Parasitic Diseases of Skin
Skin diseases in small animals represent a
big percentage of the total daily admisions in veterinary practice . Many skin problems
have a difficult diagnosis and treatment , and require referral to a veterinary specialist
, in order to shorten the time since the disease is discovered till the diagnosis is
reached , treatment is started and a prognosis can be made .
Those diseases affecting skin and adnexa , might be
classified by their cause .
Parasitic diseases are relatively frecquent in young
animals , in those living in inapropiate environmental situations, when a large humber of
animals is held on a same premise , or in the case of nutricional imbalances.
Fleas still constitute the major cause of many skin
problems in cats and dogs , and in their owners . Thoug many modern non toxic flea
insecticides , are on the market nowadays , effective control of flea population in open
air or extense premises , might be a big problem . In these cases , vet counseling and
planning of the control measures , together with a wise choice of products , will be the
clue to the erradication of the insects.
Fleas are vectors of several diseases that might be
dangerous both to animals and people . Many animals are allergic to flea bite , showing a
severe allergic dermatitis even in the presence of a very small number of fleas .
Ticks constitute another problem , specially during
summer , because it is in this season that they reproduce faster . They are blood eating
parasites that bite their victims , causing irritation , pruritus , sometimes triggering
an allergic episode , or they can inoculate microorganisms that might cause systemic
disease of concern in animals and humans . Ticks might be erradicated succesfully using
special products with prolonged activity , that lack toxicity .
Handling the infested environment might be difficult
and it needs regular spray of insecticides with faster knock down effect , and elimination
of wheeds where those insect can find a refuge .
Mange describes a group of highly contagious parasitic diseases of
skin ,caused by arthropods named mites , that dig under the skin surface . Mange is common
in young animals , in shelter conditions , or in immunedepressed animals . There is one
type of mange that might be contagious to humans ( zoonotic ) , but does not constitute a
danger to humans because it is easily controlled .
Mange treatment consists in an insecticide dip , or spray , or
pour-on formula , together with environmental measures to reduce the continuation of the
Demodectic mange or demodicosis in a very special case of
parasitosis , mainly because it is non contagious and is related to immune imbalances .
Demodicosis is not a zoonotic disease , and it has several clinical features , like the
juvenile form , the localized form and the senile or adult-onset form . The localized form
might be mistaken for ringworm .
The generalized form is severe enough to be of reserved prognosis
, might be chronic , and needs liftime treatment and parasite count and watch .
There is another form called pododemodicosis , which affects the
feet , causing nodules , fistulous tracts and abscesses , with a guarded prognosis .
Treatment is possible , reaching high percentages of healing ,
with a less dramatic prognosis . Adults that suffered from juvenile form of the disease ,
or those that had or are having a severe form of demodicosis , should never be bred ,
because the tendency to suffer the disease is inherited .
There are some other parasitic skin disease , like nodules caused
by microfilaria or filaria , or other nematodes.
Allergic reactions to insect bite or hymenoptera
stings can also be mentioned here . They can produce acute symptoms like facial edema ,
urticarial rash , pruritus , etc . , though dramatic , hardly represent a real danger to
animals . These hypersensitivities can be diagnosed via skin test , like almost all
allergies (not food allergy) , and a specific antivenom treatment might be instituted .
dermlink buenos aires ©Copyright2001
Infections of the Skin
Skin bacterial infections
are rarely produced by contact or direct action of a microorganism . Most of the
pyodermias ( pyo = pus , dermis = skin ) are a consecquence of of a contaminated skin
suffering from an inflammatory process . Those microorganisms are normal inhabitants of
the skin and lack pathogenicity , but under certain conditions , they can overgrow and
cause symptoms , specially when the barrier function of the skin is interrupted and immune
status of the animal is altered .
Citology of direct smears is the most
cost-effective tool available , simple and fast , together with culture .
Bacteria most frecquently involved in skin
infections in dogs and cats are Staphylococcus , but sometimes Escherichia coli or
Pseudomonas can be isolated from lesions . Whenever a skin infection becomes chronic or
relapses , it is important to rule out other underlying diseases , using aditional lab
work to determine what is perpetuating the infection , and if the bacteria involved has
become resistant to the drugs on use . This is done by culture , some times using biopsy
Some skin infections might look worse than they
really are . That is the case of hot spots , superficial infections or superficial
folliculitis . These cases might be caused by an underlying allergy or hypothyroidism .
Acne is a deep form of pyodermia , that affects
the hair shaft , with severe inflammation . Hair is kept on a microabscess and does not
come out of the pore , acting as a foreign body . Owners should clean and treat the
affected area once daily .
