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Name
Flea Allergy, Canine
Short Description
Flea allergy dermatitis, Flea bite hypersensitivity
Affected Animals: Any breed or sex of dog can be affected. The
average age for flea allergy is three to five years. Cats also can
be allergic to fleas.
Overview:
Dogs that have flea allergy dermatitis are
hypersensitive to the saliva a flea passes into the dog's skin when
it bites. The bite from a single flea will have a minimal affect on
a normal animal, but dogs with flea allergy will experience
immediate itching, redness and swelling. It is the dogs themselves,
and not the fleas, that typically do the worst damage. When a dog
scratches its fleabites excessively, hair loss and skin abrasions
can result. Some dogs will develop circular, red, painful sores
called hot spots that can occur anywhere on the skin, but commonly
are seen along the back and tail base.
The most common canine allergic skin disorder, flea allergy only can
be resolved by preventing the dog from being bitten by the flea and
removing all the fleas from the dog's environment. There are
medications available, however, that will alleviate the itching and
discomfort until complete flea control is achieved.
Clinical Signs: Pruritus, alopecia, barbered hairs, papules,
erythematous macules with crusts, and acute moist dermatitis can be
seen in a typical dorsal lumbar and tail base pattern. The lesions
can extend to the thighs and caudal abdominal areas. Secondary
pyotraumatic dermatitis, pyoderma, and seborrhea are commonly noted.
Chronic skin changes include thickening of the dermis with
acanthosis, hyperkeratosis and lichenification.
Symptoms: Common findings in a dog that is allergic to
fleas include increased scratching or itchiness, loss of hair, hairs
that appear broken, crusts and erosions of the skin, and pimple-like
bumps. Thickened skin with darkened areas can be seen in severe
cases. Fleas or flea feces, which can be difficult to detect,
indicate the presence of fleas. Hot spots sometimes can be seen
along the dog's back and tail base. These sores are usually
circular, red, oozing, and very painful, often requiring medical
attention.
Description:
Flea allergy is the most common canine allergic
skin disorder, affecting dogs with an abnormal sensitivity to the
saliva a flea injects into the skin when it takes a blood meal. In
reaction to flea allergen, allergic dogs will have inflammation and
irritation of their skin -- not to mention intense itchiness. Hair
loss and skin lesions can result when a dog scratches or bites its
irritated skin.
The problem may last year-round in warm climates or in flea-infested
indoor environments. In regions with cold winters, the allergy will
appear seasonally during the warm months of the year. Treatment of
flea allergy requires eliminating the fleas from the dog, other
pets, and the surroundings. Various medications can provide
temporary relief of itching for severely affected dogs until flea
control is achieved.
It may be difficult to detect fleas on a dog, but brushing it over a
white sheet may help: flea feces, a dark, black material, that falls
from the dog's hair onto the sheet would suggest the presence of
fleas. A flea comb also can be used to look for the feces or the
fleas themselves. Dogs should be examined often if itching is noted.
Diagnosis:
The symptoms of flea allergy can mimic other
disorders of the skin. Before concluding that a dog is allergic to
fleas, the examining veterinarian first will attempt to rule out
allergies to food and inhalants, internal parasites, drug reactions,
hair follicle inflammation (folliculitis), fungal infection, and
other topical parasites -- all of which may have signs similar to an
allergic reaction to fleas. A thorough history and physical exam
will be required, during which the veterinarian will analyze the
type and size of the skin lesions.
It is often very beneficial for dogs with suspected allergies to be
tested for allergens that may be causing the dog to be itchy and
uncomfortable. There are two common techniques that veterinarians
can use to determine any underlying allergies to allergens such as
fleas. One technique is called intradermal skin testing which
requires the injection of different allergens into the skin. This
usually is done by a veterinary dermatologist and may require
sedation. The second technique involves taking a blood sample and
sending it to a laboratory for allergy testing. This is called
serologic allergy testing. There are varying opinions about
serologic testing, so consultation with the examining veterinarian
will be necessary.
Prognosis: A dog with flea allergy dermatitis will always
remain allergic to fleas. The severity of this allergy typically
worsens as the dog ages. If fleas are eliminated from the dog's
environment, the dog will stop suffering the symptoms of flea
allergy. If the response is incomplete but flea control has been
achieved, the dog should be reevaluated by the veterinarian for
concurrent allergies.
Transmission or Cause: When a flea sucks blood from a dog, it passes its
saliva into the dog's skin. Dogs that are allergic to flea allergen
will experience swelling, irritation, and itchiness. When the dog
scratches the bites, further trauma to the skin -- lesions, hair
loss, and more intense itchiness -- will result. A single flea bite
can cause these symptoms in an allergic dog; animals without this
allergy must be bitten many more times before their skin becomes
irritated.
Treatment:
The goals of treatment are to alleviate the dog's
allergic reaction to fleas by preventing the flea from biting the
animal and eliminating the fleas from the environment. It is very
important that owners completely remove the fleas and their eggs
from the animal's environment. This involves the treatment of all
household animals for fleas to prevent the allergic dog from
becoming reinfested. There are many commercially available products
that kill fleas both indoors and outdoors. Additional products have
been designed for use on the dog. Professional pest extermination
companies, which usually carry a satisfaction guarantee, are also an
option. A veterinarian can customize a flea control program to meet
an allergic dog's individual needs.
Therapy for the allergic reaction is based on the severity and
history of the symptoms. Following an evaluation of the dog, the
veterinarian may prescribe any of the following medications: topical
treatments, medicated shampoos, steroids, antihistamines,
antibiotics, and fatty acid supplements such as skin oil
replacement. The examining veterinarian often will recommend a
commercially available product that kills fleas on contact, before
they have a chance to bite. These products are ideal in helping
prevent further flea allergic reactions.
The effectiveness of allergy shots, or hyposensitization, for
treating flea bite hypersensitivity remains controversial. This
method of treatment, prescribed by a veterinary dermatologist,
usually is reserved as a final therapeutic step for severely
afflicted animals not responding to strict flea control.
Prevention: Prevent fleas from entering the household. If
evidence of fleas is noted on the dog or on any other pets in the
household, early intervention can stop the problem before the
symptoms become severe.
