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Non-neoplastic lesions in beluga whales (Delphinapterus leucas) and other marine mammals from the St lawrence estuary
j. Comp. Path. 1995 Vol. 112, 257-271
N o n - n e o p l a s t i c L e s i o n s in B e l u g a W h a l e s (Delphinapterus leucas) a n d O t h e r M a r i n e M a m m a l s f r o m the St L a w r e n c e E s t u a r y S. De Guise, A. Lagac6, P. Bfland*, C. Girard and R. Higgins Facult~ de M~decine V~t~rinaire, Universit~ de Montreal, C.P. 5000, St-Hyacinthe, Quebec J2C 7C6 and *St Lawrence National Institute of Ecotoxicology, 460 du Champ-de-Mars, Suite 504, Montrdal, Qudbec, Canada H 2 Y 1B4 Surrtnlary
In a 3-year (1988-1990) pathological study, 24 carcasses of beluga whales from the St Lawrence Estuary, Qu6bec, Canada, showed numerous severe lesions, many of which had never been reported in cetaceans. The most common lesions were found in the digestive tract (21 animals) and consisted mainly of periodontitis and of erosions and ulcers in the oesophagus and the first two gastric compartments. Pneumonia, usually of parasitic origin, was also a common finding (12 animals). The adrenal glands often contained nodules (five animals) or cysts (seven animals), and mastiffs was observed in five females. Overall, the incidence of degenerative, infectious, hyperplastic or necrotic lesions, in addition to numerous neoplasms described in another paper, was considerably higher than that found in marine mammals elsewhere or in other species of marine mammal from the same waters.
Introduction Beluga whales (Delphinapterus leucas) in the St Lawrence Estuary and Gulf have been listed as an endangered population (Pippard, 1985). A retrospective analysis of commercial catches showed that the population decline was initiated by overhunting in the early 20th century (Reeves and Mitchell, 1984). Several hypotheses have been put forward to account for the failure of this population to recover during the last 40 years. Examination of carcasses recovered from the shores of the St Lawrence between 1982 and 1986 suggested a link between toxic contaminants in the St Lawrence basin food chain and the precarious state of the population (B61and et al., 1988; Martineau et al., 1988). A causal relationship was suggested between high polychlorinated biphenyl (PCB) and dichlorophenyl trichloroethane (DDT) concentrations in beluga whale tissues and various lesions contributing to mortality and to decreased reproduction. The present paper describes the non-neoplastic lesions observed in carcasses of St Lawrence beluga whales between 1988 and 1990. Other St Lawrence marine mammals and Arctic belugas were also necropsied for comparison. Correspondence to: S. De Guise, Toxen, Universit6 du Qu6bec ~t Montr6al, C.P. 8888, succ. A, Montr6al, Qu6bec, Canada H3C 3P8 0021-9975/95/030257 + 15 $08.00/0
9 1995 Academic Press Limited
258
S. De Guise et al. Materials and M e t h o d s
Stranded carcasses of 24 beluga whales and 19 smaller marine mammals, along with the carcasses of one small odontocete and one pinniped caught in nets, were carried to the necropsy room of the Veterinary College of Universit~ de Montreal. The carcasses of three large whales were examined macroscopically on the shore where they were found. After a complete macroscopical examination, tissues were fixed in 10% buffered formalin, embedded in paraffin wax, sectioned at 5-7 gm and routinely stained with haematoxylin, phloxine and saffron (HPS) for histopathological examination (Luna, 1968). Proliferation of fibrous tissue was confirmed by Masson's trichrome. Lesions and tissues were cultured on blood agar at 37~ in a 10% CO2 atmosphere and examined after 48h. In some instances cultures were incubated anaerobically. Identification of bacteria was carried out with an Analytical Profile Index diagnostic kit (Analytab Products, Ayerst Laboratories, Plainview, NY, USA). For culture of Vibrio spp., tissue samples were plated on trypticase soy agar (BBL, Cockeysville, MD, USA) with 5% bovine blood and on MacConkey agar; the plates were incubated at 37~ for 24 h. Three passages on kidney cell lines were made for each tissue submitted for virological analysis, and cultures showing a cytopathogenic effect were examined by electron microscopy. Five Arctic belugas, freshly killed by Inuit hunters at Eskimo Point (Hudson Bay) and necropsied on site provided well preserved tissue specimens from animals unexposed to industrial contaminants. Standard methods were used for ageing odontocetes (Sergeant et al., 1973; Gaskin and Blair, 1977; B~land et al., 1988) and pinnipeds (Mansfield and Fisher, 1960; Bowen et al., 1983; Mansfield, 1991). Results
St Lawrence Beluga Whales The lesions observed in the 24 St Lawrence beluga whales are summarized in Table 1. The animals examined ranged from 1"5 to > 29 years old, but only two were less than 13 years old. Neoplastic lesions in these whales have been described elsewhere (De Guise et al., 1994a).
Digestive system. Periodontitis, with necrosis of the gum immediately surrounding the teeth and deposition of blackish material on the gingival surface, was classified as severe in seven animals out of 24 examined (Fig. 1). Tooth loss was common, and only nine animals had as m a n y teeth as the minimal number reported in Arctic animals (Doan and Douglas, 1953; Kleinenberg et al., 1969). Ulcerative stomatitis was severe in three animals (Fig. 2). Ulcers of varying severity were also found in the oesophagus (three animals), the first two gastric compartments (11 animals) and the intestine (one animal). At most sites, the ulcers were small and multiple, except in the second gastric compartment, where in six whales there were one or two ulcers measuring 2-3 cm in diameter and 1-2 cm in depth near the junction with the first compartment. Animal 13-88 had an intestinal polyp, 0"5 cm in diameter, which took the form of an extension of the lamina propria containing a few muscular fibres, connective tissue and blood vessels, and was covered with normal intestinal epithelium. A chronic active hepatitis in animal 8-89 was characterized by a moderate to severe infiltration of fibrous tissue into and between the hepatic lobules,
259
Lesions in Beluga Whales Table 1 P o s t - m o r t e m and bacteriological e x a m i n a t i o n o f St Lawrence beluga w h a l e s Whale no.
Sex
Age (years.)
Lesions
Bacteria isolated
1-88
M
3"5
None
4-88
F
> 21
7-88
M
> 19
8-88
M
> 20
9-88
F
> 22
10-88
F
1"5
11-88
F
_>25
12-88
F
16
13-88
F
> 21
14-88
F
> 23
Interstitial pneumonia associated with parasitic granulomas, mild multifocal superficial haemorrhagic gastritis, penile lymphocytic dermatitis, erosions of 1st gastric compartment, emaciation Ciliated protozoal bronchopneumonia, adrenal cysts, mild chronic mastitis with foci of squamous metaplasia Severe, diffuse, fibrino-purulent peritonitis, left-side testicular necrosis, left epididymitis, severe periodontitis, oral ulceration, focal verminous bronchopneumonia, emaciation Diffuse segmental glomerulopathy, hyperacute cystitis, mild verminous multifocal bronchopneumonia, periodontitis, ulceration of 2nd gastric compartment Mild myocarditis, calcified intestinal mass, sarcoeystosis, adrenal cysts, subcutaneous haematoma Verminous bronchopneumonia, haemorrhagic segmentary enteritis Lymphocytic enteritis with eestodes, ulcerations of 1st and 2nd gastric compartments, renal and adrenal haematoma, chronic mastitis, adrenal cysts, probable toxoplasmosis (spleen) Moderate multifocal verminous pneumonia, severe erosions of the 1st gastric compartment with hydropic degeneration, adrenal nodules Diffuse alveolar damage of the lungs, mild chronic mastitis, erosions of 1st gastric compartment, oesophageal ulcerations, intestinal polyp, subcutaneous haematoma, adrenal cystic haematoma Moderate subacute mastitis
1-89
M
___27
Diffuse interstitial pneumonia, parasitic ulcerations of the 1st gastric compartment, mild periodontitis, fibrous plaques on the intima of the aorta
Site from which bacteria were isolated
Escherichia coli
Lung, liver, kidney
Pseudomonas putrefaciens
Lung, liver, kidney, peritoneal fluid, in pure culture
Mo~ganellamorganii
Liver, kidney
Plesiomonas shigelloides Intestinal contents; mesenteric lymph node, in pure culture Fibrio parahaemolyticus Lung, liver, kidney and Edwardsiella tarda Morganella morganii Intestine
Edwardsiellatarda
Lung, liver, intestine
None
Aeromonas hydrophila
Klebsiella sp. ND
Lung, kidney, Intestinal contents, mammary gland Lungs
260
S. D e G u i s e et al. Table 1 (continued)
Whale no.
