The role of anal sacs in the domestic cat

Last night, at about midnight my cat came onto my bed. He smelled horribly and the smell could only have been from the fluid produced by his anal sacs. The fluid is described as foul-smelling and is similar to the secretions produced by a skunk. I would not describe it as that bad to be perfectly honest but it is strong smelling. 

Gabriel keeping cool by resting on a book. Photo: MikeB

Just before he arrived on my bed there was a loud noise outside and the sound of his cat flap closing. I noticed three foxes in the back garden. They were young foxes and their mother was I believe in attendance but I could not see her. It appears that my cat had to navigate through these foxes to get into his home and in doing so felt insecure and deposited faeces as a marker within his territory. The fluid from anal sacs is channelled into faeces when scent marking through a small duct which opens just inside the anus.

In fact, I think as he arrived on my bed, he wanted to deposit more faeces within his territory which would have meant on my bed but he didn't because he couldn't produce any more. That is the role of anal sacs in domestic cats as I see it: scent marking - a calling card. He wanted to remind the foxes that he owned this territory. Foxes scent mark too with urine and feces. In my cat's example this is a competition between him and the foxes.

Sometimes the anal glands become inflamed because of infection when the fluid inside becomes impacted. It is thicker and darker in colour and it plugs up the anal gland. It can be removed (expressed) by a veterinarian with gentle pressure. Bacteria present in faeces can travel up the ducts referred to and enter the glands. Normally the bacteria are flushed out when the secretions pass through the ducts but if the glands are impacted the fluid does not flow normally leading to an ideal medium for bacterial growth and the infection. The end result is an anal sac abscess. They are painful and hot. Left untreated it can lead to anal sac rupture. Puss is emitted and it can spread into surrounding tissues causing further damage.

A good sign that your cat is suffering from an anal gland infection is when she scoots along the ground. This is when a cat rests her anus on the ground and then drags herself along to alleviate irritation in her bottom. She will also lick or bite her bottom or tail. It is very painful for a cat.

In addition to expressing the solidified material in the anal glands, antibiotics are administered together with anti-inflammatories and pain relief.