Pernatal skeletal injuries in two Balaenopterid whales

5 Pages·1996·2.7 MB·English

by  R A Paterson

PERINATALSKELETALINJURIES IN TWO BALAENOPTERIDWHALES
ROBERTA. PATERSON AND STEPHEN M. VAN DYCK
Paterson,R.A.&VanDyck,S.M. 19960720:Perinatalskeletalinjuriesintwobalaenopterid
whales. Memoirsofthe QueenslandMuseum39(2): 333-337. Brisbane. ISSN0079-8835.
Two recently born balaenopterid whales {Balaenoptera acutorostrata and Megaptera
novaeangliae) stranded on the coast ofsouthern Queensland exhibited similar pericranial
andriblesionsconsideredtoresultfromcompressioninjury.Birthtrauma,perhapsassociated
withcaudalpresentation,isconsideredthemostlikelycauseofthelesions. Balaenopterid
whales, skeletalinjuries, birthtrauma.
RobertA. Paterson & Stephen M. Van Dyck, QueenslandMuseum, P.O. Box3300, South
Brisbane, Queensland4101, Australia; received22 February 1996.
DESCRIPTIONS
The Queensland Museum (QM) cetacean col-
lection contains skeletal material of 11 juvenile QMJM7301. A 2.9 m long 9 minke whale
balaenopterids of which 7 are minke whales stranded at the Big Sand Hill, Moreton Island
Balaenoptera acutorostrata, 3 are humpback (27°13'S, 153°22'E) on ll.vi.87. Its flipper and
whales Megaptera novaeangliae and 1 a blue bodycolourationwastypicalofthediminutiveor
whale B.musculus musculus. Among these, Type 3 form (Best, 1985) and was illustrated in
pericranial and rib lesions are evident in 2 very Paterson (1994). The umbilicus was healed. Su-
immature specimens, 1 minke whale and 1 perficial 'cookie-cutter' lesions similar to those
humpback whale. This paper describes the described in otherexamples ofthis species (Wil-
pathology and speculates on its cause. liamson, 1975;Arnoldetal., 1987)werenotedas
FIG. 1. Minke whale QMJM7301. Radiograph demonstrating numerous bilateral ventral rib fractures. The
sternum has not been included.
334 MEMOIRSOFTHEQUEENSLAND MUSEUM
F1G. 2. Minke whale QMJM7301 (Left). Dorsal view
of skull (98cm long) demonstrating periosteal new
bone formation on the lateral aspectofthe supra-or-
bitalprocessoftheleftfrontalbone.(Right)Close-up
profile viewofthesame region.
tological examination (Fig. 5) demonstrated
well as predatory rakes near the dorsal fin. periosteal new bone formation superficial to a
Bilateral rib fractures were palpable but there sub-periostealcystconsistentwithtraumaseveral
were no wounds or scars superficial to them. weeks priorto death (J. Musgravepers.comm.).
Abundant callus (some was lost during prepara-
tion) was evident both by direct inspection and DISCUSSION
radiological examination (Fig. 1). Afterprepara-
tionoftheskullaraisedareaofshell-likeossifica-
Therearevery limiteddataconcerningthetime
tion 6.0 cm long and 2.5 cm in greatest diameter and place ofbirth ofType 3 minke whales. The
wasnotedonthelateralaspectofthesupra-orbital two smallest examined in South Africa by Best
process ofthe left frontal (Fig. 2). (1985) were 1.92 m and 2.54 m long and they
stranded at latitude 34°S in May andJuly respec-
QM JM7303. A 4.2 m long 8 humpback whale tively. The former had a raw and completely
stranded at Moon Point, Fraser Island (25°14'S, unhealed umbilicus and was considered to be a
153°00'E) on 17.10.89. It was frozen soon after very recent live birth (Best, 1985). QMJM7301
death and transported to the QM. The umbilicus was2.9mlong,andstrandingoccurredat27°Sin
was healed. Numerous bites and rakes, con- June. Its skeleton was extremely immature com-
sidered to be due to shark attack, were noted. pared with the 6 other juvenile minke whale
QM
They includedalarge fresh rightaxillary wound. skeletons in the collection and this suggests
Rib fractures (Fig. 3) were not as severe as those a very young age, probably less than 8 weeks.
in QMJM7301. During dissection a cystic There are extensive data concerning the time
pericranial lesionmeasuring 16.0cmlongand7.0 and place of birth of Southern Hemisphere
cm in greatest diameter was noted on the lateral humpback whales. The modal length at birth is
aspect of the supra-orbital process of the right 4.3 m (Chittleborough, 1958) and most births
frontal (Fig. 4). There were no soft tissue or occurin the vicinityoflatitude20°Sbetweenlate
