Feline anal sacs may not qualify (at least in polite society) as a suitable subject for cocktail party chat. But these useless little structures – tucked within the inner recesses of a cats rear end – nevertheless merit the attention of any conscientious owner. In most cats, these minuscule pouches remain hidden away harmlessly throughout an animals life. In some cases, however, they can be the source of irritation, inflammation, infection and worse.
There are two anal sacs, both embedded within the tissue of the external anal sphincter – the relaxing and contracting muscle surrounding the anal opening. Each sac, says James Flanders, DVM, is a quarter-inch to a half-inch in diameter – about the size of a large pea or maybe more like a small kidney bean.
The sacs themselves are not externally visible, says Dr. Flanders, an associate professor of clinical sciences at Cornell Universitys College of Veterinary Medicine. The only evidence of their presence is the openings of two slender tubes (ducts) that lead from the anal sacs to areas directly adjacent to the anus. These openings, Dr. Flanders points out, are each about the diameter of a pin; they can be seen, respectively, at the four oclock position on one side of a cats anus and at the eight oclock position on the other side.
Why Is There a Duct?
The purpose of the ducts is to transport a smelly, viscous fluid (secreted by many tiny glands within the walls of the anal sacs) from the sacs to the anus. This movement of fluid is initiated by muscle pressure exerted on the anal sacs, usually during defecation.
But what is the purpose of this slippery, foul-smelling fluid? Says Dr. Flanders: Some people think that it serves as a lubricant for the feces or that cats use it for marking their territory. Maybe thats the case, but no one really knows what its purpose is, since cats can function fine without it. They mark with their urine, and the amount of fluid that comes out during defecation is minimal. So the sac and the way it is designed to function is probably vestigial – something passed down from a prehistoric animal but serving no real purpose today.
Although most cats will live out their lives totally oblivious to their anal glands, sacs, ducts and secretions, a few may experience problems that range from mild and easily treatable to serious and even life-threatening.
When problems do occur, says Dr. Flanders, they usually have to do with the consistency of the glandular secretions or the anatomical structure of the anal ducts. The secretions can become thicker than they should be, perhaps due to bacterial infection, he notes, or a duct may be abnormally shaped or not as wide as it should be.
Backup Problems
Although tumors may develop in the anal glands and may pose a lethal threat, they are extremely rare, says Dr. Flanders. The vast majority of afflictions – most frequently occurring in middle-aged and elderly cats – happen when secretions cannot escape naturally through the ducts, either because the secreted fluid is too thick or the ducts are too narrow to allow its easy passage.
The sacs become progressively irritated and then inflamed as the backed-up fluid grows thicker. And when the sacs eventually become filled, they may become distended and secondary infection may develop. This process – from inflammation to impaction to secondary infection – can pose a serious health threat to a cat that is not treated promptly.
Warning Signs
In most cases, says Dr. Flanders, impacted anal sacs will not obstruct defecation. But the cat will have the feeling that it has to defecate even when it really doesnt have to, says Dr. Flanders. Youll see it straining in the litter box. And because of the irritation, it will bite and lick at the anal region. Sometimes youll be able to see that the area is irritated and red.
If these signs persist, he says, veterinary examination is needed to determine whether the cause is an anal sac problem or some other condition associated with the anus, rectum or colon.
Treatment Options
To relieve the pressure in the anal sacs, a veterinarian may don gloves and initially attempt to express the contents by gently squeezing the area around the anus between a thumb and forefinger. This can be somewhat uncomfortable for the cat, but it usually doesnt require sedation, says Dr. James Richards, editor-in-chief of CatWatch and director of the Cornell Feline Health Center. However, if this technique doesnt work, the veterinarian will insert a gloved finger into the cats anus and gently apply pressure to the swollen area to express the retained secretions. Sedation or anesthesia will most definitely be necessary in this case.
Once the excess fluid has been expressed from the sacs and the ducts have been relieved of blockage, the veterinarian will usually instill an antibacterial solution into the sacs. If significant swelling remains, the veterinarian will advise the owner to apply hot packs to the cats anal region until the swelling subsides. In addition, the veterinarian will probably prescribe an oral antibacterial medication – or a combination of antibacterial and anti-inflammatory medications – to reduce pain, swelling and inflammation.
Hopefully, says Dr. Flanders, this course of treatment will resolve the problem. If it recurs a few times, the same treatment can be repeated. But if it recurs frequently – every month or so – the anal sacs would have to be surgically removed.
