CASE REPORT OBSERVATIONS ON AN OUTBREAK OF INFESTATION OF DOGS WITH CHEYLETIELLA YASGURI AND ITS PUBLIC HEALTH IMPLICATIONS L. AYALEW AND M. VAILLANCOURT*
Introduction The description of mites belonging to the genus Cheyletiella dates back to 1878 when Megnin (20) first found them on the rabbit (Oryctolagus cuniculus) in France. These mites were assigned to the species C. parasitivorax (6, 20). Cheyletiella have since been reported on dogs, cats, foxes and badgers. The infestation of the dog with Cheyletiella was first reported by Kuscher (18) in Austria, and similar reports from other parts of the world have been increasing. Gething (12) presents a review of these infestations. Until recently, though, Cheyletiella removed from dogs have been assumed to belong to the species C. parasitivorax. However, Smiley in 1965 (23) speciated the mite found on dogs as C. yasguri, C. parasitivorax being retained for that found on rabbits. Thus, in most reports of Cheyletiella on dogs subsequent to Smiley's work, the mites have been described as C. yasguri (1, 7, 8, 9, 10, 11, 26). There has been much dispute as to whether or not C. yasguri (parasitivorax) behaves as a harmful parasite on dogs. Most of the accumulated evidence shows that Cheyletiella does induce skin lesions in dogs; variously described as cutaneous exfoliation, "scurf" or "dandruff' accompanied by intense scratching (5, 10, 14, 16, 21, 22, 24, 26, 28). Furthermore, Cheyletiella has been incriminated in skin lesions of human beings in contact with infested dogs (3, 4, 5, 7, 8, 15, 16, 17, 24, 27). Information on Cheyletiella infestation of animals in Canada is limited. The first report was made by Maclulich (19) who removed Cheyletiella from hares in Ontario. The only other literature on Cheyletiella infestation in Canada is that of Fr6chette and Harrison (11) *Department of Microbiology and Immunology, Faculty of Medicine, University of Montreal, Montreal, Quebec (Ayalew) and The Animal Hospital of Westmount, 349 Victoria Avenue, Montreal, Quebec (Vaillancourt). Present address of Dr. Ayalew: Health of Animals Branch, Agriculture Canada, 1441 St. Urbain Street, Montreal, Quebec.
who recovered C. yasguri from a pup in Quebec. In that report no skin lesions associated with the mite were found on the dog or its owner. This paper describes skin lesions of dogs and man attributable to heavy infestation with C. yasguri. Findings confirm that the mite completes its life cycle on a single dog. History and Clinical Findings On November 23, 1974 a three month old Old English Sheepdog female pup was admitted for clinical examination. The owner had bought the dog from a commercial kennel near Montreal four weeks earlier. The dog had been eating well and developing normally, but had been scratching vigorously. The owner had developed itchy skin lesions on the arms and waist over the past three weeks. A dermatologist had diagnosed her condition as scabies, and had suggested that she submit her dog for veterinary examination. The commercial kennel owner also had been complaining of similar skin lesions. The pup was in good physical condition except the coat appeared to be somewhat dry. Closer inspection revealed excessive scurf or "dandruff" extending particularly from the ears along the dorsal area to the base of the tail. Tufts of hair in affected areas had been or were easily pulled out. The horny layer of the skin was covered thickly with dry scales either in loose fragments, adhering, or fastened to hair. Thin pseudotunnels in the epidermal debris on the skin surface were scattered over the ears and the back. When palpated, these pseudotunnels could be felt as raised crusts and upon their removal, thin red cracks were left in the epithelium. From these and microscopic findings, infestation with Cheyletiella sp. was diagnosed and applications of benzyl benzoate were recommended. Subsequently, a visit was made to the kennel from which the pup was purchased. The kennel consisted of 30 dogs of different ages (seven weeks to adult) and breeds (Old English Sheepdog, Blue Danes, Bassets and
Samoyeds). Management was reasonable and
184
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Cheyletiella yasguri runs were separate and of good quality. Dogs of each breed and of similar ages were kept in groups in different runs. Eight Old English Sheepdog pups, two of which were littermates of the pup submitted to us in Montreal, were confined together. The owner of the kennel stated that most of these Old English Sheepdog pups had coat problems, similar to that of the dog examined in Montreal. The following history of the pups was given. Dams: The owner had taken three Old English Sheepdog dams (Dams 1, 2 and 3) from another commercial kennel, for whelping. These dams ranged in age from two to three years, and were all in mid- or late-pregnancy when introduced to her kennel on the 1st of August. The dams appeared normal and were eating well. It was noted, however, that Dam 1 had a rough dry coat but no veterinary consultation was sought because it was believed that the condition might be nutritional and temporary. The dams whelped on August 18, 23 and September 7, respectively. Some pups were stillborn and others had died following birth, each dam finally being left with four healthy pups. After about two weeks of nursing, Dam 1 began scratching and developing dandruff. The condition soon passed. No other dams experienced any clinical signs. Pups: By October 18, the pups of all the dams were weaned and one pup from each dam was given away. The remaining littermates from the three dams were kept together in one run. Their dams were placed in another run. At that time, all pups appeared to be normal and one was given to the owner who subsequently brought it to our clinic four weeks later. The kennel operator noticed scratching and dandruff on most of the pups from the last week of October on into November when the condition became severe in all remaining eight animals. All dogs were eating well and developing normally in spite of the infestation. From late October, the kennel operator herself developed widespread skin lesions, accompanied by constant and intense itch or irritation, over her arms, waist and legs, which her physician assumed to be hives. The "rash" on her body consisted of elevated red papules (about 3-6 mm in diameter) which were scattered in isolated groups or diffusely. Two visitors to the kennel, a lady and a young boy, also complained of similar skin lesions. These visitors had stayed with her only for a day sometime in October during which time they had played with the affected pups. By contrast, the kennel operator's husband never
had skin problems, as he seldom had the opportunity to come into direct contact with the pups.