cutaneousabnormalities superficial tothe lesion. July and mid September(Townsend, 1935; Chit-
Its raised periosteal edge was biopsied and his- tleborough, 1965; Paterson & Paterson, 1989).
PERINATALSKELETALINJURIES IN BALAENOPTERIDWHALES 335
FIG. 3. Humpback whale QMJM7303. Radiograph demonstrating healing undisplaced bilateral ventral rib
fractures. The sternum has not been included. (The vertical 'tracks' in some ribson the leftofthephotograph
resultfrom drillingto insertnumberingwires).
QMJM7303 was 4.2 m long and stranded at (Hunt & Schwab, 1992). Such an injury in
25°S in October on the western side of Fraser humans isoften life-threatening and may require
Island, a region frequented by humpback whales assisted ventilation. However, some healing was
during the southern migration (Corkeron et al., evident in the fractures of QMJM7301 and its
1994). QMJM7303 was probably less than 6 death was not due to acute chest trauma.
weeks old when it died. The lateral aspect of the supra-orbital process
Radiological opinion was sought in an attempt of the frontal would be susceptible to injury,
todate the ribfractures. They were consideredto particularlyinanimmatureanimal,ifdorsolateral
have occurred approximately 6-8 weeks before compressionoccurred. Pericranial injury,similar
death and were likely tohaveresulted fromcom- tothat in QMJM7301 andQMJM7303,occurs in
pression and not from blunt trauma (J.P. Masel, c.2% of human neonates and is termed cephal-
pers. comm.) The position and extent of the haematoma. It usually results from cranial
bilateral rib fractures are consistent with com- moulding during parturition and, as an isolated
pression injury described in human neonates by finding, is not associated with mortality or per-
Caffey (1973). The extensive fractures in sistent morbidity (Caffey, 1973). The degree of
QMJM7301 areconsideredtorepresenta 'central new bone formation in the pericranial lesion of
flair atermusedinhumantraumawhen multiple QMJM7301 (Fig.2) suggests a longer period of
rib fractures occur on both sides of the sternum survival than QMJM7303 in which new bone
336 MEMOIRS OFTHEQUEENSLAND MUSEUM
thebroadest foetal part, makesan abrupt [pelvic]
engagement. Caudal presentation hasbeen noted
in a humpback whale (Dunstan, 1957) and such
presentation inmysticetescouldbeassociatedon
occasions with the difficulties described by Ar-
thur (1964), although the pelvic structures of
cetaceansandlargeterrestrialanimalsdiffercon-
siderably. Hartley (1983) listedcontusions tothe
cranial periosteum and rib fractures among the
postmortem findings in a large series of foal
perinatal mortalities.
Weconcludeonthebasisofavailableevidence
thatthepericranialandribinjuriesinQMJM7301
and QMJM7303 were sustained during parturi-
tion. However, itremainsconjecturaliftheycon-
tributed to the premature deaths ofthese whales.
ACKNOWLEDGEMENTS
We received valuable assistance from many
persons. Patricia Paterson assisted with the dis-
section and retrieval ofQMJM7301. Vic Hislop
retrieved QMJM7303, arranged its freezing, and
transported ittothe QM.John Masel, Directorof
Metropolitan Paediatric Radiology in Brisbane,
dated the rib fractures and John Musgrave of
Sullivan, Nicolaides and Partners prepared and
diagnosed the histological specimens from
QMJM7303. Deidre Pyecroftgaveusthebenefit
of her veterinary experience and searched the
relevantliterature. BruceCowell andJeffWright
QM
of the prepared the photographs. Sophie
Kupisand StephenMarmo,oftheJindaleeMedi-
cal Centre and Royal Brisbane Hospital respec-
FIG.4. HumpbackwhaleQMJM7303. Dorsalviewof tively, took the radiographs.
skull (which measures 1 13cm in length)demonstrat-
ing periosteal new bone formation on the lateral LITERATURECITED
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(Fig- 4). nal characters and skeleton of the diminutive or
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PERINATALSKELETALINJURIESINBALAENOPTERIDWHALES 337
FIG.5.HumpbackwhaleQMJM7303.Histologicalsection(x100)fromedgeofsupra-orbitallesiondemonstrated
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