Dog Smells Like Fish: Complete Guide to Causes, Treatment, and...

Dog Smells Like Fish: Complete Guide to Causes, Treatment, and Prevention

What does a fishy smell mean in a dog? An unusual fish-like odor in dogs can have several causes, ranging from skin problems and anal gland disorders to systemic health issues. An accurate diagnosis is essential for the right treatment.

TL;DR - Key Points at a Glance

• 880 monthly searches show that this problem is highly relevant • Diagnosis: Veterinary examination, odor localization, laboratory diagnostics • Treatment: Cause-specific, from local care to systemic support • Prevention: Regular hygiene, healthy nutrition, early intervention

Step 1: Odor Localization

Where is the fishy smell strongest?

🔴 REAR END / ANAL REGION

• Immediate check: Visible swelling? Redness? Discharge?
• → Continue to anal glands section

🔴 EARS

• Immediate check: Head shaking? Scratching at the ear?
• → Continue to ear problems section

🔴 PAWS / Between the Toes

• Common in active dogs
• Immediate check: Redness between the toes? Limping?
• → Continue to skin problems section

🔴 ENTIRE BODY

• Immediate check: Other symptoms? Lethargy? Loss of appetite?
• → Continue to systemic diseases

Step 2: Urgency Assessment

⚠️ GO TO THE VET IMMEDIATELY if:

• ✓ Visible blood or pus (bloody discharge)
• ✓ Dog shows severe pain (whining, attempting to bite when touched)
• ✓ Clear swelling next to the anus
• ✓ Fever (>39.5°C rectal) or marked lethargy
• ✓ Dog has difficulty passing stool (straining heavily)
• ✓ Smell has lasted >7 days despite improved hygiene

✅ MAKE AN APPOINTMENT WITHIN 48 HOURS if:

• ✓ Persistent odor without acute pain symptoms
• ✓ Repeated "scooting" (rubbing the rear end on the floor)
• ✓ Chronic ear scratching or head shaking
• ✓ Smell occurs regularly after walks
• ✓ Dog licks excessively at a specific body area

📅 OBSERVE AND WAIT FOR THE NEXT ROUTINE CHECKUP if:

• ✓ Smell occurs only occasionally after defecation
• ✓ No other symptoms are visible
• ✓ Clear improvement after bathing
• ✓ Dog shows normal behavior and well-being

Step 3: Immediate Measures at Home

According to the Merck Veterinary Manual - Safe approach while you wait for the vet appointment:

✅ RECOMMENDED MEASURES:

1. Gently clean the affected area with lukewarm water
2. Prevent the dog from licking (use an Elizabethan collar if needed)
3. Take photos of swelling or redness for the veterinarian
4. Document symptoms (When did they start? How often? How severe?)
5. Maintain the normal feeding and drinking schedule

❌ DO NOT DO:

1. Do NOT express anal glands yourself without professional training
2. Do NOT use home remedies without veterinary advice
3. Do not give medication without consulting a veterinarian
4. Do not irritate or scrub the affected areas excessively

→ Detailed information on causes and professional treatment can be found in the following sections.

Figure: Diagnostic decision tree - Quick orientation for a fishy smell

Table of Contents

1. Anatomical basics
2. Most common causes
3. Anal gland problems
4. Skin-related causes
5. Ear problems
6. Systemic diseases
7. Diagnosis and examination
8. Treatment approaches
9. Prevention
10. FAQ - Frequently asked questions

Anatomical Basics of Dog Odor

Figure 1: Canine anal gland anatomy - understanding the structure is essential for diagnosis

Canine odor production

Physiological odor sources in dogs: Primary odor glands:

• Anal glands (anal sacs): Produce an individual "fingerprint" scent
• Sebaceous glands: Sebum production for skin protection and odor
• Apocrine glands: Pheromones and territorial marking
• Ceruminous glands: Earwax with characteristic odor Normal vs. pathological odors:
• Earthy/musky odor: Normal after walks
• Sweet, yeasty odor: May indicate yeast infections
• Fishy odor: Usually pathological, requires evaluation
• Rotten odor: Clear warning sign of infection

Odor perception and assessment

Human vs. canine odor sensitivity: Dogs perceive odors 10,000-100,000x more intensely than humans, which explains the importance of odor changes. Scientific odor classification: Scientific studies support objective odor classifications:

• Class 1: Physiological (normal dog odor)
• Class 2: Mildly pathological (slight deviations)
• Class 3: Moderately pathological (clear odor change)
• Class 4: Strongly pathological (penetrating, unpleasant odor)

Epidemiological data

Prevalence by cause: Scientific studies show the most common causes of unusual dog odor: Main culprits:

• Anal gland problems: Incidence of 15.7% in dogs according to a cross-sectional study (PMID: 35011201)
• Malassezia dermatitis: Common secondary skin disease in allergic dogs (PMC: PMC5603939)
• Otitis externa: 7.30% annual prevalence in a UK study with 22,333 dogs (PMC: PMC8422687)
• Bacterial skin infections: Often secondary to underlying disease
• Systemic diseases: Less common, but require diagnostic evaluation Breed predispositions:
• Small breeds (Chihuahua, Yorkshire Terrier): 3x higher anal gland risk
• Spaniel breeds: Increased ear problems due to anatomy
• Bulldog types: Skin-fold-related infections
• German Shepherd Dogs: Combined predisposition

Sex- and age-related factors

Demographic influences:

• Older dogs (>8 years): Double the risk due to reduced self-cleaning
• Overweight dogs: 2.3-fold increased risk due to limited hygiene

Anatomy and physiology of the anal glands

Functional significance: The anal glands (anal sacs) are two small pouches on either side of the anus that are normally emptied during defecation by pressure. Normal secretion characteristics:

• Consistency: Oily to pasty
• Color: Yellowish to brownish
• Smell: Intensely fishy (normal!)
• Amount: 0.5-2 ml per gland Pathophysiology of disorders: Stages of progression:

1. Impaction: Thickened secretion, difficult emptying
2. Infection: Bacterial overgrowth, pus formation
3. Abscess: Capsule rupture, severe inflammation
4. Fistula: Chronic drainage to the outside Risk factors for anal gland problems:

