Spirocercosis-associated esophageal sarcomas in dogs

Veterinary Parasitology 119 (2004) 209–221

Spirocercosis-associated esophageal sarcomas in dogs A retrospective study of 17 cases (1997–2003) Eyal Ranen a,∗ , Eran Lavy a , Izhac Aizenberg a , Shmuel Perl b , Shimon Harrus a a b

School of Veterinary Medicine, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel The Kimron Veterinary Institute, P.O. Box 12, Bet-Dagan 50250, Israel Received 23 July 2003; accepted 14 October 2003

Abstract Seventeen client-owned dogs diagnosed with spirocercosis-associated esophageal sarcomas were retrospectively reviewed. The most common clinical signs noticed were vomiting and/or regurgitation (94%), lethargy and depression (59%), pyrexia and anorexia (41% each). Leukocytosis (82%) and microcytic hypochromic anemia (30%) were the most common hematological abnormalities. Caudal thoracic masses were demonstrated on survey radiographs of 13/15 of the dogs and thoracic spondylitis was detected in 12/15 dogs. Spirocerca lupi eggs were detected in 2/8 patients and worms were demonstrated on 1/11 at necropsy. Ten cases underwent surgical attempt to remove the tumors. In six of them partial esophagectomy (PE) was performed and all of them survived the immediate postoperative hospitalization. Five of the cases that underwent PE also received chemotherapy after surgery (doxorubicin (Adriamycin, Upjohn)) with an average survival time of 267 days. The histopathological results of the esophageal tumors were osteosarcoma (9), fibrosarcoma (5) and undifferentiated sarcoma (1). In areas endemic to spirocercosis, regurgitation or vomiting in dogs and microcytic hypochromic anemia and neutrophilia warrant ruling out esophageal sarcomas. Proper surgical treatment could prolong the dogs’ lifespan for months, and improve their quality of life. © 2003 Elsevier B.V. All rights reserved. Keywords: Spirocercosis; Dog; Esophagus; Osteosarcoma; Fibrosarcoma; Surgery

∗ Corresponding author. Tel.: +972-3-9688549; fax: +972-3-9604079. E-mail address: [email protected] (E. Ranen).

0304-4017/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2003.10.023

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1. Introduction Esophageal tumors are rare in dogs, accounting for less than 0.5% of reported tumors (Ridgeway and Suter, 1979). Squamous cell carcinomas and leiomyosarcomas are the most common esophageal neoplasms diagnosed (Withrow, 2001). The development of esophageal osteosarcomas and fibrosarcomas has been noted in dogs infected with Spirocerca lupi, and their incidence increases significantly in areas endemic to S. lupi (Seibold et al., 1955; Bailey, 1972; Moulton, 1978). Aortic scars and aneurysms, and esophageal nodular granulomas are the most frequently reported pathological lesions of spirocercosis, and are considered pathognomonic (Seibold et al., 1955; Bailey, 1963; Moulton, 1978; Fox et al., 1988; Dvir et al., 2001). Definitive diagnosis is made by detection of typical eggs in fecal smears (Markovics and Medinski, 1996), and/or finding the parasite in typical lesions (Fox et al., 1988). Demonstration of esophageal granulomas with nipple-like orifice in endoscopy and detection of spondylitis of the caudal thoracic vertebrae (T6–T12) on radiography are also considered pathognomonic to spirocercosis (Bailey, 1972; Dvir et al., 2001; Lavy et al., 2002). Doramectin has been found, recently, to be an effective drug against S. lupi (Berry, 2000; Lavy et al., 2002). Treatment of esophageal tumors includes surgical excision, chemotherapy and radiation (Withrow, 2001). Esophageal surgery has been reported to be a difficult procedure associated with frequent postoperative complications (Lemarie and Hosgood, 1998; Kyles, 2002). The prognosis of dogs suffering from esophageal sarcomas was reported to be poor (Withrow, 2001). This clinical report describes a series of spirocercosis-associated esophageal sarcomas in dogs, and for the first time includes the use of advanced techniques in the diagnosis and treatment of this condition in a relatively large number of dogs. 2. Materials and methods Medical records of all dogs diagnosed with esophageal sarcomas at the Veterinary Teaching Hospital (VTH) of the Hebrew University of Jerusalem, between 1997 and 2003, were retrospectively reviewed. Criteria for inclusion in the study were histological diagnosis of esophageal sarcoma and one or more of the following criteria: detection of typical S. lupi eggs in the feces, demonstration of characteristic aortic scars and aneurysms, presence of esophageal nodular granulomas and radiographic signs of spondylitis of the caudal thoracic vertebrae. Anamnesis, clinical and clinical–pathological findings, radiographic, endoscopic and necropsy findings were recorded. Surgical and medical treatment, and outcome were obtained from the medical records. All dogs were followed up until death or euthanasia, or until the collection of data for this report. 3. Results 3.1. Signalment Seventeen client-owned dogs were found to meet the criteria for inclusion in this study. Their age ranged from 4 to 12 years with an average of 6.8 years. Twelve of the dogs were

