Diseases

Mange / Demodecosis

/ Dr. Christine McFadden / Leave a comment

Dr Mc Blog

 

August 27, 2014
People love the word “mange”. “He’s just a mangey old alley cat” someone will say. Used as a description for a pet with scruffy fur or unsightly skin, most people don’t realize that mange is a group of very specific skin diseases caused by parasitic mites. There are different sorts of mites, all possessing eight legs and often only visible under a microscope. There are two kinds that commonly affect the dog.

Sarcoptic mange is caused by an ugly little mite, sarcotes scabei, that burrows into the skin of both dogs and people. Often called “scabies”, it is feared primarily because of its transmission both from dogs to people and between people. Excellent treatment protocols are available for this disease.

Demodex or demodectic mange is an entirely different skin disease. First, it is NOT contagious to other pets or people. Second, the demodex canis mite burrows very deeply into the hair follicles of the skin and is sometimes harder to treat than sarcoptic mange. Puppies contract it while nursing from their mothers (strange but true). There is some thought of either an inherited predisposition or a depressed immune system allowing the pups to express the disease visually, as not all pups in a litter may be affected. When first seen, a puppy may display only a bare patch around one eye. It’s not painful and doesn’t itch, but usually looks so unsightly that it causes immediate alarm. Often the mite doesn’t show up until the pup is over six months of age, which confounded scientists trying to understand the connection between exposure and disease expression for years. For some puppies the disease can be far worse than an unsightly bald patch. The entire body may lose hair in a case of generalized demodecosis, with scabs and sores erupting as a secondary bacterial infection kicks in. Edema and swelling of the face and feet are common, making a pup truly miserable. These puppies are extremely ill, their immune system is gravely compromised and some may die.

Because the skin can only react in a limited number of ways to any disease, signs of hair loss, open sores and itching can be caused by a variety of problems : other parasites, allergies, staph and other bacterial infections, fungal infections. A veterinarian needs to examine your pet to make the correct diagnosis. A skin scraping is diagnostic for demodex- but not always for sarcoptes. A sharp blade is used to literally scrape any potential mites off the skin and the slide is examined under the microscope. Positives are slides that wiggle back at you!

Fortunately, there are several treatment options available for demodectic mange. Thirty years ago a breakthrough dip was discovered, which revolutionized the old “cover ‘em in tar” treatment. Today that dip is less frequently used as new oral and topical medications have been developed, which when combined with antibiotics and medicated shampoo treatment protocols have greatly improved the cure rate for this disease. Once treated, dogs are cured of demodex, though if allowed to breed there is a strong risk they will pass it on to some of their offspring.

Perhaps my most memorable suspect demodex case occurred a few years back. The young German Shorthair Pointer presented with some hair loss around her muzzle. The skin scraping was negative, so I started a fungal culture for ringworm. Cultures take about two weeks to run their course. When the ringworm culture was negative, the Pointer returned for a recheck. The lesions were spreading, red sores and deep cracks tracing from the bridge of her nose down the sides of her face and lips. The rash was especially bad just below her eyes, though her eyelids were surprisingly clear, the skin untouched by disease. The rest of her coat remained beautiful. I again did a skin scraping, and when negative, repeated the test. Negative. Convinced as I was that this must be demodex, I told the owner that we would start therapy immediately before this could spread further.

When I next saw the dog she was the picture of health. Her face was completely clear, new hair growing in on smooth skin. I glowed. Success is wonderful. It was the client, of course, who set me straight. A bachelor who did most of his own cooking, and not too elaborate, thank you, he frequently fixed up a can of beans. Seems the Pointer liked beans too, straight from the can. He caught her burying her nose in deep to reach that last drop.  Her face cleared up as soon as he found another disposal system for the cans. My antibiotics probably helped the secondary infection but there was no denying that my years of training had let me down. The medical texts on mange variations do not mention bean-can-itis.

Christine B. McFadden, DVM
drmc@mcmenagerie.com

Rabies

/ Dr. Christine McFadden / Leave a comment

Dr Mc Blog

May 29th, 2014

I’m going to talk about something scary today. Not an alien life form but a very real live virus called rabies. Rabies didn’t die out with Old Yeller – it is still very much with us, and definitely present in the wildlife of Merced County. In fact, Merced is considered an endemic area for the disease. We have positive cases every year! In the 30 plus years I have lived and worked here, I have watched both the Public Health Department and Animal Control cooperate to monitor Rabies positive cases turned in to the County. They map where the rabid animals were discovered, watching for “hot spots” of possible contagion in the wildlife. Positive rabid bats and skunks have been identified, often after a dog or cat has carried it into the house or killed it. But what about the animals that just quietly die in the wild, that may be carriers of the disease? This, of course, is how it is spread. Consider: Rabies virus enters the body through a direct bite or contact with the mucous membranes (eyes, mouth, nose). Once there, it slowly spreads into the nervous system, eventually reaching the brain. There is NO CURE for the disease at this point. In fact, only because the virus multiplies and spreads so slowly is it possible for post-exposure immunization to work and save human lives. Rabies is diagnosed after the brain of the suspect animal has been inspected. There is no way to diagnose the disease in a living patient.

