Anal Sac Adenocarcinoma in Dogs: Astro’s Surgery and Treatment

On Astro’s return, he was much happier and calm enough for Dr Perin to assess him and take some blood samples.

One thing that immediately stood out was his calcium level being very high at 3.62 mmol/L. This helped explain why he had been drinking and urinating so much, but it also raised concerns about an underlying cancer.

A rectal examination found a large, misshapen mass associated with Astro’s right anal sac, around two-thirds the size of an apricot. His medial iliac lymph nodes, which sit internally between the colon and spine, were also enlarged. This raised concern that the disease may already have spread beyond the primary tumour.

The likely diagnosis was anal sac adenocarcinoma.

This was serious news for Astro’s family. His excessive drinking, weight loss and changes in behaviour were already affecting his quality of life, and without treatment, his outlook was not good.

Surgery to remove the primary tumour, followed by treatment with a new generation chemotherapy for dogs with certain cancers, was put forward as an option. Dr Perin discussed both the potential benefits and the significant risks associated with operating in this area, including faecal incontinence, bowel damage and wound complications.

After taking a couple of days to consider, Astro’s family decided they weren’t ready to lose him.

Astro returned for surgery, where Dr Perin carefully removed the right anal sac and associated tumour. His anaesthetic remained stable throughout the procedure, his recovery was routine and he was able to go home that afternoon.

Testing of the removed tissue confirmed that Astro had an anal sac adenocarcinoma. His treatment plan was to begin chemotherapy after surgery, with his family able to give the tablets to him at home three times a week. It didn’t take long for everyone to notice a change.

Within days of surgery, Astro’s constant drinking had reduced towards normal. At his wound check just over two weeks later, his family reported that the excessive thirst had stopped almost immediately after the primary tumour was removed. He had also perked up enormously and was much more active around the house.

Astro’s cancer hasn’t disappeared. He will need ongoing treatment and monitoring. But a few months after a diagnosis that could have taken him from his family very quickly, he is back to enjoying a normal life at home.

For a dog who would much rather avoid veterinary attention altogether, Astro has been through a lot. Careful use of medication before his visits has allowed us to examine and monitor him without putting him through unnecessary stress, while his family have taken on his ongoing treatment at home.