Canine Anal Glands

The Scent of a Dog: stinky anal glands are a sign of good health

Warning: if you are reading this article while eating your lunch STOP RIGHT NOW, or proceed at your own risk.

Bowel function in animals is a frequent topic of conversation among animal health providers. We may get very excited that Brutus finally had a big bowel movement or that Ginger is finally having solid stools. We are not young children attracted to bathroom humour but simply, bowel function is an important indicator of health. There is a set of glands, associated with the anus, which is a frequent topic of conversation at our clinic.

These glands, called the anal glands, are paired sacs embedded in the anal sphincter (the muscle forming the anus), and are located at about four and eight o'clock. The function of these glands is a mystery. The anal glands are modified sebaceous glands, a type of gland found in the skin of mammals, usually associated with the hair follicles. Sebaceous glands produce a waxy type of matter that is released through the hair follicle. The anal glands have a small canal that opens into the anus, and the sebaceous glands which line the interior of the sac release fluid into the cavity, gradually filling it. When there is a bowel movement, the anus is stretched and part of the fluid from the gland is naturally expressed, or squeezed out. The anal glands also contract at sudden fright. Anal gland secretion is like curdled milk in texture, greenish in colour, and it normally stinks! The smell is highly fragrant with a pungent quality to it.

Anal glands do not appear to have a function. Some believe that the anal glands release a unique odour that can be identified by dogs, explaining the canine social etiquette of sniffing another dog's anus at first encounter. I have not found any evidence that the anal glands have such function. Another possibility is that pheromones, chemicals that may send signals to others for purposes of identification, are released by sweat glands – but anal glands are not sweat glands. Yet another explanation may be that fear causes muscle spasm, contracting the anal sphincter and causing the release of anal fluid. Dogs have a general tendency to be dominant over others, and if a frightened dog releases anal gland fluid (which we can sometimes smell as well), the dominant dog may then decide that he can boss the other dog around. But all of this is speculation. The bottom line is that the anal glands do not seem to have any physiologic importance, because we can remove them without causing deleterious effects.

Regardless of the function they may have, I am interested in what abnormal anal glands may indicate.

Certainly we know when they are normal: they do not make their presence known, and many dog owners do not even know that they exist. The usual first sign of abnormality is "scooting" where the dog drags his anus along the floor, carpet, or grass. Scooting occurs because the glands are overfull, causing itchiness. Some dogs will do this a couple of times on a row and stop. Dragging the anus on the ground has the effect of expressing the anal glands and, as long as the secretion is normal, no intervention is required.

However if the secretion is abnormal in quantity and/or quality, if the scooting behaviour does not stop, reoccurs very often or is followed by other signs (licking at the anus, crying, holding tail down, skin rash about the base of the tail and pelvic area), then intervention is required. The intervention may be as simple as expressing the anal glands each month. Some dogs produce so much anal gland fluid that they need help removing it. In some cases overproduction of anal gland fluid is associated with obvious skin allergies. But often there is no sign of allergies. In some dogs the secretion has increased and has changed in colour from yellow to brown; in these cases, there is blood and infection present. In other dogs, the secretion may be scant but very thick and dark, tar-like. The latter case is more common in older dogs. If such fluid is not removed, sooner or later the anal gland becomes an abscess and bursts. At that point, surgery is required.

Abnormal anal gland secretion may also be indication of a toxic overload. Modern domestic animals live in the toxic soup that we all share. They eat foods contaminated with pesticide residues, they breathe air contaminated by industrial and automobile pollutants. They are also exposed to increasing radiation from electricity and electronic communication devices.

All of the above affect the natural detoxification mechanisms, which first enter into overdrive in the attempt to eliminate toxins through every possibly secretory channel. In this regard, regular once-a-month expression of the anal gland of the dog is a natural adaptation to the modern world. However, frequent and recurrent anal gland issues may indicate that the detoxification mechanisms of the animal are impaired due to age (which is to be expected), due to other diseases, or due to inappropriate diet. In those cases, anal gland disease is just a symptom of a deeper disease which needs to be addressed.

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