All dogs examined at the kennel appeared to be in good physical condition. However, the condition of the coats of all eight Old English Sheepdog pups was poor and similar in appearance to that of the pup submitted to our clinic. The intensity of the dandruff and skin lesions on individual pups varied from moderate to severe, and in some cases the lesions extended along the legs. Two animals were severely affected: ridges of sores and hardened skin had developed on affected areas, apparently from licking and vigorous scratching. The kennel was revisited two weeks later. Four of the Old English Sheepdog pups and the three dams had been given away. Of the remaining four pups, two had been shampooed by the owner once with an acaricide, a week previously, and were confined alone in another run. The remaining two were not treated and were still housed in the same run previously used for all eight pups. No dandruff was found on the treated pups. Compared to the first visit, a lesser amount of dandruff was found on the two animals not treated. The kennel operator's skin problem had also abated. Figure 1 shows hair loss and scurfiness over the ears of one pup during the second visit to the kennel.
Parasitological Examination Deep and superficial skin scrapings were obtained from several affected areas on the pup
FIGURE 1. Lesions of ear of a pup infested with Cheyletiella yasguri. Note cutaneous exfoliation and dandruff on an opened coat. 185
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submitted originally to the clinic. Also brushings of the coat were taken using a hardbristled brush. Similarly, scrapings and brushings were taken from each of the eight Old English Sheepdog pups, their three dams and several other dogs examined at the kennel on the first visit. Two weeks later, a second series of coat specimens was taken from four of the Old English Sheepdog pups, two of which had been treated with an acaricide a week earlier. Scrapings and brushings from individual animals were saved separately for microscopic examinations. All samples were examined the day of collection using direct wet mounts in mineral oil or KOH digestion. Many living Cheyletiella, ranging in developmental stage from egg to adult (Figures 2-14), were seen in the specimens from the pup brought to our clinic and from each of FIGURE 3. Anterior aspect of Cheyletiella yasthe Old English Sheepdog pups from the first visit to the kennel. The sense organ on genu I guri showing the palpal claws (arrow). x375. of all Cheyletiella seen was heart-shaped (Figure 5) indicating the species to be C. from skin scrapings is made on the basis of yasguri (23). No other mange mite or fun- heavy curved palpal claws (Figure 3) and a gus was seen in any specimen. No mites were comblike tarsal appendage (Figure 4) at the found in specimens taken from the Old En- distal end of each leg. The heart-shaped glish Sheepdog dams or from other dogs at sense organ on genu I (Figure 5) indicates the kennel. Only fragments of adult mites and the species to be C. yasguri (23). The adult egg shells were found in samples from one of mite (Figure 2) is yellow and measures 466the untreated pups after the second visit to 500 microns long by 300-320 microns wide. Mite eggs may be fastened to hairs by loosely the kennel. woven cocoon-like strands (Figure 6). Some eggs may be free among skin debris or even Discussion In diagnosis of Cheyletiella infestation, passed in feces if the dog has been licking at morphological identification of adult mites the lesions (9, 21, 28). Eggs are nonoperculate, elliptical in shape and approximately 190 to 260 microns long by 110 to 140 microns wide. Inside, their contents vary from a developing cytoplasmic mass (Figures 6-9) to a recognizable mite larva with six folded legs (Figure 10). Extending through the blunt pole of fully developed eggs, a lancet-shaped hornlike process is visible (Figure 11). This unusual structure remains with the eggshell after hatching (10) and possibly aids the larva in breaking through the shell. Until recently, Cheyletiella species removed from dogs in different countries have been assumed to be C. parasitivorax. In 1965, however, Smiley (23) described a new species, which he named C. yasguri, from dogs in the U.S.A. Subsequent to Smiley's work, Cheyletiella recovered from dogs have been usually described as C. yasguri (1, 3, 7, 8, 9, 10, 11, 26) with C. parasitivorax by a few (4, 5, 24). C. yasguri has been recorded mostly from dogs. It is tentatively held that the dog is the natural host for C. yasguri while C. paraFIGURE 2. Adult CheyletieUa yasguri. x 150. sitivorax parasitizes rabbits. However, as 186
Cheyletiella yasguri The bulk of accumulated evidence thus appears to favor the latter contention, and it is now well recognized that Cheyletiella may in fact induce cutaneous lesions on dogs. The present observations constitute significant clinical findings caused by C. yasguri in a group of young dogs. The literature is lacking I * such a report from Canada. Frechette and Harrison (11) have previously reported recovering C. yasguri from a three month old
FIGuRE 4. Comb-like structure at the extremity of tarsus of Cheyletiella yasguri. x 1600.
