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Immediate type hypersensitivity in dogs induced by storage mites
Research in Veterinary Science/986, 40, 123-/27
Immediate type hypersensitivity in dogs induced by storage mites I. VOLLSET, Norwegian College of Veterinary Medicine, Department of Internal Medicine, Small Animals, Box 8146, Dep 0033 Oslo 1, Norway, H. J. LARSEN, Norwegian College of Veterinary Medicine, Department of Microbiology and Immunology, Box 8146, Dep 0033 Oslo 1, Norway, R. MEHL, National Institute of Public Health, Laboratory of Entomology, 0038 Oslo 1, Norway
Results of intradermal skin tests on 53 dogs, employing storage mite extracts as antigen, indicated that storage mite allergy is fairly common. Only four of 29 dogs exhibiting no allergic symptoms showed skin reactions to the most common storage mite, Acarus siro, whereas 18 out of 24 dogs with symptoms assumed to be associated with allergy showed such reactions. The passive cutaneous transfer test revealed that an immediate type hypersensitivity reaction was involved. STORAGE mites have proved to be of great importance as allergens in man (Wraith et al 1979, Woodcock and Cunnington 1980), being mainly associated with allergic disorders of the respiratory tract such as bronchial asthma or perennial rhinitis. The route of sensitisation is via the oral cavity (Wraith et aI1979). This type of allergy seems to be fairly common in Scandinavia (Hillerdal et al 1982). Acarodermatitis in man is another form of disease caused by storage mites. Direct skin contact with the mites is necessary. Mite saliva and excrements have a toxic effect on the human skin and give rise to erythematous and papulovesiculous eruptions (Mumcuoglu 1976). Data concerning the significance of storage mites in allergies in domestic animals is sparse. However, possible adverse effects on the health of cattle eating forage heavily contaminated with storage mites has been reported (Everitt 1980). Possible damage to the gut epithelium in domestic animals caused by storage mites has been postulated (Lee et al 1983), though no such association has been reported in dogs. The two main factors associated with allergy to storage mites in man are high relative humidity and occupational risk of exposure (Agha and Gnanasakthy 1981). Poorly dried cereals, and cereals stored at a relative humidity above 60 per cent, are highly susceptible to contamination with storage mites. Commercial dry dog food stored under similar adverse conditions may become infected in the same way and dogs become exposed to the mites as a
consequence. Generally, mites are quite common in northern Europe, specially in the north. The purpose of the present work was to study the importance of storage mites as a dietary allergenic factor in dogs. Materials and methods
Animals The dogs under study were divided into two groups, Group I (Table I) consisted of29 dogs with no clinical symptoms of allergy, though 16 suffered from chronic diseases. Group 2, comprising 24 dogs (Table 2), consisted of nine atopic dogs and 15 dogs with clinical symptoms possibly related to allergy. The nine atopic dogs had previously been tested for immediate skin test reactivity (ISR) to several allergens. Positive reactions were observed against house dust, house dust mites (Dermatophagoides pteronyssinus and D farinae), grass mixture, timothy (Pleum pratense) and birch (Betula alba). The dogs in both groups had been given a diet comprising mostly dry cereal before the intradermal skin tests. Exposure to sterage mites, either through the diet or the environment, was demonstrated only in some cases, ie, when diet samples were tested for storage mites.
Extracts ofstorage mites Extracts of Acarus siro and a mixture of mites, comprising mainly Glycyphagus domesticus and A siro, were prepared in the following manner, Whole body extracts of the storage mites were used. The storage mites were isolated from dry feed and stored at -70°C in a dry state until used. The extracts of the mites were prepared by grinding 10 mg of each in a mortar with a small volume of phosphate buffered normal saline (PBS), pH 7' 2. Saline was added to give a 0·1 per cent weight/volume (w/v) concentration. The extracts were then passed through a sterile 0'45 J.lm filter (Millipore) and afterwards through a 123
I. Vollset, H. J. Larsen, R. Meh/
124
TABLE 1: Intradermal skin test in dogs with no symptoms of allergy
Dog number
Skin test results Mite A siro mixture
Sex
Age (years!
