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A Case of Chronic Abdominal Actinomycosis with Severe Hepatic
Involvement in a Dog
Gavhane, D.S.,* Moregaonkar, S.D., Mhase, A.K., Sawale, G.K. and Kadam, D.P.
Department of Veterinary Pathology, Bombay Veterinary College, Parel, Mumbai-12, India.
* Corresponding Author: Dr. Gavhane Dnyaneshwar Shivaji, Department of Pathology, Bombay Veterinary College, Mumbai-12, India. Tel:
+919011443802. Email: mmaulivet@gmail.com
AB ST RAC T
The authors present a case report on abdominal actinomycosis in 7 year old German shepherd dog, which was
presented with the complaint of chronic fever, anorexia, weight loss, hematemesis and a recent history of mixed
hemoprotozoan infections. Due to the non-specific clinical presentation, the diagnosis was delayed. X-ray
and ultrasonographic examination revealed ascites; severe hepatomegaly with surface nodularity indicating
possibility of hepatic neoplasia. However, findings on necropsy and detailed histopathological investigations
confirmed the diagnosis as actinomycosis. To the best of the authors knowledge this is the rare report of
abdominal actinomycosis in dog.
Keywords: Actinomycosis; Dog; Neoplasia; Hepatomegaly.
INTRODUCTION
Actinomycosis is caused by gram positive filamentous
organism from the Actinomyces spp. and is characterized
by chronic pyogranulomatous inflammation in affected
organ (5, 9). It can establish localized as well as generalized infections. Different species such as Actinomyces bovis,
Actinomycoses israeli, Actinomyces hordeovulnare, Actinomyces
canis, Actinomyces viscosus, and Actinomyces odontolyticus
have been implicated to cause actinomycosis in humans
and animals (1, 2, 3, 5, 7, 11, 12). These microbes can localize at pleural cavity, pelvic cavity, abdominal cavity, neck
lymphnodes, bones, eyes, nervous system, and cervico-facial
region and causes different disease conditions such as osteomyelitis, lymphadenopathies, bursitis, pleuritis, pneumonia
and peritonitis. Infections are relatively common in large
animal particularly bovines (5, 7, 8, 15, 17). Abdominal
actinomycosisis is rare in animals. It usually runs a chronic
course. Non-specific signs and symptoms create difficulty
in a timely diagnosis (4).
58
Gavhane, D.S.
March 2016.indb 58
CASE HISTORY
A seven year old female German shepherd dog with
clinical presentation of chronic fever, anorexia, weight
loss, hematemesis and labored breathing was presented
to Department of Medicine, Bombay Veterinary College,
Mumbai-12, India. A month before, antibodies were detected in serum against Anaplasma phagocytophilium and
Ehrlichia canis, therefore, the dog was under treatment with
Doxycycline at 5 mg/kg BW BID (Doxy1LDR Fort, Hosur,
India). However, intermittent low grade fever continued.
Most of the hemato-biochemical observations were within
normal range (Table 1). There was mild neutrophilic leukocytosis, toxic neutrophils, microcytic hypochromic anemia
and stages of Mycoplasma haemocanis in RBCs.
Radiologic and sonographic examination revealed ascites,
severe hepatomegaly with an uneven surface having multiple
small protrusions indicative of malignancy (Fig. 1). The dog
died during emergency intervention and a detailed post
mortem investigation was carried out.
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Table 1: Hemato-biochemical observations.
Hematobiochemical
observations
WBC count
Neutrophils
RBC count
Hemoglobin
Packed Cell Volume (PCV)
Mean Corpuscular Volume
(MCV)
Platelet Count
Aspartate transaminase
Alanine transaminase
Total Bilirubin
Total Proteins
Albumin Globulin ratio
Alkaline phosphatase
Blood urea nitrogen
Creatinine
Observed values
17.8 X 103/ µl
78 X 103/ µl
4.9 X 106/ µl
7.8 gm%
29.8 %
60.52 fl
Reference Values
(7, 17)
6-17 X 103/ µl
60-77 X 103/ µl
5.5-8.5 X 106/ µl
12-18 gm%
37-55 %
66-77 fl
2.11 X 105/ µl
31.3 IU/ L
20.6 IU/L
0.3 mg/ dL
7.2 g/dL
0.6
119.2 IU/ L
12.3 mg/ dL
0.8 mg/ dL
2-5 X 105/ µl
23-66
21-102
0.1-0.5 mg/ dL
5.4-7.1 g/ dL
0.75-1.2
20-156 IU/ L
10-28 mg/ dL
0.5-1.5 mg/ dL
RESULTS AND DISCUSSION
At necropsy emaciation was evident. The abdominal cavity
contained 300-500ml of gray colored exudate with a fetid
odor with numerous sulfur colored, flat and spherical granules
measuring around 1-3 mm in size (Figure 2). The serosal
surface of intestine, urinary bladder, and mesentery were
reddish–gray in color and the surface appeared corrugated
and hyperplastic. The liver was firm, remarkably enlarged,
with rounded edges and an uneven surface. There were red
and gray black areas and multiple small nodular growths on
the surface of liver, which appeared to resemble hepatic neoplasia (Fig.3). The surface of all visceral organs and parietal
peritoneum was heavily studded with similar sulfur colored
granules (Fig.2). The gastric pyloric area showed multiple
hemorrhagic ulcers. Peritoneal fluid along with the sulfur
colored granules were harvested aseptically and processed
Figure 1: Radiographic view of lateral abdomen indicating ascites.
