Efficacy of AHR-13268, an antiallergenic compound, in the management of pruritus caused by atopic disease in dogs.

Twenty-nine pruritic, atopic dogs were entered into a double-blind, placebo-controlled, crossover study to evaluate the efficacy of an investigational antiallergenic compound, AHR-13268. Fourteen dogs were evaluated by a veterinary dermatologist (at intervals) and the owner (daily). Fifteen dogs were evaluated only by the owner. The mean (+/- SE) owner scores for pruritus, erythema, and lesions with placebo treatment (higher score = worse signs) were 3.24 (+/- 0.12), 2.73 (+/- 0.12), and 2.61 (+/- 0.09), respectively. With drug treatment, the corresponding scores were 2.89 (+/- 0.12), 2.50 (+/- 0.12), and 2.25 (+/- 0.09). Scores for pruritus and lesions (but not erythema) were significantly better with drug treatment than with placebo treatment. Investigator scores showed similar trends, but the differences were not great enough to be statistically significant. Overall, 11/29 (38%) owners reported their dogs had moderate or better improvement from drug capsules, and 4/29 dogs (14%) improved on placebo capsules. A variety of adverse effects were reported following both drug (9/29 dogs) and placebo (8/29 dogs) capsule administration, but were mild and well tolerated. Results of this study indicate that AHR-13268 has potential for empiric treatment of allergic inhalant dermatitis in some dogs.     

Evaluation of serum obtained from atopic dogs with dermatitis attributable to Malassezia pachydermatis for passive transfer of immediate hypersensitivity to that organism

OBJECTIVE: To determine the functionality of canine anti-Malassezia IgE via the passive transfer of immediate hypersensitivity localized to the skin (ie, cutaneous anaphylaxis) from atopic dogs with dermatitis attributable to overgrowth of Malassezia pachydermatis (Malassezia dermatitis [MD]) to healthy recipient dogs by use of the Prausnitz-Küstner (P-K) technique. ANIMALS: 7 clinically normal dogs, 32 atopic dogs with MD, serum from 11 atopic dogs with MD, and 3 healthy dogs without prior sensitization to M pachydermatis. PROCEDURE: Serum from atopic dogs with MD was used for P-K tests in 3 clinically normal recipient dogs. Serial dilutions of untreated, heat-inactivated, IgE-absorbed, and bovine serum albumin (BSA)-absorbed (control) aliquots of serum were injected ID in triplicate for dermal sensitization. Twenty-four, 48, and 72 hours later, a crude extract of M pachydermatis was injected ID into the sites used for sensitization injections, and immediate hypersensitivity reactions were graded on a 4-point scale. RESULTS: Untreated serum caused P-K reactivity beginning 24 hours after passive sensitization and persisting through 72 hours (titers, 1:32 to 1:64). Heat inactivation and IgE-absorption of serum eliminated P-K reactivity, whereas treatment of serum with BSA did not. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of P-K test results supports the passive transfer of cutaneous anaphylaxis by anti-Malassezia IgE and indicates it is functional in type-1 hypersensitivity reactions of atopic dogs with MD. Reduction or blockade of anti-Malassezia IgE in atopic dogs with MD may provide better clinical control of the disease.     

Effect of vaccination on serum concentrations of total and antigen-specific immunoglobulin E in dogs

OBJECTIVE: To determine the effect of vaccination on serum concentrations of total and antigen-specific IgE in dogs. ANIMALS: 20 female Beagles. PROCEDURE: Groups of 5 dogs each were vaccinated repeatedly between 8 weeks and 4 years of age with a multivalent and rabies vaccine, a multivalent vaccine only, or a rabies vaccine only. A fourth group of 5 dogs served as unvaccinated controls. Serum concentrations of total immunoglobulins and antigen-specific IgE were determined following vaccination. RESULTS:-The multivalent vaccine had little effect on serum total IgE concentrations. The concentration of IgE increased slightly following vaccination for rabies at 16 weeks and 1 year of age and increased greatly after vaccination at 2 and 3 years of age in most dogs, with a distinct variation between individual dogs. Vaccination had no effect on serum concentrations of IgA, IgG, and IgM as measured at 2 and 3 years of age. The rabies vaccine contained aluminum adjuvant in contrast to the multivalent vaccine. An increase of IgE that was reactive with vaccine antigens, including bovine serum albumin and bovine fibronectin, was detected in some of the dogs vaccinated for rabies. There was no significant correlation between serum concentrations of total IgE and antigen-specific IgE following vaccination. Serum total IgE concentration rapidly returned to preimmunization concentrations in most dogs, but high concentrations of antigen-specific IgE persisted. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination of dogs for rabies increases serum concentrations of total IgE and induces IgE specific for vaccine antigens, including tissue culture residues. Vaccination history should be considered in the interpretation of serum total IgE concentrations.     