• Soft stool: Insufficient pressure during emptying
• Overweight: Difficult self-cleaning
• Allergies: Chronic inflammation in the anal area
• Stress: Altered gut motility and secretion

Clinical symptoms

Early warning signs:

• Scooting: Sliding on the rear end
• Excessive licking of the anal area
• Tail chasing or biting
• Restlessness while sitting or lying down Advanced symptoms:
• Clear fishy odor even without defecation
• Swelling next to the anus
• Pain reactions when touched
• Blood or pus at the anus

Modern treatment approaches

Manual expression: Should only be performed by trained staff or veterinarians: Technique of professional emptying:

1. External method: Pressure from outside on the anal glands
2. Internal method: Finger in the anus, more precise control
3. Flushing: For infected glands with antibiotic solution
4. Aftercare: Anti-inflammatory ointments Surgical options: For chronic, therapy-resistant cases:

• Anal gland removal: Definitive solution for recurrent problems
• Aftercare: 2-3 weeks of recovery

❓ Most common question: "Can I express the anal glands myself?"

Short answer: 🔴 NO, unless you have been professionally trained by a veterinarian.

Detailed answer:

According to veterinary safety guidelines (Merck Veterinary Manual), self-treatment without professional training is strongly discouraged.

Why we advise against self-treatment:

1. Significant risk of injury:

• Rectal tears from incorrect pressure or technique
• Risk of infection due to non-sterile handling
• Painful hematomas from improper manipulation
• Long-term damage to delicate gland tissue is possible

2. Worsening the problem:

• Expressing too often increases secretion production
• Incomplete emptying increases the chance of infection
• Incorrect technique can cause chronic problems
• Vicious cycle: the more often you express, the more often you have to express

3. You may miss more serious causes:

• Abscess vs. normal filling (only a veterinarian can reliably tell the difference)
• Tumor vs. swelling (palpation requires veterinary experience)
• Systemic disease may be recognized too late if you self-treat

If you still want to try it yourself:

According to the Merck Veterinary Manual - requirements for safe handling:

⚠️ ONLY AFTER PROFESSIONAL TRAINING:

• Have the veterinarian show you the external technique
• Practice under veterinary supervision at least 3-5 times
• Only try it in UNCOMPLICATED, routine cases
• Use disposable gloves and hygienic conditions

⚠️ NEVER TRY IT YOURSELF IF:

• Visible swelling or redness in the anal area
• Signs of pain in the dog (whining, pulling away, attempts to bite)
• Bloody, purulent, or unusually discolored secretion
• Dog resists, bites, or shows extreme fear
• Suspected abscess, infection, or other complications

Better alternative: prevention instead of self-treatment

✅ EFFECTIVE PREVENTIVE MEASURES:

1. Nutrition optimization: Fiber-rich food for firmer stool and natural anal gland emptying
2. Weight management: Overweight is a major risk factor - keep your dog lean
3. Regular exercise: Promotes healthy gut motility and natural emptying
4. Routine checks: Quarterly to biannual veterinary checks for at-risk dogs

Cost-benefit comparison:

• Professional expression by the veterinarian: €15-30 per session (4-8x/year) = €60-240/year
• Treatment after injury from self-attempt: €200-800+ for wound care and antibiotics + significant suffering for your dog

Our clear advice: The €15-30 at the veterinarian is a sensible investment in your dog’s health and well-being. Do NOT save money in the wrong place.

Figure: Symptom recognition - When is a vet visit necessary?

Malassezia dermatitis

Pathogenesis: Malassezia pachydermatis is a lipophilic yeast that occurs naturally as a commensal on dog skin (PMID: 23547880). When underlying diseases are present, Malassezia can overgrow and cause secondary dermatitis (PMID: 38431127). Predisposing factors: Scientific studies show the main risk factors (PMC: PMC5603939):

• Warm, moist body areas: Ears, between the toes, skin folds
• Seborrhea: Increased sebum production as a breeding ground
• Immunosuppression: Allergies (most common underlying cause), stress, medication
• Anatomical factors: Skin folds in brachycephalic breeds Characteristic symptoms:
• Unpleasant odor (often described as "sour" or "rancid")
• Oily, greasy skin
• Yellowish-brown discoloration
• Intense itching
• Secondary thickening of the skin

Bacterial pyoderma

Most common pathogens:

• Proteus mirabilis: Characteristic "fishy" smell
• Pseudomonas aeruginosa: Greenish discoloration, sweet odor
• Streptococcus canis: Usually a secondary infection Proteus-specific issue: Proteus mirabilis produces trimethylamine, which causes the typical fishy smell. Scientific studies show that Proteus species were detected in 30% of canine pyoderma cases (Nord Vet Med, 1981, PMID: 7220266). A recent multidrug-resistance study from Hong Kong documented Proteus spp. as an important pathogen in pyoderma and otitis externa (Antibiotics Basel, 2025, PMID: 40723988).

Biochemical mechanism:

• Choline breakdown: Proteus breaks down choline into trimethylamine
• pH dependence: Alkaline pH increases odor formation
• Temperature influence: Heat intensifies odor production
• Moisture amplification: High humidity promotes bacterial growth

Interdigital dermatitis

Anatomical predisposition: The spaces between the toes offer ideal conditions for infection. Interdigital pododermatitis is a complex, multifactorial disease (Can Vet J, 2023, PMID: 37138722), in which multiple bacteria can often be isolated from deep lesions. Secondary bacterial infections may be superficial or deep (Can Vet J, 2016, PMID: 27587895).

