"Sarcoptic Mange"

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The PetStuff Online Newsletter
Volume 1 Issue 7  September 24, 1999


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"Sarcoptic Mange - You Can Get It"

"Mange" is a non-descript term used to imply a condition caused by mites on or near the skin surface.  This week we will discuss "Sarcoptic Mange" which is caused by a tiny burrowing mite called Sarcoptes scabiei variety canis in the dog (the "itch mite") and Notoedres cati which is quite similar and the cause of head mange in the cat.   Dogs, hogs, cattle, horses, sheep, man, etc. all have their own individual varieties of Sarcoptes mites which affect them; hence the names Sarcoptes scabiei var. canis, Sarcoptes scabiei var. bovis, Sarcoptes scabiei var. suis, etc.

"Sarcoptic Mange" the Disease
As will be described below in the life cycle of Sarcoptes scabiei, these mites like to tunnel in the upper layers of the skin. When they do so they cause the host to become sensitized and an intense inflammatory reaction occurs.  This results in an aggravating itch for the infested host. The constant scratching results in hair loss and damage to the skin by self-mutilation. Although the lesions start on the thinly haired areas such as the ears, muzzle and around the eyes, if let go the condition can spread over the entire body. Serum ( the clear component of blood) seeps out of the tunnels to the surface of the skin and causes thick scabs to form.  Secondary bacterial infection usually occurs causing pus to accompany the scabs.  "Not a pretty picture".

Diagnosis
Diagnosis is accomplished by deep skin scraping in 12 or more affected sites.  The skin must be scraped in numerous sites at the very edges of the advancing lesions. This is because the mites are usually at the head of the tunnels beneath the skin. Occasionally, Sarcoptes mites can be very difficult to retrieve and the animal is treated based on the characteristic lesions and the response to therapy.

The life cycle of Sarcoptes scabei mites
As can be seen in the image below, Sarcoptes mites spend their entire life on or in the skin. The male and female copulate on the skin surface and the male soon dies off.  The female then burrows into the upper layer of skin (stratum corneum) and begins forming a honey-comb of tunnels.   As she tunnels along eggs are laid that fill the tunnels. Adult mites feed on the serum (clear component of blood) that oozes into the tunnels from the surrounding irritated tissue.  When the female mite completes her egg laying mission she dies at the end of the tunnel.  The eggs soon hatch to form larvae and then molt to become nymphs.  The larvae and nymphs also feed on serum and skin debris. When the nymph makes a final molt to become an adult they return to the skin surface where they mate and start the life-cycle over anew.   Transmission from animal to animal is thought to be through direct contact.   Dog and cats in close contact with an infected host are succeptible. Animals can also become infected from fomites e.g. infested pens and blankets, combs, brushes, collars and any upholstered surfaces.  Young and poorly nourished animals are the most succeptible to infection.

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How is Sarcoptic Mange treated?
The Pet
Sarcoptic mange is fairly easy to kill with dips (Amitraz), pour-on miticides (alcohol based Ivomec), or oral products (Milbemycin - Interceptor). The condition also may need to be treated with an antibiotic for the secondary bacterial infection and corticosteroids to decrease the intense itch and inflammation.

The Environment
Adult Sarcoptic mange mites can live for 21 days in the environment without feeding.  For that reason all brushes, combs, collars, bedding, carpeting and upholstered surfaces must be sprayed with an insecticide.  Household flea treatment products effectively kill the adult mites.  One or two thorough applications generally destroys adults in the environment.

Can people get Sarcoptic Mange?
Yes!  Ever hear of the "Seven Year Itch"?  That's another term for Sarcoptic Mange in humans.    Like pets, humans have a particular variety of mites that can cause advanced " Sarcoptic mange".  This is totally separate variety from the ones that cause "mange" in dogs and cats; however, if the variety of mange mite that affects dogs and cats gets on a human it can cause a nasty red welt just like a mosquito bite.   Several of these bites can be rather troublesome.  Since these varieties are not well adapted to humans, they do not produce the extensive tunnels and cause the advanced lesions and scabs over the skin surface.  They just burrow in a short distance and die.   This causes inflammation and the resulting welt.

Next Week
October 1st - Anal Sac Disease & Scooting
October 8th - Buggy Ears - Ear Mites
October 17th - Feline Leukemia Disease

"Normal Heartbeat & Pulse"

You cannot recognize what is abnormal if you don't know what's normal to begin with...

Dog     Small Breeds (30# or less) 100-160 beats per minute
        Medium to Large Breeds (over 30 #) 60-100 beats per minute
        Puppies (until 1 year old) 120-160 beats per minute

Cat     160-220 beats per minute

Heartbeat

The heartbeat of the dog or cat can be felt at about the point where the left elbow touches the chest wall. To feel the heartbeat, gently bend the left front leg back at the elbow until the elbow touches the chest. Place your hand or a stethoscope over the chest at this spot to hear or palpate the heartbeat. 

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Feeling the Heartbeat

 

The Pulse

Probably more meaningful than feeling the heartbeat, feeling the pulse can tell you if blood is being circulated effectively. When feeling the pulse use your first and middle fingers with a light touch.    Practice makes perfect!

Femoral Pulse - Feeling circulation in the femoral artery on the inside of the rear leg at the position of the spot below.

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Feel Where the Leg Joins the Body at the Spot

Pedal Pulse - Front or Rear Paw

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Front Paw

RearPulse.GIF (1115 bytes)

Rear Paw

Remember to practice BEFORE an emergency requires your skill!

Credits
Images used in this publication taken from Hill's Atlas of Clinical Anatomy, Published by Veterinary Medicine Publishing Company, Inc.   A publication donated to veterinarians by the Hill's Pet Food Company to teach clients about their dogs and cats in sickness and in health.   Hill's Pet Food Company produces Hill's Prescription Diets and Science Diet Premium Pet Food.

Have A Nice Weekend

Later,  Dr Dan