Page 185 - The Veterinary Laboratory and Field Manual 3rd Edition

154 Susan C. Cork and Mani Lejeune

are a number of heads which resemble the scolex dIaGnoSIS
of the adult worm. The final host (that is, dog) • From the clinical signs coenurosis must be
becomes infected by ingesting the cyst. differentiated from other conditions which
affect the brain such as tumours, abscesses,
cLInIcaL SIGnS and dISEaSE ProcESS listeriosis, poisoning by certain plants, acute
The adult tapeworm in dogs causes no obvi- septicaemia and so on.
ous clinical disease. In the intermediate host, • Very often it is not possible to arrive at a defi-
there may be signs of nervousness and excit- nite diagnosis except during the post-mortem
ability (meningo-encephalitis) as the embryos examination.
wander about in the brain tissues. Post-mortem • Clinical epidemiology, previous history of
examination at this stage indicates the pres- cases in the area.
ence of numerous narrow tunnels in the brain.
Yellow streaks of dead tissue and small blisters trEatMEnt
are apparent on the brain surface. However, this • When the cyst is located on the surface of
tends to occur when several parasites invade the the brain surgical removal can be carried out.
brain simultaneously and in many cases these • In some instances, trephining or removal by
preliminary signs do not appear. The primary means of special trocar and cannula has given
acute stage is followed by a latent period of 4 good results.
to 6 months. This is followed by a chronic stage • Recently some anthelmintics have been tested
associated with the growth of the cyst and the for efficacy against coenurosis in sheep, for
production of pressure on the brain. The animal example praziquantel may be effective (seek
may develop stereotypic movements depending advice from the local veterinary officer for
on location of the cysts in the central nervous current recommendations).
system. Most cysts tend to develop in a region on • Regular anthelmintic medication for the
the surface of the cerebral hemisphere resulting definitive host (usually domestic dogs), for
in an animal that holds its head to one side and example, praziquantel is often very effective.
turns in a circle. Movement is usually towards
the affected side of the brain and in many cases controL MEaSurES
such animals are blind in the eye on the opposite • Prevent the final host (dog) from eating car-
side. When the parasite is lodged in the front casses potentially infected with coenurosis by
part of the brain the head is held high and the destroying the carcass.
animal steps high (trotters) or may walk in a • Regular treatment of the definitive host (dog)
straight line until it meets an obstacle. When with anthelmintics. With some products the
the cyst is found in the cerebellum the animal is dog should be confined for 48 h after treat-
easily frightened and it has a jerky and stagger- ment to facilitate the collection and proper
ing gait in the hind legs which gradually grows disposal of infected faeces.
worse and finally leads to collapse. In advanced • Education for the public with regard to the
cases, there may be actual deformity of the skull implementation of hygiene measures.
with softening of the skull bone. Post-mortem
examination usually reveals only one large vesi- Hydatidosis or echinococcosis
cle, 5 cm or more in diameter, in the brain. The
embryos arrested in other organs degenerate and Echinococcosis is caused by the tapeworm
either disappear or become a spherical encapsu- Echinococcus granulosus or E. multilocularis, which
lated body. are some of the smallest cestodes of domestic

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