Veterinary dermatology is a relatively straight forward aspect of veterinary medicine to deal with because the diseased organ is able to be visualized and palpated by the veterinarian but also by the technician and owner. The technician can and should play an integral role in cases with skin disease.
Veterinary dermatology is a relatively straight forward aspect of veterinary medicine to deal with because the diseased organ is able to be visualized and palpated by the veterinarian but also by the technician and owner. The technician can and should play an integral role in cases with skin disease. The technician can help save the doctors time as well as greatly increase client compliance. The goal of this presentation is to learn valuable techniques for helping the veterinarian deal more successfully with skin and ear cases.
Obviously each clinic or doctor is different in what roles they may want the technician to play. Some the areas where techs may be valuable are: setting the exam room for a derm case; weighing the patient; acquiring initial history; determining basic vital signs; take different skin samples (table one); analyzing samples and recording results; educating clients about how to properly do things for diagnostic purposes and therapy(table 2).
Table 1 Cutaneous samples
Many technicians will also do initial history questioning and examine ears. Certainly dermatology is an area where the technician can play a substantial role in helping the veterinarian better diagnose and manage a case.
Table 2 Client education required
Setting the exam room, Routine equipment
Any time a case is being presented for skin or ear disease it is likely that certain equipment will be needed in the exam room during the examination. The technician should make sure the exam room is adequately equipped so the veterinarian does not have to take time to go looking for what they need. The essential equipment includes items in table 3:
Table 3 Essential Equipment List
My impression of what is missing in most exam rooms are multiple clean otoscope cones so that each ear of any size can be examined with a clean cone. Also cones need to be properely cleaned prior to use. This is done by scrubbing then the cone is placed in an effective disinfectant for at least ten minutes then rinsed and allowed to dry. Another common problem is poorly charged hand held otoscopes in clinics that do not have wall mounted otoscopes.
Skin samples for cytology and skin scrapings are almost routinely needed and in many clinics the technician plays a role. The process for performing these tests involves several steps and technicians may be utilized in most of them. The first step is to determine what tests are needed and what is being tested for. This step likely will be determined by the veterinarian, generally after taking or reviewing the history and examining the patient. Once those decisions are made then the technique to be utilized for acquireing and the sample will be determined and this may be done by the veterinarian or the technician. After the sample is taken it may require processing or preparation and in most practices this is the role of the technician. The sample will need to be evaluated with a microscope. Even if the technician is not dong the microscopic evaluation properely taking and processing samples then having them waiting by the microscope is an important time saver during the examination.
Skin scraping is one of the most frequently used tests in veterinary dermatology and is recommended anytime the differential diagnosis includes microscopic ectoparasitic diseases. Skin scraping is most commonly used to verify or rule out the diagnosis of demodectic mange. It is also commonly used to try to establish the diagnosis of sarcoptic mange, cheyletiella infestations and other ectoparasitic diseases, although it does not effectively rule out sarcoptic mange. Not all skin scrapings are performed in the same way. The method of scraping for demodectic mites is different from that of scraping for sarcoptic mites. The collected material is placed on a microscope slide and mixed with oil. It is preferable, though many practitioners do not do this, to use a cover slip over this material. The value of the cover slip is that it puts the material in a flatter plane which facilitates examination and decreases the chance of getting oil on the lens. The key to a complete examination is that all the collected material be consistently and orderly examined. When looking for mites that are relatively large and clear it is best to lower the condenser source which results in better visualization. Since mites are relatively large the material can be examined at low power (4 or 10 x lens). You should start the examination at one corner and move the slide in one direction to the end of the sample. The field is then moved to the adjacent field with just slight overlap of the prior field that was examined. Then the slide is moved and the material examined back to the initial side. This back and forth Z pattern will result in all the material being examined. When a suspicious object is noted at low power you can change to a higher power to better identify it. Be extra careful to not let the lens get into the oil and there is no need to use oil immersion.