California is considered to have a high incidence of cases – over 400 cases in wildlife reported annually. Skunks and bats are the most frequent wildlife involved, but other carnivores such as  raccoons, foxes, coyotes and bobcats are often positive.

Each year one or two cases of human rabies is reported in the United States. Since 2002, 21 of 24 reported human rabies cases in the US were linked to bats, per the Center for Disease Control (CDC). July 24, 2013 a young girl was bitten by a rabid bat at the Oakland Zoo- it was not an exhibit animal, just local wildlife. She received post-exposure immunization and is fine. Easter in Bakersfield, California of 2012 was grim for the family whose pet cat bit their child, after itself contracting rabies from area bats. In June, 2011 an 8 year old girl from Willow Creek, California actually survived the disease after intensive treatment at UC Davis’s Childrens Hospital. She is only the third person in the US to survive rabies without receiving the post-bite immunizations. Most people die or become vegetables. In countries where vaccination vigilance is not as high as the United States, rabies is a serious threat : 60,000 people die from this entirely preventable disease every year! Three “islands” are isolated enough to have no rabies : Hawaii, England and Australia. Travelling with pets to these places is a complicated process as they strive to remain rabies free, protecting people and their indigenous or native wildlife from sure death.

Because wildlife cannot be vaccinated against Rabies, your FIRST LINE OF DEFENSE is to vaccinate your pets, the carnivores at highest risk of coming in contact with wildlife. ALL DOGS and CATS should be vaccinated against rabies. And you should never approach wildlife, especially when they seem sick.

If your dog or cat is bitten by a bat or suspect carnivore that isn’t available for brain examination it is presumed exposed to a rabid animal. If the bat or skunk is confirmed positive and rabid and the dog or cat is NOT current with rabies vaccination protection it may be recommended that it be immediately destroyed. If the pet is current on vaccination, by law it will still be isolated for anywhere from 10 days to 6 months, depending on the individual circumstances of the case.

If a human is bitten, whether it be a pet or a stray dog or cat, or any wildlife, it should immediately be reported to a physician. If the animal is available, it will be quarantined or its’ brain will be examined to check for rabies. The type of bite, animal involved, vaccination history and other factors will determine the recommendations made by your physician and public health authorities.

This is where your money for those darned rabies licenses go. This is what it’s all about. The message : Vaccinate your pets against rabies. It’s the law – and it’s a good one!

Christine B. McFadden, DVM
ValleyAnimalHospital
drmc@mcmenagerie.com

Heavy Metal

/ Dr. Christine McFadden / Leave a comment

 

Dr Mc Blog

May 21, 2014
She was all white, an itty bitty poodle, and absolutely miserable.  Trouble was her gums were white, too. And when you look in a dogs mouth, the gums should be bubble gum pink (exception : dogs with Chinese heritage may have black pigmented gums and tongue – called a flowered tongue – like Chow Chows). A dog that pale is anemic, meaning they don’t have the normal number of blood cells circulating, and no blood means no oxygen and no nutrients are being carried throughout the body. Anemic pets are very weak. Little SugarCube was also vomiting and had bloody diarrhea. As a veterinarian I see a fair bit of diarrhea (ask me, please!), but it is uncommon to have one so severe that the dog looks like it’s bleeding out. Nothing in SugarCube’s history gave me a clue as to cause : she was a house dog, with no exposure to rat or mouse bait (rodenticides), she didn’t travel so exotic parasites were unlikely, she was older and vaccinated so forget parvo, and her diet was neither varied nor was she given bones that might upset her stomach.

