ISSN 2398-2950      

Mediastinal diseases



  • Cause: both neoplastic and non-neoplastic conditions.
  • Signs: attributable to the respiratory or upper gastrointestinal tracts.
  • Occasionally, mediastinal space-occupying lesions will cause head, neck or forelimb edema (precaval syndrome), or Horner's syndrome if the sympathetic ganglion is affected.
  • Diagnosis: ultrasonography, thoracic radiogaphs, CT scan, cytology or histopathology.
  • Treatment: often symptomatic or surgical. Radiotherapy and chemotherapy depending on the diagnosis.
  • Prognosis: good for abscess, foreign bodies, cysts, and granulomas; fair for thymoma; poor to guarded for lymphosarcoma.



  • Mediastinal disease may be caused by various processes:
    • Trauma, eg bites to the chest area.
    • Foreign bodies causing perforation of the thoracic trachea Trachea: foreign body or esophagus Esophagus: foreign body.
    • Endoscopic or endotracheal tube damage to the trachea causing perforation.
    • Bougienage of the esophagus resulting in perforation Esophagus: perforation.
    • Neoplastic processes arising in the mediastinum or extending to it or metastasizing to it.
    • Abscess, granuloma, hematoma, or infection, eg pyothorax Pyothorax.
    • Cysts, eg bronchogenic cyst (rare).
    • Thymic hyperplasia.
    • Lymphadenopathy Lymphadenopathy.
    • Lipoma has been reported.
  • Bacterial infection - higher bacteria, such as Actinomyces spp Actinomyces pyogenes  and Nocardia spp Nocardia spp are often implicated in mediastinal disease associated with pyothorax Pyothorax.
  • Viral infection (historically >80-85% mediastinal lymphoma cases were associated with feline leukemia virus Feline leukemia virus disease, which can cause malignant transformation of lymphocytes. This is no longer the case following widespread FeLV vaccination.


  • Mediastinal pathology leads to a space-occupying lesion, with displacement of thoracic contents and consequent clinical signs.
  • Pleural effusion is a frequent finding.
  • The mediastinal pathology may relate to an underlying systemic disease condition. 
  • Respiratory symptoms elicited by space-occupying lesions, fluid accumulation or infective processes, eg abscess, in the mediastinum or thorax.
  • Dysphagia may result from displacement and occlusion of the thoracic esophagus.
  • Immunological abnormalities induced by the diseased thymus may lead to the development of paraneoplastic syndromes Cutaneous paraneoplastic syndromes.


  • Varies from peracute (fulminating mediastinitis secondary to puncture wounds, foreign bodies or esophageal rupture) to chronic (neoplasia, thymoma, benign processes).