1 2 3 4 5
F F F F M
7·0 3·0 0·3 10·0 0·3
0 0 0 0 0
0 0 0 0 0
6 7 8 9 10
F M F M M
6'0 5'5 1'1 4·0 3·0
0
0 ND 0 0 0
11 12 13 14 15
F F F M F
2·5 4'5 3·0 7·0 1·5
++ + ++
16 17 18 19 20
M M M F M
21 22
+++ 0 0 0
+
Case history Bradycardia Healthy Healthy
Otitis externa
Functional diarrhoea Myasthenia gravis Convulsion Healthy Healthy Healthy
0 0
0 0 0 0
Healthy Healthy Healthy Conjunctivitis Healthy
8·0 3·0 8·0 9·5 2·5
0 0 0 0 0
0 0 0 0 0
Cystitis Healthy Healthy Kidney disease Healthy
2·0 8'0 5·0 8·0 2'5
0 0 0 0 0
0 0 0 0 0
Healthy
24 25
F M F F F
26 27 28 29
F M M F
2·0 3·0 4'0 3·0
0 0 0 0
0 0 0 0
Chronic otitis externa Folliculitis Blue dog disease Folliculitis
4/29
1/28
23
17FI12M
4·4 ± 2·7 (SE)
Chronic otitis externa
Folliculitis Rhinitis Chronic otitis externa
Negative reaction: 0 (a wheal less than twice the diameter of the control wheal) Positive reaction: + (a wheal more than twice the diameter of the control wheal) Positive reaction using antigen concentration of O·1 per cent + w/v Positive reaction using antigen concentration of 0·01 per ++ cent w/v + + + Positive reaction using antigen concentration of 0·001 per cent w/v ND Not done
sterile O: 22 11m filter. The filtrate was stored at -70°C until use. After thawing, the mite extracts were diluted and stored at 4°C for up to 14 days. PBS was used in all dilutions of the mite extracts.
Intradermal test The intradermal test was performed on the medial thigh after shaving. No glucocorticosteroids, antihistamines, tranquillisers or sedatives had been administered during the two weeks before the test. Three concentrations (0'1,0,01 and 0·001 per cent w/v) of each mite extract were injected intradermally
(50 Ill) with a tuberculin syringe fitted with a 26 gauge needle. PBS was injected as a diluent control and histamine diphosphate solution (0'01 per cent) as a positive control. The skin reactions were measured at 20 minutes, and at four, 24 and 48 hours after the injection. A positive reaction was defined as a wheal of at least twice the size of the diluent control wheal and reactions were graded, +, + + and + + + (Tables 1 and 2).
Passive transfer test Serum samples from 10 dogs showing immediate skin test reaction, and from three healthy dogs which did not respond to antigen, were used in a PrausnitzKiistner test (PK test) (Prausnitz and Kiistner 1921). The skin of each side of the lateral thorax of the recipient dog was shaved and disinfected. This dog did not show ISR to mite antigen. Sterile untreated serum (0'1 ml) and heat inactivated serum (56°C for 30 minutes) from each dog was injected intradermally at three sites and each site was marked. Sites were challenged individually with 50 III of a 0'01 per cent mite extract four, 72 and 192 hours after the serum injection. The sites with serum from the three control dogs were challenged with both PBS and mite antigen. Wheal sizes were measured in mm and a wheal up to I mm larger than the control was considered negative and assigned O. Positive reactions were assigned as + , + + and + + + with wheal sizes 2 to 3 mrn, 4 to 5 mm and 6 mm or larger than the control wheal, respectively. Results
Allergens Maximum reaction after intradermal injection of storage mite allergen occurred after 20 minutes. The reactions were round wheals with more or less diffuse erythema. No reaction was seen four, 24 and 48 hours after injection of allergens.