Gething and Walton (13) suggest, the host specificity of Cheyletiella species requires further elu'cidation. The behaviour of Cheyletiella on dogs has been subject to much dispute for many years. One group of workers (11, 18, 21) holds the view that Cheyletiella are predators on other mites causing no clinical signs themselves on dogs. A second group of workers claims, however, that Cheyletiella live on the host as true parasites (2, 5, 10, 14, 16, 21, 22, 24, 26, 28).
FIGURE 5. Heart-shaped sense organ (arrow) on genu I of CheyletieUa yasguri. x1600. 187
CANADIAN VETERINARY JOURNAL
FIGURE 6. Two unembryonated eggs of Cheyletiella yasguri. Note the fine thread woven around the eggs which are fixed to hair. x 150.
FIGuRE 8. Segmentation of embryo of Cheyletiella yasguri. x 375.
FIGURE 7. Early developmental elongation of Cheyletiella yasguri embryo in egg. X325.
Pomeranian puppy in Quebec, but the mites were not associated with dermatitis. In the present case, virtually all the clinical signs and lesions characteristic of Cheyletiella infestation were seen. The syndrome in dogs may escape casual observation but closer inspection may reveal extensive dermatitis characterized by heavy dandruff over the ears and the entire back. Skin scrapings often show large numbers of mites in all stages of development. Furthermore, persons who were known to have been in contact with the present pups had all complained of skin problems apparently attributable to C. yasguri. The public health problem of Cheyletiella species from dogs is well recognized in other parts of the world (3, 7, 8, 15, 16, 17, 25) and the skin condition in man has been called "cheyletosis" by Hewitt et al (15). Cheyletiella infestations are known to be more severe in young dogs (8, 10, 21, 22, 24, 27) than in adults, which may only be asymptomatic carriers. This case indicates adult carrier dogs without dermatitis as a source of infestation, themselves likely escaping diagnosis. Dam 1 may have been the source of infestation in the present report. Her pups 188
. ~ .;t
Cheyletiella yasguri
could have received the mites during the direct contact of nursing. Subsequent housing of these pups with those of the other dams may have afforded the opportunity for spread to all of the animals. Active reproduction of mites with extensive dermatitis in pups is apparently followed by abatement of clinical signs within six to ten weeks. It would appear that Cheyletiella infestations are self-limiting in affected dogs, but whether this phenomenon is due to acquired immunity or to other host or parasite effects is not elucidated. Treatment with acaricides is indicated, however, to prevent the self-inflicted trauma of scratching and possible spread of mites to man. Summary An outbreak of infestation of kennel pups with Cheyletiella yasguri is reported. All nine pups which were kept in a run were affected,
..
........!
!.
FIGURE 10. Ventral view of larva of Cheyletiella yasguri in egg. Note the three pairs of legs folded in, leg 4 not being developed in larva. x 325.
n'
FIGURE 9. Early development of appendages of Cheyletiella yasguri in egg which is fixed to hair. X375.
FIGURE 11. Anterior view of Cheyletiella yasguri larva shown in Figure 10. Note the horn-like structure in focus (arrow). x600. 189
CANADIAN VETERINARY JOURNAL
FIGURE 12. A newly hatched larva ot Chejyletielkl yasguri. Note that the pair of legs 3 are still folded in.
FIGURE 14. Residual exuvial covering (egg shell) after hatching of larva of Cheyletiella yasguri. Note fine thread woven into a cocoon-like structure attached to hair. X375.
FIGURE 13. Nymph of Cheyletiella yasguri.
x150.
and one of their dams appeared to be the source of the infestation. Virtually all the developmental stages, ranging from the egg to the adult, of C. yasguri were demonstrated in the skin scrapings obtained from each affected pup. The infestation was associated with varying degress of dermatitis characterized principally by cutaneous exfoliation, scurf or dandruff and vigorous scratching. Also, persons known to have been in intimate contact with the affected animals developed skin lesions which were accompanied by an intense itch and irritation, apparently attributable to C. yasguri.
