Changes

===Rectal examination===

===Rectal examination===

Tumours of the anal sac can be detected by digital rectal palpation of the anal sac and assosiated structures.Must be performed with care as frequently the tumours are small and unilateral. Best carried out under general anaesthetic with manual compression of the caudal abdomen towards the rectum.

Tumours of the anal sac can be detected by digital rectal palpation of the anal sac and assosiated structures, this must be performed with care as frequently the tumours are small and unilateral. Best carried out under general anaesthetic with manual compression of the caudal abdomen towards the rectum.

===Biochemistry===

===Biochemistry===

===Thoracic radiographs===

===Thoracic radiographs===

At least two views to check for thoracic metastases.

At least two views to check for thoracic metastases.  

===Abdominal imaging===

===Abdominal imaging===

Caudal lateral abdominal radiographs or abdominal ultrasound to assess the medial iliac lymph nodes for metastases. When enlarged the displace the rectum ventrally as they are found ventral to the lumbar sacral disc.

Caudal lateral abdominal radiographs or abdominal ultrasound to assess the medial iliac lymph nodes for metastases. When enlarged they  displace the rectum ventrally.  

===Needle biopsy===

 

===Needle biopsy and Histopathology===

Guided by ultrasound to aspirate the effected lymph nodes.

Guided by ultrasound to aspirate the effected lymph nodes.