Cuterebra are not cute (and maggots are just plain gross)

Parasites create a buzz of excitement in a veterinary clinic. Creepy, crawly, stinky? Bring it on!

This week was especially interesting with the appearance of two different species of parasitic larvae arriving inside the skin of two of my mammal patients. The technical term for parasitic fly larvae is "myiasis."

Rabbit afflicted with Cuterebra larva

First, a father called worried that his daughter's pet bunny had been shot with a B-B gun while it was in its outside enclosure because it had a hole on either side of its neck. When the bunny arrived she was bright and alert. Although she had two large wounds on her neck that were leaking fluid and pus, I learned she was not acting sick at home. As I prodded one of Flopsy's wounds a little maggot head peeked out at me! "Cuterebra!" I exclaimed happily.

While disgusting, cuterebriasis is a common and treatable condition in rabbits. Sometimes these larvae show up in the skin of kittens, cats and dogs as well. In the spring and early summer the female Cuterebra fly lays her eggs on blades of grass. When a rabbit or other mammal brushes against the infected grass, the egg or a recently hatched maggot attaches to its fur and then eventually burrows under the skin where it sets up shop. Occasionally these maggots migrate to the wrong place (like the lungs or brain) and cause all sorts of problems, but usually they mature into grubs inside their "warble" under the skin. Eventually they drop off the animal back into the soil where they finish developing. The B-B sized holes seen on Flopsy are the grubs' tell-tale breathing holes.

Removing Cuterebra larva from its warble under the skin

I very carefully removed a pair of fat Cuterebra grubs from Flopsy's neck, cleaned the wounds and started her on an antibiotic for the secondary bacterial infection in her skin. While removing Cuterebra larvae, care must be taken not to break or rupture the grub inside the skin because the pieces will cause festering wounds.*

I know it may be a matter of personal preference, but I find that while Cuterebra are not cute, they are definitely not as disgusting as regular old maggots. Our second myiasis patient, Trina, was an obese outdoor kitty who came in crawling with maggots. Trina had a terrible skin infection around her vulva (she couldn't clean herself because she was so obese) and a ruptured anal gland abscess. Flies had been attracted to her stinky, moist, dying flesh and had laid eggs there. We pulled dozens of wriggling white maggots from Trina's skin, inside her vulva and surrounding fur. (Yes, it was gross even for us veteran parasite handlers.) Then we shaved off the nasty matted fur on her back end, cleaned her wounds and administered pain medication and antibiotics. By the time we finished Trina looked, smelled and felt a million times better. Once we get her through this rough patch, Trina's family and I will be working together to get the extra Lbs off her.

*One theory behind the medical and veterinary symbols of a "snake" wrapped around a staff may stem from a skin parasite in people called Guinea Worm (dracunculus medinensis).  A traditional method of treatment is to wrap the end of worm around a small stick, gradually and carefully twisting the stick until the worm is completely extracted from the person's skin. Breaking the worm inside the skin can create a life-threatening bacterial infection such as tetanus.

Of Mice and Mayhem: A Rodenticide Story

An urgent call comes in late one afternoon.

"My dog just ate rat poison! What do I do?"

In my experience as veterinarian and pet owner, rodenticide ingestion is a pretty common problem. My own dogs once discovered an unknown stash of warfarin pellets, ate it and then, before I could clean it up, ate the pile I made them vomit up. Geniuses. All of us.

Veterinarians field this type of call regularly. If the case involves a typical poison and is caught early, prognosis is very good with aggressive treatment. This time, however, the owner's next utterance stopped me cold.

"It's bromethalin."

Not a warfarin-type rodenticide, I thought to myself. Oh boy. And the packaging instructed not to induce vomiting, often our first line of defense in cases like this.

"I want you to hang up and call Animal Poison Control at 1-888-426-4435 and explain the situation," I instructed. "They will give you a case number for Rosco so we can handle this exactly right on our end. In the mean time, I will look into this particular rodenticide as well and call you back shortly."

Bruising on gums caused by
anti-coagulant rodenticide toxicity

As I feared, bromethalin is handled nothing like warfarin. Warfarin is an anti-coagulant that was developed for use as a rat poison by University of Wisconsin chemists in the 1940s. (It is now also widely used as an anti-clotting medication in people!) Warfarin interferes with the liver's ability to make clotting factors. Without vitamin K supplementation, affected animals bleed to death from internal and/or external bleeding. It may take one to five days before clotting problems start, but if a pet is caught in the act of eating a warfarin rodenticide, treatment begins immediately and most pets (like mine) recover uneventfully.

