l

1. PAPER
Indications, outcomes and
complications following lateral
thoracotomy in dogs and cats
OBJECTIVES: Lateral thoracotomy is widely used for surgical
management of thoracic diseases in small animals. The purpose
of this paper is to describe the indications for lateral thoracotomy in
dogs and cats and the associated outcomes and complications.
METHODS: Medical records of animals undergoing lateral
thoracotomy were reviewed and owners contacted regarding
complications and survival. Relationships between signalment
and treatment variables and outcome variables were investigated.
RESULTS: Seventy dogs and 13 cats underwent lateral thoracotomy.
Sixty-two per cent of cats and 91 per cent of dogs survived to
discharge. Survival to discharge was significantly lower in cats than
dogs, for neoplastic than non-neoplastic disease and in older
animals. Survival to discharge was higher in animals undergoing
patent ductus arteriosus ligation than in those undergoing lung
lobectomy or oesophageal surgery. Survival to discharge was not
related to surgeon experience. The incidence of complications
was not related to species, age, disease, duration of surgery,
surgeon experience or duration of thoracostomy tube placement.
A low complication rate (5 per cent) was associated with
thoracostomy tubes.
CLINICAL SIGNIFICANCE: The approach of lateral thoracotomy has
a minimal complication rate and animals with a disease requiring
this approach have a high survival rate.
A. L. MOORES, Z. J. HALFACREE,
S. J. BAINES AND V. J. LIPSCOMB
Journal of Small Animal Practice (2007)
48, 695–698
DOI: 10.1111/j.1748-5827.2007.00417.x
INTRODUCTION
Lateral thoracotomy (intercostal or rib
resection thoracotomy) is widely used for
surgical management of thoracic diseases
in dogs and cats (Orton 2003). It gives
access to approximately one-third of the
ipsilateral hemithorax, and exposure is fur-
ther improved by rib resection (Orton
2003). Indications include localised disease
within ipsilateral lung lobes, for example
primary lung lobe neoplasia; vascular
anomalies, for example patent ductus arte-
riosus (PDA); and some mediastinal dis-
eases, for example oesophageal foreign
body (McNeil and others 1997, Hunt
and others 2001, Fossum and others
2004). Lateral thoracotomy is preferred
to median sternotomy as the latter is
thought to be more difficult to perform,
to be more painful and to have more com-
plications, especially sternal osteomyelitis
(Burton and White 1996). However,
median sternotomy is the preferred tech-
nique if access to the entire thoracic cavity
is required for diagnostic or therapeutic
purposes (Orton 2003). With the increased
use of computed tomography allowing
more accurate localisation of thoracic dis-
ease and preoperative planning of a specific
surgical procedure, lateral thoracotomy
may be indicated instead of median ster-
notomy in some instances (Burk 1991).
There is little information in the veter-
inary literature regarding lateral thorac-
otomy. The purpose of this paper is to
describe the indications and demographics
for lateral thoracotomy in dogs and cats,
the thoracic procedure performed and
the associated outcomes and short- and
long-term complications.
MATERIALS AND METHODS
Medical records of animals that had under-
gone elective lateral thoracotomy for dis-
eases requiring surgical access to one
hemithorax at the Royal Veterinary College
between 1999 and 2004 were reviewed.
Information retrieved included age, sex,
indication for thoracotomy, thoracotomy
incision site, surgical procedure performed,
experience of the primary surgeon, dura-
tion of thoracostomy tube placement,
short-term (,14 days) and long-term
(.14 days) complications and survival.
Information regarding short-term compli-
cations was obtained from medical records,
referring veterinarians and owners. Owners
were contacted regarding long-term com-
plications and survival using a standard
questionnaire. This questionnaire is avail-
able to view by accessing http://www.
Department of Veterinary Clinical Sciences,
Royal Veterinary College, Hawkshead Lane,
North Mymms, Hatfield, Herts AL9 7TA
Journal of Small Animal Practice Vol 48 December 2007 Ó 2007 British Small Animal Veterinary Association 695

2. bsava.com/resources/jsap. Complications
were defined as those related to surgical
approach, thoracostomy tube, intrathoracic
procedure or original disease. Animals that
died or were euthanased within one week of
surgery were not included in follow-up and
complication data.
Relationships between patient and surgi-
cal factors, and outcome variables (survival,
complications and duration of thoracos-
tomy tube placement) were investigated
using chi-squared analysis or Fisher’s exact
tests (categorical variables) or the Mann-
Whitney U test (continuous variables). Val-
ues of P,005 were considered significant.