Active test Reactions to mite allergens in 29 non-allergic dogs are shown in Table I. The mean age of 17 female and 12 male dogs was 4·4 years (SE ± 2'7). Fourof29 nonallergic dogs reacted to A siro and one of 28 dogs reacted to the mite mixture. Table 2 shows the results of intradermal skin tests on 24 dogs with allergic symptoms. The mean age of 12 female and 12 male dogs was 3· 7 years (SE ± 2· 6). In dogs with atopic symptoms 70 per cent (14 of 20) reacted to A siro and 63 per cent (12 of 19) reacted to the mite mixture. Seventy-eight per cent (7 of 9) of the dogs with atopy
125
Storage mite hypersensitivity TABLE 2: Intradermal skin test of dogs with symptoms related to allergy Skin test results Mite mixture A siro
Sex
Age (years)
F
JoO
+++
++
2
M
7·0
+++
+
3
M
6·0
+++
+
4
M
4·5
++
++
Dog number
Case history Atopic against 0 farinae and house dust Rhinitis, atopic against pteronyssinus Rhinitis, atopic against o farinae and house dust Atopic against 0 farinae and house dust Atopic against 0 farinae
o
5
F
1·0
++
0
6 7
F M
1·0 8·0
++
+++
0
0
8
F
1-0
+++
+++
9
M
1·5
0
0
10 11 12
M F F F F M M M F M M
3·0 9·0 6·0 4·0 3·0 3·0 0·8 5·0 4·0 6,5 1·0
0
NO NO
0 0 0
0 0 0
22
M F
1·5 0·6
+++ +++
0
Diarrhoea periodically Diarrhoea for 2 months
13
14 15 16 17 18 19 20 21
++ + +++
+ +
Pododermatitis Pruritus for 3 years Pruritus for 2 years Pruritus for 1·5 years Pruritus for 2 years Reverse sneezing
++ + + ++
+++ ++ ++ ++
Atopic against 0 farinae Atopic against 0 farinae. Betula alba and Phleum pratense Atopic against 0 farinae and house dust Atopic against mixed grasses
+++
Seborrhea. pruritus Pododermatitis Pruritus, dermatitis Pododermatitis, diarrhoea Pruritus for 2 years, diarrhoea periodically
23
F
2·0
++
+
Diarrhoea for 5 months
24
F
7·5
++
++
Diarrhoea
12F/12M
3·7 ± 2'5 (SE)
18/24
15/22
For key see Table 1
TABLE 3: Passive transfer test (PK)on s~rum from dogs with ISRand from healthy dogs with no ISR
Dog number
PK reactivity in untreated serum 4h 72 h 192 h
Highest antigen dilution causing ISR
1 2 3 4 5
1:10 1:10 1:100 1:10 1:10
+++ ++ ++ +++ ++
+++ +++ ++ +++ ++
+++ +++ ++ ++ ++
6 7 8 9 10
1:10 1:100 1:100 1:10 1:1
++ +++ ++ ++ ++
+++ ++ ++ ++ +
++ +++ ++ ++ ++
11 12 13
Control Control Control
0
0
0
0 0
0 0
0
A wheal up to 1 mm larger than the control wheal
NO
Not done
+ A wheal 2-3 mm larger than the control wheal ++ A wheal 4-5 mm larger than the control wheal +++ A wheal 6 mm larger than the control wheal
PK reactivity in inactivated serum 4h 72h 192 h
"
+
+ + + + +
NO NO NO NO NO
+ +
+ + + + +
+ + + + +
0 0
0 0
NO
0 0
0
0
0 0
+ + 0
+ 0
0 0
126
I. Vo/lset, H. J. Larsen, R. Mehl
to other allergens (house dust, house dust mites and pollens) had ISR to storage mite extracts. Of 15 dogs in group 2 with no ISR to other allergens, 73' 3 per cent reacted to storage mite allergens. All four dogs with previously unexplained diarrhoea reacted to A siro and three of these dogs reacted to the mite mixture. In group 1 all of the four dogs that reacted were females. In group 2, 11 of the 12 females and seven of 12 male dogs reacted to A siro.