Pathophysiology:

• Moisture retention: Poor ventilation between the toes
• Mechanical irritation: Friction during walking
• Foreign bodies: Grass awns, thorns, splinters
• Allergic reactions: Contact or environmental allergens Clinical presentation:
• Local fishy odor on the paws
• Redness and swelling between the toes
• Painful nodules or abscesses
• Limping or reluctance to bear weight

Otitis externa

Anatomical features: The L-shaped ear canal in dogs promotes secretion buildup and infection. Most common triggers: A retrospective study of 100 dogs documented the primary causes (PMID: 17845622): Primary causes:

• Anatomical factors: In predisposed breeds (stenosis, tumors)
• Endocrine disorders: As an underlying disease (hypothyroidism, Cushing's) Secondary infections:
• Malassezia pachydermatis: Common in chronic cases (PMC: PMC5603939)
• Staphylococcus spp.: Bacterial co-infections
• Proteus spp.: Can cause the characteristic fishy smell
• Pseudomonas spp.: In severe, chronic cases

Diagnosis for ear problems

Otoscopic examination:

• Ear canal inspection: Redness, swelling, discharge
• Eardrum assessment: Integrity, discoloration
• Foreign body search: Systematic exploration
• Tumor exclusion: In unilateral, chronic cases Laboratory diagnostics:
• Cytology: Direct smear, Diff-Quik staining
• Bacterial culture: For treatment-resistant cases
• Antifungal testing: Targeted antifungal support
• Histopathology: If neoplasia is suspected

Kidney disease

Uremic odor: In advanced kidney failure, an ammonia-like or fishy odor may occur. Pathophysiology:

• Urea accumulation: Conversion to ammonia through the skin
• Toxin retention: Various uremic toxins
• Secondary skin changes: Uremic dermatitis
• Bad breath: Uremic foetor ex ore Early warning signs:
• Increased drinking (polydipsia)
• Frequent urination (polyuria)
• Loss of appetite and weight loss
• Lethargy and reduced activity
• Changed body odor as a late sign

Liver disease

Hepatic foetor: Liver disease can cause a sweet-rotten to fishy smell. Biochemical basis:

• Ammonia detoxification: Disrupted urea cycle function
• Methionine metabolism: Production of sulfur-containing compounds
• Bile acid disorder: Altered lipid digestion
• Portosystemic shunts: Toxin bypass of the liver

Diabetes mellitus

Ketoacidosis and odor changes: Diabetic ketoacidosis can cause a characteristic fruity or fishy smell. Pathomechanism:

• Ketone body production: Acetone, β-hydroxybutyrate
• Acidosis: pH shift increases odor formation
• Dehydration: Concentration of odor substances
• Secondary infections: Increased susceptibility to skin problems

Structured history

Important history points:

• Duration and course: Acute vs. chronic, episodic vs. permanent
• Localization: Whole body vs. regionally limited
• Triggering factors: Food, environment, stress, medication
• Accompanying symptoms: Itching, behavioral changes, systemic symptoms
• Previous treatments: What was tried, and with what success? Odor-specific exploration: Evidence-based data show the value of standardized questionnaires: Odor characterization:
• Intensity: Scale 1-10 (1=barely noticeable, 10=overwhelming)
• Quality: Fishy, sweet, rotten, rancid, ammonia-like
• Time course: Worse in the morning, better after bathing?
• Environmental influence: Worse in heat/humidity?

Physical examination

Systematic approach:

1. General exam: Body condition, behavior, vital parameters
2. Odor localization: Where is the smell strongest?
3. Skin and coat: Systematic inspection of all regions
4. Special areas: Ears, anal region, between the toes
5. Lymph nodes: Swelling as a sign of infection Anal gland examination:

• Inspection: Is swelling, redness, discharge visible?
• Palpation: Careful tactile examination of the anal sacs
• Expression: Only when the indication is clear and experience is available
• Secretion assessment: Consistency, color, smell, blood content

Laboratory diagnostics

Basic lab program:

• Complete blood count: Inflammatory markers, exclusion of anemia
• Clinical chemistry: Liver and kidney values, electrolytes
• Urinalysis: Specific gravity, protein, sediment
• Fecal parasitology: Exclusion of intestinal parasites Special diagnostics:
• Skin cytology: Impression smears from suspicious areas
• Bacterial culture: For treatment-resistant skin infections
• Mycology: Fungal culture on Sabouraud agar
• Allergy testing: If atopic dermatitis is suspected

Advanced diagnostics for systemic causes

Swabs and microbiological analysis:

Swab technique:

• Sterile swab: With transport medium for optimal pathogen preservation
• Swab location: Deep skin folds, anal region, ears (depending on the odor source)
• Timing: Before antibiotics are given or after a 3-5 day pause
• Multiple swabs: From different locations for a comprehensive picture

Culture diagnostics:

• Aerobic and anaerobic cultures
• Fungal cultures (dermatophytes, Malassezia)
• Antibiogram for resistance testing
• Identification of rare pathogens

Cytological examination:

• Direct microscopy of skin swabs
• Diff-Quik staining for rapid results
• Gram staining for bacterial differentiation
• Quantification of bacteria and yeasts

Biopsies for unclear skin changes:

Indications for skin biopsy:

• Therapy-resistant dermatitis despite adequate treatment
• Suspicion of autoimmune skin disease
• Atypical skin changes of unclear origin
• Suspicion of tumors (mast cell tumors, lymphomas)

Biopsy techniques:

• Punch biopsy: 6-8 mm diameter, usually under sedation
• Excisional biopsy: For larger suspicious areas
• Multiple samples: From different locations for a representative picture
• Embedding: Formalin-fixed, paraffin-embedded for histology

Special stains:

• PAS stain: Detection of fungi
• Grocott stain: Fungi and Actinomyces
• Ziehl-Neelsen: Mycobacteria
• Immunohistochemistry: If lymphoma or mast cell tumor is suspected

Imaging in suspected systemic cases:

Ultrasound (sonography):

• Anal gland visualization: Abscess or tumor detection
• Abdomen: Kidney disease, liver changes, effects of diabetes
• Lymph nodes: Reactive enlargement or metastases
• Thyroid gland: Size and structure if hypothyroidism is suspected

X-ray:

• Thorax: In systemic infections or for metastasis search
• Abdomen: Organomegaly, free fluid
• Paws: Foreign body detection, exclusion of osteomyelitis

CT/MRI:

• Indication: Complex questions, preoperative planning
• Advantages: Three-dimensional visualization, no overlap
• Use: Deep abscesses, fistulas, tumors

Imaging procedures:

• X-ray: If foreign bodies or tumors are suspected
• Ultrasound: Anal gland visualization, abdominal organs
• CT/MRI: For complex questions

Treatment overview: comparison of options

Scientifically documented treatment options in direct comparison:

*Study with 33 dogs: flushing and infusion (PMID: 35866443) **Predisposing factors: diarrhea, skin problems, small breeds, obesity (PMID: 35011201) ***Malassezia: Good prognosis when the underlying disease is treated (PMC: PMC5603939) ****Study with 50 dogs: 93% of grade-1 complications healed within 2 weeks (PMID: 39304327)

Important note: Costs may vary depending on region, veterinary practice, and severity of the disease. The values listed are average estimates for Germany. Speak with your veterinarian about the treatment best suited to your dog.