Anaesthesia, surgical and
analgesia protocol
Animals were premedicated, anaesthetised
and ventilated. Analgesia was provided
using carprofen, opioids, intercostal nerve
block and/or interpleural local anaesthesia
via the thoracostomy tube. Intercostal or
rib resection thoracotomy was performed
in a routine manner (Orton 2003). An
incision was made between the third and
10th intercostal space, determined by the
thoracic structures requiring exposure. Rib
resection was performed to allow increased
thoracic exposure. The latissimus dorsi
muscle was retracted dorsally or incised
depending on surgical exposure required.
For intercostal thoracotomy, the intercostal
muscles and parietal pleura were incised.
For rib resection thoracotomy, the perios-
teum was incised over the rib and elevated;
the rib was transected proximally and dis-
tally and discarded. Following completion
of the intrathoracic procedure, a thoracos-
tomy tube was inserted. Tube size ranged
from 12 to 30 Fr depending on patient size.
Thoracotomy closure was performed using
interrupted circumcostal sutures (inter-
costal thoracotomy) or periosteal sutures
(rib resection thoracotomy). Thoracostomy
tubes were managed aseptically and drained
every two to six hours. Tubes were removed
when no air was present or only a constant,
small volume of pleural fluid was removed
at subsequent aspirations. Ongoing veteri-
nary care was provided by the referring
practice or the referral hospital.
RESULTS
Seventy dogs and thirteen cats were iden-
tified for inclusion in the study. Thirty-
seven dogs were male (10 were neutered)
and thirty-three were female (13 were neu-
tered); median age was 18 years (range
02 to 137 years). Eight cats were male
(five were neutered) and five were female
(four were neutered); median age was 75
years (range 02 to 139 years).
There were 79 intercostal (60 left and
19 right) and four rib resection (two left
and two right) thoracotomies (Table 1).
For the 74 animals that survived more
than 48 hours post-operatively, local
anaesthesia was administered via an inter-
costal nerve block (n=26), the thoracos-
tomy tube (n=4) or both (n=35). It was
not administered in seven and information
was not available in two cases. Animals
that had not been administered local
anaesthesia were not noted to be more
painful postoperatively.
In all cases the diagnosis of disease for
example PDA, or type of disease for exam-
ple pulmonary mass, was made preopera-
tively. Thoracotomy was performed for
treatment of PDA (35 dogs and one
cat), primary pulmonary neoplasia (eight
dogs and one cat), oesophageal foreign
body removal and/or oesophageal per-
foration (six dogs and one cat), non-
pulmonary neoplasia (right atrium, thoracic
wall, mediastinum; three dogs and three
cats), pneumonia/pulmonary abscess (three
Table 1. Indications for lateral thoracotomy
Indication Species Median age Thoracotomy site
(all dogs and cats)
Disease of heart or vascular system (vascular anomalies) 46 dogs and cats 04 years (range 02 to 9 years) L4 (42 animals)
43 dogs Dogs 04 years (02 to 90 years) L5 (2 animals)
3 cats Cats 04 years (02 to 04 years) L5 rib resection (2 animals)
Lung lobectomy or pneumonectomy (pulmonary neoplasia,
pneumonia or pulmonary abscess)
16 dogs and cats 97 years (range 18 to 137 years) L5 (5 animals)
12 dogs Dogs 100 years (49 to 137 years) L6 (1 animal)
4 cats Cats 83 years (18 to 126 years) R5 (5 animals)
R6 (4 animals)
R6 rib resection (1 animal)
Oesophageal surgery 7 dogs and cats 63 years (range 03 to 131 years) L4 (1 animal)
6 dogs Dogs 62 years (03 to 100 years) L7 (1 animal)
1 cat Cat 131 years L8 (2 animals)
R8 (1 animal)
R8 rib resection (1 animal)
Not recorded (1 animal)
Subtotal pericardiectomy (pericardial effusion) 3 dogs 82 years (range 04 to 103 years) R5 (2 animals)
L5 (1 animal)
Thoracic duct ligation (chylothorax) 2 dogs 60 years (range 30 to 91 years) R9 (1 animal)
R10 (1 animal)
Other 9 dogs and cats 90 years (range 03 to 139 years)
4 dogs Dogs 76 years (18 to 99 years)
5 cats Cats 91 years (03 to 139 years)
L Left, R Right. All thoracotomies are intercostal thoracotomies unless otherwise specified
696 Journal of Small Animal Practice Vol 48 December 2007 Ó 2007 British Small Animal Veterinary Association
A. L. Moores and others

3. dogs and three cats), persistent right aortic
arch (PRAA) (three dogs and two cats),
pericardial effusion (three dogs), pul-
monic stenosis (three dogs), chylothorax
(two dogs) and one each of lung lobe
torsion, tetralogy of Fallot, broncho-
oesophageal fistula and combined PRAA
and pulmonic stenosis in dogs and one
each of tracheal avulsion and megaoeso-
phagus in cats.
