Severe dyspnoea and mortality over the last few days was seen in a group of 200 thirteen-month-old layer chickens.
Example Histopathological Description
Trachea: Four transverse sections of trachea are present and each contains similar changes. Segmentally, overlying the tracheal mucosa and extending into the lumen are irregular layers of fibrin admixed with abundant erythrocytes, necrotic cellular debris, inflammatory cells, sloughed mucosal epithelial cells and rare bacteria, collectively forming a diphtheritic membrane. The underlying mucosal epithelium is alternately eroded to ulcerated or attenuated and flattened. Scattered throughout the mucosal epithelium are frequent multinucleated cells with up to six nuclei, forming epithelial syncytia. Frequently, epithelial cell nuclei contain round, 3-6 µm diameter, eosinophilic inclusion bodies surrounded by a narrow clear halo causing margination the nuclear chromatin. Diffusely and variably expanding the underlying lamina propria and submucosa, and occasionally disrupting and effacing the mucosal epithelium, are large numbers of lymphocytes and macrophages admixed with occasional plasma cells and heterophils. Also scattered throughout are haemorrhages admixed with fibrin and necrotic cellular debris, and small blood vessels are frequently congested. Small numbers of lymphocytes and macrophages surround small blood vessels within the surrounding skeletal muscle and adventitia.
Crop: Within the lamina propria are increased numbers of lymphocytes and occasional lymphoid follicles.
Tracheitis; fibrinonecrotic and haemorrhagic, subacute, diffuse, severe, with epithelial syncytial cells and eosinophilic intranuclear inclusion bodies.
Ingluvitis; lymphocytic, chronic, multifocal, mild.
Alphaherpesviral tracheitis (Gallid herpesvirus type 1, avian infectious laryngotracheitis (ILT) virus)
The detection of ILT virus in chickens using formalin-fixed, paraffin-embedded tissue samples includes an indirect fluorescent antibody test (IFAT), immunoperoxidase staining (IP), immunohistochemistry (IHC) and DNA hybridisation. Virus isolation using embryonated chicken eggs and polymerase chain reaction (PCR) may also be performed using oral swabs or mucosal scrapings from live birds.
Most recently, real-time PCR has been used to differentiate between ILT and other avian diseases with similar presentation, such as fowlpox. Serological tests including ELISA, serum neutralisation (SN), fluorescent antibody (FA), and agar gel immunodiffusion (AGID) are also available. In this case PCR testing would be recommended to definitively confirm infection.
As ILT virus can establish latency in recovered birds with subsequent intermittent shedding, regular testing of live birds via tracheal swabbing and PCR or serological testing are also recommended. It is also advisable to rule out Newcastle disease and avian influenza by PCR (tracheal/cloacal swabs).
- Abbas, Ferhat, and James R. Andreasen Jr. Comparison of diagnostic tests for infectious laryngotracheitis. Avian diseases (1996):290-295.
- Davidson, I, Israel Raibstein, and Amira Altory. Differential diagnosis of fowlpox and infectious laryngotracheitis viruses in chicken diphtheritic manifestations by mono and duplex real-time polymerase chain reaction. Avian Pathology (2015) 44(1):1-4.
- Adair, BM et al. Comparison of serological tests for detection of antibodies to infectious laryngotracheitis virus. Avian Pathology (1985) 14(4):461-469.
- Hughes, CS et al. Latency and reactivation of infectious laryngotracheitis vaccine virus. Archives of Virology (1991) 21(1-4):213-218
A unilateral abdominal mass was removed surgically from an adult Thoroughbred mare exhibiting male behaviour.
Example Histopathological Description
Three sections of ovary are examined. Within all sections, the ovarian parenchyma is replaced by a poorly demarcated, unencapsulated, densely cellular mass composed of polygonal neoplastic cells multifocally interspersed with small amounts of fibrin and haemorrhage. Neoplastic cells are arranged into cords which border variably sized cystic cavities (micro and macrofollicular patterns), and densely cellular lobules (diffuse pattern). Lobules are separated by thick bands of dense stroma composed of streams and interlacing bundles of plump spindle-shaped cells, separated by variable amounts of collagen. Neoplastic cells frequently palisade along the supporting stroma and occasionally form variably sized rosette-like structures surrounding lakes of eosinophilic homogenous secretory product (Call-Exner bodies) or extravasated erythrocytes. Neoplastic cells are polygonal with variably distinct cell margins and small to moderate amounts of wispy, eosinophilic cytoplasm (neoplastic granulosa cells). Nuclei are round to oval with finely stippled chromatin and one to three, variably distinct nucleoli. Anisocytosis and anisokaryosis are mild and mitoses number 2 in 10 high power fields (400x). Adhered to the edge of one section is a sheet of adipose tissue. Diffusely, adipocytes are pale eosinophilic with loss of cellular detail (coagulative necrosis), and areas of acute haemorrhage and clusters of haemosiderophages are scattered throughout.
Granulosa-theca cell tumour (Sex cord-stroma tumour)
In mares, three behavioural patterns are associated with granulosa-theca cell tumours (GTCT): anoestrous, continuous or intermittent oestrus and male behaviour. Elevated serum concentrations of inhibin and testosterone in such mares are supportive of a diagnosis of GTCT.1 Oestrogen levels may also be elevated in some mares. However, the concentrations of these hormones will vary depending on the oestrous cycle and pregnancy status.1 More recently, anti-Müllerian hormone (AMH) concentrations have been used as a biomarker for this type of ovarian tumour.2 A recent study by Ball et al determined that the sensitivity of AMH for the detection of histologically confirmed GCTs was significantly greater than that of either inhibin or testosterone, or the combination of both.
- Gee EK, Dicken M, Archer RM, Herdan CL, Pauwels FE, Drayton BM. Granulosa theca cell tumour in a pregnant mare: concentrations of inhibin and testosterone before and after surgery. New Zealand Veterinary Journal 2012;60(2):160-163.
- Ball BA, Almeida J, Conley AJ. Determination of serum anti-Mullerian hormone concentrations for the diagnosis of granulosa-cell tumours in mares. Equine Veterinary Journal 2013;45(2):199-203.