Page 222 - The Veterinary Laboratory and Field Manual 3rd Edition

Parasitology 191

skin scrapings, hair samples are often collected
at the same time for other tests.
To find ear mites (for example, Otodectes sp.,
Psoroptes sp.) take samples of ear wax. Typical
signs of ear mite infection in dogs include red
sore ears due to repeated scratching, head shak-
ing and the subsequent development of aural
haematomas due to self-trauma. Treatment of
ear mites requires removal of the wax and other
debris before acaricide is added. Supportive
care to prevent further self-trauma may also be
Figure 3.45 Stray dog with advanced sarcop-
tic mange. Kathmandu, Nepal. The mite burrows required. A veterinary professional should thor-
under the skin causing irritation and, in most cases, oughly examine the animal before ear drops are
stimulates a hypersensitivity response associated given to make sure that the ear drum is intact
with intense irritation. The host animal loses hair and that there are no other complications.
and develops raw areas, especially on the legs and Demodectic mange (Demodex sp.) may affect
ear tips, as a result of self-mutilation. Secondary many species but in debilitated cattle and dogs it
bacterial infections commonly complicate diagnosis can become very severe and may result in thick-
and treatment. ened skin, hair loss (especially around the eyes)
and deep skin lesions. In dogs, there may also
be an underlying disease problem (for example,
As mentioned earlier, the clinical signs of par- hypothyroidism) and in these cases Demodex
asitic mite infestation are variable and depend sp. may be difficult to treat. Infections can be
on (1) the species of mite involved, (2) the num- diagnosed by examining skin scrapings. Animals
ber of mites present, (3) the immune status of may need antibiotic treatment for secondary
the host as well as (4) environmental factors. In bacterial infections.
some cases, a host can develop a severe hyper- Some mite infections are superficial (for
sensitivity response to the presence of mites example, Cheyletiella sp.) and in these cases
resulting in severe irritation and self-trauma, in treatment is usually quite simple. The mites can
these cases there may only be a few parasites be identified in hair or fur samples. Superficial
present. This response is often seen in cases of mites may be caught on Sellotape strips by plac-
sarcoptic mange (Sarcoptes sp.) in dogs, camels ing the sticky side of the tape on the animal’s
and pigs. Skin scrapings taken from animals skin and hair and removing it quickly. The mites
with mange should be carefully collected using and their eggs remain stuck to the tape which
a sharp sterile scalpel blade to remove a sample can be placed on a microscope slide for exami-
of the superficial and deeper epidermis. It is nation. Note that Cheyletiella species mites may
advisable to swab the area with alcohol prior to also affect humans causing a red rash around the
sample collection. If the skin condition is severe, abdomen or other areas of soft thin skin that
the wounds can be bathed in an antiseptic wash have come into contact with infested animals.
afterwards. In severe cases of sarcoptic mange
the animal may have secondary bacterial skin
disease but, as there may be few active mites
present, it might be necessary to take several
skin scrapings to isolate the mites. In addition to

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