Feline specific aspects of dermatology Flashcards
Major cutaneous reaction patterns of cats – overview
These four patterns are?
- Feline symmetrical alopecia
- Head and neck pruritus
- Miliary dermatitis
- Eosinophilic granuloma complex
These are how cats respond to many dermatological insults
– a systematic approach to find the underlying cause is therefore essential
What is known to cause the feline symetrical alopecia pictured?
- Previously called ‘feline endocrine alopecia’
- Now known most caused by overgrooming due pruritus…
Create a table for the ddx of feline symetrical alopecia?
What are persian and oriental cats predisposed to?
Persian cats predisposed to dermatophytosis
Oriental cats to psychogenic alopecia
which stage of the hair cycle each of these images depict?
What reaction pattern is seen here and what commonly causes it?
Head and neck pruritus
Causes:
- Ectoparasites (including fleas, Otodectes) - common
Hobi et al (2011):
502 pruritic cats
29% responded to flea control
7% due to other ectoparasites
36% cases due to ectoparasites
Other potential causes:
Infections
Dermatophytosis, bacterial pyoderma
Malassezia infection, respiratory viruses, cowpox
Hypersensitivities
Diet, environmental allergens, mosquito bites
Autoimmune
Pemphigus foliaceus
Neoplasia/others
SCC, feline oro-facial pain syndrome, idiopathic facial dermatitis
What are the common causes of miliary dermatitis?
Papulocrustous lesions, especially on dorsum
Common causes:
- Fleas
- Environmental and dietary hypersensitivities
But also
- Dermatophytosis
- Pyoderma
- Pemphigus foliaceus
- D.gatoi, Cheyletiella, Neotrombicula, Otodectes
What is this?
Eosinophilic granuloma complex
This is feline cowpox.
Orthopox virus: reservoir in voles/wood mice – transmitted to cats by rodent bite
Infection most common in autumn
How would you diagnose this condition?
How do you treat it?
What medications must you avoid?
In both domestic cats and cheetahs, it is important that cowpox be diagnosed promptly, because steroid treatment, which is often used in therapy of other skin conditions, is contraindicated. Although the disease is often severe in cheetahs, in domestic cats supportive treatment (broad-spectrum antibiotics, fluid therapy) is generally successful, and mortality is low.
Diagnosis:
If multiple, well-circumscribed skin lesions are present, and especially if there is a history of hunting or exposure to a rural environment, a presumptive diagnosis may be based on clinical signs. Cowpox virus infection also should be suspected when skin lesions do not respond to antibiotics. Differential diagnoses include miliary dermatitis, feline herpesvirus or calicivirus infection, eosinophilic granuloma, bite wounds, ringworm, and other chronic bacterial or fungal conditions.
Presumptive and rapid diagnosis can be made in most cases from unfixed scab, exudate, or biopsy material examined for characteristic brick-shaped orthopox virions by electron microscopy. A more accurate and sensitive method of diagnosis is by PCR, or isolation of virus in cell culture or on the chick chorioallantois. Fixed biopsy material for histologic examination and serum for antibody determination also can be sent to the laboratory.
Describe virulent systemic feline calicivirus
(VS-FCV)
Recognised since 2003
Presents as:
- cutaneous/systemic vasculitisà s/c oedema, skin ulceration
- Anorexia, pyrexia, lethargy (80%)
- Oral ulceration (50%)
- Nasal discharge (30%)
- Also respiratory distress, ocular discharge, jaundice, GI signs, coagulopathy
Predisposing factors
- Crowded high-stress environments predispose to development of FS-FCV strain
- Mild signs in cats raised in this environment but severe signs on exposure of naive cats in new homes/veterinary surgery
How should you treat cases of virulent systemic feline calicivirus and what is the prognosis?
Handle suspicious cases with care for hygiene/quarantine
Strict biosecurity for confirmed cases
Suggested Tx:
- High dose interferon
- Supportive treatment
- Systemic glucocorticoids if needed
Prognosis
- Up to 50% mortality, even if vaccinated
- Prognosis worse for older cats than kittens
What is seen here?
Pemphigus foliaceus
May arise spontaneously or occasionally secondary to drug exposure
Presentation:
- primary pustules rupture –> multifocal crusts
- Especially face, pinnae, nipples, foot pads
Sometimes caseous purulent exudate of multiple digits (‘Philadelphia feet’)
How do you diagnose and treat this condition?
Diagnosis: Clinical signs, characteristic acantholytic cells identified from lesion cytology, elimination of other pustular to crusting skin diseases from the differential list, and compatible dermatohistopathology are used to confirm one’s clinical suspicion of feline PF.
