affected.     

Hepatotoxicosis in dogs consuming a diet of camel meat contaminated with indospicine

Background Four dogs presented with clinical signs of severe hepatic disease after consuming a commercial camel meat diet. Methods Laboratory investigation revealed evidence of severe liver disease, including markedly increased serum alanine aminotransferase (ALT) activity and total bilirubin concentration, and prolonged clotting times. Results Two dogs deteriorated despite supportive therapy and were euthanased. Histologically, both livers appeared similar, with the main lesion being extensive periacinar necrosis and haemorrhage. Indospicine, a toxic amino acid of plant origin, was detected in the serum and/or plasma from all four dogs, as well as in tissues of a dog that was necropsied and in a sample of the camel meat fed to this animal. Serum biochemistry tests using blood samples collected from 15 additional dogs identified as having eaten the diet detected indospicine was in the serum of 14 and 3 had increased ALT activity. One of the latter dogs subsequently developed clinical signs of severe liver disease and was euthanased. Conclusion To the authors' knowledge, this is the first published report of the detection of indospicine residues in camel meat and the occurrence of severe, sometimes fatal, liver disease in dogs that consumed this contaminated meat.     

Diagnosis of erythema multiforme associated with thymoma in a dog and treated with thymectomy

A 7 yr old Labrador retriever initially presented for severe halitosis, mild ptylism, and depigmentation of the nasal planum. Erythema multiforme was diagnosed based on clinical signs and dermatopathology. Treatment was initiated but the condition did not resolve. Six months later, the dog was diagnosed with a mediastinal mass. Trucut biopsy was performed and histopathologic diagnosis was consistent with a thymoma. A median sternotomy was performed, the thymoma was excised, and the dog recovered well. Four months postoperatively, there were no longer any obvious erythema multiforme lesions and the skin condition was controlled without medication. Erythema multiforme may be a paraneoplastic disorder associated with thymoma in the dog, similar to thymoma-associated exfoliative dermatitis in the cat. Clinical signs of erythema multiforme may warrant performing thoracic radiographs or thoracic CT to rule out thymoma as an underlying cause.     

Food hypersensitivity in cats: 14 cases (1982-1987)

Food hypersensitivity was diagnosed in 14 cats. Clinical signs varied; pruritus (100%), alopecia (64%), and papules (21%) were the ones most commonly observed. Pruritus was localized principally to the head or to the neck or ear region in 42% of the cats. Diagnosis was made on the basis of resolution of clinical signs when cats were fed a restricted ("hypoallergenic") diet, and recurrence of signs when cats were fed their original diet or other food. The most common allergens (on the basis of dietary challenge exposure) were fish and dairy products. Age or sex predilection was not observed, and 9 (64%) of the cats were domestic shorthairs. Owners could not relate the onset of clinical signs with a recent change in diet. Three cats had concurrent flea bite, inhalant, or flea collar hypersensitivity.     

Determination of irritant threshold concentrations to weeds,trees and grasses through serial dilutions in intradermal testing on healthy clinically nonallergic dogs

Irritant threshold concentration (ITC) for intradermal testing (IDT) was determined in 31 healthy, clinically nonallergic dogs. Twenty‐three allergens were tested at five variable concentrations ranging from 1000 to 8000 PNU/mL. To distinguish irritant reactions from subclinical IgE‐mediated hypersensitivities, serum allergy testing was performed. ITCs were determined by evaluating the lowest concentration to which no dogs (0% cut‐off) and to which at least 10% of dogs (≥10% cut‐off) reacted. ITCs at the 0% cut‐off were: 1000 PNU/mL (Johnson grass), 2000 PNU/mL (Ash, Lamb’s Quarter and Bermuda), 3000 PNU/mL (Bahia, Rye, Pig Weed and Virginia Oak), 4000 PNU/mL (Marsh Elder and Maple), 5000 PNU/mL (Sorrel sheep) and 7000 PNU/mL (Cocklebur and Black Willow). ITC for Dog Fennel, Box Elder and Red Cedar was <1000 PNU/mL. ITCs at the ≥10% cut‐off were: 2500 PNU/mL (Johnson), 3000 PNU/mL (Box Elder), 5000 PNU/mL (Bahia), 6000 PNU/mL (Pigweed and Marsh Elder) and 8000 PNU/mL (Virginia Oak and Black Willow). For all other allergens, the ITC was >8000 PNU/mL and could not be determined. No significant agreement between positive values was found for the same allergen on IDT and serum allergy testing for each dog suggesting reactions caused by the determined ITCs are less likely subclinical IgE‐mediated reactions. These results suggest that ITCs may vary, also they may be very high for the allergens tested and that higher test concentrations may be used for IDT for the tested allergens without inducing an irritant reaction. Further studies are needed to evaluate the benefit of higher IDT concentrations in atopic dogs.