Monday, October 31, 2011

Vehicle versus the Vulture

About a month and a half ago, we got a call from some good samaritans telling us about a turkey vulture (Cathartes aura) that had just been hit by a car on I-10.  He was struggling on the side of the road and his wing appeared badly injured.  Unfortunately, the vulture was feeding on some road kill itself and got too close to the traffic.

The interesting thing about turkey vultures is that they feed primarily on carrion and they have an extremely acute sense of smell which they use to pick up the scent of a carcass.  This sense of smell is INCREDIBLY unique in the avian world and they are particularly good at picking up the scent of ethyl mercaptan (a gas produced by animals beginning to decay).  The olfactory lobe of a turkey vulture is well developed when compared to other avian species which helps allows a turkey vulture to actually detect odors up to 12 miles away.

When our patient arrived at the Tucson Wildlife Center he was very painful and dehydrated.  Lou Rae quickly addressed his pain management, gave fluids, and stabilized his wing with a figure-8 bandage.  He was then placed in a warm, dark incubator and allowed to rest.

When I arrived at the center, Lou Rae and Warren helped me perform a physical examination.  Unlike raptors, vultures have a wicked bite and they aren't extremely dangerous with their talons.  You have to be careful though when you handle a vulture (WARNING: ONLY PROFESSIONALS SHOULD EVER HANDLE WILD ANIMALS), because they all tend to vomit or regurgitate as a deterrent.  It definitely is effective, believe you me!  We carefully unwrapped his wing and immediately we all noticed that he had broken his humerus (the human equivalent can be visualized here).  We decided to take radiographs to see how bad the the fracture really was...

Ventrodorsal view - right humerus

AP view - right humerus

Looking down on a chicken skeleton,
showing the relation of the humerus.

An anteroposterior (AP) view is just a fancy way of us shooting the x-ray beam through the front and out of the back (of the feathers) of the wing, as the vulture is positioned next....

So the fracture itself can be considered a mid-diaphyseal fracture of the humerus which is mildly to moderately displaced.  It was going to be a tricky repair!!!  We scheduled surgery for the next morning and fasted the vulture prior to be anesthetized...follow the pictures below for the rest of the story.

First, the vulture is given a pre-med to
calm him down and allow for less gas
anesthesia to be used.  Here, isoflurane is
being given to induce anesthesia.
Once asleep we have to then intubate all
of our patients to provide a direct path
for airflow and anesthesia

We have now intubated the vulture, meaning
a tube goes from his mouth, down his trachea
and supplies gas anesthesia and oxygen to his
respiratory tract.  Notice the "red head" which
is why they are called, Turkey vultures.

The patient is then prepped to go to surgery.
The machine at the right of the picture is our
gas anesthesia machine.

I had to make a small skin incision at one end of his humerus
and then use a surgical drill to place an "intramedullary" pin
for resisting "bending" forces.  We will go over this in a bit.
A few other pins were drilled through the bone at different areas
on either side of the fracture site to add "rotational" stability.

Close up of surgery site

Close up of surgery site - labelled
Clearly not showcasing my artistic talents

We then placed a rubber drain over the pins,
and filled it with an epoxy to add support to the
external fixator (much like the bobcat jaw repair!)

The vulture was then recovered from anesthesia carefully, extubated, and when he was fully awake given a meal.  The fixator needed to stay on for at least 6 weeks and then would be reassessed via radiographs prior to removal.

Approximately 6 weeks post op

Let's briefly discuss intramedullary pins and the "bending" and "rotational" forces that a veterinarian has to be aware of when fixing a fracture on an animal.  

Intramedullary pins simply enter the "middle" cavity of a bone; most commonly a long bone.  This middle cavity is called the medulla and a pin should be approximately 60-75% of the width of the cavity.  To illustrate this, review the image below....

Once you put an intramedullary pin, into the medullary cavity... that bone will no longer be able to bend at the fracture site easily.  Consider, very lightly, a corn dog and a stick.  The hot dog in the middle would be equivalent to the medullary cavity and the outer bread covering would be the bone.  Without the stick in the middle of the corn dog, you can very easily bend and break it; but with the stick through the entire corn dog it resists "bending" forces a lot better.  Even though this stick (analogous to the intramedullary pin) provides resistance to "bending" forces, the corn dog can still rotate quite easily around a 3-dimensional axis.  This is less than ideal if a corn dog has a fracture because then it would never heal if it constantly moved!  So then to provide that "rotational" stability, you place external fixator pins through the corn dog to secure fix it along an axis to provide complete fixation.  If that doesn't make sense or you don't like corn dogs...leave a comment below and I'll try my best to come up with another food group; or if you wanted to read about this in medical terminology, follow this link about intramedullary pins and this link regarding external fixation.