Resume Les auteurs rapportent l'infestation des chiots d'un chenil par Cheyletiella yasguri. La condition affectait les neuf chiots qu'on gardait dans un parc exterieur; il semble que l'une des meres de ces chiots ait ete a l'origine de l'infestation. Les grattages cutanes de ces chiots recelaient tous les stades evolutifs de C. yasguri, de l'oeuf 'a l'adulte. L'infestation s'accompagnait de divers degres d'une dermatite qui se caracterisait surtout par de l'exfoliation cutanee, des pellicules et un grattage intense. De plus, les personnes etant venues en contact 6troit avec ces chiots developperent des lesions cutanees qui s'accompagnaient d'une demangeaison intense et d'une irritation apparemment attribuables a C. yasguri.
190
Acknowledgments We are grateful to the owner of the kennel for her generous cooperation and assistance.
Cheyletiella yasguri References 1. BAKER, K. P. Infestation of domestic animals with the mite Cheyletiella parasitivorax. Vet. Rec. 84: 561. 1969. 2. BAKER, K. P. Parasitic skin diseases of dogs and cats. Vet. Rec. 87: 452-459. 1970. 3. BAKKERs, E. J. M. and A. FAIN. Dermatitis in man and in a dog caused by the mite Cheyletiella yasguri Smiley. Br. J. Derm. 87: 245-247. 1972 4. BjARKE, T., L. HELLGREN and K. ORSTADIUS. Cheyletiella parasitivorax dermititis in man. Acta Dermatovener, Stockholm 53: 217-224. 1973. 5. BROCiS, D. C. Scurf in dogs. Vet. Rec. 89: 473. 1971. 6. CANEsTRIm, G. Prospetto del'acarofauna italiana. Part 2. Famiglie: Erythracini, cheyletini Bdellini, Eupodini e Analgesini. Atti. R. 1st Veneto Sci., Lett ed Arti. Series 6, 3 (2): 1647-1688, 1844-85. 7. DAVIS, G. B. and M. G. KYLE. Cheyletiella yasguri infestation of a dog. N.Z. vet. J. 17: 136. 1969. 8. DODD, K. Cheyletiella yasguri: widespread infestation in a breeding kennel. Vet. Rec. 86: 346-347. 1970. 9. EWING, S. A., J. E. MOSIER and T. S. Foxx. Occurrence of Cheyletiella spp. on dogs with skin lesions. J. Am. vet. med. Ass. 151: 6467. 1967. 10. Foxx, T. S. and S. A. EWING. Morphologic features, behaviour, and life history of Cheyletiella yasguri. Am. J. vet. Res. 30: 269-285. 1969. 11. FRECHETTE, J. L. and R. J. HARRISON. Cheyletiella yasguri chez un chiot. Can. vet. J. 12: 204-206. 1971. 12. GETHING, M. A. Cheyletiella infestation in small animals. Vet. Bull. 43: 63-69. 1973. 13. GETHING, M. A. and G. S. WALTON. POSsible host specificity of Cheyletiella mites. Vet. Rec. 90: 512. 1972. 14. HART, C. B. and J. C. MALONE. The occurence of the rabbit fur mite, Cheyletiella parasitivorax (Megnin, 1878) on the dog.
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Vet. ReC. 70: 991-993. 1958. 15. HEWIrr, M., G. S. WALTON and M. WATERHOUSE. Pet animal infestations and human skin lesions. Br. J. Derm. 85: 215-225. 1971. 16. HUMPHREYS, M. Cheyletiella parasitivorax infestation of the dog. Vet. Rec. 70: 442. 1958. 17. KRAL, F. and J. P. USCAVAGE. Cheyletiella parasitivorax in a dog. J. small Anim. Pract. 1: 277-278. 1961. 18. KuscHER, A. Raubmilben bein Hund. Wien. tierarztl. Mschr. 27: 10-16. 1940. 19. MACLULICH, D. A. Fluctuations in the numbers of the varying hare (Lepus americanus). Univ. Toronto Stud. Biol. Ser. No. 43. 1937. 20. MEGNIN, P. Memoire sur un nouveau groupe d'acariens, sur les cheyletides parasites. J. Anat. Physiol., Paris 14: 416-441. 1878. 21. REED, C. M. Cheyletiella parasitivorax infestation of pups. J. Am. vet. med. Ass. 138: 306-307. 1961. 22. SCHAFFER, M. H., N. F. BAKER and P. C. KENNEDY. Parasitism by Cheyletiella parasitivorax. A case report of the infestation in a female dog and its litter. Cornell Vet. 48: 440-447. 1958. 23. SMILEY, R. L. Two new species of the genus Cheyletiella (Acarina: Cheyletidae) Proc. ent. Soc. Wash. 67: 75-79. 1965. 24. SMITH, A. J. Scurf in dogs. Vet. Rec. 89: 394. 1971. 25. THOMSErr, L. R. Mite infestations of man contracted from dogs and cats. Br. med. J. 3: 93-95. 1968. 26. VEEN, Tj. SCHILLHORN VAN and J. H. BARNES. Occurence of Cheyletiella mites on pet animals in Northern Nigeria. Vet. Rec. 93: 487. 1973. 27. WEITKAMP, R. A. Cheyletiella parasitivorax parasitism in dogs. J. Am. vet. med. Ass. 144: 597-599. 1964. 28. YASGUR, I. Parasitism of kennel puppies with the mite Cheyletiella parasitivorax. Cornell Vet. 54: 406-407. 1964.
