3,sniall Anim. Pract.
(1975) 16, 689-693.
Retropharyngeal fibrosarcoma in a dog D . B. M U R D O C H
AND
R. S. JONES
Department of Veterinary Clinical Studies, Leahurst Veterinary Field Station, Neston, Wirral, Merseyside, L64 7TE
ABSTRACT A 24-year-old Alsatian dog was admitted to the University of Liverpool Field Station as a respiratory emergency after dysphagia had been observed for 6 weeks. During surgery a fibrosarcoma was found in the connective tissue of the posterior pharyngeal region. The clinical, radiological, surgical and post-mortem features are described. INTRODUCTION Acute respiratory distress is an uncommon condition in the dog. Similarly, tumours of the retropharyngeal region are riot common. I n view of the respiratory signs with the associated anaesthetic problem, it was decided to present this case report.
CASE H I S T O R Y Subject A 24-year-old male Alsatian weighing 30 Kg. History The owner had noticed that the dog was having difficulty in swallowing food for about 6 weeks before admission. Respiratory sounds became more marked until several days before admission, when it was ‘snoring’ with each respiration. CLINICAL EXAMINATION The case was referred as an acute respiratory problem. T h e dog was dull and depressed but in good bodily condition. There was dyspnoea with harsh ‘snoring’ D
689
690
D . B . M U R D O C H A N D R . S. J O N E S
sounds on both inspiration and expiration. The dog was salivating excessively with strings of viscid saliva hanging from the mouth. O n auscultation of the chest, no adventitious sounds were detected due to the harsh nature of inspiration and expiration. The mucous membranes were congested but not cyanosed. The sclerae were injected. O n admission the total white cell count was 18,900/mm3. This total consisted of: 94% polymorphs, 4 % lymphocytes, 1.5% monocytes and 0.5% band cells. The packed cell volume was 45% and the red cell count, 7.8 x 1061mm3. A large, firm mass, palpated in the retropharyngeal region, extended from the temporo-mandibular joint posteriorly towards the thoracic inlet. Examination of the mouth in the conscious animal showed that the posterior pharyngeal area was depressed ventrally. Neither the tonsils nor the superficial lymph nodes were enlarged. R A D I O G R A P H Y AND S U R G E R Y Atropine sulphate (0.6 mg) was administered intramuscularly but in view of the animal’s depressed condition, no other drugs were used at this stage. Plain lateral and dorso-ventral radiographs of the neck showed a large area of increased radioopacity extending from the vertical ramus of the mandible to the 5th cervical vertebra. The mass extended dorsally to the ventral surface of the cervical vertebrae. The trachea was depressed ventrally and the oesophagus was dilated posterior to the mass. Anaesthesia was induced with 4 ml of 5 % thiopentone sodium administered intravenously. The patient’s size suggested that a No. 12 endotracheal tube would be required. It was, however, not possible to insert this tube and, eventually, a No. 8 tube was passed into the trachea. The dog was then allowed to breathe an oxygen/halothane mixture in a closed circuit. Following intubation, respiration became markedly dyspnoeic and further radiographs showed kinking and distortion of the endotracheal tube (Fig. 1) which was partially withdrawn in order to relieve the obstruction. The skin incision began posterior to the parotid salivary gland and continued posteriorly along the left side of the neck. Blunt dissection through the superficial muscles exposed the mass which was covered by a thin fibrous capsule. When the capsule was cut, the mass extruded whitish-grey friable tissue, flecked with small areas of black pigmentation. O n further exploration of the mass, the centre was found to consist of brown necrotic tissue. As it was clear that this was an inoperable neoplasm rather than a retropharyngeal abscess, euthanasia was carried out. HISTOPATHOLOGY The tumour was highly cellular and consisted mainly of fusiform cells. The cytoplasm was acidophilic and in some areas faintly granular. T h e elongated
RETROPHARYNGEAL FIBROSARCOMA I N A DOG
69 1
FIG.1. Radiograph taken after intubation showing kinking in the endotracheal tube.
