A micro-ELISA, using horseradish peroxidase-conjugated anti-canine IgE and polystyrene microtitration wells for detection of allergen-specific IgE in canine serum, was developed. Specificity of anti-canine IgE was confirmed by reversed cutaneous anaphylaxis evaluations, gel-precipitation reactions, immunoelectrophoresis, immunoaffinity chromatography, and heat inactivation. Individual allergen blanks were used to account for variable nonspecific binding among various allergens, and results were normalized using 4 reference sera. Coefficients of variation for intra-assay and interassay variability ranged from 0.77 to 5.66% and 3.15 to 9.83%, respectively. Results observed with wells coated with mixtures of various allergen extracts yielded results approximately equal to results (average) of wells containing individual components. Agreement between ELISA and skin test results ranged from 43 to 64%, depending on allergen used.

In 6 cats, mean +/- SEM baseline plasma concentrations of cortisol, corticotropin, and alpha-melanocyte-stimulating hormone (alpha-MSH) were 87 +/- 16 nmol/L, 73 +/- 14 ng/L, and 129 +/- 12 ng/L, respectively. The cats were subjected to: handling and subsequent skin testing without anesthesia; anesthesia with 50 mg of ketamine HCl and 2.5 mg of diazepam given IV, immediately followed by handling and skin testing; and anesthesia and handling as previously described, but without skin testing. Significant (P < 0.05; multivariate analysis for repeated measures) increase in plasma cortisol, corticotropin, and alpha-MSH concentrations was observed until 20 minutes after the start of the experiments in cats undergoing physical restraint and subsequent skin testing with or without preceding anesthesia. These responses were largely abolished when anesthesia with ketamine and diazepam was only followed by handling. We conclude that, during stress in cats (in contrast to dogs), the pituitary intermediate lobe is activated to secrete alpha-MSH. In addition, the cortisol response after skin testing of cats under anesthesia may be a reasonable explanation for the reported weak skin test reactivity in cats.

Six horses with chronic obstructive pulmonary disease (COPD) and 8 horses with recurrent urticaria were skin tested with 67 extracts from 58 allergens, including pollens, epidermals, cultivated farm plants, dusts, molds, and insects. Reactions were evaluated 3 times over a 24-hour period immediately after the injections. Results were compared with those obtained from 11 clinically normal horses. All horses had positive skin test reactions. Significant difference was evident between horses with COPD and clinically normal horses for only 3.0% of the possible extract reactions, and between horses with urticaria and clinically normal horses for only 4.5% of the possible extract reactions. Horses with COPD or urticaria had greater total percentage of allergen extract reactions than did clinically normal horses. Positive reactions were observed at all 3 evaluation periods, and late-onset reactions were not always preceded by positive reaction at earlier periods. All horses with COPD or urticaria had at least 1 skin test reaction that exceeded the mean +/- 2 SD, as calculated for each of the 67 extracts for the group of clinically normal horses.

To determine the effects of 9 sedative/anesthetic drug protocols on intradermal skin testing, an experimental state of type-I hypersensitivity was created. Intradermal skin tests were performed on 6 dogs, using positive and negative controls and a series of tenfold dilutions of ASC-1 allergen prior to drug administration. Approximately 4 hours later, the dogs were given 1 of the following drugs: acepromazine (low dose and high dose); ketamine hydrochloride with diazepam; thiamylal; oxymorphone; halothane; methoxyflurane; or isoflurane. The intradermal skin test then was repeated, and was scored objectively and subjectively. Objective scores were unaffected by any of the drugs. Subjective scores were affected in that acepromazine decreased wheal size and the induration of the intradermal skin test reaction sites.