Monday, May 7, 2012

981. A total view of the skin disease

"I came to consult you because my neighbour had two poodles and refer me to you," the retired pharmacist told me. "My poodle itches all day long for many months. One injection from Toa Payoh Vets and her dog recovered from the skin problem. So she refers your surgery to me."

Performance counts.

"Please don't imagine that one injection is going to cure all skin diseases," I said. "Do you know whether your neighbour's dog suffers the same skin problem as your 4-year-old poodle?"

Four paws (top and bottom) were heavily licked and crusted with scales. Dry scales below the neck, on both elbows and on hind legs. Both checks crusted with hair loss too. Surprisingly the ear canals were normal. However, there was a 1.0 x 0.8 cm of crusty hair loss on the back of both ear flaps.
This was a very atypical case of sarcoptic mange is it was one. Normally all ear edges are crusted but the ear canals are normal. The face and eyelids and elbow scales and hair loss appeared to be due to another skin mite, demodex. I asked Dr Daniel to do skin scrapings, "Show me what your Murdoch University vet professors have taught you in skin scraping." I said. Dr Vanessa's professor taught her that all skin scapings must have oil so that mites can be seen under the microscope. Actually, it is not necessary to have messy oil soiling the microscope's lens. Mites can also be seen in a drop of water on the slide but then the university professors in Australia never taught their students this method.
So, new crops of students studiously use oil. For example, skin scraping to check for ringworm in hairs can be covered up with a scotch tape. No need oil. But the university professors taught the students that a drop of oil is the best medicine. Unfortunately, some employee vets use many drops and mess up the lens with oil and I have to send the microscope for servicing. Teaching the vet students how to take care of the expensive vet microscopes, operating table and anaesthestic machine is probably not in the Vet professor's scope of lectures.
Back to this case, the skin scrapings were negative for mites and for ringworm.
"What shampoo you use?" Dr Daniel asked the retiree who would rather have nothing to do with this dog as it was his daughter who bought it but was now too busy to care for it.

Some dog shampoos have a drying effect on the dog's skin. But in this case, the sites affected were unusual. The body, under the body and ear flap and canals were normal. A bit of brown anal sac oil. "So what is the cause?" the retiree asked me.

"First of all, you did not want a blood test done. So, I am unable to know the immune status and other health abnormalities affecting the functions of the kidney or liver. Blood tests are important and form part of the evidence-based medicine. Since there is no blood test permitted, it is not easy to rule out many possible causes."

"I understand," the pharmacist said. He had been in the line for over 50 years and know what I am talking about. "But what are the possible causes?"

"In your case, the causes are multi-factorial. Allergy may or may not be one reason. Vice such as self licking of paws due to boredom. Auto-immune diseases, demodectic mange mites, yeast and fungus deeply embeded. No mites seen in the skin scrapings does not mean there are no mites at all."

"A skin biopsy of the paws will be useful as well as a blood test." He was not in favour of that as he had retired. Yet he had two daughters who are working in high positions in the corporate world and they might be able to spare some money for the dog's treatment. But he had not asked them. He was sorry for this poddle scratching the whole day long for months and met a neighour who referred him to the Surgery with the vision of one injection cures all skin diseases.

 "OK, ask your daughter to pay the bill." I presented him the receipt. "It will be best to review 3-4 weeks later." I don't know whether he will come. Skin disease of a chronic nature can be hard to treat and will be more costly. Usually there are many causes. I did not recommend him a special diet or shampoo at this stage as the causes are varied. 

In retrospect, I believe that his dog suffers from demodectic mange but Dr Daniel was not able to show any mites with two skin scrapings. Sometimes, the mites are hard to find. Somethings the scrapings need to be deep till the skin bleeds. Whatever it is, a review in 3-4 weeks is best. Some skin infections do get cured with "one injection" but not this case. The symmetrical presentation of small almost equal areas of skin hair loss behind the back of the ear flaps, on both sides, seem to be a clue that this is an immune-mediated disease. If only, the retiree permitted a blood test. Evidence-based medicine must be practised but within the economic reality of the owner.  

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