Can Food Cause Anal Gland Issues in Dogs?

If you’ve never smelled the distinct, lingering, fishy odor of your dog’s anal glands, you’re a lucky pet parent. The pungent fluid acts as a scent marker that normally comes out when dogs poop. But some dogs have problems with their anal glands that result in infection, inflammation, abnormal discharge, or obstruction. Because food allergies can cause so many problems, pet parents often wonder if food can cause anal gland issues in dogs.

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Anal gland issues in dogs

Dealing with recurrent anal gland problems in your dog can be frustrating, resulting in emails to your vet like this: “I was just in a few weeks ago to have my dog’s anal glands expressed. He’s already scooting again, and that funky smell is back. He hates going to the vet, so I don’t want to have to bring him in constantly for this. Is there anything I can do to help prevent continued anal gland issues? I’ve read that changing his food could help, but wasn’t sure what to change it to.”

While some dogs go through life without ever having an issue with their anal glands, others seem to have trouble keeping their anal sacs empty. There are many causes for anal gland diseases in dogs, and the root of these problems isn’t totally clear. Some veterinarians have noticed that some dogs with chronic anal gland issues improve with changes to their diet. In addition to standard therapies, diet alterations may be recommended to help your dog’s anal gland problems. 

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How to tell if dog’s anal glands are full

Knowing some basic anatomy can be helpful in recognizing dog anal gland symptoms. Dogs store scent marking liquid in their anal sacs, which have openings on either side of the anus at the 4 o’clock and 8 o’clock positions. These anal sacs are lined with glandular cells that produce the distinct-smelling fluid. When a dog poops, the pressure from pushing and poop passing through the anus should cause a little bit of the fluid to come out. Full anal glands develop when this fluid doesn’t come out normally, there is excessive production of the fluid, or there is inflammation or infection within the anal sacs.

For full anal glands in dogs, symptoms can include:

• Scooting: Dogs will do an easily recognizable scoot across the floor (usually on the nicest rug in the house) in an attempt to empty their anal glands by putting direct pressure on them. They’ll lift their tail, put their butt directly on the ground, and lean back while propelling themselves across the ground with their front legs.

• Excessive licking: Even if they have trouble reaching their butt, dogs will attempt to lick at their anal glands to relieve the pressure when they’re full. They may turn to the side and look at their rear end, or assume the cat belly-grooming posture and attempt to reach it from the top. Either way, doggie kisses should be off the menu for a while after.

• Unpleasant odor: No matter the method used, successfully emptying the anal glands will smell bad. There are many ways to describe anal gland odor — fishy, metallic, rotten, dumpster fluid-y — but everyone agrees that it’s unpleasant. Unfortunately, it also tends to linger, and its oily consistency can make cleaning a challenge.

• Swelling in the anal area: In my experience, anal sacs that are simply full shouldn’t be visible from the outside, but impaction or infection can make them swell massively. Anal gland infections can cause significant redness, swelling, and pain on a dog’s rear end.

• Constipation or diarrhea: If your dog is straining to poop or has a watery stool, this can be associated with full anal glands in dogs, but they aren’t necessarily a symptom of an anal gland issue. Without the regular passage of formed stool, dogs’ anal glands can stay full.

• Discharge: Overly full anal glands can leak, especially when a dog is frightened. Infected or abscessed anal glands can also rupture out through the skin, creating bloody discharge and a giant mess.

What causes anal gland issues in dogs? 

There’s no single, unifying cause that covers every type of anal gland problem a dog can experience. Some common conditions that are associated with the development of anal gland issues include:

• Obesity: Having a fluffy butt puts dogs at risk for anal gland issues. Excessive fat in the region around the anus can compress the ducts that the anal gland material exits through, resulting in retention of the fluid and putting dogs at risk of anal sac inflammation.

• Allergies: There’s some debate about the link between anal gland issues and allergies, but many veterinarians feel that dogs with allergies have an increased risk of problems. Both food and environmental allergies may make anal gland issues more likely.

• Diet: Healthy poops are an important part of dog anal gland health. Formed stool that is large enough to stimulate release of anal gland fluid during defecation helps to keep the sacs empty and reduces the risk of inflammation or infection.

• Dog breed: A study showed that certain dog breeds are predisposed to having anal gland issues. Cavalier King Charles Spaniels are the poster children, with almost one in five having anal sac problems. Overall, small-breed dogs seem most at risk, but some large breeds like Labrador Retrievers and German Shepherds are more likely than average to develop issues as well. Brachycephalic (flat-faced) dogs are 2.6 times more likely to have anal gland issues than long-faced ones.

