Serum Immunoglobulin E Measurements and Clinical Response to Allergen-Specific Immunotherapy (ASIT) in Asian Elephants (Elephas maximus)
Baseline immunoglobulin E levels in elephant species are currently limited, and allergies are infrequently diagnosed. In this study, serum samples from three African (Loxodonta africana) and eight Asian (Elephas maximus) elephants were submitted for measurement of allergen-specific immunoglobulin E (IgE) for 91 environmental and/or 29 food allergens. High-affinity IgE Allercept analysis was performed.2 Two animals with increased IgE levels and exhibiting clinical signs were treated with allergen-specific immunotherapy (ASIT).
Case 1: One female elephant exhibited severe pruritus from April to August and a reluctance to exit the barn for these months for approximately 3 y prior to initial IgE measurement. The animal exhibited elevated IgE levels ranging from 11 to 128 HERBU, with standard of measurement based on degree of fluorescence. Positivity was reported to 18.6% of grass, weed, and tree species and insect hypersensitivity to three species: Culicoides, deer flies and horse flies. In addition to implementing environmental controls, the elephant was treated with oral antihistamines and weekly ASIT beginning 06/2015. ASIT injections were administered per manufacturer guidelines (HESKA, Loveland, CO), in increasing concentration, quantity, and frequency until a maintenance dose was reached. The elephant receives 1.5 ml/week from April to August, in combination with antihistamines and 1 ml every 2 week without antihistamines for the remainder of the year. The animal’s SCORAD indices decreased from baseline progressively each spring, with a 15% reduction in 2015 and a 44% reduction in 2016.1 Less severe to no symptoms were exhibited during fall and winter.
Case 2: One female elephant with mild, intermittent gastrointestinal discomfort was found to have significantly elevated IgE to 85.7% of environmental allergens tested, with IgE levels greater than 600 for the majority of grasses, weeds, trees, mites, and insects tested. The elephant displayed an abnormal hypersensitivity response to 24/29 foodstuffs. A major dietary exclusion trial was initiated. Concurrently, oral ASIT was initiated in 08/2016 and was administered at 1 ml BID sublingually. It is likely that total allergen load contributed to a summation effect, increasing the overall severity of symptoms, which included cuticle rubbing, inconsistent consumption of routine foodstuffs, and chronic, seasonal urticaria with variable sized wheals. The SCORAD indices have decreased 18% from baseline in the past year.1 Management of the animal’s diet has continued to prove challenging and is a work in progress. Accuracy and/or predictability of in vitro serum testing for elephant atopic dermatitis and hypersensitivity response to normal foodstuffs cannot be determined by this study; further study is needed. This study did not show strong correlation between degree of IgE elevation and severity of clinical signs; however, IgE levels decreased 61% overall in animals that were treated with ASIT, and severity of type 1 hypersensitivity reaction related clinical signs were reduced, despite a variable reduction in measured IgE levels. Measurement of serum IgE may offer insight into diagnosis and treatment of elephants displaying atopy or abdominal discomfort.
The authors would like to acknowledge Heska Corporation for measuring IgE levels, and the elephant caregivers, whose dedicated daily care makes individualized veterinary care possible.
1. Karger AG. Severity scoring of atopic dermatitis: the SCORAD index. Consensus report of the European Task Force on Atopic Dermatitis. Dermatology. 1993;186:23–31.
2. Plant JD, Neradelik MB, Polissar NL, Fadok VA, Scott BA. Agreement between allergen-specific IgE assays and ensuing immunotherapy recommendations from four commercial laboratories in the USA. Vet Dermatol. 2014;25:15-e6. doi:10.1111/vde.12104.