Ultrasonography in Hepatobiliary Evaluation of Domestic Cats ...

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Ultrasonography in Hepatobiliary
Evaluation of Domestic Cats
(Felis catus, L., 1758) Infected by
Platynosomum Looss, 1907

Márcia Salomão, DVM, MSc*
Letícia M. Souza-Dantas, DVM†
Flavya Mendes-de-Almeida, DVM, MSc‡
Aline S. Branco, DVM†
Otílio P.M. Bastos, MD, PhD§
Franklin Sterman, DVM, PhD||
Norma Labarthe, DVM, DSc*
*Departamento de Patologia e Clínica Veterinária Curso de Pós-Graduação em Ciências
Universidade Federal Fluminense

Veterinárias, Universidade Federal Rural do Rio
Niterói, Brazil
de Janeiro

Seropédica, Brazil
Curso de Pós-Graduação em Medicina
Veterinária, Faculdade de Veterinária
§Instituto Biomédico
Universidade Federal Fluminense
Universidade Federal Fluminense
Niterói, Rio de Janeiro, Brazil
Niterói, Rio de Janeiro, Brazil
||Faculdade de Medicina Veterinária e Zootecnia
Universidade de São Paulo
São Paulo, Brazil

KEY WORDS: P l a t y n o s o m u m, diagnosis,
frequency of associated alterations of bile
hepatobiliary, ultrasonography
ducts and gallbladder (29.1%) or liver, bile
ducts, and gallbladder in infected animals
(12.5%) was higher than in animals that did
not eliminate eggs (20.8% and 2.1% respec-
P l a t y n o s o m u m-infected cats are common in
tively), suggesting that associated sono-
tropical and sub-tropical regions of the
graphic alterations should be an indicator of
world. The helminths elicit unspecific clini-
P l a t y n o s o m u m spp. infection.
cal signs that are transitory, but, with the
evolution of the disease, they generally
reappear with chronic mucous diarrhea or
jaundice. Due to the absence of specific
Although different trematode species of the
clinical signs, in vivo diagnosis relies solely
families Opisthorchiidae and Dicrocoeliidae
in the detection of operculated eggs in feces.
can be found in the liver of domestic cats,1
A total of 72 cats were examined by abdom-
the genus P l a t y n o s o m u m Looss, 1907 is the
inal ultrasound and fecal samples and 33%
most commonly reported.2 The literature
were found to be infected. It was noted that
cites P. concinnum, P. illiciens, and P. fas-
although no individual sonic alteration
t o s u m infecting the gallbladder and bile
could be associated with the infection, the
ducts of cats; however, all these species
Intern J Appl Res Vet Med • Vol. 3, No. 3, 2005