• Diarrhea: Having diarrhea can increase the risk of anal gland impaction, inflammation, or abscessation. Diarrhea doesn’t stimulate emptying of anal sacs, and inflammation around the anus may allow bacteria to invade the ducts.

• Cancer: Some anal gland issues are less straightforward. Your veterinarian may notice irregularities or masses associated with your dog’s anal sacs when they are expressed. Apocrine gland anal sac adenocarcinoma is a common tumor of dogs’ anal sacs, and it has a high risk of spreading if not caught early.

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Food and dogs’ anal glands

The question of how to prevent anal gland issues in dogs is a tricky one. Surgical removal of the anal sacs may be recommended to prevent further problems in dogs who suffer from  recurrent issues. Surgery is a big step, so vets will first try to resolve any medical or dietary issues that may be causing chronic anal gland disease. Because some causes of anal gland disease are related to diet, changing your dog’s food or adding supplements may be recommended. Some common adjustments include:

• Switching to a hypoallergenic dog food: This is appropriate for dogs whose food allergies contribute to their anal gland issues. Hypoallergenic dog foods may either contain novel protein and carbohydrate sources or hydrolyzed protein. Novel diets try to reduce the allergic response by introducing something your dog’s immune system hasn’t seen before, while hydrolyzed diets break the proteins down to such small fragments that the immune system doesn’t react.

• High-fiber dog food: For dogs with dry stool or small fecal balls, a high-fiber food can help to increase the bulkiness of the feces. This can stimulate better release of the material within the anal sacs.

• Pumpkin: Canned pumpkin is commonly added to dogs’ diets to help add moisture to their stool. Pumpkin doesn’t contain a ton of fiber and can be high in calories, so it isn’t the right answer for every dog.

• Psyllium: Powdered psyllium supplements are readily available and are a good source of insoluble fiber. For dogs who need it, fiber can help to improve stool consistency, which can have beneficial effects for the anal glands.

Always consult your veterinarian before changing your dog’s diet or adding supplements to their food. I’ve seen pet parents overdo it with fiber supplements, resulting in either diarrhea or constipation. If additional fiber is needed, your vet can help you figure out the right dose for your dog.

When to seek expert help

While many anal gland issues can be resolved with regular expression of the anal glands and changes to diet, some can become significant problems. Don’t mess around back there if your dog’s rear end is swollen, reddened, painful, warm, or has discharge. Just take your dog to the vet as soon as possible to get them some relief.

Bottom line

Anal gland issues are a common source of discomfort for dogs and frustration for pet parents. Knowing the signs of full anal sacs can help you catch problems before they develop. Your veterinarian can help guide you on strategies to help control and prevent anal gland issues in your dog.

References

• Chen, Carolyn L et al. “Minimal complications observed with a modified surgical approach for treatment of canine anal sac neoplasia.” Journal of the American Veterinary Medical Association vol. 260,S1 (2021): S59-S64. doi:10.2460/javma.21.01.0008

• Corbee, Ronald Jan et al. “A Cross-Sectional Study on Canine and Feline Anal Sac Disease.” Animals : An Open Access Journal from MDPI vol. 12,1 95. 31 Dec. 2021, doi:10.3390/ani12010095

• Ehrenzweig, J. “Novel fiber-rich supplement effective for prevention and treatment of acute, episodic and chronic anal gland disease in dogs and cats.” Int J Vet Anim Med. March 2018;1(1):1-3.

• Lake, A M et al. “Gross and cytological characteristics of normal canine anal-sac secretions.” Journal of veterinary medicine. A, Physiology, Pathology, Clinical Medicine vol. 51,5 (2004): 249-53. doi:10.1111/j.1439-0442.2004.00629.x

• O'Neill, Dan G et al. “Non-neoplastic anal sac disorders in UK dogs: Epidemiology and management aspects of a research-neglected syndrome.” The Veterinary Record vol. 189,2 (2021): e203. doi:10.1002/vetr.203

• Robson, D C et al. “Cytological examination and physical characteristics of the anal sacs in 17 clinically normal dogs.” Australian Veterinary Journal vol. 81,1-2 (2003): 36-41. doi:10.1111/j.1751-0813.2003.tb11418.x

• van Duijkeren, E. “Disease conditions of canine anal sacs.” The Journal of Small Animal Practice vol. 36,1 (1995): 12-6. doi:10.1111/j.1748-5827.1995.tb02756.x