Clinical and histological evaluation of immediate and delayed flea antigen intradermal skin test and flea bite sites in normal and flea‐allergic cats

Abstract

Seven cats diagnosed as¯ea allergic by speci®c criteria and seven normal control cats were exposed to¯ea bites in a controlled manner and were given intradermal injections of 1:1000 w/v¯ea antigen. Subjective evaluation of gross lesions and documentation of histological changes at¯ea antigen intradermal skin test (IDST) and¯ea bite sites were performed at 15 min, 24 h and 48 h after IDST or¯ea exposure. Control cats did not develop an immediate gross reaction to either¯ea bites or the intradermal injection of¯ea antigen. All seven¯ea-allergic cats had an immediate gross reaction at the site of IDST with¯ea antigen; ®ve of these cats also developed immediate gross reactions to¯ea bites. Three of seven¯ea-allergic cats developed a gross 24 h and/or 48 h delayed reaction at the¯ea antigen IDST sites. These three and one other cat had both an immediate and delayed gross reaction to¯ea bites. Histological examination of 15 min skin specimens from IDST and¯ea bite sites of¯ea-allergic cats were similar with a mild lymphocytic, histiocytic and mastocytic super®cial perivascular dermatitis. Histological examination of 24 h and 48 h skin specimens from IDST and ea bite sites of¯ea-allergic cats showed that they were often indistinguishable. Histological features of IDST and¯ea bite sites of¯ea-allergic cats at 24 h consisted of a perivascular to diuse predominately eosinophilic dermatitis and mural folliculitis with variable epidermal necrosis and ulceration.

Serological, intradermal and live flea challenge tests in the assessment of hypersensitivity to flea antigens in cats (Felis domesticus)

“…These observations are in accordance with those of Slacek and Opdebeeck (1993) and Lewis et al (1999), who reported that six and seven cats, respectively, with no signs of FAD also failed to react when exposed to live flea challenge. Similarly, Kunkle et al (2003) reported that six flea-naïve queens and 18 of their kittens when aged 9-12 weeks failed to react on live flea challenge.…”

“…These observations support the recent documentation of delayed hypersensitivity responses at the site of fleabites and at the site of intradermal injections of flea allergens in cats (Lewis et al 1999). By contrast, Slacek and Opdebeeck (1993) reported immediate reactivity to flea challenge in five flea allergic cats, but none of these had delayed reactivity at 24 h. In the study of Lewis et al (1999) five out of seven flea allergic cats showed both immediate and delayed reactivity to live flea challenge, and one cat showed only delayed reactivity.…”

Evaluation of three different histamine concentrations in intradermal testing of normal cats and attempted determination of ‘irritant’ threshold concentrations for 48 allergens

“…In another study with seven healthy cats, there were no positive reactions to flea antigen at a test concentration of 1:1000 w/v (Greer Laboratories, Inc.). 21 Both studies used a histamine concentration of 0.01 mg mL −1 .…”

“…Forty-eight commercially available aqueous allergens were used for IDT ( Table 1). The allergens included eight grasses (1)(2)(3)(4)(5)(6)(7)(8), nine weeds (9-17), nine trees (18)(19)(20)(21)(22)(23)(24)(25)(26), eight moulds (27-34), three mites (35-37), five epithelia (38-42), and six insects (43-48). All allergens were obtained from Greer Laboratories, Inc., with the exception of the Tyrophagus putrescentiae test solution (storage mite), which was purchased from Center Laboratories (Port Washington, NY, USA).…”

Feline flea allergy dermatitis

“…It may be defined as a hypersensitivity state produced by the injection of antigenic material from the salivary glands of fleas (Dryden and Rust, 1994). Flea saliva allergen-specific IgE (Colombini et al 2001;Kunkle et al 2003) and both Type 1immediate (IH) and Type IV -delayed (DH) hypersensitivity reactions to flea bites and intradermal injection of flea antigens have been observed (Lewis et al 1999;Kunkle et al 2003). However, the role of IH reactions in the development of FAD is not clear as these occur in clinically normal cats exposed to fleas (Moriello and McMurdy, 1989) and studies of experimentally induced FAD (Colombini et al 2001;Kunkle et al 2003) have concluded that the clinical signs of FAD were not correlated with the occurrence of IH reactions or the detection of flea antigen-specific IgE.…”