Cysticercosis in a canine host (Canis jamiliaris) attributable to the taeniid cestode Taenia crassiceps is reported for the first time in North America. Numerous parent and daughter cysticerci occurred in a massive intrapleural and intraperitoneal infection in an apparently immunocompromised host. The largest cysticerci were ovoid to elongate. 5-9 mm in maximum length. and armed with 32-34 rostellar hooks in two rows; small hooks measured 114-143 μm long (avg. = 124 ± 8.2 μm). and large hooks were 156-180 μm (avg. = 163 ± 7.4 μm). Taenia crassiceps is widespread in boreal North America and, like a number of other taeniids, constitutes a potential risk as a zoonotic parasite. The immunological status of the host may be important in determining the outcome of infections for this and other taeniids in atypical hosts

Ebinger, William

Hoberg, Eric P.

Render, James A.

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Faculty Publications from the Harold W. Manter Laboratory of Parasitology Parasitology, Harold W. Manter Laboratory of 12-1999 Fatal Cysticercosis by Taenia crassiceps (Cyclophyllidea: Taeniidae) in a Presumed Immunocompromised Canine Host Eric P. Hoberg United States Department of Agriculture, ehoberg@ggpl.arsusda.gov William Ebinger James A. Render Follow this and additional works at: https://digitalcommons.unl.edu/parasitologyfacpubs  Part of the Parasitology Commons Hoberg, Eric P.; Ebinger, William; and Render, James A., "Fatal Cysticercosis by Taenia crassiceps (Cyclophyllidea: Taeniidae) in a Presumed Immunocompromised Canine Host" (1999). Faculty Publications from the Harold W. Manter Laboratory of Parasitology. 402. https://digitalcommons.unl.edu/parasitologyfacpubs/402 This Article is brought to you for free and open access by the Parasitology, Harold W. Manter Laboratory of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Faculty Publications from the Harold W. Manter Laboratory of Parasitology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 1174 THE JOURNAL OF PARASITOLOGY, VOL. 85, NO.6, DECEMBER 1999 J. Parasitol., 85(6),1999 p. 1174- 1178 © American Society of Parasitologists 1999 Fatal Cysticercosis by Taenia crassiceps (Cyclophyllidea: Taeniidae) in a Presumed Immunocompromised Canine Host Eric P. Hoberg, William Ebinger*, and James A. Rendert , United States Department of Agriculture, Agricultural Research Service, Biosystematics and National Parasite Collection Unit, BARC East No. 1180, 10300 Baltimore Avenue, Beltsville, Maryland 20705. *Oakland Animal Hospital, 180 East Second Street, Rochester, Michigan 48307. tAnimal Health Diagnostic Laboratory and Department of Veterinary Pathology, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824 ABSTRACT: Cysticercosis in a canine host (Canis jamiliaris) attribut-able to the taeniid cestode Taenia crassiceps is reported for the first time in North America. Numerous parent and daughter cysticerci oc-curred in a massive intrapleural and intraperitoneal infection in an ap-parently immunocompromised host. The largest cysticerci were ovoid to elongate. 5-9 mm in maximum length. and armed with 32-34 ros-tellar hooks in 2 rows; small hooks measured 114-143 ILm long (x = 124 :t 8.2 ILm). and large hooks were 156-180 ILm (x = 163 :t 7.4 ILm). Taenia crassiceps is widespread in boreal North America and, like a number of other taeniids, constitutes a potential risk as a zoonotic parasite. The immunological status of the host may be important in determining the outcome of infections for this and other taeniids in atypical hosts. Taenia crassiceps (Zeder, 1800) is a commonly occurring tapeworm in the Holarctic and circulates among canids and ro-dents across northern regions of the United States and Canada (e.g., Leiby and Whittaker, 1966; Freeman et a!., 1973; Ander-son et a!., 1990). Strobilate adults are intestinal parasites that develop in foxes (including Vulpes vulpes L. and Alopex la-gopus L.), coyotes (Canis latrans Say), and other canids such as domesticated dogs (Canis jamiliaris L.), whereas cysticerci generally occur in the musculature, subcutaneous tissues, peri-toneal, and pleural cavity of various rodents (Rausch, 1959; Freeman, 1962; Abuladze, 1965; Verster, 1969). We report a remarkable disseminated intraperitoneal, intrapleural, and pul-monary cysticercosis attributable to T. crassiceps in a young chocolate Labrador retriever from Columbus, Michigan, treated with immunosuppressive