Why Dermatology Can Feel Like Déjà Vu: When Everything Looks the Same

In veterinary practice, dermatology can feel like a never-ending cycle:
The pet improves… then flares again.
Treatments are prescribed… but compliance is difficult.
Owners get frustrated, the veterinary team gets frustrated—
and ultimately, the animal suffers.

The truth is:

Dermatology Is a Team Sport

Success in dermatology cases requires consistent collaboration.
Veterinarians, RVTs, and pet owners must work together at every step.
When RVTs are actively involved—monitoring progress, educating owners, performing rechecks—they become a high-value, irreplaceable part of the pet's healthcare team.

Why Does Everything Look the Same?

Because the skin only has a limited number of reaction patterns.
Different diseases can create similar-looking lesions, which is why derm cases require careful detective work.

The Pet Profile Matters

Signalment gives vital clues.

Species
Breed
Sex
Age
Coat Colour

Each of these influences disease predispositions and helps build a more accurate differential diagnosis list.

Differential Diagnosis: Where Every Derm Case Begins

A proper dermatology workup requires:

• Dermatologic exam

• Signalment

• Thorough history

And the Golden Rule:

Always treat for parasites first.

Body Parts Tell a Story

Certain lesion locations provide powerful diagnostic hints:

Head + Feet (especially foot pads)

Lesions like blisters (vesicles), crusting, or fissuring often point toward autoimmune or immune-mediated skin disease.

Different diseases affect different layers of the skin, which is why outward patterns can overlap.

When You See Crusting & Swollen Foot Pads

Your differential list should include:

Pemphigus
Lupus
Vasculitis
Zinc-responsive dermatosis
Hepatocutaneous syndrome
(often associated with marked crusting and painful fissures)

Spotlight: Plasma Cell Pododermatitis (Cats)

A classic example of a disease with a predictable lesion pattern.
In plasma cell pododermatitis:

Plasma cells infiltrate the footpad tissues
They separate and stretch the skin
Pads appear swollen, soft, sometimes ulcerated
Surprisingly, they are usually not painful

Superficial Necrolytic Dermatitis (SND)

Also known as Hepatocutaneous Syndrome

SND is a skin manifestation of an underlying liver problem.
It is caused by:

Liver failure
Severe liver dysfunction
Metabolic imbalance

Affected dogs often present with:

Crusting foot pads
Fissures
Erosions around the mouth, eyes, and pressure points

This is a clear example of how skin disease can reflect internal systemic disease.

Some Skin Problems Are Linked to Inside Health

Skin can reflect internal issues such as:

Hormonal diseases
- Cushing’s Disease
  - Can cause Calcinosis Cutis (chalky, thickened, irritated skin due to calcium deposits)
Immune system problems
Liver disease (e.g., Hepatocutaneous Syndrome)

This is why blood tests or additional diagnostics may be recommended.

Pets’ skin only has a few ways to show something is wrong. These patterns help us understand what’s happening underneath.

• Edema

What it means: Fluid buildup in the skin
How it looks: Puffy or swollen areas

• Erythema

What it means: Redness or inflammation
How it looks: Pink, red, or irritated skin

• Thickening

What it means: Long-term inflammation makes the skin thicken
How it looks: Firm, raised, or textured skin

• Lichenification

What it means: Chronic irritation + rubbing leads to thick, leathery skin
How it looks: Dark, rough, elephant-like skin

• Hyperpigmentation

What it means: Extra pigment due to long-term inflammation
How it looks: Skin turns dark brown, grey, or even black

• Atrophy

What it means: Skin becomes thin
How it looks: Fragile, delicate, or “paper-thin” skin

• Scaling

What it means: Excess skin flakes
How it looks: Dandruff or dry flakes

• Papules

What it means: Small bumps from inflammation
How it looks: Red bumps; can develop into pustules when white blood cells rush to the area

• Pustules → Collarettes

What it means: Infection under the skin
How it looks: Pimples filled with pus → circular scabs with a torn-looking edge (collarettes)

• Blistering / Vesicles

What it means: Fluid-filled bubbles
How it looks: Small blisters or clear bumps on the skin

• Fistulas

What it means: Deep, full-thickness draining tracts
How it looks: Open holes that ooze fluid

General Distribution Patterns

(One side worse than the other, or patches in random uneven areas)

This pattern often points to:

Infestations
Example: mites, fleas, insects

Infections
Example: bacterial or fungal areas that start small and spread unevenly

Neoplasia (Tumors / Growths)
Non-cancerous or cancerous lumps can cause localized or one-sided skin changes

• Head & Feet Affected

(Problems centered around the face, paws, or both)

This pattern is commonly seen with:

Immune-mediated skin disease
The immune system mistakenly attacks the skin, causing redness, swelling, sores, or crusting.

Demodex
A type of mite that can cause hair loss, redness, and inflammation—especially on the face and paws.

• Symmetric Alopecia

(Baldness happening evenly on both sides of the body)

Most commonly associated with:

Endocrine disorders
Examples include hormonal conditions like hypothyroidism or Cushing’s disease.

Lesions on the Ventrum, Forearms (Antebrachial Area), Feet, Elbows, Skin Folds, and Ears

These areas are classic for:

Environmental allergies (Atopy)
Pets inhale or contact allergens like pollen, dust, grasses, or molds.