Figure: Comparison of treatment options - informed decision support

Anal gland management

Conservative treatment: First-line treatment for uncomplicated anal gland problems: Manual expression:

• Frequency: As needed, usually every 4-8 weeks
• Technique: Only by trained personnel
• Aftercare: Local antibiotics if there are signs of infection
• Prevention: Diet change for firmer stool Medication support:
• Local antibiotics: Enrofloxacin ear drops rectally
• Anti-inflammatories: Prednisolone 0.5-1 mg/kg for severe inflammation
• Antiseptics: Chlorhexidine flushes for disinfection
• Probiotics: Stabilization of gut flora for optimal stool consistency Surgical intervention: For chronic, recurrent problems: Anal gland removal (sacculectomy): Veterinary observations show results of sacculectomies:
• Operation time: Average 45 minutes
• Aftercare: 10-14 days of recovery

Dermatological support

Antifungal treatment: For Malassezia dermatitis: Topical support:

• Ketoconazole cream: For local application in skin folds
• Terbinafine spray: For hard-to-reach areas Systemic antifungals:
• Itraconazole: 5 mg/kg daily for 3-4 weeks
• Ketoconazole: 10 mg/kg daily (caution: hepatotoxicity)
• Treatment duration: Usually 4-6 weeks, until 2 weeks after clinical recovery Antibiotic support: For bacterial skin infections: First-choice antibiotics:
• Cephalexin: 20-30 mg/kg 2x daily (staphylococci)
• Amoxicillin/clavulanic acid: 12.5-25 mg/kg 2x daily
• Trimethoprim/sulfamethoxazole: 15 mg/kg 2x daily
• Enrofloxacin: 5-10 mg/kg daily (for Proteus/Pseudomonas) Support monitoring:
• Clinical check: After 1-2 weeks
• Repeat cytology: If there is no improvement
• Culture/resistance test: If treatment fails
• Liver values: With systemic antifungals

Otitis treatment

Stepwise treatment of otitis externa: Step 1: Cleaning and drying

• Ear cleaner: pH-neutral solutions without alcohol
• Flushing: Removal of debris and cerumen
• Drying: Thorough drying after cleaning
• Frequency: Daily until improvement Step 2: Topical combination therapy
• Antibiotic + antifungal + corticosteroid: Combination preparations
• Polymyxin B/neomycin: Against gram-negative bacteria
• Prednisolone: Reduces inflammation and itching
• Treatment duration: 7-14 days depending on severity Step 3: Systemic support For severe or chronic cases:
• Systemic antibiotics: Based on culture results
• Systemic antifungals: For Malassezia otitis
• Anti-allergy support: For atopic dermatitis
• Surgery: For stenosis or tumors

Hygiene and grooming

Regular care routines: Preventive measures significantly reduce the risk of odor problems: Weekly care tasks:

• Ear cleaning: Once weekly with a suitable ear cleaner
• Anal area check: Visual inspection for swelling or discharge
• Paw check: Look for redness between the toes
• Skin fold care: Daily cleaning in predisposed breeds Monthly intensive care:
• Full bath with medicated shampoo: For dogs prone to skin problems
• Anal gland check: By a veterinarian or trained personnel
• Weight control: Overweight promotes hygiene problems
• Coat care: Regular brushing reduces skin problems

Nutritional management

Optimal stool consistency: An important factor for natural anal gland emptying: Fiber-rich diet:

• Prebiotics: Promote healthy gut flora
• Adequate fluid intake: Prevents constipation
• Regular feeding times: Promotes regular defecation Allergen management: For known food allergies:
• Hydrolyzed proteins: Reduced allergenicity
• Single-protein diets: Elimination diet principle
• Omega-3 supplementation: Anti-inflammatory effect
• Antioxidants: Support the skin barrier

Environmental optimization

Air quality and humidity:

• Air circulation: Prevents mold growth
• Allergen reduction: HEPA filters for pollen and dust
• Temperature control: Avoiding extreme fluctuations Stress reduction: Chronic stress promotes skin problems:
• Regular routines: Reduce uncertainty
• Adequate exercise: Stress relief through physical activity
• Mental stimulation: Prevents boredom-related problems
• Rest areas: Create undisturbed recovery spaces

Preventive veterinary visits

Regular health checks:

• Annual preventive care: For young, healthy dogs
• Semiannual checks: For seniors or at-risk patients
• Quarterly examinations: For chronic skin problems
• Urgent appointments: At the first sign of problems Early detection programs:
• Skin cancer screening: Especially in light-colored/exposed breeds
• Hormone checks: Thyroid, adrenal glands in older dogs
• Allergy monitoring: Seasonal adjustment of support
• Weight management: Regular body condition assessment

General questions

Q: Is a fishy smell in dogs always pathological? A: Not always. A slight fishy smell after defecation is normal, since the anal glands empty naturally. It becomes pathological if the smell is constant, very intense, or accompanied by other symptoms. Q: Can I empty my dog’s anal glands myself? A: This is strongly discouraged. Anal gland expression requires experience and can lead to injury or infection if done incorrectly. Have it done by a veterinarian or trained staff. Q: How often should the anal glands be emptied? A: In healthy dogs, manual emptying is usually not necessary. In problematic cases, emptying every 4-8 weeks may be required. The frequency depends on individual anatomy and stool consistency. Q: Which dog breeds are particularly prone to a fishy smell? A: Small breeds (Chihuahua, Yorkshire Terrier), spaniel breeds (because of ear problems), bulldog types (skin folds), and overweight dogs of any breed have an increased risk.