nuclei were open and vesicular, usually with two prominent nucleoli. When stained with Masson’s trichrome, large numbers of collagen fibres were seen and the tumour was classified as a fibrosarcoma. DISCUSSION Gradual onset of dyspnoea is a relatively common clinical sign in the dog, usually arising from pulmonary or other intra-thoracic lesions (Pennock & Archibald, 1968). The interesting feature of this case was the stertorous respiration which suggested a space-occupying lesion (tumour, abscess, haematoma or cyst) of either the nose, pharynx, larynx and trachea, or adjacent tissues. The clinical and radiological findings suggested a mass in the retropharyngeal region. Tumours of connective tissue are common in the dog (Mulligan, 1949; Cotchin, 1956; Runnels, Monlux & Monlux, 1965; Smith & Jones, 1966) but rare in the peripharyngeal region (Brumley, 1950; McCunn, 1953). Gorlin et al. (1959) reported that of 301 tumours of the oral/pharyngeal region in the dog, only eleven were fibrosarcomas. I n these cases, the gingiva of the lower jaw and palate seemed to be the most commonly affected sites. Howard & Nielsen (1965) examined 938 canine tumours and recorded only ten fibrosarcomas, all affecting the integument (although three anaplastic sarcomas were listed). Apart from connective tissue neoplasms, tumours in other tissues may produce the mechanical pressure symptoms of dysphagia, dysphonia and dyspnoea e.g.
692
D . B. MURDOCH A N D R . S . JONES
retropharyngeal lymph nodes, thyroid gland (Bush, 1969) and carotoid body (although in the latter cases, the mass is usually ventral to trachea-Dean & Strafuss, 1975). The incidence of neoplasia in the dog is greatest between the 6th and 7th years of age (Larsson, 1956; Mulligan, 1963). I t is interesting that this dog should be affected with such a large mass at 24 years of age. O n post-mortem, no metastases were found. Retropharyngeal abscesses can present a similar clinical picture of dysphagi? and altered respiration with tracheal displacement, and are usually a sequel tc penetration of the pharyngeal wall by a foreign body (Thordal-Christensen, 1965). Such abscesses are difficult to distinguish from retropharyngeal neoplasms, although a dog with a pharyngeal abscess has a raised temperature, exhibits pain on flexion and extension of the neck, and the development of the lesion is less protracted. I n the authors’ experience, haematomas of this region are uncommon and usually result from bite wounds in the neck. The swelling may occur either dorsal or ventral to the trachea. As with abscesses, development of the lesion is much more rapid than that of a neoplasm. Branchogenic cysts may give rise to space occupying lesions but these are extremely uncommon (Gorlin et al., 1959). This case also illustrates that insertion of an endotracheal tube does not necessarily guarantee a clear airway. Fig. 1 shows that the wall of the endotracheal tube was folded, and virtually occluded the lumen. This hazard can be avoided by using armoured endotracheal tubes which have a reinforcing layer of wire or nylon in their wall to prevent ‘kinking’ when the tube is subjected to external pressures such as the mass in Fig. 1. ACKNOWLEDGMENTS
The authors wish to thank Dr J. R. Baker for the histopathological examination, and M r G. N. Ash for referring the case. REFERENCES BRUMLEY, O.V. (1950) A Text Book of the Diseases of Small Domestic Animals. 4th Edn. Lea and Febinger, Philadelphia. BUSH,B.M. (1969) 3. small Anim. Pract. 10, 185. COTCHIN, E. ( 1956) .Neoplasms of the Domesticated Mammals. Commonwealth Bureau of Animal Health, England. DEAN,M.J. & STRAFFUSS, A.C. (1975) 3. Amer. vet. mtd. Ass. 166, 1003. GORLW, R.J., BARRON,C.N., CHAUDHRY, A.P. & CLARK, J.J. (1959) Am. 3. net. Res. 2 0 , 1032. MCCUNN, J. (1953) Hobday’s Surgical Diseases of the dog and cat. 6th Edn. Baillikre Tindall and Cox, London. S.W. (1965) Am. 3. net. Res. 26, 1 121. HOWARD, E.B. & NIELSEN, LARSSON, B. (1956) Nard. Vet. Med. 8, 130.
RETROPHARYNGEAL FIBROSARCOMA IN A DOG
693
MULLICAN, R.M. (1949) Neoplasms of the dog. 1st Edn. Williams and Wilkins Co., Baltimore. MULLICAN, R.M. (1963) Ann. New York Acad. Sci. 108, 642. PENNOCK, P.W. & AFSHIBALD, J. (1968) Canine Medicine, 1st Catcott Edn. American Veterinary Publications, California. A.W. (1965) Principles of Veterinary Pathology, 7th RUNNELLS, R.A., MONLUX, W.S. & MONLUX, Edn, Iona State, University Press. SMITH, H.A. & JONES, T.C. (1966) Veterinary Pathology, 3rd Edn, Lea and Febinger, Philadelphia. THORDAL-CHRISTENSEN, A. (1 965) Canine Surgery. 1st Archibald Edition American Vet. Publications, California.
