CASE REPORT
tures and were filled with a relatively homogeneous, acidophilic, proteinaceous material and
nematode ova (Figure 1). Some of these structures located in portal triads and appeared to be bile ducts. The fibrous tissue in the walls of the tracts exhibited a mild inflammatory response. About 50% of the inflammatory cells were eosinophils, the rest being primarily plasma cells with occasional lymphocytes. While there was some compression and pressure atrophy of hepatocytes in the parenchyma surrounding the tracts, there was no inflammatory response outside the fibrous walls. The ova were lemon shaped, bipolar, operculate and had a thick bilayered wall (Figure 2). The transparent outer wall had a radially striated appearance, whereas the light brown inner wall was more dense and opaque. The mean dimensions of ten ova were 60.6 Am long by 31.8 ,tm wide. Many ova were fragmenting and calcification of their internal structures was common. were
Capillaria hepatica in
a
Horse
P. N. NATION AND K.H. DIES*
Introduction Capillaria hepatica is
a common parasite of rodents, but has been reported from many other species of mammals, including the dog, cat, coyote, skunk and pronghorn antelope (1, 2, 3,4, 6). It also occurs in humans with at least 11 authentic cases reported (5). The most recent published reports of C. hepatica in western Canada are those of Barrett and Chalmers (1) and of Wobeser and Rock (6) describing C. hepatica in pronghorn antelope and a coyote, respectively.
Histori' of Gross Pathologi' In February 1978, a one year old male quarterhorse cross horse from Fairview, Alberta was submitted to the Peace River Regional Veterinary Diagnostic Laboratory for necropsy. He was in good bodily condition and no signs of illness had been observed prior to death. Postmortem examination revealed a gastric rupture. Incidental postmortem findings were verminous arteritis and several pale, raised foci under the hepatic capsule. There were fewer than ten of these latter regions located in the parenchyma under the capsule. They consisted of clusters of cylindrical tracts in close proximity to each other. Individual tracts were 1-3 mm in diameter and contained a friable pale grey material. Where present in the parenchyma immediately under the hepatic capsule, they caused an irregular 1-2 mm elevation of the capsule above the surrounding area, giving the hepatic capsule a mammillated appearance over the affected regions.
Discussion This is the first published report of C. hepatica in a horse. In North America, the only other report of C. hepatica in a large herbivore is given by Barrett and Chalmers (1) from four pronghorn antelope taken near Medicine Hat in southern Alberta. The life cycle of the helminth is unusual. Infective ova are ingested and hatch in the cecum of the host. Larvae enter the hepatic portal vein and are found in the liver within 52 hours after infection. Larvae in the liver usually mature to adulthood and mate within 21 days. The adults then die, leaving the eggs encapsulated in fibrous tissue. Development of the eggs to the infective stage takes place only after they are freed from the liver and exposed to optimal temperature and moisture in the presence of sufficient oxygen. This
Histopathologv Sections of liver were fixed in 10% neutral buffered formalin, embedded in paraffin, sectioned at 6 ,um and stained by a routine hematoxylin and eosin method. Microscopic examination of the hepatic lesions revealed that the tracts were fibrous-walled struc-
FIGURE
1.
Tracts in the liver of a horse containing ova of
Capillaria hepatica. Note the proteinaceous material. fibrosis and mild compression of the surrounding hepatic parenchvma. X15.
*Peace River Regional Veterinary Diagnostic Laboratory Alberta Department of Agriculture. Box 197 Fairview, Alberta TOH I LO. Present address of Dr. Nation: Regional Veterinary Diagnostic Laboratory. Alberta Department of Agriculture, P.O. Bag #1, Airdrie, Alberta TOM OBO.
315
.4
.:..mbs $.
more severe inflammatory reaction with more fibrosis than we observed in the equine liver reported in this paper.
Summariy Ova of Capillaria hepatica were found in the liver of a horse from the Fairview area of Alberta. This is the first published report of C. hepatica in the horse. Gross and microscopic lesions in the 4~~~~~~~~ ; . x e~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. .... liver caused by C. hepatica are described.