drugs. A 6-mo-old female dog weighing 53 lbs was examined for bilateral exophthalmos. The ocular condition was thought to have been caused by an immune-mediated extraocular poly-myositis. Treatment consisting of prednisolone (25 mg p.o., twice a day, POIBID; Ved Co Inc ., St. Joseph, Missouri) and Imuran® (25 mg, POIBID; e.g., Azthioprine, USP; Glaxo-Well-come, Research Triangle, North Carolina) for 33 days resulted in an improved condition except for a slight anemia with a packed cell volume (PCV) of 31.9%. Subsequent treatment con-sisting of prednisolone (20 mg, BID) and Imuran® (25 mg, BID) continued for 5 days; the latter was discontinued when clinical findings included severe ventral abdominal cutaneous bruising, jaundice, and shock with pale mucous membranes and respiratory distress. Clotting time was normal, and PCV was 30%. Serum alkaline phosphatase was 1,963 and the alanine aminotransferase (ALT) was 2,304. Radiographically, the chest and abdomen were unremarkable. A transfusion of 250 ml of canine blood was administered and amoxicilin (500 mg POI BID; Consolidated Pharmaceuticals, Baltimore, Maryland) was given. Eventually, acute hemolytic crisis and dyspnea devel-oped. Prednisolone (5 mg POIBID) along with amoxicilin were administered until the time of euthanasia, 6 days later. During this time, PCV dropped from 30 to 17%, the white blood cell count (WBC) from 20,760 to 18,700, ALT from 2,010 to 276, and alkaline phosphatase from 2,548 to 1,806. Presumed im-munosuppression in this host is consistent with high dosages of Hoberg, Ebinger & Render: Fatal Cysticercosis by Taenia crassiceps ...Copyright 1999, American Society of Parasitologists. Used by permission.RESEARCH NOTES 1175 o FIGURES 1-4. Cysticercosis by Taenia crassiceps in a canine host. 1. Gross lesions in the lung shown in transverse hand-cut sections; note cavities (arrows) containing numerous cysticerci, demarcated by connective-tissue capsules (scale = 10 mm). 2. Cysticerci within cavernous inflammatory lesion surrounded by areas of hemorrhage in the lung of a dog, shown in tissue section stained with H&E (scale = 1.5 mm) 3. Parent cysticercus fully developed with two rows of rostellar hooks, shown in tissue section from lung (scale = 200 /-Lm) . 4. Parent cysticercus showing abscolex end with numerous daughter cysticerci in various stages of development; whole mount stained with Semichon 's acetic carmine (scale = 400 /-Lm) . prednisolone and Imuran over a 33-day period and the clinical observations of liver failure and changes in the WBe. At the time of euthanasia the dog was icteric, anemic, weak, panting, and anorexic. Euthanasia was accomplished by administration of Socumb® (pentobarbital sodium at 6 gmlml; The Butler Company, Columbus, Ohio). During postmortem, numerous (too abundant to count accu-rately), ovoid to slightly elongate cysticerci, approximately 5-9 mm in length for the largest metacestodes, were found free and observed moving within the pleural and peritoneal cavities (Figs. 1, 2). The lungs were diffusely edematous and with mul-tiple hemorrhages. Additionally, multiple cavities, each con-Hoberg, Ebinger & Render: Fatal Cysticercosis by Taenia crassiceps ...Copyright 1999, American Society of Parasitologists. Used by permission.1176 THE JOURNAL OF PARASITOLOGY, VOL. 85, NO.6, DECEMBER 1999 FIGURES 5, 6. Rostellar armature of T. crassiceps showing characteristic structure of small and large hooks (scale = SO j.Lm) . 5. Parent cysticercus with completely developed hooks. 6. Rostellar armature showing hooks with incomplete development of the handle. taining 1 cysticercus or multiple cysticerci, were scattered throughout the lungs. Other tissues or organs were not involved, and otherwise appeared unremarkable. Strobil ate specimens of cestodes were not present in the small intestine. Samples of various tissues, including extraocular muscles, and numerous cysticerci were collected and fixed in buffered 10% formalin. Fixed tissues were trimmed, processed, embed-ded in paraffin, and sectioned. Tissue sections, 4-5 f.Lm thick, were stained with hematoxylin and eosin (H&E). Representa-tive metacestodes were stained with Semichon's acetic carmine, dehydrated in ethanol, cleared in xylene, and mounted entire in Canada balsam; hooks from some specimens were mounted separately to allow detailed study of structure. Histologically, extraocular muscles had extensive infiltration of