Passive tests The results of passive transfer test on a non-atopic dog with serum from healthy dogs and from dogs with ISR to mites are shown in Table 3. Three sensitisation intervals were used in these tests, between transfer of serum intradermally and challenge with storage mite extracts, ie, four, 72 and 196 hours. Some variation in effect with respect to the strength of the reaction was noted, but antibodies transferred in serum from all affected dogs in groups 1 and 2 remained bound within the skin and resulted in a reaction after 192 hours. When using inactivated serum, the successive challenge with storage mite extracts gave variable and generally weaker reactions. Discussion The present investigation showed that 18 of 24 dogs with allergic symptoms reacted to intradermal injection of storage mite extracts. The results obtained suggest a definite association between sensitisation to storage mites and allergic symptoms. Of 29 dogs with no symptoms of allergy that were challenged intradermally, only four reacted positively to mite extracts. Most dogs are probably naturally exposed to storage mites through their feed and, or, from their environment, and if they are exposed to such allergens for some time they may, develop a clinical allergic disease. The PK test was done to confirm immediate type hypersensitive reaction in dogs with ISR to storage mite antigen. The results demonstrated that clinically healthy dogs react to allergen when serum from affected dogs is injected. Heat inactivated serum from affected dogs showed a positive PK reactivity. The PK reactivity was, however, generally weaker compared to the reactivity of untreated serum. It is possible that inactivation at 56°C for 30 minutes was insufficient for complete inactivation of IgE antibodies in serum. In the literature there is some uncertainty regarding adequate inactivation time at 56°C for canine IgE. IgE is normally destroyed by heating to 56°C for 30 minutes (Tizard 1982). Halliwell et al (1975) found a decrease of 24 per cent in serum IgE content when heated to 56°C for 30 minutes and a decrease of 86 per
cent when heated for four houres. Willemse et al (1984) concluded that immunoglobulins other than IgE may be involved in the pathogenesis of atopy in the dog. By analogy, a cytophilic heat stable subclass of canine IgG could explain our observations assuming that IgE was sufficiently destroyed by heating at 56°C for 30 minutes. In this study, the dogs with symptoms related to allergy could be divided into three categories according to clinical symptoms and previous skin tests, ie, dogs with atopy to other allergens (n = 9), dogs with atopic symptoms but no ISR to other allergens (n = 11) and dogs with previously unexplained diarrhoea (n = 4). ISR to storage mites was not correlated with whether the dogs had ISR to other allergens or not. The present work revealed that the storage mite extracts contained specific non-cross reacting allergens. This has previously been described in man (Wraith et al1979, Hillerdal et aI1982). The pathogenesis of diarrhoea in dogs with ISR to storage mites has so far not been ascertained, though an allergic mode of action and mechanical insult are both possibilities. A third symptom-complex in dogs that is probably caused by storage mites is the 'storage mitedermatitis'. Dogs given cereal products contaminated with storage mites may develop a pyoderma on the lips and cheeks. In man, the saliva and excretions of the mites exert a toxic effect on the skin and cause papulovesiculous eruptions. In dogs, such a condition probably develops further to a pyodermatitis. Storage mites comprise a wide range of families and species, many of which cause rapid damage to stored food. The species concerned develop most rapidly at high relative humidities and feed on other organisms, especially fungi. Such fungi may themselves also be detrimental in that metabolic products sometimes have a toxic effect on exposed cells including cells of the immune system. Dry cereal foods should therefore be stored under dry conditions which are unfavourable to the growth of mites and fungi. In man, the frequency and severity of hypersensitivity reactions to storage mites are unexpectedly high in view of their irregular presence (Wraith et al 1979). Wraith et al (1979) concluded that allergy to storage mites in man is more significant and widespread than hitherto realised. The present paper indicates a similar situation in dogs. As allergy to storage mites appears to be fairly common in dogs, mite allergens should be included among the allergens in standard tests on dogs with relevant clinical indications, especially those fed on commercial dry foods. Acknowledgements This study was supported by a grant from the Norwegian Agricultural Research Council.
Storage mite hypersensitivity References AGHA, M. & GNANASAKTHY, A. (1981) Clinical Allergy 11, 499-504 EVERITT, B. (1980) Svensk Veteriniirtidning 32,317-318 HALLIWELL, R. E. W., SCHARTZMAN, R. M., MONTGOMERY, P. C. & ROCKEY, J. H. (1975) Transplantation Proceedings 4, 537-543 HILLERDAL, G., ZETTERSTROM, 0., JOHANSSON, S. G. 0., ENSTROM, B. & WIREN, A. (1982) Allergy 37, 475-479 LEE, J.-I., LEE, B.-H. & LEE, c.-G. (1983) Korean Journal of Veterinary Research 23,187-191 MUMCUOGLU, Y. (1976) Praxis 65, 101-104