may be synonymous.3 According to
hours after the cat ingests the parasitized
Travassos, Freitas, and Kohn4 in Brazil we
intermediary host, the metacercariae migrate
find the species P. illiciens (Braun, 1901)
through the minor duodenal papillae to the
Kossack, 1910, P. deflectens ( R u d o l p h i ,
common bile duct. Although rare, some
1819) Nicoll, 1915, and P. reficiens ( B r a u n ,
metacercariae can migrate through the
1901) Travassos, 1916, but only the P. illi-
minor duodenal papilla and reach the pan-
c i e n s parasitizes the bile ducts and gallblad-
creas through the side branches of the pan-
der of domestic cats. In this study, due to
creatic duct.2 1 The predator instinct of the
the controversy regarding nomenclature and
cats ensures that the cycle completes
the lack of recent taxonomic studies, we
because, even receiving food from their
opted for calling the parasites
owners, cats keep their habit of hunting.1 0 , 2 2
P l a t y n o s o m u m s p p .
Under experimental conditions, the pro-
Cats infected with this helminth can be
duction of eggs starts 4 to 5 weeks after the
found in tropical and sub-tropical regions all
cercariae reach the liver. The prepatent peri-
over the world. It has been described in the
od is 8 to 12 weeks. The life expectancy of
A n t i l l e s ,5 A u s t r a l i a ,6 the Bahamas,7
the adult forms, although unknown, is long
M a l a y s i a ,8 New Guinea,2 N i g e r i a ,9
as is the period of egg production.3 , 2 3 T h e
P o l y n e s i a ,2 Puerto Rico,1 0 and in the US in
pathogenesis of this infection also involves
the states of Ohio,1 1 F l o r i d a ,1 2 and Hawaii.1 3 , 1 4
the size and number of parasites. Adult par-
In Brazil, there is a recognized prevalence
asites have a flat body of ellipsoid or egg-
of 37.2%1 5 , 1 6 to 45% in the state of Rio de
like shape covered by a thin cuticle, and
Janeiro and capable of reaching 56.25%.1 7
their size varies between 2.9 to 6.7 mm in
Occurrences of P l a t y n o s o m u m spp were
length and 0.9 to 1.7 mm in width.4
also reported in the state of São Paulo1 8 w i t h
The clinical signs displayed by the cats
an incidence of 1.07% to 5.6%.1 9 , 2 0
vary, and their seriousness depends on the
The life cycle of this parasite is not well
number of adult parasites, the time of infec-
understood, but it is common knowledge
t i o n ,2 2 and on the individual reaction to para-
that cats acquire them through ingestion of
site aggression.1 0 Under experimental
small lizards. The cycle starts with the elim-
conditions, it was shown that cats with dis-
ination of eggs in the feces of infected cats.
crete infections (up to 125 parasites) remain
In the environment, the eggs are ingested by
clinically asymptomatic while animals with a
slugs or snails and within approximately 15
high number of parasites (more than 1000)
minutes miracidia emerge and migrate to
show lack of appetite and lethargy.1 0 W h e n
the connective tissue of the mollusks.
present, the clinical signs can be observed
During the next 28 days, the miracidia
between the seventh and sixteenth week after
develop to sporocysts I, generating a great
infection and include lethargy, weight loss,
number of sporocysts II, which then migrate
and abdominal tenderness. Jaundice, anorex-
to the soil through the breathing pores of the
ia, and enlargement of the liver may be
mollusks. In the environment, the stage II
observed although most cats show no recog-
sporocysts mature and in 30 days they will
nizable clinical alterations.1 0 , 2 2−2 4 B e s i d e s
contain cercariae. At this point of the cycle,
being unspecific, the signs are transitory, but,
they can be ingested by paratenic hosts such
with the evolution of the disease, the unspe-
as beetles. Lizards or frogs can ingest stage
cific symptoms generally reappear together
II sporocysts either directly from the envi-
with chronic mucous diarrhea or jaundice. In
ronment or by ingesting the infected
this stage of the disease, the animals die in
paratenic hosts. In both events, the metacer-
most cases. Jaundice observed in infected
cariae will be released and remain encysted
cats with high parasite load is related to bile
in the gallbladder of the intermediate host
stasis due to presence of high number of par-
until being ingested by the final host. A few
asites in the bile ducts. Hyperplasia or con-
Intern J Appl Res Vet Med • Vol. 3, No. 3, 2005