Introduction The description of mites belonging to the genus Cheyletiella dates back to 1878 when Megnin (20) first found them on the rabbit (Oryctolagus cuniculus) in France. These mites were assigned to the species C. parasitivorax (6, 20). Cheyletiella have since been reported on dogs, cats, foxes and badgers. The infestation of the dog with Cheyletiella was first reported by Kuscher (18) in Austria, and similar reports from other parts of the world have been increasing. Gething (12) presents a review of these infestations. Until recently, though, Cheyletiella removed from dogs have been assumed to belong to the species C. parasitivorax. However, Smiley in 1965 (23) speciated the mite found on dogs as C. yasguri, C. parasitivorax being retained for that found on rabbits. Thus, in most reports of Cheyletiella on dogs subsequent to Smiley's work, the mites have been described as C. yasguri (1, 7, 8, 9, 10, 11, 26). There has been much dispute as to whether or not C. yasguri (parasitivorax) behaves as a harmful parasite on dogs. Most of the accumulated evidence shows that Cheyletiella does induce skin lesions in dogs; variously described as cutaneous exfoliation, "scurf" or "dandruff' accompanied by intense scratching (5, 10, 14, 16, 21, 22, 24, 26, 28). Furthermore, Cheyletiella has been incriminated in skin lesions of human beings in contact with infested dogs (3, 4, 5, 7, 8, 15, 16, 17, 24, 27). Information on Cheyletiella infestation of animals in Canada is limited. The first report was made by Maclulich (19) who removed Cheyletiella from hares in Ontario. The only other literature on Cheyletiella infestation in Canada is that of Fr6chette and Harrison (11) *Department of Microbiology and Immunology, Faculty of Medicine, University of Montreal, Montreal, Quebec (Ayalew) and The Animal Hospital of Westmount, 349 Victoria Avenue, Montreal, Quebec (Vaillancourt). Present address of Dr. Ayalew: Health of Animals Branch, Agriculture Canada, 1441 St. Urbain Street, Montreal, Quebec.
who recovered C. yasguri from a pup in Quebec. In that report no skin lesions associated with the mite were found on the dog or its owner. This paper describes skin lesions of dogs and man attributable to heavy infestation with C. yasguri. Findings confirm that the mite completes its life cycle on a single dog. History and Clinical Findings On November 23, 1974 a three month old Old English Sheepdog female pup was admitted for clinical examination. The owner had bought the dog from a commercial kennel near Montreal four weeks earlier. The dog had been eating well and developing normally, but had been scratching vigorously. The owner had developed itchy skin lesions on the arms and waist over the past three weeks. A dermatologist had diagnosed her condition as scabies, and had suggested that she submit her dog for veterinary examination. The commercial kennel owner also had been complaining of similar skin lesions. The pup was in good physical condition except the coat appeared to be somewhat dry. Closer inspection revealed excessive scurf or "dandruff" extending particularly from the ears along the dorsal area to the base of the tail. Tufts of hair in affected areas had been or were easily pulled out. The horny layer of the skin was covered thickly with dry scales either in loose fragments, adhering, or fastened to hair. Thin pseudotunnels in the epidermal debris on the skin surface were scattered over the ears and the back. When palpated, these pseudotunnels could be felt as raised crusts and upon their removal, thin red cracks were left in the epithelium. From these and microscopic findings, infestation with Cheyletiella sp. was diagnosed and applications of benzyl benzoate were recommended. Subsequently, a visit was made to the kennel from which the pup was purchased. The kennel consisted of 30 dogs of different ages (seven weeks to adult) and breeds (Old English Sheepdog, Blue Danes, Bassets and
Samoyeds). Management was reasonable and
184
CAN. VET. JOUR., vol. 17, no. 7, July, 1976
Cheyletiella yasguri runs were separate and of good quality. Dogs of each breed and of similar ages were kept in groups in different runs. Eight Old English Sheepdog pups, two of which were littermates of the pup submitted to us in Montreal, were confined together. The owner of the kennel stated that most of these Old English Sheepdog pups had coat problems, similar to that of the dog examined in Montreal. The following history of the pups was given. Dams: The owner had taken three Old English Sheepdog dams (Dams 1, 2 and 3) from another commercial kennel, for whelping. These dams ranged in age from two to three years, and were all in mid- or late-pregnancy when introduced to her kennel on the 1st of August. The dams appeared normal and were eating well. It was noted, however, that Dam 1 had a rough dry coat but no veterinary consultation was sought because it was believed that the condition might be nutritional and temporary. The dams whelped on August 18, 23 and September 7, respectively. Some pups were stillborn and others had died following birth, each dam finally being left with four healthy pups. After about two weeks of nursing, Dam 1 began scratching and developing dandruff. The condition soon passed. No other dams experienced any clinical signs. Pups: By October 18, the pups of all the dams were weaned and one pup from each dam was given away. The remaining littermates from the three dams were kept together in one run. Their dams were placed in another run. At that time, all pups appeared to be normal and one was given to the owner who subsequently brought it to our clinic four weeks later. The kennel operator noticed scratching and dandruff on most of the pups from the last week of October on into November when the condition became severe in all remaining eight animals. All dogs were eating well and developing normally in spite of the infestation. From late October, the kennel operator herself developed widespread skin lesions, accompanied by constant and intense itch or irritation, over her arms, waist and legs, which her physician assumed to be hives. The "rash" on her body consisted of elevated red papules (about 3-6 mm in diameter) which were scattered in isolated groups or diffusely. Two visitors to the kennel, a lady and a young boy, also complained of similar skin lesions. These visitors had stayed with her only for a day sometime in October during which time they had played with the affected pups. By contrast, the kennel operator's husband never
had skin problems, as he seldom had the opportunity to come into direct contact with the pups.