Dorsum, Feet, Ears, and Butt Area Affected

(Back, paws, ear inflammation, perianal redness, scooting, or GI upset)
Strongly associated with:

Food Allergy
Often involves both skin signs and digestive issues.

Just the Very Extremities

(Tips of ears, tail tip, foot pads, or very end parts of the limbs)
Commonly associated with:

Vasculitis
Blood vessel inflammation causing sores, crusts, or poor healing on the farthest points of the body.
Lesions Shapes

Annular / Ring-Shaped Lesions

Appearance: Circular with central clearing

Example: Ringworm (Dermatophytosis)

Single Lesions

Appearance: Isolated lesion, not part of a cluster

Example: Can be any solitary dermatologic issue

Polycyclic Lesions

Appearance: Multiple rings that merge together

Significance: Indicates spreading infection

Grouped Lesions

Appearance: Small lesions clustered together

Example: Calcinosis Cutis

Note: Looks like “little bits all stuck together”

Serpiginous Lesions (Emergency)

Appearance: Snake-like or winding pattern

Examples / Causes:

Toxic Epidermal Necrolysis (adverse drug reaction)

Erythema Multiforme (widespread skin shedding)

Significance: Rapidly progressive; requires urgent attention

Linear Lesions

Appearance: Straight-line pattern

Examples:

Eosinophilic Granuloma Complex (EGC) in cats

Common on the back of the thighs in cat

Arciform Lesions

Appearance: Partial arcs

Significance: Suggests partial resolution of previously spreading lesions
Iris (Central Healing)/ Target Lesions

Appearance: Target Lesions

Significance: Caused by bug bite

Managing Canine Skin Health Through Diet: A First-Line Approach

Healthy skin and coat in dogs aren’t just about baths and grooming—they start from the inside out. Many skin issues in dogs, including immune-mediated skin diseases, endocrine disorders, and environmental allergies, can be influenced by nutrition. While medications may be necessary in some cases, dietary management is often the safest first step to support skin health and reduce inflammation.

1. Immune-Mediated Skin Diseases

Immune-mediated conditions, such as pemphigus or lupus, occur when a dog’s immune system mistakenly attacks its own skin cells. Nutrition can help by:

Reducing inflammation: Diets rich in omega-3 fatty acids (found in fish oil or certain high-quality dog foods) help calm the immune system.

Supporting skin barrier function: High-quality proteins and vitamins (like vitamin A and zinc) support healthy skin regeneration.

Minimizing triggers: Some dogs may react to certain proteins or additives; limited ingredient diets can identify and eliminate potential food triggers.

2. Endocrine Disorders

Hormonal imbalances, such as hypothyroidism or Cushing’s disease, often cause skin thinning, hair loss, or recurrent infections. Diet can support endocrine-related skin issues by:

Supporting overall metabolism: Balanced diets with high-quality proteins, moderate fat, and complex carbohydrates help maintain healthy hormone function.

Promoting coat quality: Essential fatty acids, biotin, and antioxidants improve hair growth and skin resilience.

Reducing secondary infections: Controlling nutrient deficiencies can decrease the frequency of bacterial or yeast skin infections.

Tip: While diet won’t correct the underlying hormonal disorder, it can strengthen skin and coat, making dogs less prone to secondary infections while awaiting medical management.

3. Environmental Allergies

Dogs can react to pollen, dust, or mold just like humans. Skin symptoms often include itching, redness, or chronic ear infections. Diet helps by:

Reducing systemic inflammation: Omega-3 fatty acids and antioxidants help calm itchy skin.
Note: Antioxidants and Skin Health: Proceed With Caution

Antioxidants are often recommended to help reduce inflammation and support skin health. However, not all antioxidant sources are equally effective for dogs**.

For example:

Blueberries and other fruits contain antioxidants, but some dogs may struggle to digest them properly or be sensitive to the natural bacteria present on the skin and in the fruit.

In certain cases, feeding such fruits could be counterproductive, causing mild digestive upset or failing to provide meaningful anti-inflammatory benefits.

Better alternatives: Omega-3 fatty acids, vitamin E, and specific veterinary-formulated antioxidant supplements tend to be more reliably absorbed and beneficial for canine skin and immune support.

Eliminating potential food allergens: Many dogs with environmental allergies also have food sensitivities. A limited ingredient or novel protein diet may reduce overall immune system burden.

Supporting gut health: A healthy gut microbiome can help modulate immune responses and may reduce hypersensitivity reactions.

Tip: Pairing dietary support with environmental management—like regular bathing or allergen avoidance—can enhance results.

Tip: A hypoallergenic or novel-protein diet trial for 8–12 weeks can reveal whether diet alone improves skin lesions.

Final Thoughts

Dermatology is complex and can sometimes feel repetitive or discouraging—but with teamwork, consistent follow-ups, and careful evaluation, progress is possible.
Skin may have limited ways to react, but strategies for diagnosing, treating, and supporting patients continue to grow. Diet is a powerful tool to support dogs’ skin health. By addressing immune responses, hormonal balance, and inflammatory triggers through nutrition, many dogs show noticeable improvement even before medications are needed. Start with small, thoughtful dietary changes, monitor your dog’s response, and always work with your veterinarian for optimal results.

Ontario Association of Veterinary Technicians. (2022). [Dermatology]. Brought to you by OAVT Seminar.

Dermatology