Sex
Age (years)
2-89
M-F* _>26
3-89
F
>_ 19
4-89
F
14
5-89
F
>_27
6-89
F
>_25
7-89
M
> 29
8-89
M
_>20
1-90
M
_> 18
2-90
M
_>23
3-90
M
> 19
4-90
F
13
5-90
F
_> 13
6-90
M
> 24
Lesions
Bacteria isolated
Ulcerative enteritis, bilateral hermaphroditism, ankylosing spondylosis, periodontitis, subcutaneous haematoma Subacute parasitic broncopneumonia, mild diffuse lymphocytic enteritis, ulcerative mamiUitis, periodontitis, adrenal nodules and cyst Parasitic eosinophilic pneumonia, mediastinal eosinophilic lymphadenitis, mild subacute enteritis with cestodes, chronic endocarditis, oesophageal ulceration, adrenal cyst, ovarian follicular cyst Bronchial inflammatory polyp, ulceration of 2nd gastric compartment, oesophageal ulcerations, sarcocystosis Fibrinous peritonitis, necropurulent mastiffs, ulceration of 2nd gastric compartment, adrenal cyst and nodule Severe necrotic ulcerative stomatitis, cervical subcutaneous and deep haematoma, parasitic ulceration in 1st gastric compartment, ulcerations of 2nd gastric compartment, periodontitis, cavernous haemangioma of the penis, adrenal cyst and nodules Severe periodontitis, chronic active hepatitis Ulcerations of 2nd gastric compartment (metastatic origin), parasitic ulcerations of 1st gastric compartment, oesophageal ulceration Mild to moderate purulent bronchopneumonia, fibrous plaques on the intima of the aorta Probable abdominal neoplasm, autolysis Moderate acute eosinophilic bronchopneumonia (verminous) with mediastinal eosiniphilic lymphadenitis, mild lymphocytic enteritis, multifocal segmental glomerulopathy Mild vaginitis, subcutaneous pyogranulomas Ulcerative stomatitis, periodontitis, ulceration of 2nd gastric compartment, thyroid abscess, mild purulent multifocal pneumonia, lymphocytic enteritis, abdominal mass (probably scar tissue), adrenal cyst and nodules
ND
ND, not done. * Hermaphrodite. i" Bowel filtrate did not kill mice.
ND
Site fiern which bactem were isolated
--
ND
Aeromonashydrophila
Lungs, liver, kidney, mammary gland
ND
ND
--
ND ND
--
Clostridium tertium
Lungs, liver, kidney
ND None
Aewmonas sp.
Liver
ClostridiumpeoCringens Clostridium sp. KingeUa kingae Aewmonas sp.
Intestinal contents]" Lung and thyroid Thyroid
Lesions in Beluga Whales
261
Fig. 1.
Periodontitis in beluga whale 8-89, allotting several teeth and characterized by periodontal necrosis of the gum, with deposition of blackish material on the surface.
Fig. 2.
Severe extensive ulcerative stomatitis in beluga whale 7-89. Half of the oral cavity was affected.
262
Fig. 3.
S. D e Guise e t al.
A section of lung from beluga whale 4-88 showing protozoa, round to elongated in shape and measuring 30-35 g m in diameter, and up to 85 g m long, with a macronucleus. A single layer of radial cilia was sometimes visible on the outer protozoal surface (arrow). T h e organisms are surrounded by neutrophils. HPS. x 504.
and between hepatocytes, isolating many of them, with a multifocal, mild to moderate infiltration of lymphocytes mostly in the portal area, and a mild to moderate hyperplasia of the bile ducts.
Respiratory system. Pneumonia, most often associated with parasites, was observed in 12 of the belugas. Reddish, whitish or greenish foci of various sizes (1-5 cm) were seen on cut section in most of the animals with pneumonia. Nematodes were present in most cases. A ciliated protozoal pneumonia was diagnosed in whale 4-88. Numerous firm nodules, 3 4 cm in diameter, were palpable in the cranial portion of the lungs. On section, these nodules were whitish to dark red and contained a sero-purulent exudate which could be squeezed out under moderate pressure. The foci consisted of a mixture of neutrophils and macrophages admixed with numerous ciliated protozoa in various stages of degeneration in the alveoli. The protozoa were round to elongate, measuring 30-35 gm in diameter, and up to 85 gm in length, with a large, round to elongate, eccentrically placed, basophilic macronucleus (Fig. 3). A single layer of cilia radiated from the outer wall. Diffuse alveolar damage, with thick hyaline membranes and a moderate amount of filamentous alveolar fibrin, was found in animal 13-88.
Endocrine system. Two types of lesion were found in the cortex of one or both
Lesions in Beluga Whales
263
Fig. 4.
An adrenal gland from beluga whale 4-g9 showing a well-defined nodule in the cortex (arrow).
Fig. 5.
An adrenal gland from beluga whale 4-89 showing two cysts filled with serous fluid in the cortex (arrow).
adrenal glands: hyperplastic nodules (five animals) and serous cysts (seven animals). The nodules (Fig. 4), which varied in size from 2-20 mm, were single or multiple and often circumscribed by a fibrous capsule of variable thickness; they frequently compressed the adjacent parenchyma. These well defined nodules differed markedly from the normal pseudolobules formed by the fibrous projections of the capsule into the parenchyma2The serous cysts (Fig. 5), which varied in size from 2-15 mm, were single or multiple, surrounded by a single layer of squamous cells, and lightly to strongly encapsulated. These
264
S. De Guise et aL
cysts usually compressed the adjacent parenchyma. Most of the adrenals bearing cysts also showed areas of moderate to severe hydropic degeneration of the cortical cells. Only one of nine animals, with cysts or nodules or both, was a male (no. 7-89). An abscess, 1 cm in diameter, containing whitish creamy pus was found in the craniolateral portion of the thyroid gland of animal 6-90.
Reproductive system. Testicular necrosis, epididymitis and peritonitis were noted in animal 7-88. The left testicle, which was much enlarged and covered by fibrin, was free within the abdominal cavity. Diffuse coagulative necrosis with pyknosis and karyorrhexis was noted throughout the left testicle, accompanied by a chronic active peritonitis on the abdominal organs. The abdominal cavity contained c. 100 litres of yellow exudate with large fibrinous tags. Pseudomonas putrefaciens was isolated in pure culture from the abdominal fluid. A follicular cyst measuring 6 x 6 x 5 cm was found on the left ovary of animal 4-89. Animal 2-89 was a true hermaphrodite and is fully described elsewhere (De Guise et al., 1994b). There were lesions in the m a m m a r y glands of seven of the 13 females. Five animals had a histologically confirmed mastitis, and mastitis was suspected from a macroscopical examination in another animal (no. 5-89). Lesions were mild to moderate and chronic in four whales, with mild to moderate squamous metaplasia in no. 4-88; animal 6-89 had a severe necro-purulent mastitis, with pus and bloody milk. A severe ulcerative mammillitis and a m a m m a r y adenocarcinoma (De Guise et al., 1994a) were also found.
Urinary System. A segmental glomerulopathy was found in two animals (8-88, 4-90). It was characterized by foci of hyaline degeneration of the afferent and efferent arterioles at the vascular pole of most of the glomeruli. Cardio-vascular system. In animal 4-89, a focal chronic valvular endocardiosis consisting of two nodules (4-5 x 0"9 x 0"9 cm and 0"9 x 0-9 x 0"8 cm) was found on the chordae tendinae of the medial leaflet of the triscupid valve. These fibrous nodules each had a calcified centre, and the surface showed partial re-epithelization from the endocardium. Fibrous proliferation on the intima formed a plaque in the aorta of animals 1-89 and 2-90, with calcification and erosion of the intima (2-90). Animal 9-88 had a mild diffuse subacute myocarditis. Other lesions. Large subcutaneous haematomas in the area of the neck or head were found in four whales, with extensions into the melon and around the atlas, axis, and adjacent vertebral canal in one animal. Ankylosing spondylosis, found in animal 2-89, was characterized by thick bridges of bone that solidly fused the ventral portions of the bodies of the 10th and 11 th thoracic vertebrae.