lymphocytes and plasma cells between myofibers and mul-tifocal necrosis and loss of myofibers. Proteinaceous fluid, blood, and many macrophages were present in alveoli. Meta-cestodes were present within capsules delimited by fibrous con-nective tissue containing eosinophils, lymphocytes, and plasma cells (Figs. 2, 3). Cysticerci were morphologically and ontogenetically consis-tent with T. crassiceps. Among 10 specimens collected from the peritoneal cavity and mounted entire, all were ovoid to elon-gate and 5-9 mm in maximum length by 3-4 mm in width; numerous specimens were considerably smaller. Cysticerci ex-hibited exogenous and endogenous budding at the polar end opposite the invaginated scolex (Fig. 4); development was pro-liferative. Among 5 scolices, the rostellum was armed with 2 rows of 16-17 small and large hooks (Figs. 5,6), respectively, for a total of 32-34. Small hooks measured 114-143 f.Lm long (n = 35; x = 124 ± 8.2 f.Lm), and large hooks were 156-180 f.Lm (n = 35; x = 163 ± 7.4 f.Lm). Representative specimens have been deposited in the U.S. National Parasite Collection, Biosystematics and National Parasite Collection Unit, USDA, Agricultural Research Service, Beltsville, Maryland (USNPC 87835). Hoberg, Ebinger & Render: Fatal Cysticercosis by Taenia crassiceps ...Copyright 1999, American Society of Parasitologists. Used by permission.Taenia crassiceps is unique among the taeniids in having a proliferative cysticercus that develops asexually by exogenous budding (Freeman, 1962). Rostellar hooks have a characteristic form, with the blade being markedly longer than the handle (Abuladze, 1965; Verster, 1969). In strobil ate specimens in ca-nids and in mature metacestodes in rodents, there are usually 30-36 hooks (occasionally as few as 28), with small hooks measuring 107-155 ILm and large hooks 155-200 ILm in length (Rausch, 1959; Freeman, 1962; Leiby and Whittaker, 1966; Verster, 1969). Chermette et ai. (1996) reported 31-34 hooks, measuring 92-153 ILm and 145- 201 ILm for small and large forms, respectively, from cysticerci infecting dogs in France. Globally, cysticercosis or coenurosis due to species of Taenia Linnaeus, 1758 in companion animals has been reported spo-radically, and most infections have been documented in feline hosts (e.g., Kingston et aI., 1984; Huss et aI., 1994). Reports of cysticercosis other than Taenia solium Linnaeus, 1758 in canine hosts are apparently rare, although dogs serve as defin-itive hosts for at least 7 species of Taenia (Verster, 1969; Cher-mette et al., 1993, 1996). In the United States, only cysticerci of T. pisiformis (Bloch, 1780) have been reported in dogs (Ivens et aI., 1969); the record herein is the first from North America for cysticercosis attributable to T. crassiceps in a canine host. In France there have been 3 reported cases of cysticercosis due to T. crassiceps in dogs (Chermette et aI., 1993, 1996). Among these hosts, 2 had cysticerci in subcutaneous tissues and 1 had a massive peritoneal infection similar to that observed in the current study. The epizootiology of canine cysticercosis is incompletely un-derstood. All cases have been in rural situations where foxes and a diversity of rodents are common (Chermette et aI., 1996). In Michigan and other boreal regions of the U.S., definitive hosts for T. crassiceps would be expected to include red fox, coyote, and dogs, whereas intermediate hosts may be repre-sented by voles and mice (e .g., species of Microtus Schrank and Peromyscus Gloger), squirrels (e.g., species of Tamias 11-liger, Sciurus Linnaeus, and Tamiasciurus Trouessart), wood-chucks (e.g., Marmota monax (Linnaeus», and other rodents (see Freeman, 1962). With respect to the current case, the lo-cality is an isolated area of northern Michigan, red foxes and coyotes are known in the local area, and the dog had recently eaten mice that had been caught by resident cats. Other com-panion animals in the household included 2 domesticated cats that were usually outside the residence. Exposure to infection for canine hosts may follow several potential routes: (1) via eggs in the environment, (2) autoinfec-tion via eggs from a strobil ate and gravid adult, and (3) via ingestion of cysticerci in the intermediate host (Freeman, 1962; Kroeze and Freeman, 1982; Chermette et aI., 1993, 1996). Rel-atively few oncospheres may be expected to result in a massive infection (Freeman, 1962), and there may be up