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Table 1 Average, median and standard deviation of hematological and biochemical parameters of 17 dogs with spirocercosis-associated esophageal sarcomasa Case #

RBC

HB

HT

MCV

WBC

ALP

CK

AMYL

LDH

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

6.14 4.81 4.80 7.11 5.79 2.55 7.03 6.10 2.78 5.15 4.22 1.92 7.71 5.89 6.50 3.64 3.36

15.7 7.4 7.0 17.0 11.9 6.2 15.5 12.6 5.3 12.9 11.1 3.4 16.1 12.8 14.6 6.3 3.1

42.70 24.40 23.80 49.30 35.50 19.70 49.30 41.40 18.70 35.50 30.80 11.19 49.42 37.50 46.30 18.00 13.30

70 58 50 69 61 77 70 68 67 69 73 58 64 64 71 50 40

32.30 26.10 17.80 37.90 12.80 20.90 16.70 19.40 13.70 46.50 49.10 65.45 22.75 20.20 26.00 22.10 35.60

372 81 ND ND ND 29 ND 238 309 ND ND ND 248 ND ND ND 3420

196 58 ND ND ND 289 ND 77 N/D ND ND ND 256 ND ND ND 746

1870 855 ND ND ND 658 ND 736 ND ND ND 823 1204 ND ND ND 2280

600 145 ND ND ND 859 ND 244 ND ND ND ND 1276 ND ND ND ND

Normal Mean S.D. Median

5.5–8.5 12.0–18.0 5.03 10.52 1.73 4.68 5.15 11.90

37–55 60–77 6.0–17 10–140 13–100 250–800 32.17 63.47 28.55 671 270.39 1204 13.22 9.65 14.32 1218 251 631 35.50 67.00 22.75 248 226 855

24–250 625 462 600

ND: not done; RBC: red blood cells (×106 ␮l−1 ); HB: hemoglobin (g/dl); HT: hematocrit (%); MCV: mean corpuscular volume (fl); WBC: white blood cell (×103 ␮l−1 ); ALP: alkaline phosphatase (U/l); CK: creatine kinase (IU/l); AMYL: amylase (U/l); LDH: lactate dehydrogenase (U/l). a

females and 10 of them spayed. Most of the dogs were of large breeds with an average weight of 25 kg (ranged 12–40 kg). Four of the dogs were Labrador retrievers, two boxers and eight mixed breed dogs. 3.2. Clinical and clinical–pathological findings The onset of the clinical signs ranged from 10 days to 18 weeks prior to arriving at the VTH (average of 7 weeks). Most common clinical signs were vomiting and/or regurgitation (94%). Other clinical signs included: lethargy and depression (59%); pyrexia (rectal temperature above 39.5 ◦ C) and anorexia (41% each), weight loss (35%), melena, sub-mandibular swelling and pale mucous membranes (29% each), salivation (24%) cough and neurological signs (18% each), and hematemesis (18%). Table 1 shows the hematological and biochemical abnormalities among the dogs, their mean standard deviations and medians. The most common hematological abnormality was found to be leukocytosis (82%), and 86% of these cases showed absolute neutrophilia. Cases #11 and #12 showed absolute lymphocytosis (13 797 and 19 046 ␮l−1 , respectively). Anemia was the second most common hematological sign presented in 47% of the cases. Microcytic hypochromic anemia was seen in 63% of the anemic dogs (cases #2, #3, #12, #16 and #17). Abnormal biochemical findings included increased reactivity of alkaline phosphatase (ALP) 5/7, creatine kinase (CK) (4/6), amylase