Lesions in Beluga Whales
265
Table 2 Post-mortern examinations of 24 St Lawrence marine m a m m a l s other than belugas
Animals
Sex
Age (years)
Lesions
Odontocetes LA-1 M
Ad
LA-2 LA-3 LA-4
M M ?
Juv 10" 7*
PP-1 F PP-2 F Mysticetes BA-1 F BA-2 F BP-I M Pinnipeds PV- 1 F PV-2 F PV-3 F PV-4 F PV-5 F PV-6 F PV-7 M PV-8 M Psp- 1 F PG-1 M PG-2 F PG-3 F HG-1 F HG-2 M HG-3 M
>9 > 1
(Caught in net); death by drowning, pneumonia, testicular abscesses, dermatitis Digestive system parasitism, cranial trauma Probable septicaemia, parasitic cysts'(Mono~ygma sp.) in abdominal cavity~ Probable septicaemia, sarcocystosis, parasitic cysts (Mono~ygmasp.) in abdominal cavityI" Verminous bronchopneumonia, hepatic flukes~" Pronounced icterus, with inanition~
0-1 ? ?
(Caught in net); death by drowning Abdominal trauma, cutaneous lacerations Severe parasitism in aorta~"
Ad Ad 1 22 0'5 13 3 13 4 20 Ad 14 Ad Ad Ad
(Caught in net); death by drowning Heart worms t Purulent bronchopneumonia t Bronchopneumonia~" Severe gastric parasitism t Multiple cranial fractures Severe gastric parasitismS" Multiple cranial fractures Non-penetrating cranial trauma Inanition, severe gastric parasitism t Multiple contusions None observed1" Moderate mediastinal emphysema, mitral insufficiency1" Non-penetrating traumas to head and neck Tracheo-bronchitis, left mitral insufficlency~"
LA = Lagenorhyncus acutus, PP = Phocoenaphocoena, BA = Balaenoptera acutorostrata, BP = Balaenopteraphysahs, PV = Phoca vitulina, Psp = Seal, unidentified species, PG = Pagophilusgroenlandicus, HG = Halichoerus grypus. Ad = adult; Juv =juvenile; ages given in years, except for LA-3 and LA-4 (*) where it is expressed as the number of growth layers in the teeth. ~"Died of natural causes.
Bacteriology. Bacteria cultured from St Lawrence beluga whale tissues in pure or heavy culture and considered significant are shown in Table 1.
Virology. An adenovirus was isolated from the intestines of a single animal (7-88) but did not appear to be associated with any lesion. Other Marine Mammals In the five Arctic belugas, moderate infiltrations of eosinophils in the lamina propria and submucosa of the gastric compartments and of the intestines were present, without gastro-intestinal helminths. These animals were aged between 3 and _> 21 years. In 10 of the St Lawrence marine mammals other than belugas, the cause of death, directly or indirectly, was h u m a n activity (Table 2). Three animals were reported caught in fishing nets; others, mainly seals (five of 15 seals
266
S. De Guise et al.
examined) with stomachs full of fish, died of head trauma. A minke whale was killed by collision with a large boat. Most lesions not resulting from human activity were associated with the presence of parasites. Discussion
Digestive system. The aetiology of the oral lesions was unknown, but similar lesions in a captive beluga whale (Hartman, 1976) and in an Atlantic bottlenose dolphin, Tursiops truncatus (Colgrove et al., 1975), regressed with treatment that included the use of antibiotics. The ulcers found in the second gastric compartment, unlike those in the first compartment, were not related to parasites. In addition to acid hypersecretion and impairment of mucosal integrity, local mucosal ischaemia caused by peristaltic contractions of the muscular sphincter between the first and second gastric compartments may have played a role in the pathogenesis, as with peptic ulcers in man (Dayal and DeLellis, 1989). PCBs, found at high concentrations in St Lawrence belugas and known to cause gastric ulcers in other species (Hansen et al., 1976), might explain the high incidence (25%) of glandular stomach ulcers, as compared with human males (6-14%) and females (2-6%) (Dayal and DeLellis, 1989). Chronic active hepatitis was reported in a dolphin by Bossart (1984), but the description did not fit the accepted definition of the disease (Kelly, 1993). The present case (animal 8-89) would therefore appear to be the first reported in a cetacean. Respiratory system. Pneumonia in cetaceans is not easily detected by palpation at necropsy, and reddish, whitish or greenish foci on cut section of the lung appeared to be the best macroscopical sign. Protozoal pneumonia occurs rarely in animals, and in man is often associated with immunosuppression, as occurs in AIDS (Cotran et al., 1989a). Holotricha spp. are frequently found in the blowhole of Atlantic white-sided dolphins, but only one case of pneumonia associated with this ciliated protozoon has been reported in a dolphin (Woodard et al., 1969). Diffuse alveolar damage, as described here, has not previously been reported in a marine mammal; it was suggestive of an acute respiratory distress syndrome. Endocrine system. The classification of the nodules in the adrenal cortex of belugas into hyperplastic nodules or adenomas according to their morphology by criteria used in domestic animals (Capen, 1993) or man (DeLellis, 1989) is difficult. Since it would seem unusual to find such a high incidence of adenomas in a single population, hyperplasia is a more likely provisional diagnosis. Adrenal hyperplasia in female grey seals (Halichoerus grypus) and ringed seals (Phoca hispida) in the Baltic Sea has been related to organochlorine pollutants (Bergman and Olsson, 1985). Adrenal cysts have not been described in domestic animals (Capen, 1993). Serous cyst formation appears to be
Lesions in Beluga Whales
267
preceded by hydropic degeneration with membrane destruction, and overstimulation of cortisol production may play an aetiological role. Similar cysts were observed in female white-sided dolphins (Lagenorhynchus acutus), but their aetiology was obscure (Geraci et al., 1978b). Thyroid abscesses are uncommon in domestic animals, and the one found in animal 6-90 is the first reported in marine mammals.
