Fleas are parasites that subside
on the blood of mammals like dogs and cats, though they can
live on other host animals as well. They have a life cycle of about six to twelve months,
and fully formed adult fleas can survive for long periods
without the blood of a host. When an adult flea finds a home on
your dog, however, it won’t likely be fasting.
The flea’s mouthparts have evolved to penetrate the skin of a
dog, especially the thin epidermal area around the abdomen and
flanks. When a dog is bitten by a
flea for its blood meal, some of the flea’s saliva is
injected through the dog’s skin layer, like backwash. Flea
saliva is what causes skin allergy in dogs. The dog reacts to
some of the antigenic materials in the saliva, such as amino
acids, aromatic compounds, phosphorus, and polypeptides. The
dog’s immune system reacts to these materials by producing
Once the flea bites an allergic pet, the dog will react in a
more pronounced manner than a dog not allergic to fleas would.
A small bump and redness may appear, and the bite will be
extremely itchy. Even one or two bites will create a
constant itching in the dog for days, while a non-allergic dog
can be bitten several times until it feels the effect of the
Flea allergies may have a genetic
component, but these allergies
are not predisposed in certain dog breeds or genders. Flea
allergies can begin as early as one year in age and generally
start when a dog is young. Dogs of any age, however, can
develop hypersensitivity to flea saliva, and conditions will
worsen with age.
If you discover a flea infestation in your home, recognizing a
flea allergy may not be obvious at first since all dogs will
react to flea bites to some
degree. Your dog’s behavior and a prominent skin condition
could indicate a flea allergy is present.
Symptoms of Flea Allergy Dermatitis
When fleas bite a dog
for its blood meal, most dogs will show discomfort, itch, and
have small red bumps on their skin. Dogs who are hypersensitive
to flea bites, however, will have stronger reactions and more
pronounced symptoms. Just one or two flea bites spread over one
or two weeks can cause severe itchiness in
Symptoms of flea
Flea allergies cause pruritis or severe itching of the
skin. Reaction to the flea saliva may manifest as redness,
pimple-like bumps, pus-filled bumps, or scabs. In severe cases,
dogs may have hair loss and skin rash. Hotspots, or painful red, circular sores
that often ooze, may appear on a dog’s backside or tail base.
Typically, a dog’s hind body is most affected by flea allergy,
though lesions can appear anywhere. Check thoroughly around
your dog’s lower back, tail, neck, and back of legs for skin
Dogs with pruritis will frequently itch and scratch their
bodies. This behavior will exacerbate the symptoms and could
lead to secondary bacterial infection. Dogs may also chew,
lick, or bite their tails, legs, and behinds. While some
itching is normal, be on the lookout for excessive itching
accompanied by skin damage. Dogs with hypersensitivity to flea
saliva also tend to groom and lick their hair obsessively.
Evidence of fleas
If you notice evidence of flea dirt or signs that your dog has
fleas, then flea allergy is a strong possibility for your dog’s
skin condition. Even after an outbreak of fleas has been
eradicated, evidence of flea bite allergy will pop up if just a
few fleas remain. In fact, most dogs with flea allergies have
very few fleas on their body because they groom more.
Dogs that ingest fleas from biting and chewing their irritated
skin will be more prone to getting tapeworm. Fleas are common hosts
of tapeworm larvae, and when a dog ingests the parasites, the
tapeworm eggs are released and spread to the dog’s small
intestine. This is an unfortunate side effect of some flea
infestations, though ingesting fleas does not indicate that a
dog is definitely allergic to flea bites. Since dogs with
flea allergies groom more, however, they are more likely to
ingest fleas and tapeworm larvae.
Because Flea Allergy Dermatitis causes a cycle of scratching
and itching, your dog cannot heal alone. Once you recognize the
symptoms, it's important to pursue treatment to keep your dog from the
discomfort of Flea Allergy Dermatitis.
This information is for informational
purposes only and is not meant as a substitute for the
professional advice of, or diagnosis, or treatment by, your
veterinarian with respect to your pet. It has, however, been
verified by a licensed veterinarian for accuracy.