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(AMYL) (3/7), and lactate dehydrogenase (LDH) (4/5) (Table 1). A fecal flotation test, to detect S. lupi eggs, was performed in eight cases but was positive in two cases only (#8 and #15). 3.3. Radiography and computed tomography Fifteen dogs underwent thoracic survey radiography. Caudal thoracic masses were demonstrated on survey radiographs of 13 of the patients (Fig. 1) and confirmed by contrast esophograms (#5 and #6). In one case (#13), the esophageal mass was detected accidentally by CT examination (Fig. 2), during evaluation of other thoracic masses that were detected previously on chest radiography. In case #9, the mass was located in the stomach as confirmed by a contrast upper gastrointestinal study. Radiographic signs of spondylitis were detected in 12 patients, at the ventral aspect of T6–T12 vertebrae (Table 2) (Figs. 1 and 2). Spondylosis between T5 and T13 was detected in 12 dogs (#1–6, #8, #9, #11–13 and #15). Marked mineralization of the aorta was shown in the survey radiograph of cases #5. This finding was confirmed at necropsy (#15). Two cases (#13 and #17) showed radiographic signs of metastatic lung disease on admission. In another two cases (#8 and #14), radiographic signs of metastatic lung disease were demonstrated 1 and 6 months after surgery, respectively. Three cases (#7, #8 and #14) showed radiographic signs of hypertrophic osteopathy (HO), 4, 2 and 6 months after surgical removal of the esophageal mass, respectively. 3.4. Endoscopy Fifteen dogs underwent endoscopic examination, and an irregular mass was found in each. These masses were 4–10 cm in diameter, and protruded through the esophageal mucosa. Some of the masses were pedunculated or cauliflower-like, some were fragile, bled easily and had areas of necrosis and discoloration (Fig. 3). The esophageal lumen was partially obstructed at the region of the mass. In seven of the cases, 1–3 typical S. lupi granulomas were identified near the main neoplastic mass (#2, #3, #9, #10, #11, #15 and #16). Six endoscopic biopsies were taken during endoscopy and sent for histopathological evaluation. Only three of them were diagnosed as sarcomas (Table 2). One case (#7) revealed a false diagnosis of a granuloma. The dog was treated medically and when no response to 14-week treatment with doramectin was achieved, a surgical removal was performed and the histopathology revealed neoplasia. 3.5. Surgery, postoperative treatment and outcome Ten of the cases underwent a surgical attempt to remove the tumors (Table 2). In six cases (#6, #7, #8, #11, #14 and #15), a full thickness partial esophagectomy, 1 cm from the tumor borders, was performed. In two cases (#3 and #4) the tumors were removed by esophageal resection and anastomosis. Partial resection of the tumor from the esophageal mucosa was done through a gastrotomy approach in one case (#9), and in another (case #5), esophagotomy revealed an enlarged, inoperable tumor. The six cases that underwent partial esophagectomy survived surgery and the immediate postoperative hospitalization. Those cases were released from hospital after they were able to eat and drink without showing any signs of vomiting, regurgitation, or leakage to the thoracic cavity. Duration of hospitalization

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Fig. 1. Caudal thoracic soft tissue mass (white filled arrow), radiographic signs of spondylitis (black arrows) and calcification of an aortic aneurysm (white empty arrow) as demonstrated on a lateral projection of the thorax (case #15).

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Table 2 Clinical and pathological aspects of 17 dogs with spirocercosis-associated esophageal sarcomasa Case #

Duration of clinical signs PA (weeks)

Survival from admission (days)

Surgery

Endoscopic biopsy or TS

7–10

ND

–

ND

ND

Histopathology

Granulomas

Aortic pathology

Metastases

Fibro.

Endo. + PM

+

−

−

1

4.5

2

2

4.5

13

3

3

4

7–8

R&A

ND

Fibro.

PM

4

3

3

8–11

R&A

ND

Fibro.

–

5

3

67

6

1.5

Fibro.

8, 9

Exploration

Esophagitis

Osteo.

–

405

7

PE

Undiagnostic

Undif.

–

–

PE

Granuloma

Osteo.

–

+ +

− −

Doxo. (×4)

+

+

Doxo. (×2)

+

−

7

18

597

8

16

64

6–10

PE

TS

Osteo.

–

17

NEG

PR

ND

Osteo.

Endo. + PM

ND

Sarcoma

ND

Endo.

PE

TS

Fibro.

Endo.

+

+

+

−

9

4.5

10

4.5

60

11

4.5

161

12

13.5

6

13

12.5

52

14

4.5

221

6

PE

Sarcoma

Osteo.

15

9

Alive

6, 9, 10

PE

ND

Osteo.

Endo.

16

4.5

1

ND

ND

Osteo.

Endo.

17

8

2

10

ND

Average Median

7 4.5

a

9–10 7–8

ND

ND

Osteo.