Reproductive system. The cause of testicular necrosis (animal 7-88) raises questions, because testicular torsion is unlikely for anatomical reasons (De Guise et al., 1995), and the absence of inflammatory cells ruled out primary orchitis. In domestic cows (Bos taurus), ovarian follicular cysts are anovulatory follicles defined by their size (>2"5 cm) and persistence (> 10 days), and are one of the most common causes of infertility (Roberts, 1986). The size of the follicular cyst found in beluga 4-89 was clearly larger than that of follicles usually seen in the species, and the cyst may have impaired the reproductive potential of this animal. In the five animals with mastitis, milk production was probably affected, either quantitatively (chronic mastitis), or qualitatively, or both (acute purulent mastitis). The mastitis in these animals, unlike that in Atlantic white-sided dolphins described by Geraci et al. (1978a), was not caused by parasites. The case of severe ulcerating mammillitis was undoubtedly sufficiently painful to interfere with suckling, thus jeopardizing survival of the calf. Urinary system. The segmental glomerulopathy observed in two belugas has not previously been described in animals. The lesions somewhat resembled those of renal diseases associated with microangiopathic haemolytic anaemia in man; in such diseases, intravascular coagulation and endothelial injury would be expected (Cotran et al., 1989b). Cardio-vascular system. Previous reports o f endocardiosis (such as that found in animal 4-89) in cetaceans are confined to two dolphins (Sweeney and Ridgway, 1975). The fibrous intimal plaques found in the aortas of two belugas (nos. 1-89 and 2-90) and the mild myocarditis found in one were similar to lesions already reported in other marine mammals (Howard, 1983). Other lesions. All belugas with haematomas had concurrent severe diseases which accounted for death. Shark bites and gunshot wounds, reported in other species and from other locations, were not seen in this study. Ankylosing spondylosis, a degenerative disease common in bulls, was found in one beluga. This lesion had already been reported in a beluga from the same population (Martineau et al., 1988); both animals were old ( > 2 6 and > 19 years). Bacteriology. Of the bacterial species isolated in significant numbers from beluga tissues, none was found repeatedly, and none was the cause of a specific
268
S. De Guise et aL
disease. They were all weak or opportunistic pathogens of the type occurring in animals already debilitated (Coles et al., 1978), and most have been reported previously in St Lawrence belugas (Martineau et al., 1988) and in other marine mammals from various parts of the world (Buck et al., 1991). Other marine mammals. The major cause of mortality in St Lawrence marine mammals other than belugas was human activity; natural causes were most often related to parasites or pneumonia. These natural causes were similar to those found in previous studies on cetaceans (Cowan, 1966; Stroud and Roffe, 1979; Cowan et al., 1986) and pinnipeds (Stroud and Roffe, 1979) in other parts of the world, except for mass mortality caused by viral infections (Geraci et al., 1982; Osterhaus and Vedder, 1988; Domingo et al., 1992) or natural toxins (Geraci, 1989; Geraci et al., 1989). Bacterial infections were considered by Howard et al. (1983) to be an important cause of mortality in marine mammals, although they were often associated with parasitic or traumatic injury. Conclusion. A high incidence of various types of chronic lesions was observed in 24 St Lawrence belugas. The lesions were usually multiple and multisystemic, and several had not been reported previously in cetaceans. The incidence of degenerative, infectious, hyperplastic or necrotic lesions, in addition to the numerous neoplasms described elsewhere (De Guise et al., 1994a), was considerably higher than that reported in other areas. Lesions that interfere significantly with the normal function of the mammary glands are a serious handicap in belugas, which have a prolonged lactation. In contrast, the cause of death in half of the St Lawrence pinnipeds and cetaceans other than belugas was related directly to human activity. In the remainder, the majority of lesions had a parasitic aetiology or were observed in the pulmonary and circulatory systems. A single lesion of the gastrointestinal tract, an eosinophilic enteritis, was seen in five Arctic belugas. These observations and other causes of death (gunshot etc.) resemble those in reports on various cetaceans and pinnipeds from other parts of the world. The results of this study, when added to those from a similar series of 21 necropsies carried out in 1983-87 on beluga whales from the same population (Martineau et al., 1988), confirm that the health status of St Lawrence beluga whales differed strikingly from that of other populations of cetaceans in the St Lawrence and elsewhere. The findings, made over a period of >8 years, are considered to be a true reflection of disease in the St Lawrence beluga whale population. Previous work showed high concentrations of organochlorines in these whales (Martineau et al., 1988). Possibly the incidence and diversity of the lesions observed are linked to exposure to toxic compounds.
Acknowledgments We wish to thank Richard Plante, Dr Robert Claveau, Dr Daniel Martineau and the Centre Oc6anographique de Rimouski for assistance and advice. The study was supported by the Wildlife Toxicology Fund (World Wildlife Fund Canada and
Lesions in Beluga Whales
269
Environment Canada), Department of Fisheries and Oceans Canada, Alcan, the World Wildlife Fund, Fondation de la Faune du Qu6bec, Environnement Quebec, Greenpeace (Canada), and Fonds Canadien d'Aide/t la Recherche. References
B61and, P., V6zina, A. and Martineau, D. (1988). Potential for growth of the St Lawrence (Ou~bec, Canada) beluga whale (Delphinapterus leucas) population based on modelling. Journal du Conseil International pour l'Exploration de la Mer, 45, 22-32. Bergman, A. and Olsson, M. (1985). Pathology of Baltic grey seal (Halichoerus gryphus) and ringed seal (Pusa hispida) females with special reference to adreno-cortical hyperplasia: is environmental pollution the cause of a widely distributed disease syndrome? Proceedings of the Symposium on Seals in the Baltic and Eurasian Lakes, Savonlinna, Finland, June 5 8, ICES, 1 27. Bossart, G. (1984). Suspected acquired immunodeficiency in an Atlantic bottlenose dolphin with chronic-active hepatitis and lobomycosis. Journal of the American Veterinary Medical Association, 185, 1413-1414. Bowen, W. D., Sergeant, D. E. and Oritsland, T. (1983). Validation of age determination in the harp seal, Phoca groenlandica, using dentinal annuli. Canadian Journal of Fisheries and Aquatic Sciences, 40, 1430 1441. Buck, J. D., Overstrom, N. A., Patton, G. W., Anderson, H. F. and Gorzelany, J. F. (199 I). Bacteria associated with stranded cetaceans from the northeast USA and southwest Florida Gulf coasts. Diseases of Aquatic Organisms, 10, 147-152. Capen, C. C. (1993). The endocrine glands. In: Pathology of Domestic Animals, Vol. 3, 4th Edit., K. V. F. Jubb, P. C. Kennedy and N. Palmer, Eds, Academic Press, New York, pp. 267 348. Coles, B. M., Stroud, R. K. and Sheggeby, S. (1978). Isolation of Edwardsiella tarda from three Oregon sea mammals. Journal of Wildlife Diseases, 14, 339-341. Colgrove, G. S., Sawa, T. R., Brown, P. F., McDowell, P. F. and Nachtigall, P. E. (1975). Necrotic stomatitis in a dolphin. Journal of ld/Tldlife Diseases, 11,460-464. Cotran, R. S., Kumar, V. and Robbins, S. L. (1989a). The respiratory system. In: Pathological Basis of Disease, 4th Edit., R. S. Cotran, V. Kumar and S. L. Robbins, Eds, W. B. Saunders, Philadelphia, pp. 755-810. Cotran, R. S., Kumar, V. and Robbins, S. L. (1989b). The kidney. In: Pathological Basis of Disease, 4th Edit., R. S. Cotran, V. Kumar and S. L. Robbins, Eds, W. B. Saunders, Philadelphia, pp. 1011-1081. Cowan, D. F. (1966). Pathology of the pilot whale Globicephala melaena. Archives of Pathology, 82, 178 189. Cowan, D. F., Walker, W. A. and Brownell, R. L. (1986). Pathology of small cetaceans stranded along southern California beaches. In: Research on Dolphins, M. M. Bryden and R. Harrison, Eds, Oxford University Press, Oxford, pp. 323-367. Dayal, Y. and DeLellis, R. A. (1989). The gastrointestinal tract. In: Pathological Basis of Disease, 4th Edit., R. S. Cotran, V. Kumar and S. L. Robbins, Eds, W. B. Saunders, Philadelphia, pp. 827 909. De Guise, S., Bisaillon, A., Seguin, B. and Lagacd, A. (1995). The anatomy of the male genital system of the beluga whale, Delphinapterus leucas, with special reference to the penis. Anatomia, Histologia, Embryologia, in press. De Guise, S., Lagac6, A. and B~land, P. (1994a). Tumors in St Lawrence beluga whales (DeIphinapterus leucas). Veterinary Pathology, 31,444-449. De Guise, S., Lagac6, A. and B61and, P. (1994b). True hermaphroditism in a St Lawrence beluga whale (Delphinapterus leucas). Journal of ~ldlife Diseases, 30, 287 29O. DeLellis, R. A. (1989). The endocrine system. In: Pathological Basis of Disease, 4th Edit., R. S. Cotran, V. Kumar and S. L. Robbins, Eds, W. B. Saunders, Philadelphia, pp. 1205-1276.