(1975) 16, 689-693.
Retropharyngeal fibrosarcoma in a dog D . B. M U R D O C H
AND
R. S. JONES
Department of Veterinary Clinical Studies, Leahurst Veterinary Field Station, Neston, Wirral, Merseyside, L64 7TE
ABSTRACT A 24-year-old Alsatian dog was admitted to the University of Liverpool Field Station as a respiratory emergency after dysphagia had been observed for 6 weeks. During surgery a fibrosarcoma was found in the connective tissue of the posterior pharyngeal region. The clinical, radiological, surgical and post-mortem features are described. INTRODUCTION Acute respiratory distress is an uncommon condition in the dog. Similarly, tumours of the retropharyngeal region are riot common. I n view of the respiratory signs with the associated anaesthetic problem, it was decided to present this case report.
CASE H I S T O R Y Subject A 24-year-old male Alsatian weighing 30 Kg. History The owner had noticed that the dog was having difficulty in swallowing food for about 6 weeks before admission. Respiratory sounds became more marked until several days before admission, when it was ‘snoring’ with each respiration. CLINICAL EXAMINATION The case was referred as an acute respiratory problem. T h e dog was dull and depressed but in good bodily condition. There was dyspnoea with harsh ‘snoring’ D
689
690
D . B . M U R D O C H A N D R . S. J O N E S
sounds on both inspiration and expiration. The dog was salivating excessively with strings of viscid saliva hanging from the mouth. O n auscultation of the chest, no adventitious sounds were detected due to the harsh nature of inspiration and expiration. The mucous membranes were congested but not cyanosed. The sclerae were injected. O n admission the total white cell count was 18,900/mm3. This total consisted of: 94% polymorphs, 4 % lymphocytes, 1.5% monocytes and 0.5% band cells. The packed cell volume was 45% and the red cell count, 7.8 x 1061mm3. A large, firm mass, palpated in the retropharyngeal region, extended from the temporo-mandibular joint posteriorly towards the thoracic inlet. Examination of the mouth in the conscious animal showed that the posterior pharyngeal area was depressed ventrally. Neither the tonsils nor the superficial lymph nodes were enlarged. R A D I O G R A P H Y AND S U R G E R Y Atropine sulphate (0.6 mg) was administered intramuscularly but in view of the animal’s depressed condition, no other drugs were used at this stage. Plain lateral and dorso-ventral radiographs of the neck showed a large area of increased radioopacity extending from the vertical ramus of the mandible to the 5th cervical vertebra. The mass extended dorsally to the ventral surface of the cervical vertebrae. The trachea was depressed ventrally and the oesophagus was dilated posterior to the mass. Anaesthesia was induced with 4 ml of 5 % thiopentone sodium administered intravenously. The patient’s size suggested that a No. 12 endotracheal tube would be required. It was, however, not possible to insert this tube and, eventually, a No. 8 tube was passed into the trachea. The dog was then allowed to breathe an oxygen/halothane mixture in a closed circuit. Following intubation, respiration became markedly dyspnoeic and further radiographs showed kinking and distortion of the endotracheal tube (Fig. 1) which was partially withdrawn in order to relieve the obstruction. The skin incision began posterior to the parotid salivary gland and continued posteriorly along the left side of the neck. Blunt dissection through the superficial muscles exposed the mass which was covered by a thin fibrous capsule. When the capsule was cut, the mass extruded whitish-grey friable tissue, flecked with small areas of black pigmentation. O n further exploration of the mass, the centre was found to consist of brown necrotic tissue. As it was clear that this was an inoperable neoplasm rather than a retropharyngeal abscess, euthanasia was carried out. HISTOPATHOLOGY The tumour was highly cellular and consisted mainly of fusiform cells. The cytoplasm was acidophilic and in some areas faintly granular. T h e elongated
RETROPHARYNGEAL FIBROSARCOMA I N A DOG
69 1
FIG.1. Radiograph taken after intubation showing kinking in the endotracheal tube.