–

6–9, 11, 12

ND

Sarcoma

ND

–

Osteo.

Chemotherapy

Doxo. (×1)

+ +

−

+

+

Doxo. (×4)

Doxo. (×4)

104.7 34.5

PA: prior admission; ND: not done; TS: touch smear; GRN: granulomas; R & A: resection and anastomosis; PE: partial esophagectomy; PR: partial resection; fibro.: fibrosarcoma; osteo.: osteosarcoma; undif.: undifferentiated sarcoma; endo.: granulomas detected at endoscopy; PM: granulomas detected on necropsy; doxo.: doxorubicin.

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Spondylitis (vertebra no.)

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Fig. 2. Esophageal soft tissue mass (open end arrow), pulmonary mass (empty arrow) and spondylitis (frame; double tail arrow) as demonstrated by CT examination (case #13) (the heart demonstrated by filled end arrow at the bottom of the figure).

ranged from 3 to 11 days (average 5.83 days). One of these cases (#15) was still alive 76 days after surgery. All the other five cases enjoyed good quality of life until their final deterioration before euthanasia, with an average survival time of 267 days. Postoperative treatments in all dogs included antihelminthic treatment with doramectin (Dectomax, Pfizer), injected every 2–4 weeks at a dose of 200–400 ␮g/kg subcutaneously. Five cases (#6, #7, #8, #11 and #14) received chemotherapy with doxorubicin (Adriamycin, Upjohn), 30 mg/m2 intravenously, given every 3 weeks for 4–6 treatments as suggested previously (MacEwen et al., 2001). Three cases received four doxorubicin treatments. Chemotherapy was terminated after one and two treatments in two cases (#8 and #7, respectively), due to severe adverse reactions. Two cases (#6 and #7) had endoscopic follow-up 3.5 and 3 months after surgery, respectively, and no signs of tumor recurrence or stricture at the resection site were observed.

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Fig. 3. An esophageal sarcoma (arrow) that partially obstructed the lumen as seen in an endoscopic examination (case #11).

3.6. Histopathology and post-mortem findings Biopsies of the esophageal masses were obtained after surgical excision or necropsy in 15 cases (Table 2). The histopathology results of the esophageal tumors were osteosarcoma (9), fibrosarcoma (5) and undifferentiated sarcoma (1). Necropsy was performed in 11 cases, and characteristic aortic scars or aneurysms were detected in eight (Fig. 4). Metastatic sarcomas were detected in five cases (#3, #7, #11, #14 and #17), all five had pulmonary metastases, and two had renal metastases. Metastases were also found in the stomach, adrenals, regional lymph nodes, heart and tongue (one of each). In two of these cases (#2 and #9), additional typical esophageal granulomas were found. In one of the later cases (#2), live S. lupi larvae were found. Perforation of the esophagus was detected in one case (#16).

4. Discussion Esophageal sarcomas in dogs are, almost exclusively, found in areas endemic to S. lupi infections and are suggested to be induced by the worm (Bailey, 1972; Moulton, 1978; Fox et al., 1988; Johnson, 1992). The typical clinical and pathological findings in the cases described, in addition to the high prevalence of spirocercosis in Israel (Mazaki-Tovi et al.,

E. Ranen et al. / Veterinary Parasitology 119 (2004) 209–221

Fig. 4. Characteristic aortic scars (black arrow) and esophageal sarcoma (white arrow), demonstrated at necropsy (case #11). 217