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Doan, K. H. and Douglas, C. W. (1953). Beluga of the Churchill region of Hudson Bay. Bulletin of the Fisheries" Research Board of Canada, 98, 1-27. Domingo, M., Visa, J., Pumarola, M., Marco, A. J., Ferrer, L., Rabanal, R. and Kennedy, S. (1992). Pathologic and immunocytochemical studies of morbillivirus infection in striped dolphins (Stenella coeruleoalba). Veterinary Pathology, 29, 1-10. Gaskin, D. E. and Blair, B. A. (1977). Age determination of harbour porpoise, Phocoena phocoena (L.) in the western North Atlantic. Canadian Journal of Zoology, 55, 18-30. Geraci, J. R. (1989). Clinical investigation of the 1987-88 mass mortality of bottlenose dolphins along the US central and south Atlantic coasts. Final Report, National Marine Fisheries Service, US Navy, Office of Naval Research, 63 pp. Geraci, J. R., Anderson, D. M., Timperi, R.J., St Aubin, D.J., Early, G. A., Prescott, J. H. and Mayo, C. M. (1989). Humpback whales (Megaptera novaeangliae) fatally poisoned by dinoflagellate toxin. Canadian Journal of the Fisheries Aquatic Sciences, 46, 1895-1898. Geraci, J. R., Dailey, M. D. and St Aubin, D . J . (1978a). Parasitic mastitis in the Atlantic white-sided dolphin, Lagenorhynchus acutus, as a probable factor in herd productivity. Journal of the Fisheries Research Board of Canada, 35, 1350-1355. Geraci, J. R., St Aubin, D.J., Barker, I. K., Webster, R. G., Hinshaw, V. S., Bean, W.J., Ruhnke, H. R., Prescott, J. H., Early, G., Baker, A. S., Madoff, S. and Schooley, R. T. (1982). Mass mortality of harbor seals: pneumonia associated with influenza A virus. Science, 215, 1129-1131. Geraci, J. R., Testaverde, S. A., St Aubin, D.J. and Loop, T. H. (1978b). A mass stranding of the Atlantic white-sided dolphin, Lagenorhynchus acutus: a study into pathobiology and life history. Reportfor the Marine Mammal Commission, Washington, D.C., 155 pp. Hansen, L. G., Wilson, D. W. and Byerly, C. S. (1976). Effects on growing swine and sheep of two polychlorinated biphenyls. American Journal of Veterinary Research, 37, 1021-1024. Hartman, R. A. (1976). Necrotic gingivitis in a white whale (Delphinapterus leucas). Veterinary Medicine~Small Animal Clinician, 71,458 459. Howard, E. B. (1983). Miscellaneous diseases. In: Pathobiology of Marine MammalDiseases, Vol II, E. B. Howard, Ed., CRC Press, Boca Raton, Florida, pp. 163-225. Howard, E. B., Britt, J. O., Matsumoto, G., Ithara, R. and Nagano, C. N. (1983). Bacterial diseases. In: Pathobiology of Marine Mammal Diseases, Vol II, E. B. Howard, Ed., CRC Press, Boca Raton, Florida, pp. 69-118. Kelly, W. R. (1993). The liver and biliary system. In: Pathology of Domestic Animals, Vol. 2, 4th Edit., K. V. F. Jubb, P. C. Kennedy and N. Palmer, Eds, Academic Press, New York, pp. 319-406. Kleinenberg, S. E., Yablokov, A. V., Belkovich, B. M. and Tarasevich, M. N. (1969). Beluga (Delphinapterus leucas): investigation of the species. Akad Nauk SSSR, Moscow, Translated by Israel Program for Scientific Translation, Jerusalem, 376 pp. Luna, L. G. (Ed.) (1968). Manual of Histologic Staining Methods of the Armed Forces Institute of Pathology, 3rd Edit., McGraw-Hill Book Company, New York, pp. 39-40. Mansfield, A. W. (1991). Accuracy of age determination in the grey seal Halichoerus grypus of eastern Canada. Marine Mammal Science, 7, 44-49. Mansfield, A. W. and Fisher, H. D. (1960). Age determination in the harbour seal, Phoca vitulina. Nature, 186, 92-93. Martineau, D., Lagac~, A., B+land, P., Higgins, R., Armstrong, D. and Shugart, L. R. (1988). Pathology of stranded beluga whales (Delphinapterus leucas) from the St Lawrence estuary, Quebec, Canada. Journal of Comparative Pathology, 98, 287 311. Osterhaus, A. D. M. E. and Vedder, E.J. (1988). Identification of virus causing recent seal deaths. Nature, 335, 20. Pippard, L. (1985). Status of the St Lawrence River population of beluga (Delphinapterus leucas). Canadian Field Naturalist, 99, 438-450. Reeves, R. R. and Mitchell, E. (1984). Catch history and initial population of white
Lesions in Beluga Whales
271
whales (Delphinapterus leucas) in the river and gulf of St Lawrence, eastern Canada. I~ Naturaliste Canadian, 111, 63-121. Roberts, S. J. (Ed.). (1986). Veterina~ Obstetrics and Genital Diseases (Theriogenology), Woodstock, Veront, pp. 478-492. Sergeant, D. E., Caldwell, D. K. and Caldwell, M. C. (1973). Age, growth and maturity of bottlenosed dolphin (Tursiops truncatus) from northeast Florida. Journal of the Fisheries Research Board of Canada, 30, 1009-1011. Stroud, R. K. and Roffe, T.J. (1979). Causes of death in marine mammals stranded along the Oregon coast. Journal of Wildlife Diseases, 15, 91-97. Sweeney, J. C. and Ridgway, S. H. (1975). Common diseases of small cetaceans. Journal of the American VeterinaryMedical Association, 167, 533-540. Woodard, J. C., Zam, S. G., Caldwell, D. K. and Caldwell, M. C. (1969). Some parasitic diseases of dolphins. Pathologia Veterinaria, 6, 257-272.
I Received,Januar7 7th, 1994 ] Accepted, December 19th, 1994J
N o n - n e o p l a s t i c L e s i o n s in B e l u g a W h a l e s (Delphinapterus leucas) a n d O t h e r M a r i n e M a m m a l s f r o m the St L a w r e n c e E s t u a r y S. De Guise, A. Lagac6, P. Bfland*, C. Girard and R. Higgins Facult~ de M~decine V~t~rinaire, Universit~ de Montreal, C.P. 5000, St-Hyacinthe, Quebec J2C 7C6 and *St Lawrence National Institute of Ecotoxicology, 460 du Champ-de-Mars, Suite 504, Montrdal, Qudbec, Canada H 2 Y 1B4 Surrtnlary
In a 3-year (1988-1990) pathological study, 24 carcasses of beluga whales from the St Lawrence Estuary, Qu6bec, Canada, showed numerous severe lesions, many of which had never been reported in cetaceans. The most common lesions were found in the digestive tract (21 animals) and consisted mainly of periodontitis and of erosions and ulcers in the oesophagus and the first two gastric compartments. Pneumonia, usually of parasitic origin, was also a common finding (12 animals). The adrenal glands often contained nodules (five animals) or cysts (seven animals), and mastiffs was observed in five females. Overall, the incidence of degenerative, infectious, hyperplastic or necrotic lesions, in addition to numerous neoplasms described in another paper, was considerably higher than that found in marine mammals elsewhere or in other species of marine mammal from the same waters.