Mankind keeps trying to invent a better mousetrap, or in this case, rodenticide. There are multiple chemical offspring of warfarin which are more potent and require longer vitamin K supplementation, but bromethalin is in a class all its own. Invented when rats became resistant to warfarin, bromethalin causes swelling within the brain and spinal cord leading to depression, stumbling, paralysis, seizures, coma and death. Unlike warfarin's vitamin K, there is no specific antidote for bromethalin toxicity. Prognosis is pretty grim, especially if pets are already showing symptoms when diagnosed.

Dog hunts rodents in his backyard

Luckily it was determined that Rosco did not ingest enough of the bromethalin brick for it to cause toxicity. The owners were told to watch Rosco closely and bring him in to the clinic for supportive care if he showed any neurological symptoms.  I'm glad to report that Rosco has had no signs of toxicity since the incident! Unfortunately, the owners now face the daunting task of locating untold numbers of bromethalin bricks buried in their backyard. In their war against the rodents invading their basement, this family has unwittingly become trapped inside a veritable mine field of deadly rodenticide bricks.

Dead hawk resulting from rodenticide toxicity

Rodenticide toxicity is not just a problem for pets. Just as mercury "bioaccumulates" in marine food chains making it dangerous for people to eat too much of certain fish from certain waters, rodenticides affect large birds of prey such as red tail hawks. These predators eat affected rodents (easy pickin' because they're sick) and over time the toxins make the birds very sick. Rodenticide poisoning and death among unintended wildlife victims is a disastrous consequence of our efforts to control rodents using increasingly potent chemicals. Just as strychnine use in Wisconsin requires special permitting because of its potential to harm non-target animals, there are many who would like to see tighter controls on modern heavy-hitting rodenticides as well. If you must use a chemical means to control rodents, please follow the package directions carefully to limit the poison's impact on non-target creatures.

Microchipping: Think Barcode Not GPS

There are many benefits to having your beloved pet microchipped. Tracking him via GPS, however, is not one of them.

A microchip provides a unique identification number to a pet. The microchip itself is not much bigger than a grain of rice and is injected under the skin between the pet's shoulder blades through a special needle. Many microchips are implanted while a pet is anesthetized for their spay or neuter, but sedation is not necessary. The momentary prick of the needle is well-tolerated by awake pets (as all of my microchipped dogs and cats can attest).

Once the microchip is implanted it must be activated or it will be of no use. Make sure you ask the person who implanted the microchip--your veterinarian or animal shelter--if they will be activating the microchip on your behalf. Regardless of who activates the microchip it is your responsibility to provide emergency contact information to the microchip company. If you move or change phone numbers, you must contact the microchip company to update their database.

There are many, many microchip providers. In the early days of microchip implantation everybody used a different type of chip with different frequency chip readers, so there were sometimes problems accessing the microchip information. For example, in those days, the animal shelter's microchip scanner might identify a microchip was present but might not be able to read the number. Fortunately, microchip companies have agreed on a standardized system and most veterinarians and animal control officers have "universal" microchip readers that can identify the number from any brand of microchip.

Nowadays, if your lost microchipped pet is picked up by the animal control officer or brought to a veterinarian, a universal microchip scanner will be passed over your pet's neck, shoulders, back and sides. Your pet's unique identification number will be typed into an online microchip search engine. Based on the brand-specific configuration of the microchip number (its number and/or letter sequence) the search engine will provide contact information for the particular microchip company. The animal control officer or veterinarian will then contact the microchip company to get your name and telephone number so you can be reunited with your pet.

Too many times, however, the database has inaccurate, out-dated information. Owners often move or get rid of phone numbers and forget to inform the microchip company. Some but not all microchip companies charge a fee to update contact information, but this nominal fee is worth the "insurance" that you can be reached if your pet is lost or stolen some time in the future.

While currently there are no GPS microchips* available, some microchip companies provide additional membership benefits beyond the "barcode" identification service. Free poison control case consultation, 24/7 veterinary advice (such as "Can my pet wait until tomorrow to be seen by his regular veterinarian for this concern or is it a true emergency?"), help locating a veterinarian while traveling, and proactive pet searches (e.g., lost dog posters sent to veterinarians, shelters and volunteer searchers in the area where a pet went missing) are some examples of additional benefits from having certain brands of microchip in place.

Pet microchips have reunited countless lost animals with their human families. There are amazing stories of pets being found hundreds of miles from home and years after disappearing, but countless more stories of momentarily lost pets being quickly returned home after a brief layover at animal control. Collars and tags can become lost or removed, but a microchip is a permanent and unique way of identifying your pet in the event it goes missing.


* There are special collars available with tracking devices, but these are used mostly on hunting or working dogs.

The Wonders of Canned Cat Food

"You are what you eat" the old saying goes. Taken literally we can get a little carried away. After all, I am not a 5'5" chunk of string cheese (much to my husband's disappointment). Of course, we all know it means our bodies will be healthier if we fuel them with health food rather than junk food.