All dogs examined at the kennel appeared to be in good physical condition. However, the condition of the coats of all eight Old English Sheepdog pups was poor and similar in appearance to that of the pup submitted to our clinic. The intensity of the dandruff and skin lesions on individual pups varied from moderate to severe, and in some cases the lesions extended along the legs. Two animals were severely affected: ridges of sores and hardened skin had developed on affected areas, apparently from licking and vigorous scratching. The kennel was revisited two weeks later. Four of the Old English Sheepdog pups and the three dams had been given away. Of the remaining four pups, two had been shampooed by the owner once with an acaricide, a week previously, and were confined alone in another run. The remaining two were not treated and were still housed in the same run previously used for all eight pups. No dandruff was found on the treated pups. Compared to the first visit, a lesser amount of dandruff was found on the two animals not treated. The kennel operator's skin problem had also abated. Figure 1 shows hair loss and scurfiness over the ears of one pup during the second visit to the kennel.
Parasitological Examination Deep and superficial skin scrapings were obtained from several affected areas on the pup
FIGURE 1. Lesions of ear of a pup infested with Cheyletiella yasguri. Note cutaneous exfoliation and dandruff on an opened coat. 185
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submitted originally to the clinic. Also brushings of the coat were taken using a hardbristled brush. Similarly, scrapings and brushings were taken from each of the eight Old English Sheepdog pups, their three dams and several other dogs examined at the kennel on the first visit. Two weeks later, a second series of coat specimens was taken from four of the Old English Sheepdog pups, two of which had been treated with an acaricide a week earlier. Scrapings and brushings from individual animals were saved separately for microscopic examinations. All samples were examined the day of collection using direct wet mounts in mineral oil or KOH digestion. Many living Cheyletiella, ranging in developmental stage from egg to adult (Figures 2-14), were seen in the specimens from the pup brought to our clinic and from each of FIGURE 3. Anterior aspect of Cheyletiella yasthe Old English Sheepdog pups from the first visit to the kennel. The sense organ on genu I guri showing the palpal claws (arrow). x375. of all Cheyletiella seen was heart-shaped (Figure 5) indicating the species to be C. from skin scrapings is made on the basis of yasguri (23). No other mange mite or fun- heavy curved palpal claws (Figure 3) and a gus was seen in any specimen. No mites were comblike tarsal appendage (Figure 4) at the found in specimens taken from the Old En- distal end of each leg. The heart-shaped glish Sheepdog dams or from other dogs at sense organ on genu I (Figure 5) indicates the kennel. Only fragments of adult mites and the species to be C. yasguri (23). The adult egg shells were found in samples from one of mite (Figure 2) is yellow and measures 466the untreated pups after the second visit to 500 microns long by 300-320 microns wide. Mite eggs may be fastened to hairs by loosely the kennel. woven cocoon-like strands (Figure 6). Some eggs may be free among skin debris or even Discussion In diagnosis of Cheyletiella infestation, passed in feces if the dog has been licking at morphological identification of adult mites the lesions (9, 21, 28). Eggs are nonoperculate, elliptical in shape and approximately 190 to 260 microns long by 110 to 140 microns wide. Inside, their contents vary from a developing cytoplasmic mass (Figures 6-9) to a recognizable mite larva with six folded legs (Figure 10). Extending through the blunt pole of fully developed eggs, a lancet-shaped hornlike process is visible (Figure 11). This unusual structure remains with the eggshell after hatching (10) and possibly aids the larva in breaking through the shell. Until recently, Cheyletiella species removed from dogs in different countries have been assumed to be C. parasitivorax. In 1965, however, Smiley (23) described a new species, which he named C. yasguri, from dogs in the U.S.A. Subsequent to Smiley's work, Cheyletiella recovered from dogs have been usually described as C. yasguri (1, 3, 7, 8, 9, 10, 11, 26) with C. parasitivorax by a few (4, 5, 24). C. yasguri has been recorded mostly from dogs. It is tentatively held that the dog is the natural host for C. yasguri while C. paraFIGURE 2. Adult CheyletieUa yasguri. x 150. sitivorax parasitizes rabbits. However, as 186
Cheyletiella yasguri The bulk of accumulated evidence thus appears to favor the latter contention, and it is now well recognized that Cheyletiella may in fact induce cutaneous lesions on dogs. The present observations constitute significant clinical findings caused by C. yasguri in a group of young dogs. The literature is lacking I * such a report from Canada. Frechette and Harrison (11) have previously reported recovering C. yasguri from a three month old
FIGuRE 4. Comb-like structure at the extremity of tarsus of Cheyletiella yasguri. x 1600.