to 13,000 eggs in a typical gravid segment (Miyaji et al., 1990). In the rodent intermediate host, complete development of the scolex requires 35- 42 days; budding occurs by 28 days PI, leading to massive infections that result from the cumulative production of cysti-cerci (Freeman, 1962). The presence of numerous parent and daughter cysticerci suggests that the dog was infected for at least several months or had initially received a large infective dose. Alternatively, the stage of development for metacestodes and the occurrence RESEARCH NOTES 1177 of both parent and daughter cysticerci in a young dog may be consistent with an infection acquired following ingestion of an intermediate host. Previous disease, stress, or medical and surgical procedures leading to an impaired immune system may predispose canines to cysticercosis (Chermette et aI., 1993, 1996). Thus, presumed immunosuppression of the dog in the current study, due to ad-ministration of prednisolone and Imuran may have been a con-tributing factor to a massive proliferative infection by T. cras-siceps; Imuran is typically used as an immunosuppressant (Cop-poc, 1988). Immunosuppression of this host is clearly suggested based on continuous treatment for 33 days at the highest rec-ommended dosages for these drugs. The immunological status of the host may be important in determining the outcome of infections for this and other taeniids. Taenia crassiceps is widespread in boreal North America and, like a number of other taeniids, constitutes a potential risk as a zoonotic parasite (Freeman et aI., 1973). Infections by T. crassiceps, however, may be particularly serious due to their proliferative nature, in contrast to cysticercosis associated with other species of Taenia. Subcutaneous infections may pose a limited clinical problem in humans, but localization in other organs could result in serious disease (Freeman et aI., 1973; Chermette et aI., 1996). The recent reports from Europe of pro-liferative infection by T. crassiceps in immunocompromised pa-tients with HIV highlights the potential importance of taeniids as zoonotic parasites (Chermette et aI., 1995). The authors thank Linda Mansfield and Alice Murphy of the Parasitology Laboratory, Animal Health Diagnostic Laboratory, Michigan State University, for their assistance during this study. We also thank Arthur Abrams of the BNPCU, ARS, Beltsville, for some photography. LITERATURE CITED ABULADZE, K. 1. 1965. Taeniata of animals and man and the diseases caused by them. In Essentials of cestodology 10, K. 1. Skrjabin (ed.). Akad Nauk SSSR, Helminthological Laboratory, Moscow. 549 p. [English Translation, 1970, by Israel Program for Scientific Translations, Jerusalem.] A NDERSON, W. 1. , D. W. SCOTT, W. E. HORNBUCKLE, J. M. KI NG, AND B. C. TENNANT. 1990. Taenia crassiceps infection in the woodchuck: A retrospective study of 13 cases. Veterinary Dermatology 1: 85-92. CHERMETTE, R. , J. BUSSIERAS, E. BIETOLA, H. MORET, M. MIALOT, AND P.-C. RAYNAL. 1996. Quelques parasitoses canines exceptionnelles en France Ill- Cysticercose proliferative du chien 11 Taenia cras-siceps: 11 propos de trois cas. Pratique Medicale and Chirurgicale de I' Animal de Compagnie 31: 125- 135. ---, ---, J. MARIONNEAU, E. BOYER, C. ROUBIN, B. PROPHETTE, H. MAILLARD, AND B. FABIANI. 1995. Cysticercose envahissante 11 Taenia crassiceps chez un patient atteint de sida. Bulletin de I' Academie Nationale de Medecine 179: 777- 783. ---, ---, M. MIALOT, AND P. C. RAYNAL. 1993. Subcutaneous Taenia crassiceps cysticercosis in a dog. Journal of the American Veterinary Medical Association 203: 263- 265. COPPoc, G. L. 1988. Chemotherapy of neoplastic diseases. In Veterinary pharmacology and therapeutics , 6th ed., N. H. Booth and L. E. MacDonald (eds.). Iowa State University Press, Ames, Iowa, p. 861 - 876. FREEMAN, R. S. 1962. Studies on the biology of Taenia crassiceps (Zed-er, 1800) Rudolphi, 1810 (Cestoda). Canadian Journal of Zoology 40: 969- 990. ---, A. M. FALLIS, M. SHEA, A. L. MABERLEY, AND J. WALTERS. 1973. Intraocular Taenia crassiceps (Cestoda) Part II. The parasite. American Journal of Tropical Medicine and Hygiene 22: 493- 495. Hoberg, Ebinger & Render: Fatal Cysticercosis by Taenia crassiceps ...Copyright 1999, American Society of Parasitologists. Used by permission.1178 THE JOURNAL OF PARASITOLOGY, VOL. 85, NO.6, DECEMBER 1999 Huss, B. T., M. A. MILLER, R. M. CORWIN, E. P. HOBERG, AND D. F ... LEIBY, P. D., AND F. H. WHITIAKER. 