Pet owners have become extremely health conscious on behalf of their cats and dogs. They realize that the food Fluffy and Fido eat day in and day out must be nutritious and wholesome. Sometimes the adage "you get what you pay for" applies to pet foods but sometimes it does not. Consumers will be wise to remember that all pet food companies aim to make a profit through selling their product. Pet food marketing strategically plays upon our emotions as animal lovers. We want to feel we are doing everything possible to provide a safe and satisfying life for our pets.

Rather than take out a second mortgage on your home to buy that premium bag of dry cat food, please take a moment to read about a "revolutionary" approach to feeding felines. An approach that may reverse feline diabetes, reduce the incidence of urinary crystals and kidney disease, decrease food-related vomiting and allergies, and keep your cat lean and playful into old age.

The answer to your cat's prayers (even if he doesn't know it yet) is canned cat food. When I said this was a "revolutionary" approach I was being ironic. Canned cat food more closely mimics the diet felines evolved to eat--mice.

A mouse is a high protein, high moisture, low carbohydrate meal. Dry cat chow is a low protein (or mostly plant-based protein), low moisture, and through-the-roof-high carbohydrate meal. Eating an exclusive diet of dry cat kibble leaves the modern cat morbidly obese and chronically dehydrated. Obesity leads to diabetes, cancer, arthritis, skin problems, and more. Chronic dehydration assaults the kidneys, and triggers bladder diseases ranging from infection to crystals/stones to sterile cystitis. Poor quality or species-inappropriate proteins are claimed to trigger skin allergies and gastrointestinal inflammation ("puking cats"). Quality of life suffers as cats put up with discomfort on these many levels. Is it unlikely that some of this angst shows up as "bad" behavior?

I do not believe dry cat food is evil personified. However, kibble is just not perfect nutrition for the mighty feline hunter. It is a myth that dry cat food helps keep a cat's teeth clean. If you ate nothing but granola, never brushed your teeth and never visited a dentist...I shudder at the thought.

You may argue that canned food gives your cat the runs or makes him puke (this is usually a temporary problem during transition). Or worse that he doesn't like to eat it at all. Unfortunately, switching from highly-addictive carb-rich dry food to high-protein wet food is not always a simple task. Is it always easy to put down the bag of nachos and pick up a stalk of celery instead? Dry cat food is coated in a highly appetizing animal digest that makes kibble as tasty to most kitties as fast food is to most Americans (hmmm, is there a correlation?) It can take months to convince some cats that canned food is...well, the cat's meow. It took eight months and untold patience on his caregiver's part before my diabetic patient Tucker relinquished his dry food in favor of the canned variety. Lo and behold his diabetes improved practically overnight! Dr. Lisa Pierson, DVM's handout "Transitioning Feline Dry Food Addicts to Canned Food" is an amazing how-to manual on teaching cats to love canned diets.


Ounce for ounce canned food is more expensive than dry kibble. For those cat owners who spare no expense, it may be a small thing to re-allocate the money spent on the premium dry food to cans instead. For those of us who operate on a tighter budget, we can certainly compromise. Is it affordable and practical for you to feed one moist meal a day? Even just several canned food meals a week can improve the overall health, activity and attitude of your feline friend.

Some tasty tidbits:
1) Normal cat poop is not voluminous and stinky. Cats that eat quality animal-protein moist foods exclusively pass smaller, firmer, less odorous stools. If you've even seen coyote or raccoon scat in the woods, you'll understand what a predator's waste should look like -- including your cat's.
2) Cats did not evolve eating fish. They evolved eating rodents and birds. While most cats like the taste of fishy cat foods, try not to feed fish varieties exclusively. I haven't seen "mouse" or "sparrow" flavored canned foods in the pet store yet, so you will have to stick to "beef" and "chicken" for now. (Yes, there are frozen raw food diets out there that more closely mimic a cat's wild diet...more on this later.)
3) If your cat gets on board with you and eats nothing but canned food from here on out, make sure it is "complete and balanced". Canned foods labeled "for intermittent or supplemental feeding only" are missing essential vitamins, minerals and amino acids -- fine as a snack, not for a lifetime.
4) Wet food diets do present very real challenges in the mechanics of feeding. We have become so used to shoveling dry food into our cats' bowls that it seems like the natural thing to do. It takes more thought and care to keep moist food fresh and appetizing. One suggestion is to freeze several meals and put out two meals each day--one meal warmed to "mouse body" temperature and the second left frozen to thaw throughout the day.
5) A mouse is approximately 30 calories. Cool factoid, huh? The average wild cat eats 7-10 mice per day, which is the equivalent of 210-300 calories. And they burn a lot of calories actually catching, killing and eating that mouse! (Oh yes, cats that eat wild meals like mice should be dewormed regularly...just because something is all natural does not mean it is completely without negative side effects.) Check to see how many calories are in a single 8 ounce cup of your cat food...