Cheyletiellosis: Night of the Walking Dandruff

Sorry to mislead you into thinking this blog was going to be about the ever popular zombie creature. It's actually about a different kind of monster, a microscopic mite commonly referred to as "walking dandruff" that likes to prey on bunnies. What better time to talk about mite monsters than Easter? What if the cute little twitch in Peter Cottontail's nose is because of an itch?

Meet "Lucky," a young rabbit presented to our veterinary clinic during the winter of 2014 because of a recently noticed skin condition. Lucky was missing large clumps of hair between his shoulder blades, and the area was covered in huge flakes of white dandruff. His physical examination was rather unremarkable besides his obvious skin disease. He did not even act that itchy, but his skin was quite red everywhere and the hair fell out easily anywhere you parted it.

The other rabbit in the home, kept separately, showed no symptoms of skin disease. The bunnies had been adopted over a year ago and had spent some time penned outside during the warmer months of 2013, but had no interaction with each other much less other animals.

Examination of the affected rabbit revealed a large amount
of dandruff, hair loss and red, irritated skin.

I suspected the "walking dandruff" mite even though no movement was seen in the flakes of dead skin. The official name for this parasitic insect is Cheyletiella and there are numerous species which can plague various mammals from rabbits to dogs to cats. Cheyletiella ("kai-la-tee-ell-a") are highly contagious and can even bite people, but they can't live on us for long. The mites tend to live on the animal's skin within the keratin level; they less commonly invade the nasal passages. The mites are fairly large as mites go, and their scurrying among the excess amounts of dead skin produced in response to irritation resulted in the nickname "walking dandruff."


Animals acquire Cheyletiellosis by direct contact with an afflicted animal in most cases. However, the mites and their eggs can also survive for a short period (days to weeks) within bedding and the environment, so transmission may occur via indirect contact as well. Some animals carry around Cheyletiella mites but don't show symptoms at all! 

At the center of the field are two Cheyletiella mites as well
as a large mite egg.

Definitive diagnosis of Cheyletiellosis in Lucky was swift and satisfying. I collected some dandruff from his back on the sticky side of transparent tape and applied the entire thing to a glass slide. At relatively low magnification under the microscope, I saw numerous mites and mite eggs amid hair shafts and epithelial skin cells.

In some cases, mite bodies and eggs may be seen during microscopic evaluation of a stool sample instead. This is a good way to diagnose Cheyletiellosis in cats. Because they are such fastidious self-groomers, infected cats often ingest the excess dandruff as well as the mites making diagnosis from physical examination alone more difficult.

Fortunately, treatment of "walking dandruff" is much easier than eliminating an apocalypse of the walking dead. Various treatments are available to kill Cheyletiella mites. Because rabbits are weirdly sensitive to certain topical insecticides--for instance, over-the-counter products containing fipronil, well-tolerated in dogs and cats for the treatment and prevention of fleas, are devastatingly toxic to rabbits--we selected topical prescription-only selamectin which has been used safely and effectively in rabbits for mites of various kinds.

Dr. Kim Everson applies a dose of medicine to Lucky to treat
his bad case of Cheyletiella mites.

In addition to thoroughly cleaning the hutches and surrounding environment as well as replacing the bedding and feed hay, we decided to treat the asymptomatic rabbit as well. Both bunnies will receive a small amount of medicine on the skin between the shoulder blades once a month for several months in a row. Any mite bites on the humans in the household are expected to resolve once the bunnies have completed treatment.

Shortly after the first dose of medicine, Lucky was reportedly showing signs of improvement in his skin. By now, he should be feeling fine -- just in time for delivering the family's Easter baskets!

Getting Crabby





Quick. When I say "family pet" what do you think of?

 

A friendly, floppy-tongued dog? A sleek, sly-eyed cat? Maybe if you live rurally, the image of a handsome horse or frisky goat pops into your head. A Google image search for "family pet" returns a plethora of photos of people with their dogs; however, photos of kids with a duck, chicken and a giant boa constrictor also dot the first webpage.