Demodectic Mites: Generally multiple scrapings from new lesions should be obtained. For demodex the key is to scrape deep enough and small areas are all that need to be scraped. The affected skin can be squeezed to extrude the mites from the hair follicles. It is helpful to apply a drop of mineral oil to the skin site being scraped or to the scalpel blade or spatula to facilitate the adherence of material to the blade. Additional material is obtained by scraping the skin deeply until capillary bleeding is produced. An alternative technique that can be used in areas where skin scrapings may be more difficult, i.e. periocular or interdigital, is the hair plucking technique. In this technique hairs are gently plucked and the hairs are examined in mineral oil on a glass slide as you would with a skin scraping. Many times mites can be identified at the level of the hair bulb. With either technique there is an important difference in recording the results. For demodex it is not just the presence of mites but important to also record information about the population observed. The approximate number of mites and ratio of live to dead should be recorded. In addition to number of live and dead mites it is also important to identify the relative number of each stage, adult, larvae and egg. This is entered into the record and some clinics use a form for each scraping result in cases of demodex that are being treated. It seems that skin scraping is a straight forward, easy laboratory procedure, however many demodecosis cases are referred to specialists in which false negative skin scraping findings led to misdiagnosis, or skin scrapings were not performed.
Scabies Mites: Canine sarcoptic mites reside within the superficial epidermis however, because small numbers of mites are usually present they are difficult to find. In contrast to scrapings for demodex, scrapings for scabies are superficial but should cover large areas. Multiple superficial scrapings are indicated with emphasis on the pinnal margins and elbows. The more scrapings performed, the more likely a diagnosis, however even with numerous scrapings, scabies cannot be ruled out because of negative results. Despite this, skin scrapings should be performed in any chronically, poorly responsive pruritic dog. When examining the collected material numbers are irrelevant so once a mite, egg, larvae or even mite feces are seen a diagnosis is confirmed and the rest of the material does not need to be examined.
Diet trials are an important part of the work up in itchy dogs. Often clients spend a lot of time and money doing diet trials and become frustrated when the find out a trial was not really done correctly. In some cases they blame the veterinarian for this failure. An important job for the technician is to always simplify and protect the clinic from being blamed by emphasizing to owners that nothing it to be ingested or swallowed by a dog on a hypoallergenic diet trial but the foods the veterinarian has okayed. Anything else whether given intentionally by a human or found by the dog can ruin a diet trial. This is a key point that should always be taught and often the clinic will have other information that the technician should reinforce whenever a diet trial is recommended.
Prior to performing an ear exam specific equipment is needed that the technician is often involved with set up and insuring that this equipment is functional. Otoscopes must have a strong light and power source combined with at least 10x magnification that allows focusing within the normal length of the ear canal. If a battery charged light is used make sure they are fully charged and as batteries get older they should be changed. When they no longer charge fully to give a bright light or do not hold a charge long enough they should be changed. If any of these components is not present otoscopic examinations may not be totally effective. One of the most common mistakes made in practice is the use of hand help battery operated otoscopes that no longer have enough power to adequately light the deep ear canal. In general every clinic should have at least one plug in otoscope that is not dependent of having fresh fully charged batteries. Various sizes of otoscope cones are needed to be able to examine the different size and breeds of dogs and cats seen in practice. Cones should be properly disinfected, cleaned and dry or rinsed prior to using. The cones are often being searched for and it is helpful to have multiple cones of each size in every exam room and where ear procedures are performed. During the day these should be checked so doctors are not spending time looking for clean cones. Many practitioners' utilize diagnostic otoscope heads. In general we prefer the surgical otoscope head, which allows more manipulation and angulation as well as easier use with cleaning and therapeutic procedures that require passing instruments or tubes into the ear canal with concurrent visualization.
The technique for doing proper otoscopic examination is one that allows complete as visualization as possible with minimal pain or trauma. Many dogs or cats will allow a carefully done otoscopic exam but resist or make it impossible to complete an examination if the technique is not optimum. Examinations are best done on a table to allow for appropriate orientation of the scope. Though large breed dogs may be able to be done on the floor is the head is held high enough and the operator is kneeling on the floor. The head should be high enough to allow the observed to move the otoscope into a more horizontal position. Occasionally it is easier to examine an ear of a dog lying in lateral recumbence on a table. The muzzle should be directed slightly towards the thoracic inlet. It is often the job of the technician to properly hold the dog or cats muzzle for the proper exam. It is the natural tendency is for the head to be tilted as the examination starts. This will redirect the cone tip resulting in more pain. The pinna should be pulled up and out from the base of the skull, which helps to straighten the ear canal and minimize the blocking of the lumen by the auricular projection that is present near the junction of the vertical and horizontal canal. The tip of the cone is passed down the lumen of the ear canal while the operator is visualizing the canal through the otoscope cone. Attempting to insert the cone without visualization is a sure way to "hit" the canal epithelium, which can be painful even in a normal ear. The cone is then moved slowly into the vertical canal, visualizing as you go, then the otoscope handle is rotated downward so the cone approaches a horizontal position. The movement is best accomplished when the ear is also pulled up and out over the tip of the cone so that the two processes happen simultaneously. Proper placement at the junction often allows visualization into the horizontal canal and if necessary advancement into the horizontal canal. Deep penetration into the horizontal canal is only done if necessary to visualize the tympanum.