Safety and immunologic effects after inoculation of inactivated and combined live-inactivated dermatophytosis vaccines in cats

OBJECTIVE: To determine antidermatophyte immunologic effects of an experimental combined live-inactivated dermatophytosis vaccine (CLIDV) and a commercial inactivated dermatophytosis vaccine (IDV) in cats and to evaluate adverse effects associated with administration of these vaccines. ANIMALS: 20 healthy juvenile domestic shorthair cats. PROCEDURE: Cats were injected with 2 doses of CLIDV at the standard dosage or 1 dose of CLIDV at 10 times the standard dosage; IDV was administered at the manufacturer-recommended dosage. Cats were observed for illness and reactions at inoculation sites. Periodically, samples were obtained for fungal culture, lymphocyte blastogenesis test (LBT) as an indicator of cell-mediated immunity against dermatophyte antigens, and antidermatophyte IgG titers. Following vaccination, cats were challenge-exposed by topical application of Microsporum canis macroconidia and examined weekly for clinical signs of dermatophytosis. RESULTS: of 10 cats given CLIDV developed focal crusts at the injection site that resolved without treatment; these were areas of dermatophyte infection with the vaccine strain. Antidermatophyte IgG titers increased significantly with all vaccination protocols. Cellular immunity against M canis increased slightly and variably during the vaccination period and did not differ significantly between vaccinated and control cats. All cats developed dermatophyte infection after challenge exposure. Vaccination with CLIDV or IDV was associated with slightly reduced severity of initial infection. CONCLUSIONS AND CLINICAL RELEVANCE: Noculation with IDV or CLIDV did not provide prophylactic immunity against topical challenge exposure with M canis. Inoculation with either vaccine did not provide a more rapid cure of an established infection.     

Allergen-specific IgG antibodies in cats with allergic skin disease

An enzyme-linked immunosorbent assay was developed for quantifying feline serum allergen-specific IgG directed against selected house dust, pollen and flea allergens. The assay was used to compare allergen-specific IgG concentrations in sera from healthy cats, cats with non-dermatologic illness, confirmed allergic cats and undiagnosed pruritic cats. Our results demonstrate that cats with confirmed allergic skin disease have significantly more IgG directed against house dust, flea and ryegrass allergens than other cat groups examined. These results support the theory that cats with allergic skin disease have an underlying T_H2 lymphocyte response that directs production of both allergen-specific IgG and IgE.     

Prospective study of bacterial overgrowth syndrome in eight dogs

Eight dogs with cutaneous lesions, clinical signs and cytological findings compatible with bacterial overgrowth syndrome were compared with four healthy dogs. The affected dogs were treated for 28 days with 30 mg/kg/day cephalexin. The results showed that the syndrome was a superficial cutaneous disorder characterised by marked pruritus, greasy seborrhoea, offensive odour, erythema, lichenification, hyperpigmentation, excoriations and alopecia involving principally the ventral aspect of the body, but no papules, pustules, epidermal collarettes or crusts; it was caused by overgrowths of Staphylococcus intermedius all over the body surface. Histopathological findings included a superficial, perivascular, hyperplastic and spongiotic dermatitis with a mixed inflammatory infiltrate, but no lesions suggestive of a true pyoderma. In the affected dogs, anti-staphylococcal immunoglobulin G levels were high, but anti-staphylococcal immunoglobulin E levels were low, suggesting that staphylococcal hypersensitivity is not the underlying pathogenic process. The antibiotic treatment improved the condition of all the dogs, but five of the eight had an underlying allergic skin disease.     

Serum immunoglobulin E concentrations in West Highland White Terrier puppies do not predict development of atopic dermatitis

Sera from 154 West Highland White Terrier puppies between 6 and 12 weeks of age were assayed for total IgE using a sandwich ELISA method. Development of clinical signs of atopic dermatitis in these dogs was monitored by use of an annual owner questionnaire, until the dog reached 3 years of age. Of 114 evaluated dogs, skin disease severe enough to warrant veterinary examination was reported in 52 (46%) during the three study years. A diagnosis of atopic dermatitis was made by the attending veterinarian in 28 dogs (25%). Certain litters had an especially high prevalence of apparently atopic dogs, consistent with the genetic predisposition towards atopy in this breed, but clear evidence of consistent heritability was not present. The median IgE concentration in 154 puppies at 6–12 weeks of age was 0.9 units mL⁻¹, with a skewed distribution. Significant ( P < 0.01) variation in serum IgE concentrations was observed between litters, with median serum IgE concentrations for a litter ranging from 0 to 27.7 units mL⁻¹. The median serum IgE concentration in puppies that later developed clinical signs of atopic dermatitis was not significantly different from that of puppies that remained healthy. There were no apparent correlations or significant differences found between serum IgE concentration as a puppy, parental history of skin disease, and subsequent emergence of clinical signs of atopic dermatitis. We conclude that early total serum IgE determinations seem to have little usefulness in predicting the later onset of atopic dermatitis in this breed.