Integumentary (Skin) System: Anal Sac Abscess

 

 Provided to you by: Atlas of Veterinary Clinical Anatomy

Normal Anal Gland Fluid:  Thin liquid, brown, and fishy.

Abnormal Anal Gland Content: 

Anal Gland Impaction: Grey, Creamy,  Thick with particles painful or non painful to express

• Fluid becomes thick, toothpaste-like
• Grey or off-white color
• Particles = cellular debris, thickened secretions

Indication: Glands not emptying properly during bowel movements= Soft or inconsistent stools, Low stool bulk, Chronic gut inflammation

Connection to overall health: 

Allergic or dietary inflammation which is very common in dogs with:

• Food sensitivities
• Environmental allergies
• IBD, PLE, pancreatitis history

Summery

An Allergy-driven inflammation is part of the cause for thickens anal gland secretions which alters gland lining and prevents natural emptying

Chronic anal sac Impaction + inflammation (sacculitis): Creamy grey discharge, gritty texture, may be painful or non painful to express, may have a sour or metallic odor (not just fishy)

• Fluid becomes creamy grey or brown- like chocolate mousse- Secretions become thick, stagnant, and inflammatory
• Particles: Fine granules - Cellular debris + bacteria create the gritty particles
• Inflammation alters the odor (metallic/sour vs fishy)- Secretions is stagnant and inflammatory

Indications: Not an acute abscess, but long-standing irritation= Anal glands do not empty fully

Connection to overall health: 

Even without obvious itching or diarrhea; chronic low-grade food intolerance causes the following:  

• Food triggers intestinal inflammation
• Inflammation extends to anal sac lining (shared immune response)
• Glands overproduce thick, abnormal secretions
• Results in grey, creamy fluid with debris

Common dietary triggers:

• Chicken, beef, egg
• Soy, wheat, barley
• Peas, lentils (in sensitive dogs) 

Summary

Stool quality is the key factor, and is often driven by diet, allergies, or GI disease. Fixing stool consistency and gut inflammation is more effective than repeated gland expression alone.

Elimination Trials 

Any known allergies or GI diagnoses

Incorrect fiber profile (most common diet error)

Especially when diet claims to have fiber, it may definitely have fiber sources, however the issue falls to it may have the wrong type.

Incorrect Fiber type Mechanism: 

• Excess soluble fiber → soft stools (Soft stools fail to compress anal sacs)
• Glands partially empty → fluid stagnates
• Stagnation = thickened grey discharge with granules

Often seen in diets heavy in:

• Beet pulp only
• Inulin/chicory root
• Gums (guar, xanthan)

High-moisture toppers without insoluble fiber Mechanism: 

 Fat level too high for the dog’s tolerance. Even if “within normal” on the label.

• High fat → looser stool transit
• Incomplete anal sac expression
• Fat also increases gland secretion viscosity
• Leads to creaminess and gritty sediment

Common culprits:

• Salmon-heavy foods
• Added oils (fish, coconut, sunflower)
• Rich treats (cheese) or raw fat trims

Protein digestibility mismatch Mechanism:

When a protein source is not well digested or accepted by dog's body

• Undigested protein ferments in colon
• Alters bacterial balance
• Changes gland secretion pH
• Produces sour/metallic odor
• Increases cellular debris → granules

**Even “high quality” proteins can cause this if not tolerated.

 Frequent diet changes or topper rotation without a stable base diet Mechanism:

The importance of finding and sticking to a base diet that is accepted by your dog's digestive and immune system. 

• Constant microbiome disruption
• Variable stool firmness
• Chronic gland irritation
• Thick, abnormal secretions persist

These Anal Gland issues is NOT usually caused by

• Lack of hygiene
• Normal aging alone
• Not expressing glands often enough
• Infection alone (diet creates the environment first)
• 
  

Early abscess formation: Greyish pus-like fluid, Particles may be white or yellow, Dog may scoot, lick, or show discomfort, may include pain, swelling, blood, or fever

Anal Gland Problems never happen at random, however early symptoms are less commonly noted and usually not given preventative care long-term after treatment. 

How diet affects anal gland consistency

Anal glands rely on firm, well-formed stools to empty properly.

Diet factors that cause thick, grey discharge

• Low fiber or wrong fiber type
• Excess fat (especially in sensitive dogs)
• Food intolerances → gut inflammation
• Highly processed or poorly digestible proteins
• Frequent diet changes

Diet adjustments that usually help

1. Correct fiber type (not just more fiber)

Best options: Soluble + insoluble fiber balance

• Pumpkin (plain, small amounts)
• Psyllium husk (very small, vet-guided)
• Certain prescription GI or anal-gland-support diets

Avoid:

Excess beet pulp alone or Too much soluble fiber → softer stools

Single, well-tolerated protein

• Reduces immune-driven inflammation
• Helps normalize gland secretions

If allergies suspected:

Remove triggers table food, treats, toppers, indefinitely make a list if you have to to prevent exposure.    Change kibble with vet guidance to one that may be a better alternative.

Moderate fat (not low, not high)

• Excess fat → loose stools → impaction
• Too low fat → poor stool bulk

Consistent feeding schedule (Yes this matters especially as pet ages, their system becomes like a clock)

• Predictable bowel movements
• Better natural gland expression

⚠️ Frequent expression without fixing diet can worsen inflammation long-term