Treatment of feline PF: Treatment requires immune suppression and immunomodulation. Do not treat pemphigus foliaceus without a diagnosis and elimination of other differentials.
What does this cat have?
Idiopathic facial dermatitis of the Persian cat
Persians, Persian crosses
Unknown cause
Presentation:
- Dark waxy debris in facial folds, around eyes, chin
- +/- erythema, pruritus
- +/- bacterial/Malassezia infection
- +/- submandibular lymphadenopathy
Treatment
- Partial improvement in some with corticosteroids or itraconazole
- Ciclosporin effective in others
- But no consistently effective treatment –> guarded prognosis
What is this?
Feline Plasma Cell Pododermatitis
PPD is characterized by infiltration of plasma cells into the tissue of the paw pad. This cellular infiltration results in pronounced swelling of the foot pads, and can produce soft, mushy paw pads (hence the name pillow paws).
Diagnosis:
As you can see from the images, the clinical appearance is quite striking! The primary differential diagnosis is an eosinophilic granuloma, although this is usually limited to one foot pad. Aspiration cytology of PPD should reveal predominantly plasma cells. Although definitive diagnosis is classically achieved via biopsy, it may not be necessary in a cat with swelling of multiple foot pads and consistent aspiration cytology findings. If the clinical findings and aspiration cytology are equivocal, then biopsy of the foot pad is recommended. Because many cats with PPD are FIV positive, I recommend all cases be tested.
Treatment:
For milder cases, I recommend starting with doxycycline at 10 mg/kg once daily. Because of risk of esophageal stricture, cats should either take a liquid form of doxycycline, or the pill should be followed by a water chaser. Treatment should continue until the pads are normal, which can take several months.
Discuss Feline paraneoplastic alopecia
(‘Shiny cat syndrome’)
- Rare condition affecting older cats (>10yo)
- Acts as marker for underlying malignancy – pancreatic tumour most commonly
- Alopecia develops over weeks/months. Usually affects ventrum initially, then spreads to limbs. Head frequently spared
- +/- focal erythema, shiny skin
- +/- crust, waxy debris – 2° Malassezia infection
- +/- systemic signs, e.g. weight loss
What is this?
Feline thymoma-associated exfoliative dermatitis
Presentation
- Non-pruritic scaling and mild erythema
- Head/pinnae –> more generalised scaling/alopecia
- +/- crusts, ulcers, brown waxy clawfold exudate
- +/- secondary Malassezia dermatitis –> pruritus
Diagnosis
- Histopathology of skin
- Demonstration of anterior mediastinal mass, +/- pleural effusion, on radiography
- Ultrasound guided cytology/histopathology can confirm thymoma
- CT scan to stage mass
Treatment
- Surgical removal of mass curative: median survival time of nearly 2 years
- Radiation therapy for non-resectable tumours reported
Describe the Neuropathic disease Feline idiopathic ulcerative dermatitis?
Presentation
- Non-healing ulceration between scapulae or dorsal neck
- Violent episodes of self trauma, with variable pain/pruritus between
- May follow injection/spot-on but many with no obvious inciting cause
Diagnosis
- Diagnostic workup to eliminate infectious, allergic, ectoparasitic causes. Also eliminate trauma, burns
- Biopsy supports diagnosis: chronic cases with linear sub-epidermal fibrosis
Prognosis
- Guarded as underlying cause unknown
- Relapse common
Management
- Treat secondary infection, if present
- Prevent self trauma till healed
- Cover area
- Bandage feet
- Soft Claws
If recurs, consider medical treatment
- Systemic corticosteroids (after resolution of infection)
- some refractory
- Surgical excision?
- some recur
- Off label use of gabapentin or topiramate reported effective in some cases
- supports involvement of neuropathy
What is Feline orofacial pain syndrome (FOPS)?
Neuropathy, similar to trigeminal neuralgia
Predilection for Burmese/ Burmese crosses
Presentation
- Self trauma to tongue, lips, buccal mucosa
- Exaggerated licking/pawing at mouth
- Predisposed to by oral lesions/dental disease/dental eruption. May be triggered by dental procedure
- Stress involved also. Worse in cats with poor coping strategies in multicat households
Diagnosis
- Appropriate clinical signs
- Elimination of other diagnoses
Treatment
- Prevent self-mutilation
- Soft Claws
- ?Buster collars/Comfy collars
- Treat any dental disease
- Environmental changes to reduce stress, e.g.
- Provide private area for cat
- Provide adequate resources
- Food, water, resting places, latrines, entry/exit points from territory
- Feline anti-stress pheromone preparations
- Anecdotal reports of successful treatment with phenobarbital, gabapentin, amitriptyline