Introduction Beluga whales (Delphinapterus leucas) in the St Lawrence Estuary and Gulf have been listed as an endangered population (Pippard, 1985). A retrospective analysis of commercial catches showed that the population decline was initiated by overhunting in the early 20th century (Reeves and Mitchell, 1984). Several hypotheses have been put forward to account for the failure of this population to recover during the last 40 years. Examination of carcasses recovered from the shores of the St Lawrence between 1982 and 1986 suggested a link between toxic contaminants in the St Lawrence basin food chain and the precarious state of the population (B61and et al., 1988; Martineau et al., 1988). A causal relationship was suggested between high polychlorinated biphenyl (PCB) and dichlorophenyl trichloroethane (DDT) concentrations in beluga whale tissues and various lesions contributing to mortality and to decreased reproduction. The present paper describes the non-neoplastic lesions observed in carcasses of St Lawrence beluga whales between 1988 and 1990. Other St Lawrence marine mammals and Arctic belugas were also necropsied for comparison. Correspondence to: S. De Guise, Toxen, Universit6 du Qu6bec ~t Montr6al, C.P. 8888, succ. A, Montr6al, Qu6bec, Canada H3C 3P8 0021-9975/95/030257 + 15 $08.00/0
9 1995 Academic Press Limited
258
S. De Guise et al. Materials and M e t h o d s
Stranded carcasses of 24 beluga whales and 19 smaller marine mammals, along with the carcasses of one small odontocete and one pinniped caught in nets, were carried to the necropsy room of the Veterinary College of Universit~ de Montreal. The carcasses of three large whales were examined macroscopically on the shore where they were found. After a complete macroscopical examination, tissues were fixed in 10% buffered formalin, embedded in paraffin wax, sectioned at 5-7 gm and routinely stained with haematoxylin, phloxine and saffron (HPS) for histopathological examination (Luna, 1968). Proliferation of fibrous tissue was confirmed by Masson's trichrome. Lesions and tissues were cultured on blood agar at 37~ in a 10% CO2 atmosphere and examined after 48h. In some instances cultures were incubated anaerobically. Identification of bacteria was carried out with an Analytical Profile Index diagnostic kit (Analytab Products, Ayerst Laboratories, Plainview, NY, USA). For culture of Vibrio spp., tissue samples were plated on trypticase soy agar (BBL, Cockeysville, MD, USA) with 5% bovine blood and on MacConkey agar; the plates were incubated at 37~ for 24 h. Three passages on kidney cell lines were made for each tissue submitted for virological analysis, and cultures showing a cytopathogenic effect were examined by electron microscopy. Five Arctic belugas, freshly killed by Inuit hunters at Eskimo Point (Hudson Bay) and necropsied on site provided well preserved tissue specimens from animals unexposed to industrial contaminants. Standard methods were used for ageing odontocetes (Sergeant et al., 1973; Gaskin and Blair, 1977; B~land et al., 1988) and pinnipeds (Mansfield and Fisher, 1960; Bowen et al., 1983; Mansfield, 1991). Results
St Lawrence Beluga Whales The lesions observed in the 24 St Lawrence beluga whales are summarized in Table 1. The animals examined ranged from 1"5 to > 29 years old, but only two were less than 13 years old. Neoplastic lesions in these whales have been described elsewhere (De Guise et al., 1994a).
Digestive system. Periodontitis, with necrosis of the gum immediately surrounding the teeth and deposition of blackish material on the gingival surface, was classified as severe in seven animals out of 24 examined (Fig. 1). Tooth loss was common, and only nine animals had as m a n y teeth as the minimal number reported in Arctic animals (Doan and Douglas, 1953; Kleinenberg et al., 1969). Ulcerative stomatitis was severe in three animals (Fig. 2). Ulcers of varying severity were also found in the oesophagus (three animals), the first two gastric compartments (11 animals) and the intestine (one animal). At most sites, the ulcers were small and multiple, except in the second gastric compartment, where in six whales there were one or two ulcers measuring 2-3 cm in diameter and 1-2 cm in depth near the junction with the first compartment. Animal 13-88 had an intestinal polyp, 0"5 cm in diameter, which took the form of an extension of the lamina propria containing a few muscular fibres, connective tissue and blood vessels, and was covered with normal intestinal epithelium. A chronic active hepatitis in animal 8-89 was characterized by a moderate to severe infiltration of fibrous tissue into and between the hepatic lobules,
259
Lesions in Beluga Whales Table 1 P o s t - m o r t e m and bacteriological e x a m i n a t i o n o f St Lawrence beluga w h a l e s Whale no.
Sex
Age (years.)
Lesions
Bacteria isolated
1-88
M
3"5
None
4-88
F
> 21
7-88
M
> 19
8-88
M
> 20
9-88
F
> 22
10-88
F
1"5
11-88
F
_>25
12-88
F
16
13-88
F
> 21
14-88
F
> 23
Interstitial pneumonia associated with parasitic granulomas, mild multifocal superficial haemorrhagic gastritis, penile lymphocytic dermatitis, erosions of 1st gastric compartment, emaciation Ciliated protozoal bronchopneumonia, adrenal cysts, mild chronic mastitis with foci of squamous metaplasia Severe, diffuse, fibrino-purulent peritonitis, left-side testicular necrosis, left epididymitis, severe periodontitis, oral ulceration, focal verminous bronchopneumonia, emaciation Diffuse segmental glomerulopathy, hyperacute cystitis, mild verminous multifocal bronchopneumonia, periodontitis, ulceration of 2nd gastric compartment Mild myocarditis, calcified intestinal mass, sarcoeystosis, adrenal cysts, subcutaneous haematoma Verminous bronchopneumonia, haemorrhagic segmentary enteritis Lymphocytic enteritis with eestodes, ulcerations of 1st and 2nd gastric compartments, renal and adrenal haematoma, chronic mastitis, adrenal cysts, probable toxoplasmosis (spleen) Moderate multifocal verminous pneumonia, severe erosions of the 1st gastric compartment with hydropic degeneration, adrenal nodules Diffuse alveolar damage of the lungs, mild chronic mastitis, erosions of 1st gastric compartment, oesophageal ulcerations, intestinal polyp, subcutaneous haematoma, adrenal cystic haematoma Moderate subacute mastitis
1-89
M
___27
Diffuse interstitial pneumonia, parasitic ulcerations of the 1st gastric compartment, mild periodontitis, fibrous plaques on the intima of the aorta
Site from which bacteria were isolated
Escherichia coli
Lung, liver, kidney
Pseudomonas putrefaciens
Lung, liver, kidney, peritoneal fluid, in pure culture
Mo~ganellamorganii
Liver, kidney
Plesiomonas shigelloides Intestinal contents; mesenteric lymph node, in pure culture Fibrio parahaemolyticus Lung, liver, kidney and Edwardsiella tarda Morganella morganii Intestine
Edwardsiellatarda
Lung, liver, intestine
None
Aeromonas hydrophila
Klebsiella sp. ND
Lung, kidney, Intestinal contents, mammary gland Lungs
260
S. D e G u i s e et al. Table 1 (continued)
Whale no.
Sex
Age (years)
2-89
M-F* _>26
3-89
F
>_ 19
4-89
F
14
5-89
F
>_27
6-89
F
>_25
7-89
M
> 29
8-89
M
_>20
1-90
M
_> 18
2-90
M
_>23
3-90
M
> 19
4-90
F
13
5-90
F
_> 13
6-90
M
> 24
Lesions
Bacteria isolated
Ulcerative enteritis, bilateral hermaphroditism, ankylosing spondylosis, periodontitis, subcutaneous haematoma Subacute parasitic broncopneumonia, mild diffuse lymphocytic enteritis, ulcerative mamiUitis, periodontitis, adrenal nodules and cyst Parasitic eosinophilic pneumonia, mediastinal eosinophilic lymphadenitis, mild subacute enteritis with cestodes, chronic endocarditis, oesophageal ulceration, adrenal cyst, ovarian follicular cyst Bronchial inflammatory polyp, ulceration of 2nd gastric compartment, oesophageal ulcerations, sarcocystosis Fibrinous peritonitis, necropurulent mastiffs, ulceration of 2nd gastric compartment, adrenal cyst and nodule Severe necrotic ulcerative stomatitis, cervical subcutaneous and deep haematoma, parasitic ulceration in 1st gastric compartment, ulcerations of 2nd gastric compartment, periodontitis, cavernous haemangioma of the penis, adrenal cyst and nodules Severe periodontitis, chronic active hepatitis Ulcerations of 2nd gastric compartment (metastatic origin), parasitic ulcerations of 1st gastric compartment, oesophageal ulceration Mild to moderate purulent bronchopneumonia, fibrous plaques on the intima of the aorta Probable abdominal neoplasm, autolysis Moderate acute eosinophilic bronchopneumonia (verminous) with mediastinal eosiniphilic lymphadenitis, mild lymphocytic enteritis, multifocal segmental glomerulopathy Mild vaginitis, subcutaneous pyogranulomas Ulcerative stomatitis, periodontitis, ulceration of 2nd gastric compartment, thyroid abscess, mild purulent multifocal pneumonia, lymphocytic enteritis, abdominal mass (probably scar tissue), adrenal cyst and nodules
ND
ND, not done. * Hermaphrodite. i" Bowel filtrate did not kill mice.
ND
Site fiern which bactem were isolated
--
ND
Aeromonashydrophila
Lungs, liver, kidney, mammary gland
ND
ND
--
ND ND
--
Clostridium tertium
Lungs, liver, kidney
ND None
Aewmonas sp.
Liver
ClostridiumpeoCringens Clostridium sp. KingeUa kingae Aewmonas sp.
Intestinal contents]" Lung and thyroid Thyroid
Lesions in Beluga Whales
261
Fig. 1.
