Episode 29 - How Complex is Eosinophilic Granuloma Complex?

Show Notes

This month, the Skin Flint team welcome RCVS & European Specialist Debbie Gow to the platform to explore Eosinophilic granuloma complex (EGC).

(00:00) John Sue and Paul introduce the podcast.

 

Chapter 1 – What on Earth Is Eosinophilic Granuloma Complex?

 

(02:55) Sue welcomes Debbie Gow to the podcast and invites her to introduce herself. Debbie shares that she is a specialist in veterinary dermatology, working at a busy referral hospital outside Edinburgh. She describes her role in setting up the dermatology service, working with a resident and derm nurse, and her continued involvement in CPD and writing.

 

(04:05) Sue introduces the topic: eosinophilic granuloma complex (EGC) in cats. She jokes that it’s sometimes referred to as “eosinophilic granuloma confusion” due to its complexity and terminology. She asks Debbie to break it down explaining that EGC is an umbrella term for three lesion types:

1. Linear granulomas: Seen on the backs of legs, chin, or in the mouth. May or may not be itchy.
2. Plaques: Often pruritic, ulcerated, and secondarily infected. Found on the ventrum or medial thighs.
3. Indolent ulcers: Located on the upper lip, may appear crater-like.

 

(07:28) Sue asks about miliary dermatitis. Debbie considers it a separate reaction pattern, not part of EGC, though also common and allergy-associated.

(08:15) John asks about age, breed, or sex predispositions. Debbie explains that while any cat can be affected, young adult cats (6 months to 5 years) are most likely to develop these lesions. Females may be slightly overrepresented, but evidence is limited.

(09:27) John inquires about geographical prevalence. Debbie confirms EGC is seen globally wherever cats are present and exposed to allergy triggers.

 

Chapter 2 – Lookalikes, Lip Lesions & Licking Cats: Sorting the EGC Puzzle

(10:21) Sue asks whether EGC lesions are pathognomonic or if there are important differentials. Debbie stresses the importance of not assuming a diagnosis without investigation whilst they can have a classical appearance:

Cytology is key to identifying eosinophils.

Differentials include squamous cell carcinoma (particularly for lip ulcers), mycobacteria, fungal infections, and viral diseases.  

(12:37) Sue asks about a minimum diagnostic approach. Debbie advises:

• Cytology
• Wood’s lamp and trichogram to rule out dermatophytosis
• Consideration of biopsies if in doubt

 

(14:08) Sue asks how to perform cytology. Debbie describes:

• Tape prep for dry lesions
• Cotton bud for moist/crusted areas
• Direct impression with a slide

 

(14:59) Sue asks how often infection is present. Debbie says:

• Infections are uncommon but more likely with plaques due to licking
• Cytology helps assess if antibiotics are needed
• Most cases are treated with anti-inflammatories rather than antibiotics

 

(16:52) John asks about allergic patterns in cats. Debbie describes four main reaction patterns:

• Miliary dermatitis
• Head and neck pruritus
• Ventral overgrooming
• Eosinophilic lesions

She notes cats may display multiple patterns and also non-skin signs like conjunctivitis, otitis, or sneezing.

(19:02) John asks if specific allergies present with specific signs. Debbie says it’s inconsistent. While flea allergy is often associated with miliary dermatitis and food allergy with head/neck pruritus, patterns vary and aren’t reliable for diagnosis.

 

Chapter 3 – Practical Approaches: From Kitchen Floor to Referral Door

 

(21:23) John asks what owners might notice or try at home. Debbie recommends:

• Observing behaviour
• Keeping a diary
• Ensuring flea control
• Considering recent diet or environmental changes

 

(23:30) Sue asks about food trial myths. Debbie emphasises:

• Over-the-counter “hypoallergenic” foods are not suitable for true food trials
• Prescription hydrolysed diets or novel proteins (e.g. ostrich, kangaroo, crocodile) are required
• Food trials should run for ~8 weeks

She also recommends:

• Treat toppers to help encourage eating
• Short-term feeding is usually nutritionally safe
• Veterinary nutritionist input for longer-term plans

 

(28:43) Sue asks how to start a food trial if a cat is self-traumatising. Debbie uses concurrent systemic treatment (usually steroids) to control inflammation during the trial, tapering meds over 4–6 weeks if possible.

(30:05) John asks for the first steps as a guide for primary care vets. Debbie recommends her first steps would be to rule out ectoparasites with full household flea control, possibly whilst beginning topical/systemic treatment as needed for comfort

(32:10) Sue asks what to do when left with suspected environmental allergy. Debbie describes:

• Referral approach: Intradermal testing and immunotherapy if cost allows (40–75% success rate)
• Primary care approach: Use steroids at the lowest effective dose
• Importance of prioritising flea control and food trial first as they are often curative

 

(36:50) Sue and Debbie have a healthy debate on the relative benefits of allergy testing when immunotherapy is not being considered as an option. 

(41:08) John wraps up the episode, thanking Debbie for simplifying a complex topic and helping listeners better understand eosinophilic granuloma complex in cats.

John asks Paul and Sue another probing - if not questionable - question.