 

My family currently shares our home with two dogs and two cats, wonderful but common mammals. Last spring we got a little adventurous and invited a lovely juvenile corn snake into our midst. Having successfully adjusted to reptile care, we recently branched out to hermit crabs. Our first hermit crab was a Christmas present for our preschooler. At the time, I thought that was a strange, potentially painful gift for a 3-year-old.

 

I was wrong.

 

Hermit crabs are not slimy, stinky or especially dangerous. They have distinct personalities and are surprisingly social. When we visited the pet store to pick out our first crab (named Gooby by our son), we handled numerous crabs in order to find the perfect pet. Most were shy and pulled into their shells with their large claw effectively "blocking the door". Gooby, however, poked out his legs and began climbing around my hand. He (we later learned) was cautious as we took turns looking at and petting him, but his retreats into his shell were momentary. The one and only pinch the kids or I have yet received was at the pet store on my thumb. It was more surprising than painful!

 

Hermit Crab races

Gooby has since been joined by a similarly-sized hermit crab named Crab (also named by the preschooler). When selecting Crab, we were more concerned with size than temperament, trying to reduce the chance of one of the crabs killing the other for its shell. Crab was initially somewhat timid, but has begun to "come out of its shell" with gentle handling. Crab's sex is undetermined at this time. While Gooby is a bit of an exhibitionist, stretching far out of his shell to reveal his lack of gonopores (the sign of maleness), Crab is still a bit more reserved.

 

Our curiosity will remain unsatisfied for as long Crab decides to stay close to home. There is no pulling a hermit crab from its shell against its will. Apparently it would rather die first. We are still waiting for the first shell upgrade which might allow us to glimpse Crab or Gooby’s full hermit crab body in all its glory. In anticipation of The Move, we have provided several empty shells with openings just slightly larger than our crabs’ largest claw.

 

In their natural environment, hermit crabs are primarily land dwellers. In fact, their primary requirement for salt water is to breed. Breeding in captivity is unlikely, so it doesn’t actually matter if Crab is a boy or girl!

 

In addition to being relatively easy to care for—our inexpensive all-inclusive pet store crabitat will keep our duo going for a while—hermit crabs are not known to transmit zoonotic diseases to people. This is in contrast to aquatic pet turtles and many reptiles which can transmit Salmonella bacteria to their handlers. Even so, we all practice thorough hand-washing after playing with our hermit crabs just to be on the safe side.

 

The hermit crab is a crustacean in the phylum Arthropoda to which insects and arachnids such as spiders also belong. This relationship information is important to me because while I admire spiders from afar I do not think I would like to cuddle a Tarantula. Yet I have found I absolutely adore playing with our spider-like hermit crabs. The firm, cool grip of their exoskeletal limbs, their cute beady on-stalk eyes and wiggly antennae, and their funny, friendly antics have made me a crab convert!

 

The Skinny on Intestinal Worms

One day last summer my fearless sister-in-law plucked a "slug" from her cat Izzie's bottom and sent me a video of the little bugger crawling around on her desktop. Sarah launched into a tangle of theories of where Izzie could have picked up a tiny slug. I suppressed a giggle. "Uh, Sarah, that's not a slug. That is a tapeworm."


Cats and dogs share our beds and kiss our babies. They also prey on rodents, scavenge dead animals, eat stool and lick their bottoms. Yep. It's gross. Limit the grossness by regularly giving your pet a dewormer. There are more types of wiggly intestinal worms than you probably care to imagine with different types of medicines necessary for each. Here's the low down!


