DERMATOLOGY
The first clinical signs usually occur before 1 year
of age in 48% of CAFR dogs compared to 16% with
atopic dermatitis.11
Clinical features
Although no age or sex predilections have been documented, many cases occur at an early age (less than
1 year).
• Non-seasonal pruritus is the most important clinical sign. The severity of the pruritus varies16. Pruritus without visible skin lesions often precedes
the development of skin lesions in most (47%) affected dogs.13
Most dogs and cats with CAFR have permanent
pruritus that is not obviously related to ingestion
of the offending diet.2
• If there is a seasonal worsening of the pruritus,
concurrent atopic dermatitis is possible and
should be addressed once the CAFR is controlled11, or the dog eats a varied diet and is intermittently exposed to the allergen(s).1
allergies to parasites (e.g. flea allergic dermatitis),
metabolic disorders (e.g. hypothyroidism with deep
pyoderma) or in rare cases dermatophytosis need to
be ruled out. Bacterial or Malassezia infections should
also be identified and treated appropriately since they
often worsen pruritus.
•
The gold standard to diagnose CAFR is the resolution of clinical signs when an elimination diet
is fed exclusively for a minimum of 6 – 8 weeks
followed by a relatively immediate recurrence of
clinical signs after a challenge with previously fed
food items. The diagnosis is confirmed after resolution of signs when the elimination diet is fed
again.11
It is usually easiest to perform the challenge with a
small amount of previously fed dog food. In dogs
with CAFR clinical signs generally manifest within
2 weeks of challenge although, very often already
within 2-48 hours. If the dog does not relapse with
“dog food” then other previously fed treats should
be introduced one by one.7 A “new” dietary component should be added every 2 weeks.
The distribution of the clinical signs is exactly the
same as in canine atopic dermatitis with the face, periocular areas, ears, axillae, inguinal region, ventral abdomen, perianal area and palmar and/or plantar and
dorsal interdigital skin most commonly involved.4
Other treatments are often instituted along with
the start of the elimination diet trial such as antibiotic or antifungal therapy for concurrent microbial infections, treatment of otitis externa and
temporary anti-pruritic medications. It is important
to continue with the diet after this treatment has
finished in order to determine whether the clinical
improvement is sustained or merely as a result of
the antimicrobial and other treatment itself.
In a study of 843 atopic dogs minor clinical differences were found between CAFR and CAD cases but
were not sufficient to differentiate between CAFR and
CAD. The only way to differentiate between them is
by doing an elimination diet trial. A partial response
suggests both food and environmental triggers.
Otitis externa commonly occurs in dogs with CAFR:
occurring in 24% as the only clinical signs and in 80%
as part of the clinical picture.11The otitis externa is
usually bilateral but can also be unilateral.13 Secondary infections often complicate the otitis externa.
Malassezia pachydermatis is usually the predominant
organism early in the course, while Staphylococcus
spp. and gram negative organism infections often develop in chronic cases.13
In 10-31% of the cases very subtle concurrent gastrointestinal signs e.g. intermittent vomiting, loose stool,
chronic diarrhea, flatulence, increased frequency of
defecation and borborygmus were identified in dogs
with CAFR.11,13
CAFR dogs can also present with other dermatological
conditions, such as seborrhoea, superficial pyoderma,
Malassezia dermatitis, vasculitis, urticaria, erythema
multiforme and symmetric lupoid onychodystrophy.
Diagnosis
Before considering CAFR or CAD other causes of
pruritic skin disease such as parasitic infestations (e.g.
sarcoptic mange, demodicosis, cheyletiellosis, fleas),
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Issue 06 | DECEMBER 2015 | 26
The elimination diet trial
Most dogs with CAFR will have at least a partial
response to an elimination diet in 6 - 8 weeks. In
most cases clinical cutaneous symptoms improve
after 4 – 6 weeks on the diet, whereas gastrointestinal signs, where present, usually improve within
2 weeks.11
Maximum improvement may take as long as 10 –
13 weeks. In some patients clinical sympto \