1966. Occurrence of Taenia cras-OBRIEN. 1994. Fatal cerebral coenurosis in a cat. Journal of the siceps in the conterminous United States. Journal of Parasitology American Veterinary Medical Association 205: 69- 71. IVENS, v., J. D. CONROY, AND N. D. LEVINE. 1969. Taenia pisiformis cysticerci in a dog in Illinois. American Journal of Veterinary Re-search 30: 2017- 2020. KINGSTON, N., E. S. WILLIAMS, R. C. BERGSTROM, W. C. WILSON, AND R. MILLER. 1984. Cerebral coenuriasis in domestic cats in Wyo-ming and Alaska. Proceedings of the Helminthological Society of Washington 51: 309-314. KROEZE, W. K., AND FREEMAN, R. S. 1982. Taenia crassiceps: Fate of cysticerci following ingestion by the mouse. Experimental Parasi-tology 54: 425- 431. 52: 786. MIYAJI, S., Y. OKU, M. KAMIYA, M. OKAMOTO, M . OHBAYASHI, A. UCH-IDA, AND R. L. RAUSCH. 1990. Growth of a Japanese isolate of Taenia crassiceps in intermediate and definitive hosts. Parasitology Research 76: 351-354. RAUSCH, R. L. 1959. Studies on the helminth fauna of Alaska. XXXv. On the identity of certain cestodes (Taeniidae) from foxes. Pro-ceedings of the Helminthological Society of Washington 26: 125-131. VERSTER, A. 1969. A taxonomic revision of the genus Taenia Linnaeus, 1758 s. str. Onderstepoort Journal of Veterinary Research 36: 3-58. Hoberg, Ebinger & Render: Fatal Cysticercosis by Taenia crassiceps ...Copyright 1999, American Society of Parasitologists. Used by permission.

Fatal Cysticercosis by \u3ci\u3eTaenia crassiceps\u3c/i\u3e (Cyclophyllidea: Taeniidae) in a Presumed Immunocompromised Canine Host

UNL | Libraries

University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Faculty Publications from the Harold W. Manter 
Laboratory of Parasitology Parasitology, Harold W. Manter Laboratory of 
12-1999 
Fatal Cysticercosis by Taenia crassiceps (Cyclophyllidea: 
Taeniidae) in a Presumed Immunocompromised Canine Host 
Eric P. Hoberg 
United States Department of Agriculture, ehoberg@ggpl.arsusda.gov 
William Ebinger 
James A. Render 
Follow this and additional works at: https://digitalcommons.unl.edu/parasitologyfacpubs 
 Part of the Parasitology Commons 
Hoberg, Eric P.; Ebinger, William; and Render, James A., "Fatal Cysticercosis by Taenia crassiceps 
(Cyclophyllidea: Taeniidae) in a Presumed Immunocompromised Canine Host" (1999). Faculty 
Publications from the Harold W. Manter Laboratory of Parasitology. 402. 
https://digitalcommons.unl.edu/parasitologyfacpubs/402 
This Article is brought to you for free and open access by the Parasitology, Harold W. Manter Laboratory of at 
DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Faculty Publications from 
the Harold W. Manter Laboratory of Parasitology by an authorized administrator of DigitalCommons@University of 
Nebraska - Lincoln. 
1174 THE JOURNAL OF PARASITOLOGY, VOL. 85, NO.6, DECEMBER 1999 
J. Parasitol., 85(6),1999 p. 1174- 1178 
© American Society of Parasitologists 1999 
Fatal Cysticercosis by Taenia crassiceps (Cyclophyllidea: Taeniidae) in a Presumed 
Immunocompromised Canine Host 
Eric P. Hoberg, William Ebinger*, and James A. Rendert , United States Department of Agriculture, Agricultural Research Service, 
Biosystematics and National Parasite Collection Unit, BARC East No. 1180, 10300 Baltimore Avenue, Beltsville, Maryland 20705. *Oakland Animal 
Hospital, 180 East Second Street, Rochester, Michigan 48307. tAnimal Health Diagnostic Laboratory and Department of Veterinary Pathology, 
College of Veterinary Medicine, Michigan State University, East Lansing, Michigan 48824 
ABSTRACT: Cysticercosis in a canine host (Canis jamiliaris) attribut-
able to the taeniid cestode Taenia crassiceps is reported for the first 
time in North America. Numerous parent and daughter cysticerci oc-
curred in a massive intrapleural and intraperitoneal infection in an ap-
parently immunocompromised host. The largest cysticerci were ovoid 
to elongate. 5-9 mm in maximum length. and armed with 32-34 ros-
tellar hooks in 2 rows; small hooks measured 114-143 ILm long (x = 
124 :t 8.2 ILm). and large hooks were 156-180 ILm (x = 163 :t 7.4 
ILm). Taenia crassiceps is widespread in boreal North America and, like 
a number of other taeniids, constitutes a potential risk as a zoonotic 
parasite. The immunological status of the host may be important in 
determining the outcome of infections for this and other taeniids in 
atypical hosts. 