A
FIGURE 2. Ova of Capillaria hepatica in the liver. Note the radially striated outer wall, dense inner wall and degenerative changes. X370.
can occur when the original host dies and decomposes, or alternatively, when the liver of the original host has been eaten by a predator and the eggs passed with the feces to the ground (5). It is interesting to note that many of the ova were calcified and/or fragmenting. Perhaps the liver of the horse may be an inhospitable environment for C. hepatica ova. Barrett and Chalmers (1) noted that mineralization of ova was also a salient feature in the liver of the pronghorn antelope they examined. In the pronghorn antelope there was a
316
Resume Les auteurs ont vu des oeufs du nematode Capillaria hepatica, dans le foie d'un cheval de la region de Fairview, en Alberta. I1 s'agit de la premiere publication de cette parasitose, chez le cheval. Les auteurs decrivent les lesions macroscopiques et microscopiques du foie de ce cheval. Footnote Tissue sections from the liver of this horse showing Capillaria hepatica ova have been deposited in the National Museum of Natural Sciences Invertebrate Collection (Parasites), Invertebrate Zoology Division, Ottawa, Canada. Accession # NMCIC (P) 200. REFERENCES
1. BARRETT, M. W. and G. A. CHALMERS. Capillaria hapatica (Nematoda: Trichuridae) in pronghorn antelope (Antiliocapra americana) in Alberta. J. Wild]. Dis. 8: 332-334. 1972. 2. BAYLIS. H. A. On the structure and relationship of the
3. 4.
5. 6.
nematode Capillaria hepatica (Hepaticola) Bancroft. J. Parasit. 23: 533-534. 1931. LAYNE. J. N. Host and ecological relationships of the parasitic helminth Capillaria hepatica in Florida mammals. Zoologica 53: 107-122. 1968. LAYNE. J. N. and C. E. WINEGARNER. Occurrence of Capillaria hepatica (Nematode: Trichuridae) in the spotted skunk in Florida. J. Wildl. Dis. 7: 256-257. 1971. OLSEN. 0. w. Animal Parasites: Their Life Cvcle and Ecology. Baltimore, Maryland: University Park Press. 1974. WOBESER. G. and T. W. ROCK. Capillaria hepatica (Nematoda: Trichuridae) in a coyote. J. Wildl. Dis. 9: 225-226. 1973.
tures and were filled with a relatively homogeneous, acidophilic, proteinaceous material and
nematode ova (Figure 1). Some of these structures located in portal triads and appeared to be bile ducts. The fibrous tissue in the walls of the tracts exhibited a mild inflammatory response. About 50% of the inflammatory cells were eosinophils, the rest being primarily plasma cells with occasional lymphocytes. While there was some compression and pressure atrophy of hepatocytes in the parenchyma surrounding the tracts, there was no inflammatory response outside the fibrous walls. The ova were lemon shaped, bipolar, operculate and had a thick bilayered wall (Figure 2). The transparent outer wall had a radially striated appearance, whereas the light brown inner wall was more dense and opaque. The mean dimensions of ten ova were 60.6 Am long by 31.8 ,tm wide. Many ova were fragmenting and calcification of their internal structures was common. were
Capillaria hepatica in
a
Horse
P. N. NATION AND K.H. DIES*
Introduction Capillaria hepatica is
a common parasite of rodents, but has been reported from many other species of mammals, including the dog, cat, coyote, skunk and pronghorn antelope (1, 2, 3,4, 6). It also occurs in humans with at least 11 authentic cases reported (5). The most recent published reports of C. hepatica in western Canada are those of Barrett and Chalmers (1) and of Wobeser and Rock (6) describing C. hepatica in pronghorn antelope and a coyote, respectively.
Histori' of Gross Pathologi' In February 1978, a one year old male quarterhorse cross horse from Fairview, Alberta was submitted to the Peace River Regional Veterinary Diagnostic Laboratory for necropsy. He was in good bodily condition and no signs of illness had been observed prior to death. Postmortem examination revealed a gastric rupture. Incidental postmortem findings were verminous arteritis and several pale, raised foci under the hepatic capsule. There were fewer than ten of these latter regions located in the parenchyma under the capsule. They consisted of clusters of cylindrical tracts in close proximity to each other. Individual tracts were 1-3 mm in diameter and contained a friable pale grey material. Where present in the parenchyma immediately under the hepatic capsule, they caused an irregular 1-2 mm elevation of the capsule above the surrounding area, giving the hepatic capsule a mammillated appearance over the affected regions.