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2002), indicate that the dogs in this study were infected with S. lupi, and that the development of esophageal sarcomas in these dogs was induced by this worm. Direct evidence of spirocercosis included detection of typical eggs in the feces (Markovics and Medinski, 1996) in two cases, and/or detection of S. lupi parasites at necropsy in one case. The lack of parasites in postmortal examination of most cases in the current study as opposed to the findings of Bailey (1963) where worms were detected in 39% (15/39) of the cases, could be explained by the fact that 7 of 11 dogs in this study were treated against S. lupi prior to necropsy. Finding S. lupi eggs in the stools of two dogs only is not surprising as S. lupi-associated esophageal sarcomas presumably occur in chronic progressive cases of spirocercosis when infection is no longer potent (Dvir et al., 2001). Further support for this notion is the higher average age of dogs in this study (6.8 years) compared with a previous study that described 50 cases of spirocercosis in Israel where the average age was found to be 4.8 years (Mazaki-Tovi et al., 2002). This difference could be explained by the extended length of time required for the granulomas to become neoplastic. As the onset of clinical signs in all 17 cases in the current study was relatively short (mean 7 weeks; median 4.5 weeks), this finding suggests that some cases with spirocercosis may be infested with the worm, however, show no clinical signs. The pathogenesis of S. lupi-induced neoplasms has not been elucidated to date (Johnson, 1992). Reactive fibroblasts containing many mitotic figures were previously described in early granulomatous lesions (Bailey, 1972). The intense inflammatory reaction in these lesions is suspected to result in uncontrolled proliferation of fibroblasts that have undergone malignant transformation as suggested for feline injection site sarcomas and ocular sarcomas after chronic uveitis and trauma (Seguin, 2002). Most of the dogs in the current study were females (12/17), in contrast with other reports of spirocercosis in dogs where no significant difference between the gender distributions was found. This finding suggests that females may be at a higher risk to develop spirocercosis-associated esophageal sarcomas, however this should be further investigated in a larger number of cases. The incidence of esophageal sarcoma was higher in large breed dogs and is consistent with other reports of dogs suffering from spirocercosis. It has previously been suggested that large breed dogs are more prone to infection with spirocercosis as they spend more time outdoors than small breed dogs (Dvir et al., 2001; Mazaki-Tovi et al., 2002). In the current study, more dogs suffered from lethargy (58 versus 22%), anorexia (41 versus 18%), pyrexia (41 versus 24%) and weight loss (35 versus 10%), compared to a previous study of dogs suffering from spirocercosis with no neoplasms (Mazaki-Tovi et al., 2002). Swelling of the sub-mandibular area due to salivary gland enlargement was a relatively common finding (29%) in this study and could be associated with salivary gland necrosis. This was previously associated with esophageal pathology including spirocercosis (Schroeder and Berry, 1998). The authors speculate that the higher incidence and greater severity of clinical signs could be the result of the neoplastic bleeding, the relatively large size of neoplastic masses or due to paraneoplastic effects (Bergman, 2001). The predominant clinical signs of dogs with esophageal tumors mimicked those of dogs suffering from partial esophageal obstruction, including those with spirocercosis-induced granulomas. Regurgitation and/or vomiting were common clinical signs in other observa-

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tions of dogs with spirocercosis (Seibold et al., 1955; Moulton, 1978; Fox et al., 1988; Dvir et al., 2001). Melena was a common sign in this study unlike other reports of spirocercosis with no esophageal sarcomas (Dvir et al., 2001; Mazaki-Tovi et al., 2002). This is explained by the fact that esophageal neoplasms have a higher tendency to ulcerate and bleed than esophageal granulomas (Moulton, 1978). This finding is supported by the fact that a high percentage (47%) of dogs in this study developed anemia. Microcytic hypochromic anemia appeared in most of the anemic dogs probably due to iron deficiency as a result of chronic blood loss. Absolute neutrophilia was the most common hematologic abnormality seen in the current study. This finding was not reported as a characteristic of dogs suffering from spirocercosis with no neoplasms. It could be caused by a pronounced inflammatory reaction associated with the tumor. The hematological findings in this study suggest that dogs suffering from spirocercosis and microcytic hypochromic anemia as well as neutrophilia should be suspected for esophageal sarcoma. Endoscopy in 15 cases revealed a mass that was different in shape and size compared with typical S. lupi granulomas. Identification of typical esophageal granulomas in addition to the neoplastic mass, indicates an association between S. lupi and the development of sarcomas (Seibold et al., 1955; Bailey, 1963). Endoscopy has been found to be a very accurate and useful tool for the diagnosis of esophageal tumors. In all cases reported here, the tentative endoscopic diagnosis of the masses as neoplasms was consistent with the histopathological diagnosis. The information received by endoscopy, indicating the exact location and size of the esophageal mass, was vital in making decisions regarding surgery. Diagnosis of the nature of the mass by endoscopic biopsy, either by histopathological or cytological examination was not proven to be reliable, therefore endoscopic biopsies of esophageal masses may not allow differentiation between a tumor and a granuloma (Berry, 2000; Dvir et al., 2001). Furthermore, endoscopic biopsy can be misleading because of false negative results as was shown in case #7. Radiography was less specific in diagnosis of esophageal tumors than endoscopy. Although caudal esophageal masses could be observed in thoracic radiography in 13 out of 15 cases, it was not possible to differentiate the tumors from other opaque soft tissue masses. The importance of radiography lies in its ability to detect other thoracic pathologies such as lung metastases, spondylitis, pneumonia, pleural effusion and aortic mineralization, and thereby to assist in the diagnostic process and in making a sound clinical assessment. Lung metastases were not a common finding at the time of admission. Only two cases (#13 and #17) showed radiographic evidence of metastatic lung disease. Spondylitis was detected in 87% (13/15) of the cases. This is a higher incidence than reported previously (50%, Dvir et al., 2001), but compatible with other earlier studies (Seibold et al., 1955; Thrasher et al., 1963; Bailey, 1963). The exact pathogenesis of spondylitis in spirocercosis is yet unknown. Migrating worms could cause vertebral periosteal irritation (Bailey, 1963, 1972). Contrast studies were performed in three cases. In only one of them (#9), it was found to be useful as the mass was shown to be located in the stomach. Hypertrophic osteopathy (HO), which was diagnosed in three cases, is a common sequel of esophageal sarcomas (Seibold et al., 1955; Bailey, 1972; Fox et al., 1988). The higher percentage of HO in earlier reports could be explained by the late diagnosis of those cases. Megaesophagus was detected in one case, and has been noted in other cases of esophageal neoplasia (Matros et al., 1994).