strictive fibrosis of the bile duct may occur,
tion of ketamine chlorhydrate (Vetaset®, Fort
causing obstruction of bile flow to the duode-
Dodge Saúde Animal Ltda., Campinas, Brazil)
n u m .2 The presence of the parasites in the
at the dose of 10 mg/kg and xylazine chlorhy-
bile tract can favor secondary bacterial con-
drate (Rompum®, Bayer do Brasil S.A., São
tamination and contribute to the development
Paulo, Brazil) at the dose of 2 mg/kg.3 4
of cholangitis and liver abscesses and
The samples of feces were obtained
increase the risk of cholangiocarcinoma and
from the sedated animals after spontaneous
pyogenic cholangitis.2 5−2 8
defecation or directly collected from the
Due to the absence of specific clinical
rectum. The samples were transferred to
signs, the diagnosis techniques are of spe-
appropriate vials without conserving agent
cial importance.1 0 Conclusive diagnosis in
and maintained at 4˚ C for up to 24 hours,
vivo is made through detection of operculat-
then processed using the Faust’s technique.3 5
ed eggs in the feces,2 2 although this depends
The ultrasound exams were carried out
on the technique employed2 9 and on the
with portable bidimensional equipment
number of samples examined.1 7 U l t r a s o u n d
(General Electrics [GE]® Logiq 100
examination is the method of choice for
Pro)with multifrequency transducers (1 con-
diagnosing jaundice in humans, and its use
vex of 5.0−7.5 MHz, 1 linear of 7.5−1 0 . 0
in veterinary medicine is increasing.3 0 It is,
MHz). Tricotomy was performed with a
however, a subjective technique because the
shaving machine (Shave Machine Golden
same sonographic aspect can appear in dif-
A5 Oster® with blade 40). After cleaning the
ferent diseases and their interpretation is
area with a dry paper towel, ultrasound gel
thus dependant on the skills of the operator
was applied (Carbogel®). The best images
and on objective evaluation parameters.3 1 , 3 2
were selected and recorded in a video
The objective of this project was to
graphic printer (Video Graphic Printer
study the hepatobiliary characteristics
S o n y® UPP 895 MD) with appropriate ultra-
detectable with ultrasound for obtaining a
sound printing paper (Ultrasound Printing
better knowledge of evaluation parameters
Paper Sony® UPP-110 HG).
of ultrasound findings in cats infected with
The animals were examined in dorsal as
P l a t y n o s o m u m s p p .
well as left and right lateral decubitus posi-
tion. Images from liver, gallbladder, and
bile ducts were taken in longitudinal, trans-
The study included domestic cats of more
versal and oblique plane.
than 6 months of age3 3 collected from differ-
Ultrasonographic Criteria
ent parts of urban Rio de Janeiro. These ani-
The size of the liver was evaluated subjec-
mals were submitted to ultrasonographic
tively based on its position in the abdomen
and coproparasitological examinations with-
in relation to the transducer. The parameters
in a maximum interval of 60 days.
and criteria for evaluation are presented in
All the cats were examined with the free
Table 1.
and informed consent of the owners. The
lifestyle of the animals was classified as fol-
Statistical Analysis
lows: 1) free, living without direct supervi-
For analysis of discrete data frequency was
sion; 2) semi-confined, living under direct
used. For comparison of 2 proportions, the z
supervision and receiving food regularly but
test was used.4 0 Differences were considered
with access to the streets; or 3) confined,
significant when P < 0.05.
cats held in a household without having
access to the streets. The study was con-
ducted in a double-blind fashion.
Seventy two animals (33 males and 39
For the ultrasound procedures, the cats
females) were included in the study.
were sedated intramuscularly with a combina-
Thirty-three percent of them (24/72) were
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GB p
Figure 1.
Table Sonographic
Moderate 1. distension, images of gallbladders
walls, hyperechoic
and Parameters walls
echogenic Felis (p), catus(GB)
content and of Platynosomum
(c).Normalanechoic content; spp. B) infected cats.
Accentuated A)
and Parameters
Bile LiverDucts of and Criteria
Domestic Cats for
( Evaluating Liver , the L., Ultrasound
Exam of
in the costal arch
the Liver, Gallbladder,
Hepatic vessels
Gradual reduction
Homogeneous and
of diameter
more apparent dilation of vessels
Related to ingesta
Pyriform, oval or round —
Not visualized
>2 mm
Not visualized
>4 mm at the maximum
<4 mm
point of distension
Bile ducts
NWM = not worth mentioning.
infected with P l a t y n o s o m u m spp. The
The ultrasound findings of the liver,
number of infected females was higher
gallbladder (Figure 1), and bile ducts
(38.5%; 15/39) than that of infected males
(Figure 2) occurred with similar frequency
(27.3%; 9/33), although the difference was
in animals that eliminated and those that did
not significant. The lifestyle of the studied
not eliminate eggs of P l a t y n o s o m u m s p p .
animals influenced the prevalence of the
(Figure 3, Table 3).
infection. There was significant difference
The frequency of associated alterations
among the free-living (42%; 21/50) and
of bile ducts and gallbladder (29.1%) or
confined cats (7.1%; 1/14). The frequency
liver, bile ducts, and gallbladder in infected
of infection of the semi-confined cats
animals (12.5%) was higher than in animals
(28.6%; 2/7) showed no significant differ-
that did not eliminate eggs (20.8% and 2.1%
ence in comparison to free-living and con-
respectively), although the differences were
fined cats (Table 2).
not significant (Table 4).
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Table 2.