Educating and teaching clients to clean either with home cleansers that do not require rinsing or a bulb syringe is an important aspect to controlling proliferative otitis cases. The clients role in treating the ears needs to be clear as does the importance of follow up which is discussed below. Cleaning is helpful for several reasons. Debris and microbes are removed thus decreasing overgrowth and the environment favorable to overgrowth. Inflammatory mediators are also removed and folds are temporarily opened. The clean ear is more likely to be reached by medication used topically. Pressure from debris is at least temporarily removed from the deep ear canal and tympanic membrane if it is still present. In atopic dogs allergens that are present on the skin surface or trapped within the cerumen and debris on the pinna and in the ear canal are also removed or at least the allergen load is decreased. It is the authors opinion that keeping ears clean is the most important aspect of managing proliferative otitis and to adequately accomplish this clients must be able to do this at home or frequent follow up visits with cleaning will be required. In severely inflamed, painful ears home cleaning should be delayed as many dogs will not tolerate these procedures until after the inflammation and pain is resolved. Therefore home cleaning is usually recommended following the initial therapy. There are two main ways for clients to clean ears at home.
Ear wash or rinse is the most common method used at home. This technique has the client instill a mild cleanser into the ear until the canal has been filled to the external orifice as well as apply the cleanser to the external orifice and concave pinna. This tends to be a little messy and should be done outside or in a bathroom or even shower stall. There are two important aspects to this technique. First since the cleanser may not be rinsed out the cleanser must be safe to leave in an ear and non irritating. There are numerous cleansers on the market. Generally it is best for this type of cleanser to be alcohol free, utilize a gentle cleanser and have some disinfectant activity. The second important aspect to this technique in dogs with significant horizontal canal build up is adequate massage of the auricular and annular cartilage. To effectively massage the annular cartilage the client must be educated about the location and need for deep digital palpation. Following several minutes of massage the material is allowed to be shaken out and then the external orifice and concave pinna is wiped clean with tissue or cotton balls. Do not allow excessive use of cotton tipped applicators down the ear canal as these commonly push debris deeper into the ear canal. In general this rinse technique is not as effective as bulb syringing due to the inability to massage with fluid the last portion of the horizontal ear canal which is contained within the boney external acoustic meatus.
Bulb syringing is generally more effective in cleaning the horizontal canal and gets the ear canal cleaner than the wash/rinse technique. It is somewhat more labor intensive, messy and requires that clients are adequately trained and the patient will tolerate the procedure. This technique is usually only used once it has been determined the client is not doing adequate cleaning with ear rinsing technique. In general the tympanum should be intact if cerumenolytics are going to be used because the client may not be able to adequately rinse away all residual drugs and repetitive application could be dangerous especially if not being rinsed out. When the tympanum is not intact the same mild cleansers used for home ear rinsing are used even with the bulb syringe. Clients should be instructed about the proper pressure and speed to squeeze the bulb syringe. This is best determined by initially practicing with air and learning how hard and fast they can squeeze without hearing the air coming out of the bulb syringe. Only lukewarm or body temperature fluids should be used for flushing. The nipple of the bulb syringe should be placed loosely in the external orifice of the ear canal so that once flushing is started they rapidly see the flush solution exiting the ear canal. Allowing adequate back flow helps prevent excessive pressure building up against the tympanum. Flushing is continued with fresh solution until no debris is seen coming from the ear canal. They should not use the bulb syringe to aspirate fluid out of the ear as the inside of the syringe may become contaminated with pathogenic organisms. Following flushing with a bulb syringe a cleanser disinfectant or disinfectant dryer solution is used to help dry the ear canal and remove residual rinse water.