Taenia crassiceps (Zeder, 1800) is a commonly occurring 
tapeworm in the Holarctic and circulates among canids and ro-
dents across northern regions of the United States and Canada 
(e.g., Leiby and Whittaker, 1966; Freeman et a!., 1973; Ander-
son et a!., 1990). Strobilate adults are intestinal parasites that 
develop in foxes (including Vulpes vulpes L. and Alopex la-
gopus L.), coyotes (Canis latrans Say), and other canids such 
as domesticated dogs (Canis jamiliaris L.), whereas cysticerci 
generally occur in the musculature, subcutaneous tissues, peri-
toneal, and pleural cavity of various rodents (Rausch, 1959; 
Freeman, 1962; Abuladze, 1965; Verster, 1969). We report a 
remarkable disseminated intraperitoneal, intrapleural, and pul-
monary cysticercosis attributable to T. crassiceps in a young 
chocolate Labrador retriever from Columbus, Michigan, treated 
with immunosuppressive drugs. 
A 6-mo-old female dog weighing 53 lbs was examined for 
bilateral exophthalmos. The ocular condition was thought to 
have been caused by an immune-mediated extraocular poly-
myositis. Treatment consisting of prednisolone (25 mg p.o., 
twice a day, POIBID; Ved Co Inc ., St. Joseph, Missouri) and 
Imuran® (25 mg, POIBID; e.g., Azthioprine, USP; Glaxo-Well-
come, Research Triangle, North Carolina) for 33 days resulted 
in an improved condition except for a slight anemia with a 
packed cell volume (PCV) of 31.9%. Subsequent treatment con-
sisting of prednisolone (20 mg, BID) and Imuran® (25 mg, 
BID) continued for 5 days; the latter was discontinued when 
clinical findings included severe ventral abdominal cutaneous 
bruising, jaundice, and shock with pale mucous membranes and 
respiratory distress. Clotting time was normal, and PCV was 
30%. Serum alkaline phosphatase was 1,963 and the alanine 
aminotransferase (ALT) was 2,304. Radiographically, the chest 
and abdomen were unremarkable. A transfusion of 250 ml of 
canine blood was administered and amoxicilin (500 mg POI 
BID; Consolidated Pharmaceuticals, Baltimore, Maryland) was 
given. Eventually, acute hemolytic crisis and dyspnea devel-
oped. Prednisolone (5 mg POIBID) along with amoxicilin were 
administered until the time of euthanasia, 6 days later. During 
this time, PCV dropped from 30 to 17%, the white blood cell 
count (WBC) from 20,760 to 18,700, ALT from 2,010 to 276, 
and alkaline phosphatase from 2,548 to 1,806. Presumed im-
munosuppression in this host is consistent with high dosages of 
Hoberg, Ebinger & Render: Fatal Cysticercosis by Taenia crassiceps ...Copyright 1999, American Society of Parasitologists. Used by permission.
RESEARCH NOTES 1175 
o 
FIGURES 1-4. Cysticercosis by Taenia crassiceps in a canine host. 1. Gross lesions in the lung shown in transverse hand-cut sections; note 
cavities (arrows) containing numerous cysticerci, demarcated by connective-tissue capsules (scale = 10 mm). 2. Cysticerci within cavernous 
inflammatory lesion surrounded by areas of hemorrhage in the lung of a dog, shown in tissue section stained with H&E (scale = 1.5 mm) 3. 
Parent cysticercus fully developed with two rows of rostellar hooks, shown in tissue section from lung (scale = 200 /-Lm) . 4. Parent cysticercus 
showing abscolex end with numerous daughter cysticerci in various stages of development; whole mount stained with Semichon 's acetic carmine 
(scale = 400 /-Lm) . 
prednisolone and Imuran over a 33-day period and the clinical 
observations of liver failure and changes in the WBe. At the 
time of euthanasia the dog was icteric, anemic, weak, panting, 
and anorexic. Euthanasia was accomplished by administration 
of Socumb® (pentobarbital sodium at 6 gmlml; The Butler 
Company, Columbus, Ohio). 