Deep pyodermia or furunculosis is commonly
observed in german shepherd dogs and shepherd crosses . This disease is severe and related
to an immunological deffect and other yet unknown causes . It needs an aggressive and long
term planned therapy , where corticosteroids have no place . It is really helpful to
entirely clip the dog´s coat , in order to bathe frecquently and obtain the most
antiinflammatory and healing effect of topical therapy .
Bacterial folicullitis is very commun , specially
in short coated dog breeds . Its clinical feature might be mistaken for ringworm or
dermatophyte infection . It is strongly recommended that those dogs have a thorough
allergy and thyroid screening .
Cats suffer from abscesses caused by bite wounds .
Those wounds should be treated agressively with antibiotics and surgical access. Affected
cats should be screened for feline leukemia virus and feline immunodefficiency virus.
Treatment of skin infections should be planned in
advance , chosing the right antibiotic , which dosage and schedule should correspond to
the diagnossis already made . Topical therapy sometimes results in less combination of
oral or systemic drugs , because it reduces inflammation , pruritus , pain , irritation ,
and it helps healing and soothing the affected skin .
When the owner suspends treatment by his/her own ,
or when they modify the dosage already given by the specialist , this can result in
bacterial resistance ( misuse of antibiotics ) .
Our advice is that , whenever your pet suffers
from a skin infection that becomes chronic , difficult to be treated, or relapses despite
treatment , you should contact a dermatologist . It saves you money , and saves suffering
to your pet .
dermlink buenos aires ©Copyright2001
- Fungal diseases of skin
- Dermatophyte or Fungal
Infections of the Skin ( Ringworm )
over 200.000 species of fungi on our planet , only less than 200 are able to produce
infections or contaminations in humans and animals . Some fungi colonize skin and adnexa (
hair , nails ) producing ringworm or dermatomycoses . Others are inoculated via trauma or
puncture wounds , causing deep mycoses . Some others are inhaled and can produce severe
systemic illness . Some fungi can cause hypersensitivity .
Dermatophytosis or ringworm affects only skin
surface , colonizing hair and nails . Some of these microorganisms are called yeast (
Candida , Malassezia ) , and are perpetuated under altered environmental conditions over
the skin surface .
An animal or a person can get ringworm by spores
on earth or premises ( furniture , fabrics , kennels ) , by direct contact with a carrier
( sound animal ) or an ill animal .
Diagnosis is relatively simple by culturing hair
samples obtained by combing the entire coat with a dental brush, hair samples and nail
pieces . Those samples should be submitted to a bacteriology-micology laboratory ,
speciallized in veterinary microbiology . The results are read after 3 to 4 weeks .
Meanwhile , some quick tests like direct observation under microscope or DTM culture ,
that identify only spores , not species implicated .
Treatment consists in antimycotic drugs , given
orally formover 3-4 weeks , plus shampoo therapy ( and rinses) . A special consideration :
environment should be treated agressively with bleach on floors and walls , and special
products on fabrics , vacuum bags , etc .
Yeast infections overgrowth incidence has
increased over the past years . Malassezia , Candida are contaminants that take advantage
of altered environmental conditions on the skin surface . They produce an irritative
dermatitis , often allergy-like . Previous treatments with antibiotics or corticosteroids
for skin problems can favor yeast overgrowth .
The typical animal suffering from yeast overgrowth
presents an allergic or seborrheic dermatitis , bad odor and itchiness . The major
complaint is one of an animal that was responding to treatment but not any longer , and
that bad odor returne quickly after bathing , together with redness and pruritus ( as soon
as a couple of hours after bathing ) . This problem requires identification ( easily done
by citology ) , and treatment with antimycotic and shampo .
Subcutaneous or deep mycosis constitue a risk for
public health and should be address correctly by speciallized professionals . Treatment is
often discouraging . Most of these severe infections are found on immune-impaired animals
Mold hipersentivity is diagnosed by allergy
testing ( mostly intradermal testing ) . Species most frecquently involved are :
Aspergillus, Alternaria , Mucor , Cladosporium , Helminthosporium . Once identified ,
treatment is started with vaccines . It is important to keep in mind that mold spores are
found on moisture ( walls , rooms , damp , garden debris kept moist , etc . ) .
Catteries are a special chapter . They need a
special plan in order to obtain populations of kitties completely ringworm-free , to be
given or sold . This special programmes should be instituted by a specialist .
dermlink buenos aires
buenos aires ©Copyright