Tapeworm

• Tapeworms are a common small intestinal parasite in cats and dogs.
• Cats and dogs pick up tapeworms by eating infected fleas or rodents.
• Signs of infection are seeing tapeworm segments (e.g., grains of rice, sesame seeds or slugs!) in the stool or around the anus. A fecal float is rarely helpful in diagnosis unless the technician finds tapeworm segments in the stool sample.
• Some tapeworm species are contagious to people and can cause intestinal problems or dangerous neurological disease.
• It may be necessary to treat for flea infestation at the time of tapeworm diagnosis.
• Tapeworm dewormer is notoriously expensive and not included in most heartworm preventatives -- make sure you ask your veterinarian for advice on treating tapeworms.  

Whipworm

• Whipworms are a common cause of large bowel diarrhea in dogs.
• A heavy infestation can cause bloody stool, weight loss, anemia and dehydration.
• Whipworm infections are tough to diagnose on routine fecal floats because egg production is small, shedding is intermittent and the eggs don’t “float” well. Therefore, even with a negative fecal float, your veterinarian may still recommend aggressive deworming if suspicion is high.
• Whipworm eggs can remain hidden in the soil for up to 7 years! That means you must keep your dog on a monthly whipworm dewormer for a very long time to avoid reinfection.
• Whipworm dewormer is not found in most heartworm preventatives, but there are some that include it so ask your veterinarian.

Hookworm

• Hookworms are commonly found in dogs and cats.
• Hookworms feed on intestinal tissue causing blood loss and inflammation in the GI tract.
• Severe infection may lead to anemia, debilitation and even death, especially in young animals.
• Hookworms can infect people (Ewww!) by penetrating the skin or by being accidentally ingested. Infection in humans can cause an itchy rash or inflammation within internal organs.
• A routine fecal float performed by your veterinarian is used to diagnose hookworm infections.
• Many monthly heartworm preventatives also control hookworm infections, especially when used year-round. 

Roundworm

• Roundworms are the most common intestinal parasite of dogs and cats. Assume every puppy and kitten has a roundworm infestation even though worms are rarely seen in the stool. Some animals with very bad infections will pass "spaghetti-like" worms in the stool or vomit. 
• Adult worms live in the intestines depriving the host of nutrients. 
• Common signs may include diarrhea, weight loss, swollen abdomen, vomiting or no signs at all.
• Dogs and cats pick up roundworms from their mother or from infected feces. The potting soil in houseplants is a reported source of roundworm eggs for indoor-only felines! 
• Humans can accidentally ingest roundworm eggs. Infection in humans can cause blindness or organ damage (yikes!).
• Many heartworm preventatives are helpful in treating roundworms, but may need to be used year-round to be most effective.

Heartworm

• Not an intestinal worm, I know! Heartworms live in the heart and lungs of infected dogs and cats.
• Mosquitoes transmit immature heartworms from infected animals to healthy dogs and cats. Even "indoor only" dogs and cats are at risk...have you never been subjected to the whiny nighttime hum and nip of rogue indoor mosquitoes?
• Untreated, heartworm disease is fatal and treatment itself can have dangerous side effects. 
• In dogs, signs of infection may include coughing, difficulty breathing, sluggishness or no signs at all. Cats usually have signs of respiratory disease (similar to asthma), vomiting, lethargy or--you guessed it--no signs at all.
• Heartworm infection can be diagnosed with a simple blood test.
• Heartworm is easily prevented with a variety of safe medications that can be given orally or applied to the skin once a month. As discussed above, many heartworm preventatives do double duty as an intestinal dewormer and some also treat fleas! Your veterinarian can help you sort out the options.

The take home message is that parasites are almost never diagnosed by the naked eye. I hear it time and again: "My dog doesn't have worms. His poop looks normal." You will generally only see worms if your pet has tapeworms or has a really, really bad roundworm infestation! Next, almost all intestinal parasites require multiple courses of deworming medication to be effective. Like fleas, certain stages in the worm's life cycle are resistant to treatment, so you need to deliver the punch repeatedly! Finally, some parasites are contagious to people (especially children and immune-suppressed individuals) making preventative deworming that much more important in certain households.

