Page 221 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery

liver lobe. Compression of the caudal vena cava may
cause transient ascites. Obstruction or strangulation of
VetBooks.ir tract, will cause additional clinical signs. Myelolipomatosis
herniated organs, especially parts of the gastrointestinal
(multiple firm raised white nodules of adipose tissue) and
portal hypertension have also been described when liver
lobes have become incarcerated (Frye and Taylor, 1968;
Schuh, 1987; Hay et al., 1989).
PPDH has also been suggested as the cause of intra-
pericardial cyst formation in dogs and cats, and pericardial
cysts may be seen associated with the PPDH, or may be
identified following PPDH repair. It is hypothesized that
these lesions are cystic haematomas, caused by prenatal
herniation of falciform fat or omentum from the peritoneal
cavity into the pericardial sac, with subsequent closure of
the hernia in some cases. In three of nine cases of intra-
pericardial cysts, a small PPDH was also apparent. (a)

Diagnosis: Clinical signs associated with this condition 17.3
may become apparent at any age and some animals with Peritoneopericardial
the disease remain free of signs their whole life. In some diaphragmatic hernia.
animals, physical examination is unremarkable (Evans and (a) Lateral and (b)
Biery, 1980). PPDH was an incidental finding in approxi- ventrodorsal views of
the thorax, showing an
mately half the patients in one study (Burns et al., 2013). enlarged cardiac
Clinical signs are diverse and reflect the range of organ silhouette containing
systems that may be affected and the severity of the com- loops of small intestine
promise. Most commonly, cardiorespiratory signs (dysp- ventrally and to the
noea, tachypnoea, coughing, wheezing and poor exercise right (arrowed). There
are also a reduced
tolerance) and gastrointestinal signs (vomiting and diar- number of sternebrae
rhoea) are seen. and failure of fusion of
Physical examination may reveal abnormalities of the the caudal sternebra
sternum and defects in the cranial abdominal wall (Bellah (dysraphism).
et al., 1989). Auscultation of the chest may yield muffled
heart and lung sounds, and heart murmurs in those
animals with coexisting congenital heart disease. Rotation
of the heart within the enlarged pericardial sac may be suf-
ficient to cause a murmur in the absence of heart disease (b)
(Eyster et al., 1977). Patients may present with overt signs
of right-sided heart failure or caudal caval compression,
such as ascites (Frye and Taylor, 1968).
Electrocardiographic abnormalities reported include masses, cysts and cardiomegaly. The presence of coexist-
alteration in the mean electrical axis, due to displacement ing congenital heart disease may also be identified by
of the heart, and arrhythmias. these means.
Thoracic radiography reveals a grossly enlarged, Contrast radiographs are of limited use. A positive
rounded or ovoid cardiac silhouette, which may be accom- contrast barium upper gastrointestinal study may reveal
panied by an abnormal convex projection at the caudal barium-containing loops of small intestine overlying the
border (Figure 17.3). The soft tissue opacities of the heart cardiac shadow, if part of the gastrointestinal tract has
and diaphragm are continuous ventrally (positive silhouette herniated (Figure 17.4). Negative and positive contrast
sign). In cats, the identification of the dorsal peritoneoperi- peritoneography may demonstrate anatomical continuity
cardial mesothelial remnant between the heart and between the peritoneal cavity and the pericardium, but a
diaphragm is a common radiographic sign of PPDH (Berry false negative result may occur if the viscera have sealed
et al., 1990). The existence of sternal abnormalities can be the defect in the diaphragm (Evans and Biery, 1980).
confirmed radiographically.
The presence of other opacities, such as gas (e.g. Treatment: In many animals with PPDH, the hernia is an
linear gas-filled bowel), fat (e.g. omentum or falciform liga- incidental finding, particularly in mature adult and geriatric
ment), soft tissue (e.g. liver lobes or loops of small intestine) cats, and care should be taken when making a decision to
or mixed soft tissue/mineral opacities (e.g. faeces-filled manage the condition surgically (Burns et al., 2013). Surgery
large intestine) confirms the existence of abdominal viscera is more commonly performed in younger cats and in cats
within the thoracic cavity, and the restriction of these opac- with more obvious clinical signs referable to the hernia.
ities by the pericardium differentiates PPDH from a trau- The principles of surgical correction of a PPDH are
matic diaphragmatic rupture (Evans and Biery, 1980). similar to those for a traumatic diaphragmatic rupture. A
Changes in the position of the abdominal viscera or an ventral midline laparotomy approach gives the best access
abnormal stomach axis may also suggest herniation. to the defects in the diaphragm and any associated
Ultrasonography is a simple and reliable non-invasive defects of the cranioventral abdominal wall. Extension of
method of confirming the diagnosis. Examination may be the incision with a caudal median sternotomy may be
performed with the transducer in a subcostal or parasternal required if adhesions have developed or if abdominal
position. Herniation of abdominal viscera may be identified organs have herniated cranially into the mediastinum from
and differentiated from pericardial effusion, pericardial the pericardium (Figure 17.5).

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