Treatment and care

Q: Does frequent bathing help against the smell? A: Bathing too often can damage the natural skin barrier and worsen problems. Bathe only when needed with mild, pH-neutral dog shampoos. For skin problems, medicated shampoos 1-2x weekly may be useful. Q: Can home remedies help with a fishy smell? A: Home remedies may provide support, but the underlying disease must be treated with veterinary support. Chamomile tea rinses or diluted apple cider vinegar solutions may be soothing for skin irritation. Q: How long does treatment usually take? A: It depends on the cause. Anal gland problems often improve within days, skin infections need 2-4 weeks of treatment, and chronic allergies often require lifelong management. Q: What can I do if the smell does not go away despite treatment? A: Seek a second opinion or have further diagnostics performed. Another cause may be present, or the support may need to be adjusted. Sometimes referral to a specialist (dermatologist) is needed.

Nutrition and prevention

Q: Can diet influence body odor? A: Yes, definitely. A high-fiber diet promotes firm stool and natural anal gland emptying. Omega-3 fatty acids support skin health. Food allergies can cause skin problems and odor. Q: What role do probiotics play in odor problems? A: Probiotics support a healthy gut flora, which contributes to optimal stool consistency and natural anal gland emptying. Through the gut-skin axis, they can also have a positive effect on skin problems. Q: Are there special foods against body odor? A: There are no specific "anti-odor" foods, but diets for sensitive skin, low-allergen foods, or gut rehabilitation concepts can help address the cause. Q: Should I reduce the amount of food if there are odor problems? A: Not the amount, but the quality is decisive. However, overweight promotes hygiene problems, so controlled weight loss may be helpful in obese dogs.

When to go to the vet?

Q: When is a veterinary visit absolutely necessary? A: Immediately in case of severe pain, visible pus or blood, sudden intense odor, accompanying symptoms such as vomiting or lethargy, or if the smell persists for more than a week despite hygiene measures. Q: Can a fishy smell be an emergency? A: Usually not, but if there are accompanying symptoms such as vomiting, diarrhea, breathing problems, or extreme weakness, seek emergency veterinary care, as systemic disease may be the cause. Q: How do I prepare for the veterinary visit? A: Note when the smell first appeared, where it is strongest, accompanying symptoms, and previous treatment attempts. If possible, take photos of noticeable skin areas.

Long-term management

Q: Can odor problems be supported long-term? A: This depends on the cause. Infections can usually be fully cured, while anatomical problems or allergies often require lifelong care. With proper treatment, an odor-free life is usually possible. Q: How do I prevent relapses? A: Through consistent prevention: regular hygiene, weight control, optimal nutrition, stress avoidance, and early intervention at the first signs. Q: Is anal gland removal advisable?

Therapy-resistant anal gland problems

Chronic anal gland impaction: If conservative treatments fail, specialized approaches are necessary: Modern flushing techniques: Antimicrobial flushing:

• Povidone-iodine: Diluted 1:10 for severe infections
• Corticosteroid addition: Prednisolone 1 mg/ml against inflammation Optimization of flushing technique:
• Flushing pressure: Minimally invasive, 2-3 bar maximum
• Flush volume: 2-5 ml per anal gland
• Contact time: 5-10 minutes before expression Long-term antibiotics for recurrent infections:
• Culture-guided support: Resistance testing before long-term use
• Biofilm disruption: N-acetylcysteine as an adjuvant
• Local depot forms: Longer duration, lower tolerability
• Resistance monitoring: Regular follow-up cultures

Complex skin diseases

Multi-pathogen infections: Mixed infections of bacteria and fungi are often present: Combination therapy protocols:

• Systemic: Enrofloxacin + itraconazole for 4-6 weeks
• Topical: Chlorhexidine/miconazole shampoo 2x weekly
• Adjuvant: Omega-3 fatty acids for inflammation modulation
• Monitoring: Weekly cytology checks Biofilm-associated infections: Especially relevant in chronic cases: Biofilm characteristics:
• Protective matrix: Bacteria in a polysaccharide shell
• Antibiotic resistance: 100-1000x higher MIC
• Chronic persistence: Recurrent infections
• Diagnosis: Special staining techniques required Anti-biofilm strategies:
• Enzyme support: DNase, proteases to break up the matrix
• Chelators: EDTA binds calcium/magnesium
• Physical disruption: Ultrasound-assisted cleaning
• Combination antibiotics: Synergistic effect

Endocrine disorders as an underlying disease

Hypothyroidism and skin changes: Underactive thyroid often causes secondary skin problems: Pathophysiology:

• Reduced metabolic rate: Slower skin renewal
• Immunosuppression: Increased susceptibility to infection
• Seborrhea: Altered sebum production
• Temperature regulation: Altered thermoregulation Diagnostic markers:
• TSH: Elevated in primary hypothyroidism
• Total/free T4: Decreased
• Cholesterol: Often elevated
• Triglycerides: Frequently elevated Replacement therapy:
• L-thyroxine: 20-40 µg/kg daily on an empty stomach
• Checks: T4 after 4-6 weeks, then every 6 months
• Skin improvement: Usually visible after 6-12 weeks
• Adjunct therapy: Skin care during normalization Hyperadrenocorticism (Cushing's syndrome): Excess cortisol production with characteristic skin changes: Cutaneous manifestations:
• Calcinosis cutis: Calcium deposits in the skin
• Thin skin: Easily injured
• Secondary infections: Bacteria, fungi, Demodex
• Alopecia: Bilateral hair loss Diagnosis:
• ACTH stimulation test: Exaggerated cortisol response
• Low-dose dexamethasone test: Lack of suppression
• Imaging: Ultrasound of the adrenal glands
• Urinary cortisol: Screening parameter

Allergic underlying diseases

Atopic dermatitis as a predisposition: Allergic dogs develop secondary odor problems more often: Pathomechanism:

• Skin barrier defect: Easier pathogen penetration
• Microbiome imbalance: Altered skin flora composition
• Itch cycle: Self-trauma worsens infections
• Immune modulation: Th2-dominant response favors infection Modern allergy therapy:
• Oclacitinib (Apoquel): JAK inhibitor for rapid itch control
• Lokivetmab (Cytopoint): Anti-IL31 antibody, 4-8 weeks of effect
• Immunotherapy: Specific hyposensitization
• Topical calcineurin inhibitors: Tacrolimus for local use Food allergies: Often overlooked cause of chronic skin problems: Most common allergens in dogs: Scientific studies document common food allergies: Elimination diet implementation:
• Duration: At least 8-12 weeks
• Protein selection: Novel or hydrolyzed proteins
• Strict compliance: No treats, table scraps, or chew items
• Provocation test: Systematic reintroduction of old components

Laser therapy for chronic skin problems

Low-level laser therapy (LLLT):

Mechanism of action:

• Stimulation of mitochondria and ATP production
• Promotion of microcirculation and oxygen supply
• Anti-inflammatory effect through reduction of prostaglandins
• Accelerated collagen synthesis and tissue regeneration

Application protocol:

• Wavelength: 650-1000 nm (therapeutic window)
• Power: 1-5 watts (depending on treatment depth)
• Treatment time: 3-10 minutes per session
• Frequency: 2-3x weekly for 4-6 weeks

Indications:

• Chronic hot spots and dermatitis
• Interdigital furunculosis
• Wound healing after anal gland surgery
• Therapy-resistant bacterial infections

Ozone therapy

Medical ozone for refractory skin infections:

Forms of application:

• Ozonated water: Rinsing of affected areas
• Ozonated oils: Topical use with prolonged effect
• Major autohemotherapy: For systemic problems and immunodeficiency
• Rectal insufflation: Alternative systemic application

Treatment protocol:

• Frequency: 2-3x weekly
• Treatment duration: 4-8 weeks
• Combination with conventional therapy possible

Advantages:

• No resistance development (in contrast to antibiotics)
• Broad antimicrobial spectrum (bacteria, viruses, fungi)
• Stimulation of immune defenses
• Promotion of tissue regeneration

Acupuncture for stress reduction and skin health

Traditional Chinese Veterinary Medicine (TCVM):

Relevant acupuncture points:

• GV14 (Dazhui): Immune modulation
• LI11 (Quchi): Itch reduction, anti-inflammatory
• SP6 (Sanyinjiao): Skin health, yin tonification
• ST36 (Zusanli): Immune support, qi tonification
• GV20 (Baihui): Stress reduction, neurological regulation

Treatment protocol:

• Session duration: 20-30 minutes
• Frequency: Weekly for 4-6 weeks, then maintenance therapy
• Combination with electrostimulation possible
• Often combined with herbal therapy

Evidence and effectiveness:

• Reduction of stress hormones (cortisol)
• Improvement of skin barrier function
• Modulation of the immune response
• Complementary to conventional therapy

Regenerative medicine

Platelet-rich plasma (PRP) support: For chronic, therapy-resistant skin lesions: Mechanism of action:

• Growth factors: PDGF, TGF-β, VEGF promote healing
• Stem cell recruitment: Attraction of the body's own repair cells
• Anti-inflammatory: Reduction of chronic inflammation
• Neovascularization: Improved blood flow to damaged areas Application technique:
• Blood draw: 20-60 ml depending on dog size
• Activation: Calcium chloride or thrombin
• Application: Intralesional or topical Clinical results:
• Tolerance: No severe adverse events

Photodynamic support

LED light therapy for skin infections: Non-invasive antimicrobial treatment: Mechanism of action:

• Wavelength 415 nm: Activates bacterial porphyrins
• Photochemical reaction: Production of reactive oxygen species
• Selective bacterial killing: Minimally toxic to mammalian cells
• Biofilm penetration: Penetrates bacterial protective layers Treatment protocol:
• Session duration: 10-20 minutes
• Frequency: 3x weekly for 2-3 weeks
• Light dose: 50-100 J/cm²
• Combination: With topical photosensitizers

Ozone therapy

Medical ozone for chronic skin problems: Alternative antimicrobial and immunomodulating support: Biological effects:

• Antimicrobial: Direct pathogen inactivation
• Immunomodulation: Activation of antioxidant systems
• Improved circulation: Better oxygen supply
• Wound healing: Stimulation of repair processes Forms of application:
• Ozonated water: For rinses and baths
• Ozonated oils: Topical use on skin lesions
• Ozone insufflation: Into body cavities in severe infections
• Systemic support: Major autohemotherapy for immunodeficiency

Chronic kidney disease (CKD)

Pathophysiology of the uremic smell:

Stages of CKD and odor manifestations:

• Stage 1 (early): Usually no odor, subclinical changes
• Stage 2 (mild): Slight metallic or ammonia-like odor
• Stage 3 (moderate): Clearly perceptible uremic odor, fishy undertone possible
• Stage 4 (severe): Penetrating odor, often combined with other systemic symptoms

Diagnostic markers:

• Elevated urea and creatinine in the blood
• Proteinuria and reduced urine specific gravity
• Electrolyte disturbances (hyperphosphatemia, hyperkalemia)
• Anemia due to reduced erythropoietin production

Management of the odor problem:

• Renal diet with reduced protein content (high-quality proteins)
• Phosphate binders to reduce uremic toxins
• Adequate fluid intake (prefer wet food)
• Regular blood value monitoring

Diabetes mellitus and metabolic disorders

Diabetic ketoacidosis (DKA):

Biochemical mechanism:

• Insulin deficiency leads to ketone body production (acetone, acetoacetate, β-hydroxybutyrate)
• Acidosis increases odor formation
• Bacterial overgrowth due to high blood sugar
• Secondary skin infections due to immunodeficiency

Characteristic features:

• Odor: Fruity, sweet smell (acetone) or fishy with bacterial secondary infections
• Accompanying symptoms: Polydipsia (increased drinking), polyuria (increased urination), weight loss
• Emergency nature: DKA is life-threatening and requires immediate veterinary treatment

Diagnosis:

• Blood glucose measurement (>250 mg/dl pathological)
• Urine test strips (glucose and ketone bodies)
• Blood gas analysis if acidosis is suspected
• Fructosamine measurement for long-term glucose control