nuclei were open and vesicular, usually with two prominent nucleoli. When stained with Masson’s trichrome, large numbers of collagen fibres were seen and the tumour was classified as a fibrosarcoma. DISCUSSION Gradual onset of dyspnoea is a relatively common clinical sign in the dog, usually arising from pulmonary or other intra-thoracic lesions (Pennock & Archibald, 1968). The interesting feature of this case was the stertorous respiration which suggested a space-occupying lesion (tumour, abscess, haematoma or cyst) of either the nose, pharynx, larynx and trachea, or adjacent tissues. The clinical and radiological findings suggested a mass in the retropharyngeal region. Tumours of connective tissue are common in the dog (Mulligan, 1949; Cotchin, 1956; Runnels, Monlux & Monlux, 1965; Smith & Jones, 1966) but rare in the peripharyngeal region (Brumley, 1950; McCunn, 1953). Gorlin et al. (1959) reported that of 301 tumours of the oral/pharyngeal region in the dog, only eleven were fibrosarcomas. I n these cases, the gingiva of the lower jaw and palate seemed to be the most commonly affected sites. Howard & Nielsen (1965) examined 938 canine tumours and recorded only ten fibrosarcomas, all affecting the integument (although three anaplastic sarcomas were listed). Apart from connective tissue neoplasms, tumours in other tissues may produce the mechanical pressure symptoms of dysphagia, dysphonia and dyspnoea e.g.
692
D . B. MURDOCH A N D R . S . JONES
retropharyngeal lymph nodes, thyroid gland (Bush, 1969) and carotoid body (although in the latter cases, the mass is usually ventral to trachea-Dean & Strafuss, 1975). The incidence of neoplasia in the dog is greatest between the 6th and 7th years of age (Larsson, 1956; Mulligan, 1963). I t is interesting that this dog should be affected with such a large mass at 24 years of age. O n post-mortem, no metastases were found. Retropharyngeal abscesses can present a similar clinical picture of dysphagi? and altered respiration with tracheal displacement, and are usually a sequel tc penetration of the pharyngeal wall by a foreign body (Thordal-Christensen, 1965). Such abscesses are difficult to distinguish from retropharyngeal neoplasms, although a dog with a pharyngeal abscess has a raised temperature, exhibits pain on flexion and extension of the neck, and the development of the lesion is less protracted. I n the authors’ experience, haematomas of this region are uncommon and usually result from bite wounds in the neck. The swelling may occur either dorsal or ventral to the trachea. As with abscesses, development of the lesion is much more rapid than that of a neoplasm. Branchogenic cysts may give rise to space occupying lesions but these are extremely uncommon (Gorlin et al., 1959). This case also illustrates that insertion of an endotracheal tube does not necessarily guarantee a clear airway. Fig. 1 shows that the wall of the endotracheal tube was folded, and virtually occluded the lumen. This hazard can be avoided by using armoured endotracheal tubes which have a reinforcing layer of wire or nylon in their wall to prevent ‘kinking’ when the tube is subjected to external pressures such as the mass in Fig. 1. ACKNOWLEDGMENTS
The authors wish to thank Dr J. R. Baker for the histopathological examination, and M r G. N. Ash for referring the case. REFERENCES BRUMLEY, O.V. (1950) A Text Book of the Diseases of Small Domestic Animals. 4th Edn. Lea and Febinger, Philadelphia. BUSH,B.M. (1969) 3. small Anim. Pract. 10, 185. COTCHIN, E. ( 1956) .Neoplasms of the Domesticated Mammals. Commonwealth Bureau of Animal Health, England. DEAN,M.J. & STRAFFUSS, A.C. (1975) 3. Amer. vet. mtd. Ass. 166, 1003. GORLW, R.J., BARRON,C.N., CHAUDHRY, A.P. & CLARK, J.J. (1959) Am. 3. net. Res. 2 0 , 1032. MCCUNN, J. (1953) Hobday’s Surgical Diseases of the dog and cat. 6th Edn. Baillikre Tindall and Cox, London. S.W. (1965) Am. 3. net. Res. 26, 1 121. HOWARD, E.B. & NIELSEN, LARSSON, B. (1956) Nard. Vet. Med. 8, 130.
RETROPHARYNGEAL FIBROSARCOMA IN A DOG
693
MULLICAN, R.M. (1949) Neoplasms of the dog. 1st Edn. Williams and Wilkins Co., Baltimore. MULLICAN, R.M. (1963) Ann. New York Acad. Sci. 108, 642. PENNOCK, P.W. & AFSHIBALD, J. (1968) Canine Medicine, 1st Catcott Edn. American Veterinary Publications, California. A.W. (1965) Principles of Veterinary Pathology, 7th RUNNELLS, R.A., MONLUX, W.S. & MONLUX, Edn, Iona State, University Press. SMITH, H.A. & JONES, T.C. (1966) Veterinary Pathology, 3rd Edn, Lea and Febinger, Philadelphia. THORDAL-CHRISTENSEN, A. (1 965) Canine Surgery. 1st Archibald Edition American Vet. Publications, California.