To date, the vulture is doing very well and currently has his external fixator off!  The volunteers, along with Lou Rae, Warren, and Lisa have also been performing routine physical rehabilitation on his wing to help strength his muscles.  He is even starting to fly short distances in one of the flight cages!  He currently lives with Egor (a Black Vulture) and while I was trying to record a video of our patient flying, Egor didn't take kindly to candids of his friend and chased me out of the cage... (I'll try again in the near future and post it if I get a good shot!)

Saturday, October 15, 2011

Update on the Coughing Coyote!

It's been a long road, but our little coyote friend that had SEVERE pneumonia is finally getting better.  It is because of the volunteers (along with Lou Rae and Warren), that our coyote friend finally can breathe without constant wheezing and is now playing with his food rather than staring at it!  I would like to take this opportunity to really thank everyone who works/volunteers at TWC for a wonderful job that they do; without them the animals that are injured, abandoned, or sick that are brought into the wildlife center would never have a chance....

About two weeks ago, we were really concerned about the coyote.  His wheezing and coughing became more consistent than it ever had been and we were afraid that our antifungals and antibiotics that he was on just wasn't cutting it.  We decided that we needed to do bloodwork and a bronchoalveolar lavage to figure out the EXACT cause for the pneumonia.  Blood was carefully drawn by Lou Rae and submitted for analysis at Southern Arizona Veterinary Specialty and Emergency Center (SAVSEC).  We needed really specific tests (testing for valley fever and Ehrlichia) along with a complete blood count and biochemistry profile.  Once the blood was brought to SAVSEC, it was prepared and sent off to the laboratory (results to follow down below).

To do a bronchoalveolar lavage the coyote needed careful sedation.  We had to be very careful not to compromise his respiratory system and choose appropriate sedatives for the task.  But, you may ask yourself, what the heck is a bronchoalveolar lavage; or otherwise affectionately called BAL?  Let's look a little bit at the anatomy of the the respiratory system of a dog first....

When you first look in the mouth of a dog, or coyote in our case, the first thing you will see is the oral cavity consisting of the teeth, tongue, gums, etc.  If you look past the tough however, you will see something called the epiglottis which is a very important piece of cartilage that helps block food, water, and other debris from entering the trachea (otherwise known as the windpipe) unexpectedly.  When you "swallow funny" or a friend says "it went down the wrong pipe" sometimes a small amount of food or fluid will enter the trachea bypassing the epiglottis, thus triggering a coughing effect in an attempt to get it out of the trachea!  Right above (in anatomical terms "above" is more commonly referred to as dorsal) the epiglottis, if you continue following it back (or in anatomical terms, caudal) you will enter the trachea.  This whole thing can be viewed in the image below....

Canine upper respiratory anatomy

The trachea is a cartilaginous structure that runs down the neck and then splits (called bifurcates) near the base of the heart.  The first "split" or bifurcation are called the primary bronchus and then it branches even  further eventually making bronchioles (very, very, very small wind tunnels that do not contain the cartilage as support).  If you think of a tree with all of its branches, you can sort of visualize what the trachea (equivalent to a trunk of a tree) turns into.  This allows the air that we breath to then enter the lungs...

Trachea anatomy

Now, once the air enters these tiny little branches (bronchioles) it comes to the lung tissue.  Microscopically, the lung tissue looks like little balloons and the interface where the air meets the blood stream is called the alveoli (pronounced al-vee-OH-li).  If you talk about just "one" alveoli it's called alveolus (pronounced al-vee-OH-lus).  The alveoli are basically one cell thick!  REALLY THIN!  And this helps the oxygen in the air we breath enter the bloodstream supplying the rest of our body with oxygen that is essential to life!  Also at this point, since the air has gone through the trachea, then the bronchus (primary, secondary, tertiary) then the bronchioles; the air that is usually dry and sometimes not body temperature is warm and humid - perfect for the red blood cells!

Lung anatomy

So, now we put it all together and then you have the anatomy that looks like the picture below...