127
PRAUSNITZ, C. & KOSTNER, H. (1921) Zentralblau fur Bakteriologie, I. Abt. Orig, 86, 160-169 TIZARD, I. (1982) An Introduction to Veterinary Immunology. Philadelphia, W. B. Saunders. pp 48-50 WILLEMSE, A., NOORDlZIJ, A., RUTTEN, V. P. & BERNADlNA, W. E. (1984) Thesis, Rijksuniversiteit te Utrecht. pp 105-120 WOODCOCK, A. A. & CUNNINGTON, A. M. (1980) Clinical Allergy 10, 609-615 WRAITH, D. G., CUNNINGTON, A. M. & SEYMOUR, W. M. (1979) Clinical Allergy 9,545-561
Accepted February 26, 1985
Immediate type hypersensitivity in dogs induced by storage mites I. VOLLSET, Norwegian College of Veterinary Medicine, Department of Internal Medicine, Small Animals, Box 8146, Dep 0033 Oslo 1, Norway, H. J. LARSEN, Norwegian College of Veterinary Medicine, Department of Microbiology and Immunology, Box 8146, Dep 0033 Oslo 1, Norway, R. MEHL, National Institute of Public Health, Laboratory of Entomology, 0038 Oslo 1, Norway
Results of intradermal skin tests on 53 dogs, employing storage mite extracts as antigen, indicated that storage mite allergy is fairly common. Only four of 29 dogs exhibiting no allergic symptoms showed skin reactions to the most common storage mite, Acarus siro, whereas 18 out of 24 dogs with symptoms assumed to be associated with allergy showed such reactions. The passive cutaneous transfer test revealed that an immediate type hypersensitivity reaction was involved. STORAGE mites have proved to be of great importance as allergens in man (Wraith et al 1979, Woodcock and Cunnington 1980), being mainly associated with allergic disorders of the respiratory tract such as bronchial asthma or perennial rhinitis. The route of sensitisation is via the oral cavity (Wraith et aI1979). This type of allergy seems to be fairly common in Scandinavia (Hillerdal et al 1982). Acarodermatitis in man is another form of disease caused by storage mites. Direct skin contact with the mites is necessary. Mite saliva and excrements have a toxic effect on the human skin and give rise to erythematous and papulovesiculous eruptions (Mumcuoglu 1976). Data concerning the significance of storage mites in allergies in domestic animals is sparse. However, possible adverse effects on the health of cattle eating forage heavily contaminated with storage mites has been reported (Everitt 1980). Possible damage to the gut epithelium in domestic animals caused by storage mites has been postulated (Lee et al 1983), though no such association has been reported in dogs. The two main factors associated with allergy to storage mites in man are high relative humidity and occupational risk of exposure (Agha and Gnanasakthy 1981). Poorly dried cereals, and cereals stored at a relative humidity above 60 per cent, are highly susceptible to contamination with storage mites. Commercial dry dog food stored under similar adverse conditions may become infected in the same way and dogs become exposed to the mites as a
consequence. Generally, mites are quite common in northern Europe, specially in the north. The purpose of the present work was to study the importance of storage mites as a dietary allergenic factor in dogs. Materials and methods
Animals The dogs under study were divided into two groups, Group I (Table I) consisted of29 dogs with no clinical symptoms of allergy, though 16 suffered from chronic diseases. Group 2, comprising 24 dogs (Table 2), consisted of nine atopic dogs and 15 dogs with clinical symptoms possibly related to allergy. The nine atopic dogs had previously been tested for immediate skin test reactivity (ISR) to several allergens. Positive reactions were observed against house dust, house dust mites (Dermatophagoides pteronyssinus and D farinae), grass mixture, timothy (Pleum pratense) and birch (Betula alba). The dogs in both groups had been given a diet comprising mostly dry cereal before the intradermal skin tests. Exposure to sterage mites, either through the diet or the environment, was demonstrated only in some cases, ie, when diet samples were tested for storage mites.
Extracts ofstorage mites Extracts of Acarus siro and a mixture of mites, comprising mainly Glycyphagus domesticus and A siro, were prepared in the following manner, Whole body extracts of the storage mites were used. The storage mites were isolated from dry feed and stored at -70°C in a dry state until used. The extracts of the mites were prepared by grinding 10 mg of each in a mortar with a small volume of phosphate buffered normal saline (PBS), pH 7' 2. Saline was added to give a 0·1 per cent weight/volume (w/v) concentration. The extracts were then passed through a sterile 0'45 J.lm filter (Millipore) and afterwards through a 123
I. Vollset, H. J. Larsen, R. Meh/
124
TABLE 1: Intradermal skin test in dogs with no symptoms of allergy
Dog number
Skin test results Mite A siro mixture
Sex
Age (years!