This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login


This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login


This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login


This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Camero C M, Neumann Z L, Garrett L D (2019) Long-term survival in six cats with mediastinal cysts. J Feline Med Surg 21(10), 998-1002 PubMed.
  • Fournier Q, Bavcar S, Philbey A W, Smith S, Varjonen K (2019) A previously undescribed cutaneous paraneoplastic syndrome in a cat with thymoma. Vet Dermatol 30(4), 342-e98 PubMed.
  • Rick T, Kleiter M, Schwendenwein I, Ludewig E, Reifinger M et al (2019) Contrast-enhanced ultrasonography characteristics of intrathoracic mass lesions in 36 dogs and 24 cats. Vet Radiol Ultrasound 60, 56-64 PubMed.
  • Rohrer Bley C, Meier V, Schneider U (2018) Dosimetric benefit of adaptive radiotherapy in the neoadjuvant management of canine and feline thymoma-An exploratory case series. Vet Comp Oncol 16(3), 324-329 PubMed.
  • Spugnini E P, Menicagli F, Pettorali M, Baldi A (2017) Ultrasound guided electrochemotherapy for the treatment of a clear cell thymoma in a cat. Open Veterinary Journal 7(1), 57-60 PubMed.
  • Griffin M A, Sutton J S, Hunt G B, Pypendop B H, Mayhew P D (2016) Video-Assisted Thoracoscopic Resection of a Noninvasive Thymoma in a Cat with Myasthenia Gravis Using Low-Pressure Carbon Dioxide Insufflation. Vet Surg 45(S1),O28-O33 PubMed.
  • Nagata N, Miyoshi T, Otake Y, Suzuki H, Kagawa Y et al (2016) Temporal deterioration of neurological symptoms and increase of serum acetylcholine receptor antibody levels after thymectomy: a case report of a cat with myasthenia gravis. J Vet Med Sci 78(12), 1893-1896 PubMed.
  • Letendre J A, Boysen S (2015) Cranial vena cava syndrome secondary to cryptococcal mediastinal granuloma in a cat. Can Vet J  56(4), 365-369 PubMed.
  • Jung J, Choi M (2015) Nonsurgical resolution of caudal mediastinal paraesophageal abscess in a cat. J Vet Med Sci 77(4), 499-502 PubMed.
  • Fabrizio F, Calam A E, Dobson J M et al (2014) Feline mediastinal lymphoma: a retrospective study of signalment, retroviral status, response to chemotherapy and prognostic indicators. J Feline Med Surg 16(8), 637-644 PubMed.
  • Patterson M M, Marolf A J (2014) Sonographic characteristics of thymoma compared with mediastinal lymphoma. J Am Anim Hosp Assoc 50(6), 409-413 PubMed.
  • Pintore L, Bertazzolo W, Bonfanti U, Gelain M E, Bottero E (2014) Cytological and histological correlation in diagnosing feline and canine mediastinal masses. J Small Anim Pract 55, 28-32 PubMed.
  • Sato H, Fujino Y, Chino J, Takahashi M, Fukushima K et al (2014) Prognostic Analyses on Anatomical and Morphological Classification of Feline Lymphoma. J Vet Med Sci 76(6), 807-811 PubMed.
  • Hill P B, Brain P, Collins D, Fearnside S, Olivry T (2013) Putative paraneoplastic pemphigus and myasthenia gravis in a cat with a lymphocytic thymoma. Vet Dermatol 24(6), 646-649 PubMed.
  • Thomas E K, Syring R S (2013) Pneumomediastinum in cats: 45 cases (2000–2010) J Vet Emer Crit Care 23(4) 429-435 PubMed.
  • Nickel J, Mison M (2011) Intrathoracic lipoma in a cat. J Am Anim Hosp Assoc 47(6), e127-130 PubMed.
  • Singh A, Boston S E, Poma R (2010) Thymoma-associated exfoliative dermatitis with post-thymectomy myasthenia gravis in a cat. Can Vet J 51(7), 757-760 PubMed.
  • Fujino Y, Liao C-P, Zhao Y S, Pan J, Mathes L E (2009) Identification of a novel common proviral integration site, flit-1, in feline leukemia virus induced thymic lymphoma. Virology 386 16-22 PubMed.
  • Lara-Garcia A, Wellman M, Burkhard M J, Machado-Parrula C, Valli V E et al (2008) Cervical thymoma originating in ectopic thymic tissue in a cat. Vet Clin Pathol 37(4), 397-402 PubMed.
  • Zitz J C, Birchard S J, Couto G C, Samii V F, Weisbrode S E et al (2008) Results of excision of thymoma in cats and dogs: 20 cases (1984-2005). J Am Vet Med Assoc 232(8), 1186-1192 PubMed.
  • Louwerens M, London C A, Pedersen N C, Lyons L A (2005) Feline Lymphoma in the Post–Feline Leukemia Virus Era J Vet Intern Med 19, 329-335 PubMed.
  • Yoon J, Feeney D A, Cronk D E, Anderson K L, Ziegler LE (2004) Computed tomographic evaluation of canine and feline mediastinal masses in 14 patients. Vet Radiol Ultrasound 45( 6), 542-546 PubMed.
  • Koutinas C K, Papazoglou L G, Saridomichelakis M N et al (2003) Caudal mediastinal abscess due to a gras awn (Hordeum spp) in a cat. J Feline Med Surg (1), 43-46 PubMed.
  • Tidwell A S (1998) Ultrasonography of the thorax (excluding the heart). Vet Clin North Am 28 (4), 993-1015 PubMed.
  • Day M J (1997) Review of thymic pathology in 30 cats and 36 dogs. JSAP 38 (9), 393-403 PubMed.
  • Rogers K S & Walker M A (1997) Disorders of the mediastinum. Comp Cont Ed Pract Vet 19 (1), 69-83 VetMedResource.
  • Roush J K, Bjorling D E, Lord P (1990) Diseases of the retroperitoneal space in the dog and cat. JAAHA 26 (1), 47-54 VetMedResource.
  • Scott-Moncrieff J C, Cook J R Jr. & Lantz G C (1990) Acquired myasthenia in a cat with thymoma. JAVMA 196 (8), 1291-1293 PubMed.
  • Parker N R, Walker P A & Gay J (1989) Diagnosis and surgical management of esophageal perforation. JAAHA 25 (5), 587-594 VetMedResource.
  • Gruffydd-Jones T L, Gaskell C J, Gibbs C (1979) Clinical and radiological features of anterior mediastinal lymphosarcoma in the cat - a review of 30 cases. Vet Rec 104 (14), 304-307 VetMedResource.

Other sources of information

  • Withrow & MacEwen’s Small Animal Clinical Oncology (2020) 6th Edition. Saunders.

Can’t find what you’re looking for?

We have an ever growing content library on Vetlexicon so if you ever find we haven't covered something that you need please fill in the form below and let us know!


To show you are not a Bot please can you enter the number showing adjacent to this field

 Security code