Canine Respiratory Anatomy all put together

Now we can revisit this medical procedure called the bronchoalveolar lavage (BAL).  I'll preface this with a slight warning... Lou Rae and myself are vaccinated against rabies and therefore qualified to work with wild mammals.  You never know what animal may carry rabies so DO NOT TOUCH ANY WILD ANIMALS OR EVEN UNVACCINATED DOGS/CATS; leave that to the professionals.  The coyote needed to be sedated because we needed to "lavage" the lower airway with sterile saline.  Once sedated (and with an intravenous catheter in place) we placed an endotracheal tube (meaning into the trachea) and gave the coyote some 100% oxygen while we prepped the instruments needed to perform the procedure - STERILE INSTRUMENTS ARE REALLY IMPORTANT HERE.  We used a sterile red rubber catheter and carefully inserted it into the endotracheal tube, down the trachea.  We then introduced sterile saline into the red rubber catheter to allow it to lavage or wash the tissues in the lung.  After a few minutes, we then took a sterile catheter and drew up the fluid we just pushed down into the lungs.  This enables us to then submit a sample of the cells and possible infectious agent of what is causing the pneumonia in the coyote.  And we got some really good samples!  We submitted it to the Arizona Veterinary Diagnostic Laboratory to Carlos Reggiardo, DVM, PhD, DACVM (a veterinary microbiologist).  Unfortunately, it did not find a cause for the pneumonia and our sample only consisted of a large amount of inflammatory cells.  You can read a little bit more (actually A LOT more) about BAL here.

Our bloodwork returned and showed an extremely high white blood cell count (consistent with some sort of infection).  Ehrlichia titers were negative.  Our valley fever titers, however, did show that the coyote was exposed (we will talk about immunology during another post) to the fungal organism (Coccidioides immitis)!

So using this information we discontinued the antibiotics and concentrated on the antifungals for treatment along with some anti-inflammatories... And, wouldn't you know it... his most recent radiographs are MUCH improved - take a look!

Right lateral - October 1, 2011

Compared to what he looked like initially....

Right lateral - August 19, 2011

And there you have it....thankfully the coughing coyote is no longer coughing or wheezing.  I hope that we only continue to see improvement in this little guy!  His recovery from this horrible fungal pneumonia is only attributable to the volunteers, rehabilitators (Lou Rae, Lisa, and Warren), SAVSEC, and to you...the donor.  Which makes our ability to protect Southern Arizona's wildlife everyday possible.

Monday, October 3, 2011

Bobcat under the boat!

A little more than 2-weeks ago, the Tucson Wildlife Center responded to a call regarding a bobcat under a boat (Fox News report). Unfortunately, the bobcat had been stealing chickens from the homeowner and was subsequently trapped with leghold traps attached to both hindlimbs and dragged him over a wall and then underneath a boat to sit there for a full day.  The Tucson Wildlife Center was called to the property and carefully rescued the animal.  There are many other ways that the homeowner could have gone about removing/relocating the bobcat from the property humanely.  Calling the Tucson Wildlife Center (520-290-WILD or 520-290-9453) is one of the easiest ways to get information on how to deal with the humane removal and relocation of our wild friends.

Lou Rae called me at 9pm concerned about the damage done to the bobcat's feet and his level of dehydration.  The bobcat was sitting under a boat without any access to water for over 10 hours and the leghold traps remained in place.  I met her at Southern Arizona Veterinary Specialty and Emergency Center (SAVSEC) to stabilize him, address his pain, and do some diagnostic tests before bringing him to the center.

Stabilizing an animal requires quick assessment of the ABC's which stands for airway, breathing, and circulation.  The bobcat appeared to be breathing rapidly (called tachypnea or tachypneic) which could have been a result of pain associated with the traps/trauma or could mean some sort of chest injury.  His respiratory effort, however, was normal and his lung sounds were normal bilaterally.  His blood pressure was low (systolic-60mmHg) so we bolused him fluids intravenously while we finished his physical examination.  Blood pressure is measured as systolic (sis-TOL-ik) and diastolic (di-a-STOL-ik) pressures. "Systolic" refers to blood pressure when the heart beats while pumping blood. "Diastolic" refers to blood pressure when the heart is at rest between beats.