1 2 3 4 5
F F F F M
7·0 3·0 0·3 10·0 0·3
0 0 0 0 0
0 0 0 0 0
6 7 8 9 10
F M F M M
6'0 5'5 1'1 4·0 3·0
0
0 ND 0 0 0
11 12 13 14 15
F F F M F
2·5 4'5 3·0 7·0 1·5
++ + ++
16 17 18 19 20
M M M F M
21 22
+++ 0 0 0
+
Case history Bradycardia Healthy Healthy
Otitis externa
Functional diarrhoea Myasthenia gravis Convulsion Healthy Healthy Healthy
0 0
0 0 0 0
Healthy Healthy Healthy Conjunctivitis Healthy
8·0 3·0 8·0 9·5 2·5
0 0 0 0 0
0 0 0 0 0
Cystitis Healthy Healthy Kidney disease Healthy
2·0 8'0 5·0 8·0 2'5
0 0 0 0 0
0 0 0 0 0
Healthy
24 25
F M F F F
26 27 28 29
F M M F
2·0 3·0 4'0 3·0
0 0 0 0
0 0 0 0
Chronic otitis externa Folliculitis Blue dog disease Folliculitis
4/29
1/28
23
17FI12M
4·4 ± 2·7 (SE)
Chronic otitis externa
Folliculitis Rhinitis Chronic otitis externa
Negative reaction: 0 (a wheal less than twice the diameter of the control wheal) Positive reaction: + (a wheal more than twice the diameter of the control wheal) Positive reaction using antigen concentration of O·1 per cent + w/v Positive reaction using antigen concentration of 0·01 per ++ cent w/v + + + Positive reaction using antigen concentration of 0·001 per cent w/v ND Not done
sterile O: 22 11m filter. The filtrate was stored at -70°C until use. After thawing, the mite extracts were diluted and stored at 4°C for up to 14 days. PBS was used in all dilutions of the mite extracts.
Intradermal test The intradermal test was performed on the medial thigh after shaving. No glucocorticosteroids, antihistamines, tranquillisers or sedatives had been administered during the two weeks before the test. Three concentrations (0'1,0,01 and 0·001 per cent w/v) of each mite extract were injected intradermally
(50 Ill) with a tuberculin syringe fitted with a 26 gauge needle. PBS was injected as a diluent control and histamine diphosphate solution (0'01 per cent) as a positive control. The skin reactions were measured at 20 minutes, and at four, 24 and 48 hours after the injection. A positive reaction was defined as a wheal of at least twice the size of the diluent control wheal and reactions were graded, +, + + and + + + (Tables 1 and 2).
Passive transfer test Serum samples from 10 dogs showing immediate skin test reaction, and from three healthy dogs which did not respond to antigen, were used in a PrausnitzKiistner test (PK test) (Prausnitz and Kiistner 1921). The skin of each side of the lateral thorax of the recipient dog was shaved and disinfected. This dog did not show ISR to mite antigen. Sterile untreated serum (0'1 ml) and heat inactivated serum (56°C for 30 minutes) from each dog was injected intradermally at three sites and each site was marked. Sites were challenged individually with 50 III of a 0'01 per cent mite extract four, 72 and 192 hours after the serum injection. The sites with serum from the three control dogs were challenged with both PBS and mite antigen. Wheal sizes were measured in mm and a wheal up to I mm larger than the control was considered negative and assigned O. Positive reactions were assigned as + , + + and + + + with wheal sizes 2 to 3 mrn, 4 to 5 mm and 6 mm or larger than the control wheal, respectively. Results
Allergens Maximum reaction after intradermal injection of storage mite allergen occurred after 20 minutes. The reactions were round wheals with more or less diffuse erythema. No reaction was seen four, 24 and 48 hours after injection of allergens.