Periodontitis in beluga whale 8-89, allotting several teeth and characterized by periodontal necrosis of the gum, with deposition of blackish material on the surface.
Fig. 2.
Severe extensive ulcerative stomatitis in beluga whale 7-89. Half of the oral cavity was affected.
262
Fig. 3.
S. D e Guise e t al.
A section of lung from beluga whale 4-88 showing protozoa, round to elongated in shape and measuring 30-35 g m in diameter, and up to 85 g m long, with a macronucleus. A single layer of radial cilia was sometimes visible on the outer protozoal surface (arrow). T h e organisms are surrounded by neutrophils. HPS. x 504.
and between hepatocytes, isolating many of them, with a multifocal, mild to moderate infiltration of lymphocytes mostly in the portal area, and a mild to moderate hyperplasia of the bile ducts.
Respiratory system. Pneumonia, most often associated with parasites, was observed in 12 of the belugas. Reddish, whitish or greenish foci of various sizes (1-5 cm) were seen on cut section in most of the animals with pneumonia. Nematodes were present in most cases. A ciliated protozoal pneumonia was diagnosed in whale 4-88. Numerous firm nodules, 3 4 cm in diameter, were palpable in the cranial portion of the lungs. On section, these nodules were whitish to dark red and contained a sero-purulent exudate which could be squeezed out under moderate pressure. The foci consisted of a mixture of neutrophils and macrophages admixed with numerous ciliated protozoa in various stages of degeneration in the alveoli. The protozoa were round to elongate, measuring 30-35 gm in diameter, and up to 85 gm in length, with a large, round to elongate, eccentrically placed, basophilic macronucleus (Fig. 3). A single layer of cilia radiated from the outer wall. Diffuse alveolar damage, with thick hyaline membranes and a moderate amount of filamentous alveolar fibrin, was found in animal 13-88.
Endocrine system. Two types of lesion were found in the cortex of one or both
Lesions in Beluga Whales
263
Fig. 4.
An adrenal gland from beluga whale 4-g9 showing a well-defined nodule in the cortex (arrow).
Fig. 5.
An adrenal gland from beluga whale 4-89 showing two cysts filled with serous fluid in the cortex (arrow).
adrenal glands: hyperplastic nodules (five animals) and serous cysts (seven animals). The nodules (Fig. 4), which varied in size from 2-20 mm, were single or multiple and often circumscribed by a fibrous capsule of variable thickness; they frequently compressed the adjacent parenchyma. These well defined nodules differed markedly from the normal pseudolobules formed by the fibrous projections of the capsule into the parenchyma2The serous cysts (Fig. 5), which varied in size from 2-15 mm, were single or multiple, surrounded by a single layer of squamous cells, and lightly to strongly encapsulated. These
264
S. De Guise et aL
cysts usually compressed the adjacent parenchyma. Most of the adrenals bearing cysts also showed areas of moderate to severe hydropic degeneration of the cortical cells. Only one of nine animals, with cysts or nodules or both, was a male (no. 7-89). An abscess, 1 cm in diameter, containing whitish creamy pus was found in the craniolateral portion of the thyroid gland of animal 6-90.
Reproductive system. Testicular necrosis, epididymitis and peritonitis were noted in animal 7-88. The left testicle, which was much enlarged and covered by fibrin, was free within the abdominal cavity. Diffuse coagulative necrosis with pyknosis and karyorrhexis was noted throughout the left testicle, accompanied by a chronic active peritonitis on the abdominal organs. The abdominal cavity contained c. 100 litres of yellow exudate with large fibrinous tags. Pseudomonas putrefaciens was isolated in pure culture from the abdominal fluid. A follicular cyst measuring 6 x 6 x 5 cm was found on the left ovary of animal 4-89. Animal 2-89 was a true hermaphrodite and is fully described elsewhere (De Guise et al., 1994b). There were lesions in the m a m m a r y glands of seven of the 13 females. Five animals had a histologically confirmed mastitis, and mastitis was suspected from a macroscopical examination in another animal (no. 5-89). Lesions were mild to moderate and chronic in four whales, with mild to moderate squamous metaplasia in no. 4-88; animal 6-89 had a severe necro-purulent mastitis, with pus and bloody milk. A severe ulcerative mammillitis and a m a m m a r y adenocarcinoma (De Guise et al., 1994a) were also found.
Urinary System. A segmental glomerulopathy was found in two animals (8-88, 4-90). It was characterized by foci of hyaline degeneration of the afferent and efferent arterioles at the vascular pole of most of the glomeruli. Cardio-vascular system. In animal 4-89, a focal chronic valvular endocardiosis consisting of two nodules (4-5 x 0"9 x 0"9 cm and 0"9 x 0-9 x 0"8 cm) was found on the chordae tendinae of the medial leaflet of the triscupid valve. These fibrous nodules each had a calcified centre, and the surface showed partial re-epithelization from the endocardium. Fibrous proliferation on the intima formed a plaque in the aorta of animals 1-89 and 2-90, with calcification and erosion of the intima (2-90). Animal 9-88 had a mild diffuse subacute myocarditis. Other lesions. Large subcutaneous haematomas in the area of the neck or head were found in four whales, with extensions into the melon and around the atlas, axis, and adjacent vertebral canal in one animal. Ankylosing spondylosis, found in animal 2-89, was characterized by thick bridges of bone that solidly fused the ventral portions of the bodies of the 10th and 11 th thoracic vertebrae.
Lesions in Beluga Whales
265
Table 2 Post-mortern examinations of 24 St Lawrence marine m a m m a l s other than belugas
Animals
Sex
Age (years)
Lesions
Odontocetes LA-1 M
Ad
LA-2 LA-3 LA-4
M M ?
Juv 10" 7*
PP-1 F PP-2 F Mysticetes BA-1 F BA-2 F BP-I M Pinnipeds PV- 1 F PV-2 F PV-3 F PV-4 F PV-5 F PV-6 F PV-7 M PV-8 M Psp- 1 F PG-1 M PG-2 F PG-3 F HG-1 F HG-2 M HG-3 M
>9 > 1
(Caught in net); death by drowning, pneumonia, testicular abscesses, dermatitis Digestive system parasitism, cranial trauma Probable septicaemia, parasitic cysts'(Mono~ygma sp.) in abdominal cavity~ Probable septicaemia, sarcocystosis, parasitic cysts (Mono~ygmasp.) in abdominal cavityI" Verminous bronchopneumonia, hepatic flukes~" Pronounced icterus, with inanition~
0-1 ? ?
(Caught in net); death by drowning Abdominal trauma, cutaneous lacerations Severe parasitism in aorta~"
Ad Ad 1 22 0'5 13 3 13 4 20 Ad 14 Ad Ad Ad
(Caught in net); death by drowning Heart worms t Purulent bronchopneumonia t Bronchopneumonia~" Severe gastric parasitism t Multiple cranial fractures Severe gastric parasitismS" Multiple cranial fractures Non-penetrating cranial trauma Inanition, severe gastric parasitism t Multiple contusions None observed1" Moderate mediastinal emphysema, mitral insufficiency1" Non-penetrating traumas to head and neck Tracheo-bronchitis, left mitral insufficlency~"
LA = Lagenorhyncus acutus, PP = Phocoenaphocoena, BA = Balaenoptera acutorostrata, BP = Balaenopteraphysahs, PV = Phoca vitulina, Psp = Seal, unidentified species, PG = Pagophilusgroenlandicus, HG = Halichoerus grypus. Ad = adult; Juv =juvenile; ages given in years, except for LA-3 and LA-4 (*) where it is expressed as the number of growth layers in the teeth. ~"Died of natural causes.
Bacteriology. Bacteria cultured from St Lawrence beluga whale tissues in pure or heavy culture and considered significant are shown in Table 1.