and Distribution
Lifestyle of
(urban Domestic
region of Cats Rio de Infected
Janeiro).by Platynosomum
spp. (+)*
According to Total
Different letters in columns significant at a level of % (z = 2112; P = 0.035).
*Coproparasitological exam.35
†The lifestyle of one of the animals was not reported by the responsible caretaker (female that did not shed eggs of
Platynosomum spp.).
Figure 2.
ing 0.6 Images
cm; B) of bile ducts
Distended and (BiD) Aof Platynosomum
tortuous with bullet-like spp. infected
shape (in B cats.
detail, A) right Distended,
inferior measur
corner). -C
Figure 3.
Faust’s Photomicrographs
(C) technique.
Egg with (A) Egg of eggs
disrupted with of poorly the genus Platynosomum
operculum. visible operculum; (B) found
Egg with in the feces
well–defined of cats using
The number of females eliminating eggs
The free-living cats were more frequently
was not higher than that of males although it
infected than the confined cats, suggesting
is to be expected that females get infected
that a constant and abundant source of food
more often while teaching their offspring to
together with restricted access to prey
h u n t .4 1 However, it is known that urban
reduced the risk of P l a t y n o s o m u m s p p .
females form colonies where the provision
infection. The fact that no difference in
of food is constant and abundant, while
infection frequency was observed between
males either join the female colonies or tran-
confined and semi-confined cats may be
sit among them.4 2 , 4 3 Thus, the free-roaming
attributed to the sample size of semi-con-
females living in urban centers only eat prey
fined cats.
as a complement and mostly hunt to teach
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their young, rarely eating the prey but gener-
ally offering it to the kittens.4 1 C o n s e q u e n t l y ,
it is possible that the first infection with
P l a t y n o s o m u m spp. is acquired by the young
animals while learning to hunt.
When analyzing the ultrasonographic
parameters in a hepatobiliary system in iso-
lation (liver, gallbladder, or bile ducts) and
relating them to the elimination of eggs of
the parasite, it can be noted that none of the
alterations was more frequent in infected
cats than in cats not eliminating eggs (Table
3). The changes on the liver such as
enlargement and echogenicity of the hepatic
parenchyma detected in the ultrasound exam
were only observed in animals that did not
eliminate eggs.
These alterations normally reflect histo-
logical alterations like fibrosis and vacuolar
degeneration that can be observed in the
ultrasound exam in an advanced stage of
liver disease, including disease caused by
parasites of the genus P l a t y n o s o m u m.4 4
Thus, in the course of platynosomiasis,
lesions probably appear in the ultrasound
exam in an advanced stage of the disease
and may be dependent on the parasite load.
P l a t y n o s o m u m spp. infection may have
influenced the sonographic aspect of the
gallbladder walls of the cats, given that
hyperechogenicity was more frequent among
infected cats. This aspect, however, was also
observed among animals that did not elimi-
nate eggs of the parasite, suggesting that
hyperechogenicity: 1) can indicate an unspe-
cific inflammatory process; 2) can be an arti-
fact of the technique; or 3) can indicate
individual alterations.3 8 , 3 9 Thus, hypere-
chogenicity may be due to a series of fac-
tors, among them inflammation caused by
parasites of the genus P l a t y n o s o m u m.
Another alteration of the bile ducts was
echogenic content that, when observed, was
more frequent in infected cats (71.4%). This
alteration possibly is a consequence of a
long fasting period,3 9 , 4 5 and perhaps appeared
more frequently among infected cats due to
the inflammatory process or to partial bile
duct obstruction caused by the parasites.
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Table 4. Distribution
Ultrasonographic Lof Domestic
region of Rio de Alterations
Janeiro, GBof Cats
May the BiDInfected
Liver (L), L/GBby Platynosomum
2003-September 2004).L/BiD (GB), GB/BiDspp. and (PL) Bile and Ducts
(BiD) (urban
(+) Cats that eliminated Platynosomum spp.; (-) cats that did not eliminate eggs of Platynosomum spp.; NWM = not
worth mentioning.
Furthermore, 3 animals presented with
tor for serial coproparasitological exams as
accentuated distension of the gallbladder
the elimination of eggs of P l a t y n o s o m u m
together with extrahepatic biliary obstruc-
spp. is weak and intermittent.2 9
tion, not noted in any of the animals of the
Moreover, the low sensitivity of the
other group. This emphasizes the possibility
coproparasitological exams using only one
of platynosomiasis being involved in the
s a m p l e1 7 may at least in part explain the 12
obstruction of the bile ducts, especially in
cats that did not eliminate eggs of
animals developing ductal fibrosis as a con-
P l a t y n o s o m u m spp., but presented with 2 or
sequence of the presence of adult forms of
3 structures with sonographic alterations.
the parasite.2 2
Besides, the lesions associated with low par-
The ultrasound evaluation of the bile
asite loads (<10 adult forms) may not appear
ducts showed that this structure presented
in the ultrasound exams4 4 and some of the 5
alterations more frequently (55.5%; 40/72),
parasitized animals that did not present
independently of parasitosis. Considering
lesions possibly hosted few parasite forms.
only the infected animals, alterations in the
bile ducts were observed in 67% (16/24),
emphasizing the importance of examining
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