Mange: Ugly Duckling Stories

Most of us have heard of mange, but we don’t necessarily know what it is, and we may never have actually laid eyes on it. I’d never seen it till I worked at an inner city animal shelter, where dogs with mange were regular guests. In the worst cases, dogs were almost hairless, their naked skin red as a sunburn, raw and angry, crusty and scaly, scabby and oozy. They looked forlorn, forsaken, and if I’m honest, pretty gross.

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Tommy, a three month old stray with severe Demodex mange.

And every time I met one, I fell deeply in love. What can I say, I’m a sucker for a sad story.

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Maybelle, another mangy puppy, nearly bald.
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Tommy, wrapped in my sweatshirt, napping under my desk.

How did these dogs get this way? And could such sad stories end well? (Spoiler alert: Yes–they’ll live happily ever after.)

Ick! What IS mange?

Mange is a nasty skin infection whose tell-tale sign is fur loss. The culprit is a microscopic, parasitic mite–a rotten little stinker with eight legs (yep, an arachnid, like a spider) that takes up residence in hair follicles. There are two main types of mange in dogs. Sarcoptic mange is caused by Sarcoptes scabei, the same species we can thank for scabies in people. Demodex mange comes from an infestation of Demodex canis mites.  This is the kind we saw routinely at my shelter, so that’s what we’ll look at.

Most dogs have a modest-sized colony of Demodex mites hanging out in their skin, just minding their own business. A strong immune system keeps the mite population under control, fending off mange. When it’s weakened, though–e.g. by malnutrition–mite numbers can balloon, and mange takes hold. Our shelter dogs with mange were usually pretty skinny, which could explain their susceptibility. There are also genetic factors that can make dogs more vulnerable to mange.

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Hungry Maybelle, feasting on hot dogs.

(Side note: You don’t even want to know what mites are living on you, but there are plenty. Same deal, though; as long as you’re healthy, you’ll probably never hear from them.)

eyelash mite
http://www.psmicrographs.co.uk/blog/2012/09/default.aspx

OK, I couldn’t resist. This is Demodex folliculorum, the near spittin’ image of Demodex canis. But guess where this beast from hell lives? In your EYELASHES! Well, maybe not in yours. But probably.

Baths and more baths

Mange is diagnosed by scraping the skin with a scalpel, smearing whatever you come up with onto a slide, and checking it out under a microscope. Once you know you’re dealing with Demodex, it’s time to start a laborious series of medicated baths, spaced two weeks apart. Curing mange takes time, usually three months of active treatment at a minimum, and up to seven months for severe or resistant cases. “Cured” means a full year of negative skin scrapes after the final treatment.

So it’s no walk in the park, for the dog or the dog’s people. But visible improvement is fast and steady, and full recovery is the norm. And demodectic mange can’t be passed to other dogs, other animals, or people. So don’t delay–kiss a mangy dog today!

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Happy endings for mangy mutts

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Tommy spent a few months living with an awesome foster mom, plumped up and grew back all his hair, and got adopted.
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Maybelle got adopted within a week of arriving at the shelter. Who could resist that face?

For more information, check out PetMD, WebMD. To adopt a wonderful dog, with or without mange, visit the Washington Humane Society.

 

What the Dog Saw

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How do dogs see the world?

Inside-of-a-Dog-coverThat’s deep, if you’re talking about a dog’s point of view on life. (For one of the best books ever written on the canine umwelt, check out Alexandra Horowitz’s Inside of a Dog.) But for our purposes, I’m talking in literal terms. What are dogs’ actual eyeballs taking in, specifically in terms of colors? Are they colorblind, like some say? Do they see in black and white? What about ultraviolet light?

Let’s look at a real-life case. In my dog training class last night, students taught their dogs to touch their nose to a Post-It note. You might wonder: Why ask a dog to put its nose on a piece of paper? Why a sticky piece of paper? What color is the paper?

To which I’d respond: If your dog can touch a target, like a Post-It, then he can learn to touch it wherever you hold it. If it’s sticky, you can attach it to something–a wall, say–and let go. Service dogs, for example, can be taught to flick light switches on and off using this method.

Oh, and the color of the paper? Yellow.

Does that seem random? Irrelevant? Consider this: Dogs’ eyes are equipped with cones (color receptors) for perceiving yellows and blues, but not reds. (This is typical of other non-human mammals.) I so don’t want to get into the anatomy, physiology and neurobiology of the visual system; I can barely comprehend it, much less explain it. Let’s stick with this: Dogs see red (and orange and pink), as shades of gray. And greens look pretty much like reds–as they do to the 8% of humans (mostly male) who are red-green colorblind.

from www.petadvisor.com
from http://www.petadvisor.com

The image above contrasts how humans see the visible spectrum with how it looks to dogs. See how the yellow stands out amidst the drabness?

510vi9+RcEL._SY344_BO1,204,203,200_In her superb book Animals in Translation, Temple Grandin describes cows who refused to walk up a ramp with a yellow rain slicker draped over the railing, and who avoided a building with a yellow ladder propped against it. She intuits that the cows were spooked by the high color contrast between the yellow objects and their surroundings. For “dichromatic” animals (those that see in two colors rather than three), color contrasts can be distracting or frightening. “Anything yellow will really pop out at them,” Grandin explains.

https://smilegotnessa.wordpress.com/2013/02/18/differences-between-a-dog-and-a-humans-visual-perception/
https://smilegotnessa.wordpress.com

I don’t use yellow sticky notes to distract or scare dogs; I just picked the easiest color for targeting because it “pops out”. Likewise, I always buy yellow tennis balls for my dog, because I assume they’re easier to track in the air and on the ground. Pet stores sell tons of red, pink, orange, and green dog toys, which look bright and cheery to us, but to a dog, their murky hues make them easy to lose against any greenish, reddish, brownish or grayish background.

Does a dog’s-eye view seem a little dreary compared to ours? Before we get too smug, let’s remember that dogs’ primary sense is smell, and scent must form an olfactory tapestry that’s vibrant beyond our imagination. Plus, dogs’ crappy color vision still has ours beat in one regard: They see UV.

Let’s review: Dogs have cones for yellows and blues. Humans have an additional type for reds. Plenty of birds and bugs have a fourth type of cone that is sensitive to ultraviolet light. Even without these cones, our retinas could receive some UV light if the lenses of our eyes weren’t specially designed to block it out. Scientists figured this shielding feature was shared by non-human mammals.

millipedes-blacklightGuess what? When two British scientists shone light through the eyeballs of a wide assortment of dead mammals, they discovered a lot of them–from hedgehogs to okapis to, yes, dogs–have lenses that let some UV light penetrate to the retina. That means things that glow for us under a black light look a bit glow-y to a dog in normal light, for example snow and pee. A snowman that’s been urine-marked by every pup on the block could be a lurid spectacle indeed. What else must look weird to them?

This discovery got a lot of media attention, but I haven’t seen much follow-up analyzing how dogs might use this secret sense. Have you? Till then, let’s just end with another question–

When has your dog had a weird reaction to something that looked normal to you? Or overlooked something you thought was plain as day? Do you think color perception might have something to do with it?