Virology. An adenovirus was isolated from the intestines of a single animal (7-88) but did not appear to be associated with any lesion. Other Marine Mammals In the five Arctic belugas, moderate infiltrations of eosinophils in the lamina propria and submucosa of the gastric compartments and of the intestines were present, without gastro-intestinal helminths. These animals were aged between 3 and _> 21 years. In 10 of the St Lawrence marine mammals other than belugas, the cause of death, directly or indirectly, was h u m a n activity (Table 2). Three animals were reported caught in fishing nets; others, mainly seals (five of 15 seals
266
S. De Guise et al.
examined) with stomachs full of fish, died of head trauma. A minke whale was killed by collision with a large boat. Most lesions not resulting from human activity were associated with the presence of parasites. Discussion
Digestive system. The aetiology of the oral lesions was unknown, but similar lesions in a captive beluga whale (Hartman, 1976) and in an Atlantic bottlenose dolphin, Tursiops truncatus (Colgrove et al., 1975), regressed with treatment that included the use of antibiotics. The ulcers found in the second gastric compartment, unlike those in the first compartment, were not related to parasites. In addition to acid hypersecretion and impairment of mucosal integrity, local mucosal ischaemia caused by peristaltic contractions of the muscular sphincter between the first and second gastric compartments may have played a role in the pathogenesis, as with peptic ulcers in man (Dayal and DeLellis, 1989). PCBs, found at high concentrations in St Lawrence belugas and known to cause gastric ulcers in other species (Hansen et al., 1976), might explain the high incidence (25%) of glandular stomach ulcers, as compared with human males (6-14%) and females (2-6%) (Dayal and DeLellis, 1989). Chronic active hepatitis was reported in a dolphin by Bossart (1984), but the description did not fit the accepted definition of the disease (Kelly, 1993). The present case (animal 8-89) would therefore appear to be the first reported in a cetacean. Respiratory system. Pneumonia in cetaceans is not easily detected by palpation at necropsy, and reddish, whitish or greenish foci on cut section of the lung appeared to be the best macroscopical sign. Protozoal pneumonia occurs rarely in animals, and in man is often associated with immunosuppression, as occurs in AIDS (Cotran et al., 1989a). Holotricha spp. are frequently found in the blowhole of Atlantic white-sided dolphins, but only one case of pneumonia associated with this ciliated protozoon has been reported in a dolphin (Woodard et al., 1969). Diffuse alveolar damage, as described here, has not previously been reported in a marine mammal; it was suggestive of an acute respiratory distress syndrome. Endocrine system. The classification of the nodules in the adrenal cortex of belugas into hyperplastic nodules or adenomas according to their morphology by criteria used in domestic animals (Capen, 1993) or man (DeLellis, 1989) is difficult. Since it would seem unusual to find such a high incidence of adenomas in a single population, hyperplasia is a more likely provisional diagnosis. Adrenal hyperplasia in female grey seals (Halichoerus grypus) and ringed seals (Phoca hispida) in the Baltic Sea has been related to organochlorine pollutants (Bergman and Olsson, 1985). Adrenal cysts have not been described in domestic animals (Capen, 1993). Serous cyst formation appears to be
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preceded by hydropic degeneration with membrane destruction, and overstimulation of cortisol production may play an aetiological role. Similar cysts were observed in female white-sided dolphins (Lagenorhynchus acutus), but their aetiology was obscure (Geraci et al., 1978b). Thyroid abscesses are uncommon in domestic animals, and the one found in animal 6-90 is the first reported in marine mammals.
Reproductive system. The cause of testicular necrosis (animal 7-88) raises questions, because testicular torsion is unlikely for anatomical reasons (De Guise et al., 1995), and the absence of inflammatory cells ruled out primary orchitis. In domestic cows (Bos taurus), ovarian follicular cysts are anovulatory follicles defined by their size (>2"5 cm) and persistence (> 10 days), and are one of the most common causes of infertility (Roberts, 1986). The size of the follicular cyst found in beluga 4-89 was clearly larger than that of follicles usually seen in the species, and the cyst may have impaired the reproductive potential of this animal. In the five animals with mastitis, milk production was probably affected, either quantitatively (chronic mastitis), or qualitatively, or both (acute purulent mastitis). The mastitis in these animals, unlike that in Atlantic white-sided dolphins described by Geraci et al. (1978a), was not caused by parasites. The case of severe ulcerating mammillitis was undoubtedly sufficiently painful to interfere with suckling, thus jeopardizing survival of the calf. Urinary system. The segmental glomerulopathy observed in two belugas has not previously been described in animals. The lesions somewhat resembled those of renal diseases associated with microangiopathic haemolytic anaemia in man; in such diseases, intravascular coagulation and endothelial injury would be expected (Cotran et al., 1989b). Cardio-vascular system. Previous reports o f endocardiosis (such as that found in animal 4-89) in cetaceans are confined to two dolphins (Sweeney and Ridgway, 1975). The fibrous intimal plaques found in the aortas of two belugas (nos. 1-89 and 2-90) and the mild myocarditis found in one were similar to lesions already reported in other marine mammals (Howard, 1983). Other lesions. All belugas with haematomas had concurrent severe diseases which accounted for death. Shark bites and gunshot wounds, reported in other species and from other locations, were not seen in this study. Ankylosing spondylosis, a degenerative disease common in bulls, was found in one beluga. This lesion had already been reported in a beluga from the same population (Martineau et al., 1988); both animals were old ( > 2 6 and > 19 years). Bacteriology. Of the bacterial species isolated in significant numbers from beluga tissues, none was found repeatedly, and none was the cause of a specific
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disease. They were all weak or opportunistic pathogens of the type occurring in animals already debilitated (Coles et al., 1978), and most have been reported previously in St Lawrence belugas (Martineau et al., 1988) and in other marine mammals from various parts of the world (Buck et al., 1991). Other marine mammals. The major cause of mortality in St Lawrence marine mammals other than belugas was human activity; natural causes were most often related to parasites or pneumonia. These natural causes were similar to those found in previous studies on cetaceans (Cowan, 1966; Stroud and Roffe, 1979; Cowan et al., 1986) and pinnipeds (Stroud and Roffe, 1979) in other parts of the world, except for mass mortality caused by viral infections (Geraci et al., 1982; Osterhaus and Vedder, 1988; Domingo et al., 1992) or natural toxins (Geraci, 1989; Geraci et al., 1989). Bacterial infections were considered by Howard et al. (1983) to be an important cause of mortality in marine mammals, although they were often associated with parasitic or traumatic injury. Conclusion. A high incidence of various types of chronic lesions was observed in 24 St Lawrence belugas. The lesions were usually multiple and multisystemic, and several had not been reported previously in cetaceans. The incidence of degenerative, infectious, hyperplastic or necrotic lesions, in addition to the numerous neoplasms described elsewhere (De Guise et al., 1994a), was considerably higher than that reported in other areas. Lesions that interfere significantly with the normal function of the mammary glands are a serious handicap in belugas, which have a prolonged lactation. In contrast, the cause of death in half of the St Lawrence pinnipeds and cetaceans other than belugas was related directly to human activity. In the remainder, the majority of lesions had a parasitic aetiology or were observed in the pulmonary and circulatory systems. A single lesion of the gastrointestinal tract, an eosinophilic enteritis, was seen in five Arctic belugas. These observations and other causes of death (gunshot etc.) resemble those in reports on various cetaceans and pinnipeds from other parts of the world. The results of this study, when added to those from a similar series of 21 necropsies carried out in 1983-87 on beluga whales from the same population (Martineau et al., 1988), confirm that the health status of St Lawrence beluga whales differed strikingly from that of other populations of cetaceans in the St Lawrence and elsewhere. The findings, made over a period of >8 years, are considered to be a true reflection of disease in the St Lawrence beluga whale population. Previous work showed high concentrations of organochlorines in these whales (Martineau et al., 1988). Possibly the incidence and diversity of the lesions observed are linked to exposure to toxic compounds.
Acknowledgments We wish to thank Richard Plante, Dr Robert Claveau, Dr Daniel Martineau and the Centre Oc6anographique de Rimouski for assistance and advice. The study was supported by the Wildlife Toxicology Fund (World Wildlife Fund Canada and
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Environment Canada), Department of Fisheries and Oceans Canada, Alcan, the World Wildlife Fund, Fondation de la Faune du Qu6bec, Environnement Quebec, Greenpeace (Canada), and Fonds Canadien d'Aide/t la Recherche. References
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I Received,Januar7 7th, 1994 ] Accepted, December 19th, 1994J