Forty-three dogs and three cats (55 per
cent) had a surgical procedure for vascular
anomalies, 12 dogs and four cats (19 per
cent) had a lung lobectomy or pneumo-
nectomy, six dogs and one cat (8 per cent)
had oesophageal surgery, three dogs (4 per
cent) had a pericardiectomy, two dogs
(2 per cent) had thoracic duct ligation
and four dogs and five cats (11 per cent)
had other procedures (Table 1).
Surgery was performed by faculty sur-
geons (n=65 [57 survivors, eight non-
survivors]) or residents (n=16, all survived)
and was not recorded in two cases (one
survivor, one non-survivor). The majority
of cases (12/16) performed by residents
were for PDA ligation.
Of 74 cases surviving more than five
days, thoracostomy tubes were maintained
for 20 minutes to 11 days (Table 2).
Duration was significantly longer in ani-
mals with pre-existing pleural, mediastinal
or pulmonary disease, (median 30 hours)
than animals undergoing elective surgery
for vascular anomalies (median 6 hours)
(P,0001).
Five cases (6 per cent) were euthanased
intraoperatively because of inoperable
disease (non-pulmonary neoplasia in three
cats, pulmonary neoplasia in one dog and
oesophageal rupture in one cat).
Four dogs (5 per cent) died because of
respiratory/cardiac arrest during or within
48 hours of surgery for treatment of pul-
monic stenosis, pneumonia, neoplasia and
oesophageal foreign body/rupture. One
dog and one cat (2 per cent) were eutha-
nased because of persistent dyspnoea, five
to seven days after lung lobectomy for
treatment of pneumonia, presumably
because of disease beyond the excised lobe.
Post-mortem examination in the dog later
identified undiagnosed neoplasia in the
excised lobe.
Seventy-two animals (63 dogs and nine
cats, 87 per cent) survived to discharge.
Survival rate was significantly lower in cats
(62 per cent) than in dogs (91 per cent)
(P=0012) and in animals with neoplastic
disease (60 per cent) than in animals with
non-neoplastic disease (93 per cent)
(P=0004). Median age was 11 and 18
years in surviving cats and dogs, respec-
tively, and 126 and 100 years in non-
surviving cats and dogs, respectively.
Animals that survived to discharge were
significantly younger than those that did
not (P,0001). Survival to discharge
was significantly greater in animals under-
going ligation of PDA or PRAA (100 per
cent) than those undergoing lung lobec-
tomy (69 per cent) (P=0001) or oesopha-
geal surgery (71 per cent) (P=0019), but
there was no difference between lung
lobectomy and oesophageal surgery (P=
1000). There was no difference in survival
rates to discharge between cases operated
by faculty surgeons (85 per cent) or resi-
dents (100 per cent) (P=0195).
Short-term complications were seen in
35/72 animals (47 per cent) (Table 3).
Twenty-eight were related to the surgical
approach, comprising seroma or ventral
oedema (n=16), excessive wound inflam-
mation (n=6), ipsilateral thoracic limb
lameness (n=3) and wound discharge
(n=3). Five animals had complications
associated with the thoracostomy tube,
including leakage of fluid and subcutane-
ous emphysema. Two had complications
associated with the intrathoracic surgery
(haemorrhage). Five dogs had compli-
cations related to the original disease. Inci-
dence of complications was not associated
with age (P=0215), species (P=0158),
underlying disease (pre-existing disease
compared with elective surgery for vascu-
lar anomalies, P=0479), surgical proce-
dure (vascular, oesophageal or lung
lobectomy, P=0753 to 1000), duration
of surgery (P=0346), surgeon experience
(P=0260) or duration of thoracostomy
tube placement (P=0238).
Long-term follow-up was available for
53/72 animals (72 per cent) that survived
to discharge and complications occurred
in 3/53 (Table 3). One was related to
the surgical approach (rib fracture), one
was related to the underlying disease
(oesophageal stricture) and in one the
cause was not known (pyothorax).