When faced with a problem like this, we start at the beginning : basic blood work and x-rays. These two simple tools are the building blocks upon which so many further diagnostic tests depend. They rule in – or out- many possibilities of disease causes. Because we can run these simpler tests in–hospital, we knew within the hour that SugarCube had a life-threatening form of anemia, a hemolytic anemia, where the body is bursting its own cells but, more oddly, she had a metallic foreign object in her stomach. It was shaped liked a hoop earring, which the owner identified but couldn’t place when the dog might have gotten it. This was one of the few times when my work with birds came in handy for another species. Birds frequently chew and bite on odd objects and frequently present for “heavy metal toxicity” (nope, not a music over-load). Both lead poisoning and zinc toxicity are treated the same in birds, but symptomatically there’s one huge difference : both can kill, but only zinc causes a hemolytic anemia. So as we stared at these x-rays, I hypothesized that the foreign object in Sugarcube’s stomach was poisoning her and we had to get it out. But how on earth was she going to live through surgery? There wasn’t time for the antidote to work, even if we had enough on hand for a dog (we didn’t and the stuff, Calcium versenate, isn’t stocked by regular or human hospital pharmacies). We began treatment to shore up her immune system, started IV’s to stabilize her, and began a blood transfusion. Within hours of entering our hospital, we took SugarCube to surgery.

We entered her abdomen, going right through the belly button, and quickly examined her intestine, spleen and other abdominal organs. Gently palpating (feeling) her stomach, the metal ring could be felt. Fixing it in place with a finger, we sliced into her stomach and removed….a penny. A copper Lincoln head penny! That had been in her stomach for so long that the natural gastric juices (weak hydrochloric acid) had worn away the face and created a hole in the middle of the coin, faking us out that it was an earring when seen by x-ray! (Trivia break : Copper pennies minted after 1981 are filled with : zinc! Thank you birds – all the ducks, geese, and an occasional chicken that swallow pennies). Our diagnosis was confirmed and with the source of her poisoning removed, we quickly sewed everything back up and awakened SugarCube. She went on to make a full recovery .

Christine B. McFadden, DVM

drmc@mcmenagerie.com

A Helping Hand (Corneal Ulcers)

/ Dr. Christine McFadden / Leave a comment

Dr Mc Blog

May 14, 2014
“As I was saying, my daughter says that there’s something wrong with her eye. You see it’s kind of mattering and she keeps it closed pretty tight. My daughter gave me some medicine to put in it, but it’s not better, so she said maybe I should see you.”

“Ah”, I said, a trifle overcome. As I gazed at the little cocker spaniel quivering on the exam table I could only be grateful that at last they had sought professional help. She was a pretty little dog but today her head hung low, the eyelids of her right eye neatly pasted together. It looked painful. I had to place eye drops infiltrated with a local anesthetic into her eye before she would let me examine it.

And what an eye! The entire cornea, or outer clear layer that covers the eyeball, was fuzzy blue, a sign of swelling and fluid accumulation (corneal edema) between the thin corneal layers. At the center of the eye a small pit could be seen. This was an ulcer, a hole punctured in the eye by a sharp object – shrubs, cats, foxtails, a bit of trash caught by a face hanging out the car window? It was obvious, too, that the body had tried to heal itself : a fine network of thin vessels traced their way to the edge of the ulcer, to increase circulation and carry off infection cells. (This is why products like Visine are a no-no – constricting the blood vessels prolongs irritation, though the eye will look more clear). Fortunately the ulcer, though severe, was not very deep. A very deep ulcer that has almost pierced the eye will have a deep blue-black appearance and is called a descemetocoele, named for the last of the last ten thin corneal layers that prevent a dog’s eyeball from leaking all over his face. A descemetocoele ulcer often requires corneal surgery.

I applied a small amount of an orange stain containing fluorescein dye to the cornea and watched it turn green over the ulcerated area, outlining the extent of the ulcer nicely. An intact cornea will not take the dye.

I turned to the couple to discuss treatment, now satisfied that I knew the extent of the problem. As I opened my mouth the elderly gentleman hurried to fill me in on my options. “Now don’t you be suggesting surgery. My daughter warned me about those. Said she had a dog done once where they sewed the eyelid up and she could hardly get the medicine in.” Helplessly I asked, “But did it get better?” “Oh yeah, but my daughter didn’t like it.” “But”, I protested, “sewing the third eyelid (inner eyelid – dogs and cats have them, people don’t) up and over the ulcer protects it from further injury and keeps it from drying out. For a small ulcer it isn’t necessary but this has been going on for some time.” “No, ma’am”, the man held firm. “My daughter told me not to do it.”

Well, you do the best you can. The little cocker was given some antibiotic eye drops and some other eye medications, with strict instructions to return within 5 days. That eye took more than twice as long as most to heal, until it would no longer take up the fluorescein stain, and she would always bear a scar. The little dog felt much better, but the client had his own views. On our last visit he surveyed the eye with deep satisfaction. “Yep”, he said, “My daughter told me it was healing up just fine. I only brought her in cuz I knew you’d want to learn from this.”

Christine B. McFadden, DVM

drmc@mcmenagerie.com