Once we were able to bring the bobcat's blood pressure to normal limits, we carefully removed the traps from his legs and continued with the physical examation.  He had a lot of swelling noticed along his back feet and some puncture wounds acquired from the traps.  On palpation of his back paws, no crepitus was appreciated along his metatarsals.  

Canine skeleton showing location of metatarsals

This physical exam finding (no crepitus), strongly suggests that the bobcat may have been lucky - despite being trapped for over 10 hours - and have escaped without any fractures to his hindlimbs!  To further investigate this hypothesis, we decided to take radiographs.

Despite the absence of fractures to his hindlimbs, he still suffered from severe soft-tissue injury and required pain medications and wound cleaning.  Upon further examination, the right-side of his jaw appeared very unstable.  Concerned that he may have a jaw fracture, we decided to concentrate the rest of the radiographic study to his skull.

Right lateral oblique

Right lateral oblique labeled

And even a more dramatic view of the mandible fracture....

Left lateral

left lateral labeled
The fracture was to the right mandible (lower part of the jaw) and can by classified as a comminuted fracture. A comminuted fracture simply means a fracture in which the bone has broken into a number of pieces (seen within the green segment highlighted above).  Repair of a fracture like this is very challenging, as the surgeon does not have a lot of places to help stabilize the rest of the jaw.  It also suggests that the bobcat experienced a very high-powered blow (hit) to the face.  Coupled with possible metal fragments (the bright little dots scattered along the face on the radiographs), we were initially concerned with a gun shot but no entry wounds to the face were observed on physical examination.  The jury is still out; but we know for sure that this poor guy was hit, and hit real hard in the face.

After we addressed pain management, stabilized him with fluids, and took the radiographs; Lou Rae then ventured back in the middle of the night back to the wildlife center to let him rest quietly...

The next morning, Lou Rae, Dr. Ted Berghausen and myself  prepared for our bobcat for surgery.  We all knew it was going to be very challenging but wanted to try and give this guy a chance.  The bobcat was pre-medicated with pain medications and light sedatives to make him tractable to work with (great care and respect was taken to ensure the bobcat and surrounding personnel were safe).  We carefully placed an intravenous catheter in a back leg to supply the patient with fluids, antibiotics, and pain medication throughout the entire procedure.  He was then given stronger sedatives to allow us to place an endotracheal tube to keep him under general anesthesia.  Then we got started and found exactly how many pieces his jaw was in....

In this picture, the bobcat is laying on his
back and the tip of his chin is towards the
top of the photo.  The exposed bone is a few
of the many pieces we actually found during
the surgery, making fixation very difficult.
We then decided that since there were
so many pieces, what we needed to do
was to stabilize the larger pieces of the jaw
by drilling pins into the bone and connecting
the pins together to make an external fixator.

Two pins in place along mandible

Pins were reinforced using an epoxy

In an ideal world, we would have placed the pins on the side of the bobcat's jaw but we were concerned that if he were able to see it, he would paw at it and remove it himself.  By placing it underneath his jaw, we risk drilling through some tooth roots, but it was absolutely necessary to help repair his jaw.

Before we recovered him from anesthesia, we tested the stability of his jaw and found that the fixator (pins and epoxy) was very strong and that his "smile" was now straight.  Lou Rae and I came up with strict treatment plans for the bobcat over the next few weeks and we woke him up.  He recovered uneventfully from anesthesia and his pain appears very well under control.

It initially took him a few days until he started eating but now has consistently accepted his morning and evening meals (not chickens).  The ultimate plan is to keep him at the center over the next 6-8 weeks until we can sedate him and take additional radiographs of his jaw to assess healing.  Once his jaw bones appear fused, we will then remove his fixator (pins and epoxy) and be able to release him.  We will keep you updated with his progress!

Just is because of your donations that this bobcat will someday be out in the wild again, keeping nature in balance....

Notes to readers/case discussion:
We are very fortunate in Southern Arizona to have wildlife at our doorstep.  We have to respect our unique environment and make a conscious effort to not harm or threaten any that may visit our backyards.  We also have to remember that they were here first.  If you are ever concerns about any wildlife that may be getting "too close" for comfort or interfering with your life, please contact the Tucson Wildlife Center for ideas or recommendations.  It is not appropriate, regardless of the law, to put these animals through needless suffering when we have answers just a phone call away.  Rescue, Rehab, and Release....

Special thanks to Dr. Stephanie Szabo, VMD, Diplomate ACVS for all of her help discussing possible surgical approaches...