Active test Reactions to mite allergens in 29 non-allergic dogs are shown in Table I. The mean age of 17 female and 12 male dogs was 4·4 years (SE ± 2'7). Fourof29 nonallergic dogs reacted to A siro and one of 28 dogs reacted to the mite mixture. Table 2 shows the results of intradermal skin tests on 24 dogs with allergic symptoms. The mean age of 12 female and 12 male dogs was 3· 7 years (SE ± 2· 6). In dogs with atopic symptoms 70 per cent (14 of 20) reacted to A siro and 63 per cent (12 of 19) reacted to the mite mixture. Seventy-eight per cent (7 of 9) of the dogs with atopy
125
Storage mite hypersensitivity TABLE 2: Intradermal skin test of dogs with symptoms related to allergy Skin test results Mite mixture A siro
Sex
Age (years)
F
JoO
+++
++
2
M
7·0
+++
+
3
M
6·0
+++
+
4
M
4·5
++
++
Dog number
Case history Atopic against 0 farinae and house dust Rhinitis, atopic against pteronyssinus Rhinitis, atopic against o farinae and house dust Atopic against 0 farinae and house dust Atopic against 0 farinae
o
5
F
1·0
++
0
6 7
F M
1·0 8·0
++
+++
0
0
8
F
1-0
+++
+++
9
M
1·5
0
0
10 11 12
M F F F F M M M F M M
3·0 9·0 6·0 4·0 3·0 3·0 0·8 5·0 4·0 6,5 1·0
0
NO NO
0 0 0
0 0 0
22
M F
1·5 0·6
+++ +++
0
Diarrhoea periodically Diarrhoea for 2 months
13
14 15 16 17 18 19 20 21
++ + +++
+ +
Pododermatitis Pruritus for 3 years Pruritus for 2 years Pruritus for 1·5 years Pruritus for 2 years Reverse sneezing
++ + + ++
+++ ++ ++ ++
Atopic against 0 farinae Atopic against 0 farinae. Betula alba and Phleum pratense Atopic against 0 farinae and house dust Atopic against mixed grasses
+++
Seborrhea. pruritus Pododermatitis Pruritus, dermatitis Pododermatitis, diarrhoea Pruritus for 2 years, diarrhoea periodically
23
F
2·0
++
+
Diarrhoea for 5 months
24
F
7·5
++
++
Diarrhoea
12F/12M
3·7 ± 2'5 (SE)
18/24
15/22
For key see Table 1
TABLE 3: Passive transfer test (PK)on s~rum from dogs with ISRand from healthy dogs with no ISR
Dog number
PK reactivity in untreated serum 4h 72 h 192 h
Highest antigen dilution causing ISR
1 2 3 4 5
1:10 1:10 1:100 1:10 1:10
+++ ++ ++ +++ ++
+++ +++ ++ +++ ++
+++ +++ ++ ++ ++
6 7 8 9 10
1:10 1:100 1:100 1:10 1:1
++ +++ ++ ++ ++
+++ ++ ++ ++ +
++ +++ ++ ++ ++
11 12 13
Control Control Control
0
0
0
0 0
0 0
0
A wheal up to 1 mm larger than the control wheal
NO
Not done
+ A wheal 2-3 mm larger than the control wheal ++ A wheal 4-5 mm larger than the control wheal +++ A wheal 6 mm larger than the control wheal
PK reactivity in inactivated serum 4h 72h 192 h
"
+
+ + + + +
NO NO NO NO NO
+ +
+ + + + +
+ + + + +
0 0
0 0
NO
0 0
0
0
0 0
+ + 0
+ 0
0 0
126
I. Vo/lset, H. J. Larsen, R. Mehl
to other allergens (house dust, house dust mites and pollens) had ISR to storage mite extracts. Of 15 dogs in group 2 with no ISR to other allergens, 73' 3 per cent reacted to storage mite allergens. All four dogs with previously unexplained diarrhoea reacted to A siro and three of these dogs reacted to the mite mixture. In group 1 all of the four dogs that reacted were females. In group 2, 11 of the 12 females and seven of 12 male dogs reacted to A siro.