Gething and Walton (13) suggest, the host specificity of Cheyletiella species requires further elu'cidation. The behaviour of Cheyletiella on dogs has been subject to much dispute for many years. One group of workers (11, 18, 21) holds the view that Cheyletiella are predators on other mites causing no clinical signs themselves on dogs. A second group of workers claims, however, that Cheyletiella live on the host as true parasites (2, 5, 10, 14, 16, 21, 22, 24, 26, 28).
FIGURE 5. Heart-shaped sense organ (arrow) on genu I of CheyletieUa yasguri. x1600. 187
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FIGURE 6. Two unembryonated eggs of Cheyletiella yasguri. Note the fine thread woven around the eggs which are fixed to hair. x 150.
FIGuRE 8. Segmentation of embryo of Cheyletiella yasguri. x 375.
FIGURE 7. Early developmental elongation of Cheyletiella yasguri embryo in egg. X325.
Pomeranian puppy in Quebec, but the mites were not associated with dermatitis. In the present case, virtually all the clinical signs and lesions characteristic of Cheyletiella infestation were seen. The syndrome in dogs may escape casual observation but closer inspection may reveal extensive dermatitis characterized by heavy dandruff over the ears and the entire back. Skin scrapings often show large numbers of mites in all stages of development. Furthermore, persons who were known to have been in contact with the present pups had all complained of skin problems apparently attributable to C. yasguri. The public health problem of Cheyletiella species from dogs is well recognized in other parts of the world (3, 7, 8, 15, 16, 17, 25) and the skin condition in man has been called "cheyletosis" by Hewitt et al (15). Cheyletiella infestations are known to be more severe in young dogs (8, 10, 21, 22, 24, 27) than in adults, which may only be asymptomatic carriers. This case indicates adult carrier dogs without dermatitis as a source of infestation, themselves likely escaping diagnosis. Dam 1 may have been the source of infestation in the present report. Her pups 188
. ~ .;t
Cheyletiella yasguri
could have received the mites during the direct contact of nursing. Subsequent housing of these pups with those of the other dams may have afforded the opportunity for spread to all of the animals. Active reproduction of mites with extensive dermatitis in pups is apparently followed by abatement of clinical signs within six to ten weeks. It would appear that Cheyletiella infestations are self-limiting in affected dogs, but whether this phenomenon is due to acquired immunity or to other host or parasite effects is not elucidated. Treatment with acaricides is indicated, however, to prevent the self-inflicted trauma of scratching and possible spread of mites to man. Summary An outbreak of infestation of kennel pups with Cheyletiella yasguri is reported. All nine pups which were kept in a run were affected,
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FIGURE 10. Ventral view of larva of Cheyletiella yasguri in egg. Note the three pairs of legs folded in, leg 4 not being developed in larva. x 325.
n'
FIGURE 9. Early development of appendages of Cheyletiella yasguri in egg which is fixed to hair. X375.
FIGURE 11. Anterior view of Cheyletiella yasguri larva shown in Figure 10. Note the horn-like structure in focus (arrow). x600. 189
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FIGURE 12. A newly hatched larva ot Chejyletielkl yasguri. Note that the pair of legs 3 are still folded in.
FIGURE 14. Residual exuvial covering (egg shell) after hatching of larva of Cheyletiella yasguri. Note fine thread woven into a cocoon-like structure attached to hair. X375.
FIGURE 13. Nymph of Cheyletiella yasguri.
x150.
and one of their dams appeared to be the source of the infestation. Virtually all the developmental stages, ranging from the egg to the adult, of C. yasguri were demonstrated in the skin scrapings obtained from each affected pup. The infestation was associated with varying degress of dermatitis characterized principally by cutaneous exfoliation, scurf or dandruff and vigorous scratching. Also, persons known to have been in intimate contact with the affected animals developed skin lesions which were accompanied by an intense itch and irritation, apparently attributable to C. yasguri.
Resume Les auteurs rapportent l'infestation des chiots d'un chenil par Cheyletiella yasguri. La condition affectait les neuf chiots qu'on gardait dans un parc exterieur; il semble que l'une des meres de ces chiots ait ete a l'origine de l'infestation. Les grattages cutanes de ces chiots recelaient tous les stades evolutifs de C. yasguri, de l'oeuf 'a l'adulte. L'infestation s'accompagnait de divers degres d'une dermatite qui se caracterisait surtout par de l'exfoliation cutanee, des pellicules et un grattage intense. De plus, les personnes etant venues en contact 6troit avec ces chiots developperent des lesions cutanees qui s'accompagnaient d'une demangeaison intense et d'une irritation apparemment attribuables a C. yasguri.
