Abstract

Dietary hypersensitivity (food allergy) was documented in captive tigers (Panthera tigris tigris) and highly suspected in a case of anterior enteritis in an Asian elephant (Elephas maximus). This diagnosis was reached on the basis of clinical signs, specific IgE antigen food testing in model species, and resolution of signs with the correction of diet. Diet hypersensitivity should be considered as a possible underlying source of inflammation in such species as black rhinoceros, gorillas, pandas, cheetahs, and toucans.

Case 1

A diet trial was initiated in 1.1 Bengal tigers at Busch Gardens Tampa Bay. The tigers were 5 years-old hand reared siblings, in good general health and chosen due to the relative ease of voluntary blood collections from the tail vein. The current commercial horsemeat diet (Diet A) was substituted with a beef-based product (Diet B). In addition to being beef based, flaxseed oil was supplemented in this product. The diets were transitioned from Diet A to Diet B over a 9-day period so that on Day 10 the cats were on 100% of Diet B. Blood was collected prior to initiation of the trial and once the cats were established on the new diet. Acceptance of the new diet was fair but eventually 100% was taken. The weight of the food was kept the same and after 1 month on the new food the female tiger had gained 10 pounds. This female had several bouts of regurgitation during this month and her coat had become dull and course. The diet was stopped and the tiger was returned to the original Diet A. Two more attempts were made to convert this tiger to Diet B with the same clinical presentation at each attempt. Food allergen testing has also been conducted at a commercial veterinary food allergen testing facility (Bio-Medical Services, Austin, TX, USA, www.bmslab.com). (VIN editor: Original link not accessible 1-25-2021). The male tiger was then transitioned to Diet B over 9 days. This diet was readily consumed but on Day 4 a considerable amount of vomitus was found from this tiger. This tiger was depressed and not responding to staff normally. The next morning the tiger was brighter and allowed blood collection form the lateral tail vein. Complete blood count and serum biochemistry panel were unremarkable. A food allergen profile was also conducted on this sample and two samples collected prior to the trial. The trial was stopped and Diet A was resumed. The male ate 100% of Diet A for 2 days and returned to normal. A food allergen profile suggested a hypersensitivity to flaxseed in the male and flaxseed and beef in the female (Table 1).

Table 1. Food allergen profiles of 1.1 Bengal tigers. Diet A samples were collected just prior to the start of the transition. (N=Negative ≤150, BL=Borderline 151–174, BL-P=Borderline-Positive 175–199, P=Positive 200–400, HP=Highly Positive >400)

Case 2

A female Asian elephant (Elephas maximus), Studbook No. 32, DOB 1973, had a history of intermittent colic with regurgitation. The female also had voluminous, non-formed stools that had been accepted as normal for this individual. During these episodes the elephant typically had a stretched-out posture and abducted elbows. Occasionally she would lie down but was not seen to be distended. There seemed to be a strong correlation with bran administration and/or stealing food from others with the onset of these episodes, especially with the most recent ones. Blood work typically would demonstrate a pre-renal azotemia. Therapy was symptomatic and consisted of analgesics, fluids, and fasting. A tentative diagnosis of anterior enteritis was made. A retrospective evaluation of food allergen testing was conducted at a commercial veterinary food allergen testing facility (Bio-Medical Services, Austin, TX, USA, www.bmslab.com). (VIN editor: Original link not accessible 1-25-2021). Three dates with clinical episodes are demonstrated with two dates pulled randomly from the serum bank in which no signs of gastrointestinal distress were noted (Table 2). Table 3 provides food allergen profiles from other female Asian elephants in the same herd. As a result of this testing, wheat bran has been removed from #32’s routine. Consideration should be given to the potential of chronic antigenic stimulation as an underlying etiology in other species.

Table 2. Food allergen profile of Asian elephant in Case 2. Italics indicate sample taken during clinical episodes of colic. (N=Negative ≤150, BL=Borderline 151–174, BL-P=Borderline-Positive 175–199, P=Positive 200–400, HP=Highly Positive >400)

Table 3. Food allergen profiles from November and December 2005 of five female Asian elephants in herd with elephant in Case 2. (N=Negative ≤150, BL=Borderline 151–174, BL-P=Borderline-Positive 175–199, P=Positive 200–400, HP=Highly Positive >400)

Discussion

Food allergy is an adverse response to food or a food additive with a proven immunologic basis.⁴ Clinical presentation of food allergies in domestic carnivores typically involves the skin or gastrointestinal tract. In cats, specific adverse reactions have been documented to beef, dairy products, and fish.⁵ Diagnostic testing relies heavily on dietary elimination trials. Serologic testing is not considered reliable in animals.² In the case of the tigers, a clinical response was seen after removal of the diet suspected of causing the clinical problems. Enzyme-linked immunosorbent assay (ELISA) using domestic cats as a model correlated well with the changes seen. The reactivity to flaxseed is noteworthy. Linolenic acid (C18:3 n-3) is required as 1–2% of the caloric intake in domestic cats and dogs.³ Flaxseed is an added component to diet B and is reflected in the antigen profiles in both tigers and in the fatty acid profile of the diet analysis (Table 4). Cats appear to have a limited capacity in the production of the higher homologues of linolenic acid and this in fact may be responsible for the poor reproductive performance seen in domestic queens fed high vegetable fats diets.³ Excessive amounts of plant-based omega 3 fatty acids in a strict carnivore may lead to adverse effects, possibly becoming an antigenic source for a reaction. The reaction to beef noted in the female tiger is consistent with what has been documented in domestic cats. Intake of fatty acid by grazing ruminants would be affected by the forage species consumed.1 This is also shown in Table 4. Antibiotic residues are also more likely to be relayed in domestic beef production versus commercial horse meat production and may provide a source of food allergy or food intolerance. Significant health problems in captive cheetahs have been greatly reduced in captive cats and recently-caught wild cheetahs by feeding venison and range-fed donkey (L. Marker pers. comm. 2003). (VIN editor: Table 4 not provided).

In Case 2, there is a strong correlation to consuming excessive wheat bran and the clinical episodes of anterior enteritis. The food allergen ELISA suggests a hypersensitivity to wheat, a commercial grain that would be considered novel to a grazing species like Asian elephants. The primary ingredient of the commercial elephant supplement fed is wheat middlings but none of the other animals in this herd have had any apparent issues related to this ingredient (Table 3). Given that this elephant had chronic loose stool for years, further investigation into wheat as a source of the problem is warranted and underway. Pruritis is the typical presentation to food allergens in horses. Wild oats, white clover, and alfalfa have been recognized as antigens in horses.⁶ The use of wheat bran as a laxative in captive elephants is common practice. The use of good quality grass hay will eliminate the need for this practice and may avoid any potential problems.

Reprinted with permission of the Comparative Nutrition Society (CNS). 2006. Proc. Sixth Biennial Conference, Keystone, Colorado. Information in the CNS abstracts is not peer reviewed and cannot be considered endorsed by the society.

Literature Cited

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