DISCUSSION
The most common indication for a lateral
thoracotomy in this study was treatment
of vascular anomalies, especially PDA,
in young dogs. This may reflect a higher
incidence or higher rate of referral com-
pared with other diseases. The survival rate
to discharge was high (87 per cent), but
with lower survival in cats than previously
Table 2. Duration of thoracostomy tube placement in animals surviving more than five days
Indication Duration of thoracostomy tube placement
,4 hours 5 to 12 hours 13 to 24 hours 1 to 3 days 4 to 7 days .7 days Not recorded
Disease of heart or vascular system 14 10 17 2 1 1
Lung lobectomy or pneumonectomy
Neoplasia 2 3
Pneumonia/abscess 1 3 2 1
Oesophageal disease 3 2
Non-pulmonary neoplasia 1 2
Pericardial effusion 2 1
Chylothorax 1 1
Other 2 2
Total 16 13 26 13 2 1 3
Journal of Small Animal Practice Vol 48 December 2007 Ó 2007 British Small Animal Veterinary Association 697
Lateral thoracotomy in dogs and cats

4. reported (Bellenger and others 1996). The
high survival rate in dogs and in young
animals may reflect the number of dogs
treated for PDA (Hunt and others
2001). Mortality was usually associated
with the underlying disease, specifically
neoplasia. The survival rate to discharge
was higher than previously reported for
median sternotomy (44 per cent mortality
rate) (Burton and White 1996) but it is
difficult to make comparisons because
of different indications between surgical
approaches (Burton and White 1996,
Mellanby and others 2002).
Reported complications following in-
tercostal thoracotomy are uncommon
(Orton 2003). In a report by Ringwald
and Birchard (1989), 36 per cent of dogs
had complications and 50 per cent had
postoperative pain. In the current study,
complications of the intrathoracic pro-
cedure and disease, for example intra-
thoracic haemorrhage, tended to be
clinically significant, but were rare. Com-
plications associated with thoracostomy
tube use were minimal. Most short-term
complications were associated with the
surgical approach and were of minor clin-
ical significance. The high incidence of
wound complications may reflect the fact
that owners were more likely to note
a complication than the medical records,
or the definition of complication. Most
complications, such as incisional oedema,
are common to any surgical procedure.
Seroma formation was seen in a similar
number of animals undergoing ovariohys-
terectomy (Berzon 1979). Burton and
White (1996) noted incisional oedema
in the majority of dogs undergoing
median sternotomy and did not consider
it a complication. There was no evidence
that the incidence of complications was
related to patient factors, indication for
surgery, surgical site or surgeon experi-
ence, although faculty surgeons were more
likely to perform complex procedures.
Most thoracotomies were performed
between the third and sixth intercostal
space; differences in complication rates
between cranial and caudal thoracotomies
are therefore difficult to establish.
Three dogs had temporary lameness,
which has previously been reported
(Burton and White 1996, Walsh and
others 1999). Postulated causes include
pain, limb overextension or incision or
retraction of the latissimus dorsi. All cases
were associated with left fourth intercostal
thoracotomy, which may be because of
surgical trauma or may reflect the number
of surgical approaches. In humans, leaving
the latissimus dorsi and serratus ventralis
muscles intact is associated with less post-
operative pain (Bethencourt and Holmes
1998). Subcutaneous emphysema noted
in one case was most probably caused
by leakage around the thoracostomy tube
and did not cause a clinical problem.
Long-term complications were rare.
Rib fracture may have occurred because
of excessive rib retraction or following
wound closure, but did not require treat-
ment. Fracture of sternebrae has been
documented following median sternot-
omy (Burton and White 1996). One
dog developed methicillin-resistant Sta-
phylococcus aureus pyothorax. Wound
infection rates have not been previously
reported for lateral thoracotomies. The
infection rate presented here is lower than
that following median sternotomy (11 to
36 per cent) (Ringwald and Birchard
1989, Burton and White 1996, Dunning
2003) which may reflect the patient and
underlying disease, reduced tissue trauma
or shorter surgery times for lateral thora-
cotomies (Brown and others 1997).
Conclusions
Animals with intrathoracic disease that
warrants a lateral thoracotomy have a high
survival rate to discharge. The surgical
approach has a low complication rate sim-
ilar to general surgical complications.
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Table 3. Short- and long-term complications
Cause of complication Short-term complications Long-term complications
Surgical approach
Seroma/ventral oedema 16
Excessive wound inflammation 6
Thoracic limb lameness 3
Wound discharge 3
Rib fracture 1
Thoracostomy tube 5
Intrathoracic surgery 2
Original disease 5 1
Unknown cause 1
698 Journal of Small Animal Practice Vol 48 December 2007 Ó 2007 British Small Animal Veterinary Association
A. L. Moores and others