Discussion This is the first published report of C. hepatica in a horse. In North America, the only other report of C. hepatica in a large herbivore is given by Barrett and Chalmers (1) from four pronghorn antelope taken near Medicine Hat in southern Alberta. The life cycle of the helminth is unusual. Infective ova are ingested and hatch in the cecum of the host. Larvae enter the hepatic portal vein and are found in the liver within 52 hours after infection. Larvae in the liver usually mature to adulthood and mate within 21 days. The adults then die, leaving the eggs encapsulated in fibrous tissue. Development of the eggs to the infective stage takes place only after they are freed from the liver and exposed to optimal temperature and moisture in the presence of sufficient oxygen. This
Histopathologv Sections of liver were fixed in 10% neutral buffered formalin, embedded in paraffin, sectioned at 6 ,um and stained by a routine hematoxylin and eosin method. Microscopic examination of the hepatic lesions revealed that the tracts were fibrous-walled struc-
FIGURE
1.
Tracts in the liver of a horse containing ova of
Capillaria hepatica. Note the proteinaceous material. fibrosis and mild compression of the surrounding hepatic parenchvma. X15.
*Peace River Regional Veterinary Diagnostic Laboratory Alberta Department of Agriculture. Box 197 Fairview, Alberta TOH I LO. Present address of Dr. Nation: Regional Veterinary Diagnostic Laboratory. Alberta Department of Agriculture, P.O. Bag #1, Airdrie, Alberta TOM OBO.
315
.4
.:..mbs $.
more severe inflammatory reaction with more fibrosis than we observed in the equine liver reported in this paper.
Summariy Ova of Capillaria hepatica were found in the liver of a horse from the Fairview area of Alberta. This is the first published report of C. hepatica in the horse. Gross and microscopic lesions in the 4~~~~~~~~ ; . x e~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. .... liver caused by C. hepatica are described.
A
FIGURE 2. Ova of Capillaria hepatica in the liver. Note the radially striated outer wall, dense inner wall and degenerative changes. X370.
can occur when the original host dies and decomposes, or alternatively, when the liver of the original host has been eaten by a predator and the eggs passed with the feces to the ground (5). It is interesting to note that many of the ova were calcified and/or fragmenting. Perhaps the liver of the horse may be an inhospitable environment for C. hepatica ova. Barrett and Chalmers (1) noted that mineralization of ova was also a salient feature in the liver of the pronghorn antelope they examined. In the pronghorn antelope there was a
316
Resume Les auteurs ont vu des oeufs du nematode Capillaria hepatica, dans le foie d'un cheval de la region de Fairview, en Alberta. I1 s'agit de la premiere publication de cette parasitose, chez le cheval. Les auteurs decrivent les lesions macroscopiques et microscopiques du foie de ce cheval. Footnote Tissue sections from the liver of this horse showing Capillaria hepatica ova have been deposited in the National Museum of Natural Sciences Invertebrate Collection (Parasites), Invertebrate Zoology Division, Ottawa, Canada. Accession # NMCIC (P) 200. REFERENCES
1. BARRETT, M. W. and G. A. CHALMERS. Capillaria hapatica (Nematoda: Trichuridae) in pronghorn antelope (Antiliocapra americana) in Alberta. J. Wild]. Dis. 8: 332-334. 1972. 2. BAYLIS. H. A. On the structure and relationship of the
3. 4.
5. 6.
nematode Capillaria hepatica (Hepaticola) Bancroft. J. Parasit. 23: 533-534. 1931. LAYNE. J. N. Host and ecological relationships of the parasitic helminth Capillaria hepatica in Florida mammals. Zoologica 53: 107-122. 1968. LAYNE. J. N. and C. E. WINEGARNER. Occurrence of Capillaria hepatica (Nematode: Trichuridae) in the spotted skunk in Florida. J. Wildl. Dis. 7: 256-257. 1971. OLSEN. 0. w. Animal Parasites: Their Life Cvcle and Ecology. Baltimore, Maryland: University Park Press. 1974. WOBESER. G. and T. W. ROCK. Capillaria hepatica (Nematoda: Trichuridae) in a coyote. J. Wildl. Dis. 9: 225-226. 1973.