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Acknowledgments We are grateful to the owner of the kennel for her generous cooperation and assistance.
Cheyletiella yasguri References 1. BAKER, K. P. Infestation of domestic animals with the mite Cheyletiella parasitivorax. Vet. Rec. 84: 561. 1969. 2. BAKER, K. P. Parasitic skin diseases of dogs and cats. Vet. Rec. 87: 452-459. 1970. 3. BAKKERs, E. J. M. and A. FAIN. Dermatitis in man and in a dog caused by the mite Cheyletiella yasguri Smiley. Br. J. Derm. 87: 245-247. 1972 4. BjARKE, T., L. HELLGREN and K. ORSTADIUS. Cheyletiella parasitivorax dermititis in man. Acta Dermatovener, Stockholm 53: 217-224. 1973. 5. BROCiS, D. C. Scurf in dogs. Vet. Rec. 89: 473. 1971. 6. CANEsTRIm, G. Prospetto del'acarofauna italiana. Part 2. Famiglie: Erythracini, cheyletini Bdellini, Eupodini e Analgesini. Atti. R. 1st Veneto Sci., Lett ed Arti. Series 6, 3 (2): 1647-1688, 1844-85. 7. DAVIS, G. B. and M. G. KYLE. Cheyletiella yasguri infestation of a dog. N.Z. vet. J. 17: 136. 1969. 8. DODD, K. Cheyletiella yasguri: widespread infestation in a breeding kennel. Vet. Rec. 86: 346-347. 1970. 9. EWING, S. A., J. E. MOSIER and T. S. Foxx. Occurrence of Cheyletiella spp. on dogs with skin lesions. J. Am. vet. med. Ass. 151: 6467. 1967. 10. Foxx, T. S. and S. A. EWING. Morphologic features, behaviour, and life history of Cheyletiella yasguri. Am. J. vet. Res. 30: 269-285. 1969. 11. FRECHETTE, J. L. and R. J. HARRISON. Cheyletiella yasguri chez un chiot. Can. vet. J. 12: 204-206. 1971. 12. GETHING, M. A. Cheyletiella infestation in small animals. Vet. Bull. 43: 63-69. 1973. 13. GETHING, M. A. and G. S. WALTON. POSsible host specificity of Cheyletiella mites. Vet. Rec. 90: 512. 1972. 14. HART, C. B. and J. C. MALONE. The occurence of the rabbit fur mite, Cheyletiella parasitivorax (Megnin, 1878) on the dog.
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Vet. ReC. 70: 991-993. 1958. 15. HEWIrr, M., G. S. WALTON and M. WATERHOUSE. Pet animal infestations and human skin lesions. Br. J. Derm. 85: 215-225. 1971. 16. HUMPHREYS, M. Cheyletiella parasitivorax infestation of the dog. Vet. Rec. 70: 442. 1958. 17. KRAL, F. and J. P. USCAVAGE. Cheyletiella parasitivorax in a dog. J. small Anim. Pract. 1: 277-278. 1961. 18. KuscHER, A. Raubmilben bein Hund. Wien. tierarztl. Mschr. 27: 10-16. 1940. 19. MACLULICH, D. A. Fluctuations in the numbers of the varying hare (Lepus americanus). Univ. Toronto Stud. Biol. Ser. No. 43. 1937. 20. MEGNIN, P. Memoire sur un nouveau groupe d'acariens, sur les cheyletides parasites. J. Anat. Physiol., Paris 14: 416-441. 1878. 21. REED, C. M. Cheyletiella parasitivorax infestation of pups. J. Am. vet. med. Ass. 138: 306-307. 1961. 22. SCHAFFER, M. H., N. F. BAKER and P. C. KENNEDY. Parasitism by Cheyletiella parasitivorax. A case report of the infestation in a female dog and its litter. Cornell Vet. 48: 440-447. 1958. 23. SMILEY, R. L. Two new species of the genus Cheyletiella (Acarina: Cheyletidae) Proc. ent. Soc. Wash. 67: 75-79. 1965. 24. SMITH, A. J. Scurf in dogs. Vet. Rec. 89: 394. 1971. 25. THOMSErr, L. R. Mite infestations of man contracted from dogs and cats. Br. med. J. 3: 93-95. 1968. 26. VEEN, Tj. SCHILLHORN VAN and J. H. BARNES. Occurence of Cheyletiella mites on pet animals in Northern Nigeria. Vet. Rec. 93: 487. 1973. 27. WEITKAMP, R. A. Cheyletiella parasitivorax parasitism in dogs. J. Am. vet. med. Ass. 144: 597-599. 1964. 28. YASGUR, I. Parasitism of kennel puppies with the mite Cheyletiella parasitivorax. Cornell Vet. 54: 406-407. 1964.