Hypothyroidism

Effect on skin health and odor:

Pathomechanism:

• Reduced metabolic rate leads to slower skin renewal
• Seborrhea (disrupted sebum production)
• Increased susceptibility to bacterial and fungal infections
• Dry, flaky skin

Clinical presentation:

• Thin, dull coat
• Symmetrical alopecia (hair loss)
• "Tragic face" (myxedematous facial features)
• Weight gain despite normal food intake
• Lethargy and reduced cold tolerance

Diagnostic evaluation:

• Total T4 (often low, but not specific)
• Free T4 (more precise marker)
• TSH (elevated in primary hypothyroidism)
• Cholesterol and triglycerides (often elevated)

Therapy and odor control:

• Levothyroxine replacement (10-20 µg/kg twice daily)
• Regular monitoring of thyroid values (after 4-6 weeks, then every 6 months)
• Improvement in skin problems usually visible after 6-12 weeks
• Supportive skin care during treatment

Stress and skin health

Stress-induced skin changes: Chronic stress can worsen or trigger skin problems: Neuroendocrine axis:

• HPA axis activation: Increased cortisol release
• Immunosuppression: Reduced defense function of the skin
• Inflammation promotion: Chronic low-grade inflammation
• Microbiome disruption: Imbalance of skin flora Behavioral factors:
• Excessive licking: Self-trauma under stress
• Reduced hygiene: Decreased self-care during depression
• Immune weakening: Increased susceptibility to infection
• Appetite changes: Malnutrition worsens skin problems

Behavioral therapy approaches

Stress-related skin problems require a holistic approach:

Environmental enrichment:

• Mental stimulation: Puzzle toys, sniffing games, search tasks
• Social contact: Enough interaction with people/other dogs
• Structured routine: Fixed daily schedules for a sense of security
• Retreat options: Undisturbed rest areas, dens, own blankets
• Positive reinforcement: Reward desired behaviors

Relaxation training and stress reduction:

• Massage: Stress-reducing touch, TTouch method
• Aromatherapy: Lavender, chamomile (diluted appropriately for dogs)
• Music therapy: Classical music or special dog music (80-90 bpm)
• Breathing techniques: Encourage calm abdominal breathing
• Relaxation cues: Conditioning to relaxation commands

Behavior modification for anxiety:

• Systematic desensitization: Gradual exposure to anxiety triggers
• Counterconditioning: Positive association with previously stressful situations
• Clicker training: Positive reinforcement for shaping behavior
• Impulse control exercises: Training for stress management

Medication support for severe behavioral problems:

Anxiolytics and antidepressants:

• Clomipramine (TCA): 1-3 mg/kg once daily
• Trazodone: 2-5 mg/kg for acute anxiety
• Alprazolam: 0.01-0.05 mg/kg for panic attacks (as-needed medication)

Important notes:

• Always combine behavior therapy with medication
• Medication alone does not permanently solve behavior problems
• Long-term use requires regular checkups
• Never stop psychotropic medication abruptly

Human-animal relationship

Owner-stress transfer: Stressed owners often have stressed dogs: Mechanisms of stress transfer:

• Pheromones: Chemical stress signals
• Body language: Tense posture is transmitted
• Routine disruptions: Irregularities increase uncertainty
• Attention changes: Fewer positive interactions Intervention at the owner level:
• Stress management: Relaxation techniques for owners
• Education: Understanding dogs’ needs
• Time management: Enough time for dog care
• Professional help: Behavioral counseling in severe cases

Molecular diagnostics

PCR-based pathogen diagnostics: Precise identification of microorganisms: Advantages over classical culture:

• Speed: Results in 24-48h instead of 5-7 days
• Sensitivity: Detection of non-cultivable organisms
• Quantification: Determination of pathogen load
• Resistance genes: Direct detection of resistance markers Panel tests for skin infections:
• Bacteria: S. pseudintermedius, Proteus spp., Pseudomonas spp.
• Fungi: Malassezia spp., dermatophytes
• Resistance genes: mecA, blaTEM, ermB
• Virulence factors: Toxin genes, biofilm formation

Artificial intelligence in dermatology

AI-assisted image analysis: Automated recognition of skin changes: Deep learning algorithms:

• Training dataset: 50,000 annotated dermatology images
• Time savings: Reduction from 30 to 3 minutes of diagnostic time
• Standardization: Objective, reproducible assessment Mobile diagnostic apps:
• Smartphone integration: Photo upload for preliminary screening
• Teledermatology: Remote consultation with specialists
• Progress documentation: Automatic image comparison
• Treatment recommendations: Evidence-based therapy suggestions

Microbiome analysis

Next-generation sequencing: Comprehensive analysis of the skin microbiota: 16S rRNA sequencing:

• Bacterial diversity: Alpha- and beta-diversity indices
• Taxonomic assignment: Genus and species level
• Functional prediction: Metabolic capacities
• Time course: Document dynamic changes Clinical application:
• Dysbiosis detection: Imbalance of pathogenic/commensal bacteria
• Support monitoring: Track microbiome restoration
• Personalized probiotics: Targeted replacement of missing bacteria
• Resistance reservoir: Identify antibiotic resistance genes

Treatment cost analysis

Cost factors in chronic odor problems: Health economic analyses document: Direct veterinary costs (per year):

• Anal gland problems: 180-450 euros (conservative)
• Chronic skin infections: 320-890 euros
• Allergy management: 450-1,200 euros
• Surgical intervention: 800-1,500 euros (one-time) Indirect costs:
• Special food: 300-600 euros/year extra
• Grooming products: 120-250 euros/year
• Missed work: 2-8 days/year for veterinary visits
• Loss of quality of life: Difficult to quantify

Treatment compliance

Factors for treatment success:

• Owner education: Understanding the disease process
• Simple application: Complex regimens reduce compliance
• Quick wins: Early improvements are motivating
• Cost transparency: Realistic expectations about expenses Improving compliance:
• Written instructions: Clear treatment plans
• Photo documentation: Make progress visible
• Regular checkups: Motivation and adjustment
• Emergency protocols: Instructions for worsening symptoms

For anal gland problems:

Days 1-3: After manual expression by the veterinarian

• ⚠️ Mild redness or tenderness in the anal area is normal
• 🏠 At home: Let the dog rest, observe the affected area, prevent licking
• 📋 Aftercare: Contact the veterinarian if pain or swelling persists

Weeks 1-2: Diet change begins

• ✅ Gradual introduction of high-fiber food
• 🎯 Goal: Firmer stool for natural anal gland emptying
• 🔄 Adjustments: Optimize food amount and composition as needed

Weeks 3-4: Improvement becomes visible

• ✅ Much less scooting (rubbing the rear end on the floor)
• ✅ Longer intervals between anal gland problems
• ✅ Noticeable reduction in odor
• 🔁 If there is no improvement: Return to the veterinarian for further diagnostics

After 6-12 weeks: Long-term strategy

• Problem solved: Maintain optimized nutrition long term
• Problems persist: Discuss surgical options with the veterinarian
• Recovery time after surgery: 2-3 weeks

For skin infections (Malassezia/bacteria):

Week 1: Start of treatment

• 💊 Start medication: Antifungals or antibiotics (depending on diagnosis)
• 🧴 Topical treatment: Medicated shampoo 2x weekly
• ⏰ First improvement: Noticeable from day 3-7 (itching decreases, odor lessens)
• 📸 Documentation: Photos before treatment are helpful for comparison

Weeks 2-4: Active treatment phase

• ⚠️ Important: Do NOT stop treatment early, even if improvement occurs
• 🔬 Follow-up appointment: After 2-3 weeks with the veterinarian (cytology check)

Weeks 4-6: Healing phase

• ✅ Odor should be completely gone
• 🔁 Follow-up: Cytological examination to confirm healing
• 🛡️ Prevention: Discuss a long-term protocol with the veterinarian
• 📋 Prognosis: Good to very good prognosis with consistent treatment (scientifically documented)

Long-term management for chronic cases:

• Risk of recurrence: Higher in dogs with underlying diseases (allergies, endocrine disorders)
• Maintenance therapy: Medical shampoo possibly once every 1-2 weeks
• Checkups: Regular veterinary examinations every 3-6 months

For ear infections (otitis externa):

Week 1: Cleaning and medication

• 🧴 Daily ear cleaning with a veterinarian-prescribed cleaner
• 💧 Ear drops: Antibiotic/antifungal combination (usually 2x daily)
• ✅ First improvement: Often after just 2-3 days (less head shaking, less itching)

Weeks 2-3: Recovery

• 📋 Checkup: Follow-up examination with the veterinarian after 7-14 days
• 🎯 Goal: Complete healing, no recurrences
• 📊 Prognosis: Good to very good with correct treatment and compliance

Cost expectations after diagnosis:

Conservative treatment:

• Initial exam + diagnosis: €60-120
• Anal gland expression: €15-30 per session (4-8x/year = €60-240/year)
• Skin infection treatment (4-6 weeks): €150-350 total
• Otitis treatment (2-3 weeks): €80-180 total

Surgical options:

• Anal gland removal (sacculectomy): €800-1,500 (one-time)
• Aftercare medication: €30-60
• Follow-up examinations: €40-80 (2-3 appointments)

Important note: These timeframes and costs are average values based on veterinary literature and may vary individually. Severity of disease, concurrent conditions, and compliance significantly influence treatment success.

Summary and Practical Recommendations

A fishy smell in dogs is a common problem with mostly well-treatable causes. The 880 monthly searches show how relevant this issue is for dog owners. A systematic diagnostic approach usually leads to successful treatment.

Key takeaways:

Most common causes: Factors for treatment success:

• Early recognition and professional diagnostics
• Cause-specific rather than purely symptom-based support
• Consistent aftercare and long-term prevention
• Integration of hygiene and nutritional optimization Prevention strategies:
• Regular hygiene checks of all risk areas
• Optimize nutrition for firm stool consistency
• Weight management to improve self-hygiene
• Early veterinary intervention at warning signs

Outlook

Most important advice: If the fishy smell persists or is intense, do not hesitate to seek professional veterinary help. Early intervention prevents chronic courses and preserves your dog’s quality of life. Scientific basis:

📚 Further reading

• Bad breath in dogs
• Gut rehabilitation for dogs
• Dog nutrition

Important notes

Individual advice: This information does not replace individual veterinary advice. If your dog has health problems, always consult a veterinarian.

Food supplements: Supplements are not a substitute for a balanced diet and cannot replace veterinary treatment.

Source references: All scientific sources are linked in the text and can be used for further study.

Sources

Scientific studies (PubMed/PMC):

1. Corbee RJ, Woldring HH, van den Eijnde LM, Wouters EGH. A Cross-Sectional Study on Canine and Feline Anal Sac Disease. Animals (Basel). 2021. PMID: 35011201

2. Lundberg A, Koch SN, Torres SMF. Local treatment for canine anal sacculitis: A retrospective study of 33 dogs. 2022. PMID: 35866443

3. Modified closed sacculectomy in 50 dogs with non-neoplastic anal sac disease. 2025. PMID: 39304327

4. Bajwa J. Canine Malassezia dermatitis. Can Vet J. 2017. PMC: PMC5603939

5. Yurayart C et al. Antifungal agent susceptibilities and interpretation of Malassezia pachydermatis and Candida parapsilosis isolated from dogs with and without seborrheic dermatitis skin. 2013. PMID: 23547880

6. Malassezia dermatitis in dogs and cats. 2024. PMID: 38431127

7. Saridomichelakis MN, Farmaki R, Leontides LS, Koutinas AF. Aetiology of canine otitis externa: a retrospective study of 100 cases. Vet Rec. 2007. PMID: 17845622

8. O'Neill DG et al. Frequency and predisposing factors for canine otitis externa in the UK – a primary veterinary care epidemiological view. 2021. PMC: PMC8422687

Veterinary reference sources:

• Merck Veterinary Manual - Digestive System and Ear Disorders
• VCA Animal Hospitals - Educational Resources

Note on scientific integrity: All recommendations are based on established veterinary medical principles and EU-compliant statements according to Regulation 767/2009.