During postmortem, numerous (too abundant to count accu-
rately), ovoid to slightly elongate cysticerci, approximately 5-
9 mm in length for the largest metacestodes, were found free 
and observed moving within the pleural and peritoneal cavities 
(Figs. 1, 2). The lungs were diffusely edematous and with mul-
tiple hemorrhages. Additionally, multiple cavities, each con-
Hoberg, Ebinger & Render: Fatal Cysticercosis by Taenia crassiceps ...Copyright 1999, American Society of Parasitologists. Used by permission.
1176 THE JOURNAL OF PARASITOLOGY, VOL. 85, NO.6, DECEMBER 1999 
FIGURES 5, 6. Rostellar armature of T. crassiceps showing characteristic structure of small and large hooks (scale = SO j.Lm) . 5. Parent 
cysticercus with completely developed hooks. 6. Rostellar armature showing hooks with incomplete development of the handle. 
taining 1 cysticercus or multiple cysticerci, were scattered 
throughout the lungs. Other tissues or organs were not involved, 
and otherwise appeared unremarkable. Strobil ate specimens of 
cestodes were not present in the small intestine. 
Samples of various tissues, including extraocular muscles, 
and numerous cysticerci were collected and fixed in buffered 
10% formalin. Fixed tissues were trimmed, processed, embed-
ded in paraffin, and sectioned. Tissue sections, 4-5 f.Lm thick, 
were stained with hematoxylin and eosin (H&E). Representa-
tive metacestodes were stained with Semichon's acetic carmine, 
dehydrated in ethanol, cleared in xylene, and mounted entire in 
Canada balsam; hooks from some specimens were mounted 
separately to allow detailed study of structure. 
Histologically, extraocular muscles had extensive infiltration 
of lymphocytes and plasma cells between myofibers and mul-
tifocal necrosis and loss of myofibers. Proteinaceous fluid, 
blood, and many macrophages were present in alveoli. Meta-
cestodes were present within capsules delimited by fibrous con-
nective tissue containing eosinophils, lymphocytes, and plasma 
cells (Figs. 2, 3). 
Cysticerci were morphologically and ontogenetically consis-
tent with T. crassiceps. Among 10 specimens collected from 
the peritoneal cavity and mounted entire, all were ovoid to elon-
gate and 5-9 mm in maximum length by 3-4 mm in width; 
numerous specimens were considerably smaller. Cysticerci ex-
hibited exogenous and endogenous budding at the polar end 
opposite the invaginated scolex (Fig. 4); development was pro-
liferative. Among 5 scolices, the rostellum was armed with 2 
rows of 16-17 small and large hooks (Figs. 5,6), respectively, 
for a total of 32-34. Small hooks measured 114-143 f.Lm long 
(n = 35; x = 124 ± 8.2 f.Lm), and large hooks were 156-180 
f.Lm (n = 35; x = 163 ± 7.4 f.Lm). Representative specimens 
have been deposited in the U.S. National Parasite Collection, 
Biosystematics and National Parasite Collection Unit, USDA, 
Agricultural Research Service, Beltsville, Maryland (USNPC 
87835). 
Hoberg, Ebinger & Render: Fatal Cysticercosis by Taenia crassiceps ...Copyright 1999, American Society of Parasitologists. Used by permission.
Taenia crassiceps is unique among the taeniids in having a 
proliferative cysticercus that develops asexually by exogenous 
budding (Freeman, 1962). Rostellar hooks have a characteristic 
form, with the blade being markedly longer than the handle 
(Abuladze, 1965; Verster, 1969). In strobil ate specimens in ca-
nids and in mature metacestodes in rodents, there are usually 
30-36 hooks (occasionally as few as 28), with small hooks 
measuring 107-155 ILm and large hooks 155-200 ILm in length 
(Rausch, 1959; Freeman, 1962; Leiby and Whittaker, 1966; 
Verster, 1969). Chermette et ai. (1996) reported 31-34 hooks, 
measuring 92-153 ILm and 145- 201 ILm for small and large 
forms, respectively, from cysticerci infecting dogs in France. 