Your Pet Pooped on the Floor: Why Your Vet Can't Assume It's Behavioral

Here's the scenario. A family adopts two "teenaged" spayed female cats from the shelter. These two teeny boppers are welcomed into the household by the older neutered male cat and the family's dog. The introduction appears seamless. The new kitties cuddle with the labrador and cavort with the cat. But someone has pooped on the couch! And the rug! The owners know it's one of the cats but which one? Is it Mister, latently unhappy about sharing his digs? Is it one of the new kitties, unsure of her surroundings or just reveling in her new freedom to go where she pleases? The poops are pretty normal looking, so it seems like a behavioral issue.


As the family's veterinarian, my first response is "we gotta get a stool sample and run some tests." The only way to diagnose a behavioral toileting problem is to rule out medical causes first.  


"But how will we know whose poop is whose?"

Sometimes that matters and sometimes it doesn't. I like to run the fecal tests on the aberrant stool...one that's softer or yuckier than most or the one that's been deposited where it doesn't belong. The owner of the stool-- when we're talking cats--usually doesn't matter if the problem is infectious or parasitic. Because cats generally share litter boxes we assume that if one of them has worms (for example) they all have worms and all need to be treated accordingly.

Before long I was in possession a fresh sample from one of the new kitties. When evaluating a stool sample for abnormalities, the first test is simple observation. Yes, it's gross, but what does it look like? How does it smell? Sometimes we'll probe the sample with a be-gloved hand checking for foreign material or worms, but 3 out of 5 senses is as far as it goes! This sample happened to be soft but formed with a portion being slightly runny. 

In my veterinary practice a complete fecal test includes a smear, a float and a Giardia "snap" test. These in-house tests identify the most common causes of inappropriate defecation and outright diarrhea.

The fecal float is the test most well known. This checks for parasites such as worms and Coccidia. Coccidia are a species-specific protozoa that commonly affect young or immune-suppressed pets. As for worms, most animals with light worm loads do NOT have worms visible in their stool, so please don't get a false sense of security that your pet is worm-free just because you see no worms! The fecal float helps us identify intestinal worm infestations by showing those worms' eggs. If the worms inside the pet are not reproductively mature or simply not shedding eggs on a particular day, this test may be falsely negative for worms.

The fecal smear helps identify a bacterial overgrowth of the intestines. Every normal gut has a mixture of beneficial bacteria that help digest the food and provide essential nutrients. A wide variety of internal or external factors can destroy this delicate balance and cause abdominal discomfort and/or diarrhea. Luckily most abnormal findings on the fecal smear are not contagious to other pets and people.

Meet Giardia

The final part of the complete fecal test a Giardia "snap" test. This is a highly accurate test to identify active Giardia infections. Giardia is a contagious and zoonotic (i.e., affects people) protozoal parasite that is  common in the environment. The parasite unfortunately also rears its ugly head in shelters and breeding facilities from time to time.

Lo and behold, while the first two tests showed no significant abnormalities, the kitty's Giardia test was an obvious positive. Wow! Even though the kitty's stools have appeared pretty normal, she has an infectious and contagious medical condition. This is the most likely explanation for poop on the couch and rug, NOT a behavioral quirk. 


The good news is this kitty has a treatable medical condition rather than a behavioral problem. The bad news is all the dogs and cats in the house need treatment because of their close quarters. Shed in the feces, Giardia cysts (i.e., eggs) can remain viable in the yard, litter box, bedding and pets' fur and cause re-infection, so a thorough environmental scouring is necessary. The pets were bathed, their bedding and litter boxes washed, and the yard picked up. Each pet is currently undergoing treatment for Giardia to be on the safe side. The owners have been warned to practice good hygiene when handling the animals and to contact their physician for further advice regarding the zoonotic nature of this parasite.


It is said time and again in veterinary school, "You miss more by not looking than by not knowing." Even though the stool appeared normal and there were plenty of possible explanations for the couch poop, we discovered an important medical problem with our thorough test. Thank goodness we checked! And I'm sure the owners will feel the same way after they've completed a hellish week of medicating three feisty felines!