Figure 2: Opened abdominal cavity showing diffuse peritonitis, grayish
exudate and neumerous sulfur colored granules.
Figure 3: Severe hepatomegaly with uneven surface and neumerous
nodular and villous outgrwoths mimicking tumor.
Figure 4: Cytology of peritoneal exudate showing filamentous, branching,
ray-fungus like organisms and macrophages (1000 X, Field’s Stain).
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for isolation and identification of causative agent using the
BacT/ALERT 3D system (BioMerieux, India Pvt. Ltd).
Samples pieces of all organs were collected and immediately
fixed in 10% neutral buffered formalin for routine histopathological study.
Cytology of smears made of peritoneal fluid stained
with Romanowsky stain and Field’s stain (S008-9, Himedia,
India), revealed numerous foamy macrophages, mesothelial
cells, lymphocytes and degenerating neutrophils along with
bunches of numerous filamentous organisms resembling rayfungi (Fig. 4).Histologically, sections of liver showed several
degenerating hepatocytes, atrophy and distortion of hepatic
chords. Sinusoids were dilated and massively infiltrated with
mononuclear cells (Fig. 5). Portion of liver with nodular areas
revealed fibrous connective tissue encapsulated abscesses
containing mononuclear cells, degenerated neutrophils
and centrally placed sulfur granules containing bunches of
filamentous ray rods radiating outwards and surrounded by
pink proteinaceous material i.e. Splendore-Hoeppli reaction
(Fig. 6 and 7).
On the surface of liver, serosa of abdominal organs and
parietal peritoneum, villous like projections made of angiofibroblastic tissue composed of loose fibrous connective tissue
intermixed with numerous small capillaries, and infiltrating
mononuclear cells were noticed (Fig. 8). The lining epithelium of these villous projections consisted of proliferating
hypertrophied mesothelial cells (Fig.8). Duplicate sections of
all tissues were stained with Brown-Brenn’s grams stain (10),
Figure 5: Histological section of liver showing destruction, atrophy
of hepatic cords, dilatation of sinusoidal space, massive infiltration
of mononuclear cells in sinusoids (Green arrow) and proliferation of
fibrocytes in central vein area (Blue arrow) (400 X, H&E).
Figure 6: Characteristic sulfur granule (Green arrow) typical of
Actinomyces spp. in histological section of liver and agnio-fibroblastic
growths (Blue arrow) (400 X, H&E).
Figure 7: Ray fungus like filamentous bacterial colonies (Green arrow),
Splendore Hoepli reaction (Blue arrow) and PAS positive organism
(Upper left) (400 X, H&E).
Figure 8: Histological section of liver showing villous like growth
of angio-fibroblastic tissue (Green arrow) lined by proliferation
hypertrophied mesothelial cells (Black arrow) (400 X, H&E).
Gavhane, D.S.
March 2016.indb 60
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Periodic Acid Schiff (PAS) stain (Himedia, India), Gomori
methanamine silver (GMS) stain (10), Ziehl Neelsin (ZN)
acid fast (Himedia, India), Kinyoun’s modified acid fast
(Sigma Aldrich, USA) and Fite stain (14).
A panel of different stains used indicated the bacteria
to be Gram positive, PAS positive, Gomori methenamine
silverGMS positive, Modified ZN acid fast negative,
Kinyoun’smodified acid fast negative and Fite stain negative.
Whereas actinomyces have very thin branching filamentous
rods, Nocardia spp. are variably gram positive, modified acid
fast and in systemic infection do not show PAS positivity
(8). Culture in the Automated BacT/ALERT 3D System
confirmed the bacteria as Actinomyces spp.
Due to the subacute to chronic presentation, the nonspecific signs and symptoms, diagnosis in such cases is
frequently delayed. The dog was under immunosupression
due to already existing hemoprotozoan infections and long
term chemotherapy, which might have helped to establish
actinomycosis. The exact mode of spread of bacteria cannot
be ascertained. In hepatic involvement, the portal of entry
of bacteria is presumably hematogenous (5). Perforating
ulcers in the gastrointestinal tract, penetrating objects such
as pointed awns and faulty closure of the uterine stumps after
hysterectomy or through penetrating intrauterine devices are
proposed causes (5, 8). The dog presented here was police
sniffer dog which was under daily observation. Therefore,
chances of rice awns contamination in rice seems less, however, small sharp bone fragments (chicken or fish meal) may
have mechanism of action similar to that of penetrating awns.
The reports on actinomycoses in dog are very scarce as the
incidence is extremely rare. They are characterized as chronic
progressive (5). Surgical fistulas to drain exudate and long
term penicillin therapy for 6 to 12 months are proposed in
such cases (5, 14). Animals should be examined for recurrence
after discontinuing medication. Similar clinical presentations
as well as similar patho-morphological findings have been
reported in human with abdominal actinomycosis (8, 14).
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