Globally, cysticercosis or coenurosis due to species of Taenia 
Linnaeus, 1758 in companion animals has been reported spo-
radically, and most infections have been documented in feline 
hosts (e.g., Kingston et aI., 1984; Huss et aI., 1994). Reports 
of cysticercosis other than Taenia solium Linnaeus, 1758 in 
canine hosts are apparently rare, although dogs serve as defin-
itive hosts for at least 7 species of Taenia (Verster, 1969; Cher-
mette et al., 1993, 1996). In the United States, only cysticerci 
of T. pisiformis (Bloch, 1780) have been reported in dogs (Ivens 
et aI., 1969); the record herein is the first from North America 
for cysticercosis attributable to T. crassiceps in a canine host. 
In France there have been 3 reported cases of cysticercosis due 
to T. crassiceps in dogs (Chermette et aI., 1993, 1996). Among 
these hosts, 2 had cysticerci in subcutaneous tissues and 1 had 
a massive peritoneal infection similar to that observed in the 
current study. 
The epizootiology of canine cysticercosis is incompletely un-
derstood. All cases have been in rural situations where foxes 
and a diversity of rodents are common (Chermette et aI., 1996). 
In Michigan and other boreal regions of the U.S., definitive 
hosts for T. crassiceps would be expected to include red fox, 
coyote, and dogs, whereas intermediate hosts may be repre-
sented by voles and mice (e .g., species of Microtus Schrank 
and Peromyscus Gloger), squirrels (e.g., species of Tamias 11-
liger, Sciurus Linnaeus, and Tamiasciurus Trouessart), wood-
chucks (e.g., Marmota monax (Linnaeus», and other rodents 
(see Freeman, 1962). With respect to the current case, the lo-
cality is an isolated area of northern Michigan, red foxes and 
coyotes are known in the local area, and the dog had recently 
eaten mice that had been caught by resident cats. Other com-
panion animals in the household included 2 domesticated cats 
that were usually outside the residence. 
Exposure to infection for canine hosts may follow several 
potential routes: (1) via eggs in the environment, (2) autoinfec-
tion via eggs from a strobil ate and gravid adult, and (3) via 
ingestion of cysticerci in the intermediate host (Freeman, 1962; 
Kroeze and Freeman, 1982; Chermette et aI., 1993, 1996). Rel-
atively few oncospheres may be expected to result in a massive 
infection (Freeman, 1962), and there may be up to 13,000 eggs 
in a typical gravid segment (Miyaji et al., 1990). In the rodent 
intermediate host, complete development of the scolex requires 
35- 42 days; budding occurs by 28 days PI, leading to massive 
infections that result from the cumulative production of cysti-
cerci (Freeman, 1962). 
The presence of numerous parent and daughter cysticerci 
suggests that the dog was infected for at least several months 
or had initially received a large infective dose. Alternatively, 
the stage of development for metacestodes and the occurrence 
RESEARCH NOTES 1177 
of both parent and daughter cysticerci in a young dog may be 
consistent with an infection acquired following ingestion of an 
intermediate host. 
Previous disease, stress, or medical and surgical procedures 
leading to an impaired immune system may predispose canines 
to cysticercosis (Chermette et aI., 1993, 1996). Thus, presumed 
immunosuppression of the dog in the current study, due to ad-
ministration of prednisolone and Imuran may have been a con-
tributing factor to a massive proliferative infection by T. cras-
siceps; Imuran is typically used as an immunosuppressant (Cop-
poc, 1988). Immunosuppression of this host is clearly suggested 
based on continuous treatment for 33 days at the highest rec-
ommended dosages for these drugs. The immunological status 
of the host may be important in determining the outcome of 
infections for this and other taeniids. 
Taenia crassiceps is widespread in boreal North America 
and, like a number of other taeniids, constitutes a potential risk 
as a zoonotic parasite (Freeman et aI., 1973). Infections by T. 
crassiceps, however, may be particularly serious due to their 
proliferative nature, in contrast to cysticercosis associated with 
other species of Taenia. Subcutaneous infections may pose a 
limited clinical problem in humans, but localization in other 
organs could result in serious disease (Freeman et aI., 1973; 
Chermette et aI., 1996). The recent reports from Europe of pro-
liferative infection by T. crassiceps in immunocompromised pa-
tients with HIV highlights the potential importance of taeniids 
as zoonotic parasites (Chermette et aI., 1995). 
The authors thank Linda Mansfield and Alice Murphy of the 
Parasitology Laboratory, Animal Health Diagnostic Laboratory, 
Michigan State University, for their assistance during this study. 
We also thank Arthur Abrams of the BNPCU, ARS, Beltsville, 
for some photography. 
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Fatal Cysticercosis by \u3ci\u3eTaenia crassiceps\u3c/i\u3e (Cyclophyllidea: Taeniidae) in a Presumed Immunocompromised Canine Host

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