Passive tests The results of passive transfer test on a non-atopic dog with serum from healthy dogs and from dogs with ISR to mites are shown in Table 3. Three sensitisation intervals were used in these tests, between transfer of serum intradermally and challenge with storage mite extracts, ie, four, 72 and 196 hours. Some variation in effect with respect to the strength of the reaction was noted, but antibodies transferred in serum from all affected dogs in groups 1 and 2 remained bound within the skin and resulted in a reaction after 192 hours. When using inactivated serum, the successive challenge with storage mite extracts gave variable and generally weaker reactions. Discussion The present investigation showed that 18 of 24 dogs with allergic symptoms reacted to intradermal injection of storage mite extracts. The results obtained suggest a definite association between sensitisation to storage mites and allergic symptoms. Of 29 dogs with no symptoms of allergy that were challenged intradermally, only four reacted positively to mite extracts. Most dogs are probably naturally exposed to storage mites through their feed and, or, from their environment, and if they are exposed to such allergens for some time they may, develop a clinical allergic disease. The PK test was done to confirm immediate type hypersensitive reaction in dogs with ISR to storage mite antigen. The results demonstrated that clinically healthy dogs react to allergen when serum from affected dogs is injected. Heat inactivated serum from affected dogs showed a positive PK reactivity. The PK reactivity was, however, generally weaker compared to the reactivity of untreated serum. It is possible that inactivation at 56°C for 30 minutes was insufficient for complete inactivation of IgE antibodies in serum. In the literature there is some uncertainty regarding adequate inactivation time at 56°C for canine IgE. IgE is normally destroyed by heating to 56°C for 30 minutes (Tizard 1982). Halliwell et al (1975) found a decrease of 24 per cent in serum IgE content when heated to 56°C for 30 minutes and a decrease of 86 per
cent when heated for four houres. Willemse et al (1984) concluded that immunoglobulins other than IgE may be involved in the pathogenesis of atopy in the dog. By analogy, a cytophilic heat stable subclass of canine IgG could explain our observations assuming that IgE was sufficiently destroyed by heating at 56°C for 30 minutes. In this study, the dogs with symptoms related to allergy could be divided into three categories according to clinical symptoms and previous skin tests, ie, dogs with atopy to other allergens (n = 9), dogs with atopic symptoms but no ISR to other allergens (n = 11) and dogs with previously unexplained diarrhoea (n = 4). ISR to storage mites was not correlated with whether the dogs had ISR to other allergens or not. The present work revealed that the storage mite extracts contained specific non-cross reacting allergens. This has previously been described in man (Wraith et al1979, Hillerdal et aI1982). The pathogenesis of diarrhoea in dogs with ISR to storage mites has so far not been ascertained, though an allergic mode of action and mechanical insult are both possibilities. A third symptom-complex in dogs that is probably caused by storage mites is the 'storage mitedermatitis'. Dogs given cereal products contaminated with storage mites may develop a pyoderma on the lips and cheeks. In man, the saliva and excretions of the mites exert a toxic effect on the skin and cause papulovesiculous eruptions. In dogs, such a condition probably develops further to a pyodermatitis. Storage mites comprise a wide range of families and species, many of which cause rapid damage to stored food. The species concerned develop most rapidly at high relative humidities and feed on other organisms, especially fungi. Such fungi may themselves also be detrimental in that metabolic products sometimes have a toxic effect on exposed cells including cells of the immune system. Dry cereal foods should therefore be stored under dry conditions which are unfavourable to the growth of mites and fungi. In man, the frequency and severity of hypersensitivity reactions to storage mites are unexpectedly high in view of their irregular presence (Wraith et al 1979). Wraith et al (1979) concluded that allergy to storage mites in man is more significant and widespread than hitherto realised. The present paper indicates a similar situation in dogs. As allergy to storage mites appears to be fairly common in dogs, mite allergens should be included among the allergens in standard tests on dogs with relevant clinical indications, especially those fed on commercial dry foods. Acknowledgements This study was supported by a grant from the Norwegian Agricultural Research Council.
Storage mite hypersensitivity References AGHA, M. & GNANASAKTHY, A. (1981) Clinical Allergy 11, 499-504 EVERITT, B. (1980) Svensk Veteriniirtidning 32,317-318 HALLIWELL, R. E. W., SCHARTZMAN, R. M., MONTGOMERY, P. C. & ROCKEY, J. H. (1975) Transplantation Proceedings 4, 537-543 HILLERDAL, G., ZETTERSTROM, 0., JOHANSSON, S. G. 0., ENSTROM, B. & WIREN, A. (1982) Allergy 37, 475-479 LEE, J.-I., LEE, B.-H. & LEE, c.-G. (1983) Korean Journal of Veterinary Research 23,187-191 MUMCUOGLU, Y. (1976) Praxis 65, 101-104
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PRAUSNITZ, C. & KOSTNER, H. (1921) Zentralblau fur Bakteriologie, I. Abt. Orig, 86, 160-169 TIZARD, I. (1982) An Introduction to Veterinary Immunology. Philadelphia, W. B. Saunders. pp 48-50 WILLEMSE, A., NOORDlZIJ, A., RUTTEN, V. P. & BERNADlNA, W. E. (1984) Thesis, Rijksuniversiteit te Utrecht. pp 105-120 WOODCOCK, A. A. & CUNNINGTON, A. M. (1980) Clinical Allergy 10, 609-615 WRAITH, D. G., CUNNINGTON, A. M. & SEYMOUR, W. M. (1979) Clinical Allergy 9,545-561
Accepted February 26, 1985