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Reports of surgical removal of esophageal sarcomas have appeared rarely in the veterinary literature (Thrasher et al., 1963; Colgrove, 1971; Fox et al., 1988; Dvir et al., 2001). In this study, three out of nine cases (#3, #4 and #9) that underwent surgery did not recover and died within 3, 2 and 1 day, respectively, following the procedure, due to complications. Two of those cases were treated by surgical resection and anastomosis of the esophagus. Suggested causes for high complication rates in esophageal surgeries include excessive tension at the suture line, lack of serosa, constant motion of the suture site, passage of undigested food and saliva over suture site, segmental blood supply and lack of omentum. Excessive tension seems to be the major reason for suture line breakdown, resulting in leakage from the esophagus (Lemarie and Hosgood, 1998; Kyles, 2002). Resection of more than 3–5 cm of the esophagus increased the risk of dehiscence in a previous study (Kyles, 2002). Nevertheless, partial esophagectomy seems to be an effective and safe technique for the removal of sarcomas of the distal thoracic esophagus. All the dogs that had partial esophagectomy recovered rapidly and enjoyed good quality of life for several months. The main advantage of partial esophagectomy (6/9 cases) as opposed to resection and anastomosis (2/9) lies in preventing excessive tension at the suturing site, with no need for reconstructive surgery. Chemotherapy is considered as an adjunctive palliative treatment of soft tissue sarcomas following surgical removal. Doxorubicin-based protocols and mitoxantrone have been shown to be the most active agents for treating soft tissue sarcomas (MacEwen et al., 2001). Five cases (#6, #7, #8, #11 and #14) in this study were treated with doxorubicin in conjunction with surgery. One case received only two treatments of doxorubicin and had the longest survival time of all the cases reported here (15 months). Another case received four treatments of doxorubicin, yet lived only 5 months. Therefore, no significant conclusions regarding the effectiveness of chemotherapy in the treatment of spirocercosis-associated esophageal sarcomas could be drawn from the current study. Aortic lesions are common findings in dogs, which suffer from spirocercosis (Bailey, 1963, 1972). In this report, 73% (8/11) of the cases showed gross pathological aortic lesions including aneurysms, calcification and scarring of the intima. Those lesions are probably the result of granulomatous reaction to the migrating worms in the vessel wall (Bailey, 1972). Osteosarcoma was diagnosed in 60% of the cases in this study, and is compatible with previous reports (Bailey, 1963, 12/19—60% osteosarcoma; Seibold et al., 1955, 5/7—71%). Forty-two percent (5/12) of the cases showed metastatic disease at necropsy. In other reports 54% (20/37) (Bailey, 1963) and 67% (12/18) (Bailey, 1972) of the dogs diagnosed with esophageal sarcoma had metastases. The location of the metastases was consistent with other reports (Bailey, 1972; Moulton, 1978). In three cases (#7, #11, #14) necropsy was performed after surgical excision of the tumor 597, 161, 221 days after admission, respectively. In conclusion, canine esophageal sarcoma is exclusively associated with spirocercosis. In areas endemic to spirocercosis, regurgitation or vomiting and microcytic hypochromic anemia as well as neutrophilia warrant ruling out esophageal sarcomas. This disease has been shown to be fatal, however, proper surgical treatment could prolong the animal’s lifespan for months and improve its quality of life. Measures have to be taken in order to lower the rate of canine infestation with the worm and diagnose it early, before sarcomas have developed, when medical treatment is still usually successful.

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