Thursday, January 27, 2011

Spider Bites

I think of winter as a time when bugs and snakes and things that cause nasty bite wounds are asleep.  While this is mostly true for our friend the rattlesnake, I learned last week that it is not so for spiders, when I was called out to see Venus, a 12 yo thoroughbred mare.
Venus was fine the night before when her owners closed up the barn, but they came out Sunday morning to find her standing in her stall with her head down, breathing heavily, unwilling to move, with a severely swollen hind leg.  On my arrival, initial examination revealed an elevated heart rate (80 beats per minute/normal 40), respiratory rate (24 breaths per minute, normal 12), and temperature (104.5 F, normal on a digital thermometer 99-100).  Venus was exquisitely painful - her breathing was shallow and panting, when forced to move she hopped on her right hind leg, and the leg was 3x normal size, from the pastern to the stifle.  The swelling in her leg was warm and very painful to touch.  After careful examination of the leg, I discovered a tiny red spot on the lateral aspect  of her metatarsus (outside of the cannon bone).  The skin immediately surrounding this spot was weeping a clear yellow fluid.

The rule outs for acute, severe swelling and lameness in a limb are abscess, infection, and fracture.  The most common is a foot abscess.  However, it would be extremely unusual for a hoof abscess to cause swelling extending this far up the limb and such a high fever to develop in just 12 hours.  Nevertheless, I pulled out my hoof testers and performed a careful examination of the hoof before crossing this one off the list.  Next to eliminate was fracture of the tibia or femur.  These bones in the upper limb, when broken, may be associated with severe swelling of the surrounding muscle masses.  However, the presence of a high fever was not consistent with fracture, and once Venus was brought out of her stall and moved around a bit, she did bear full weight on the leg when standing.  This did not completely eliminate the possibility of fracture, but made it less likely.  Upon discovery of the red spot with serum oozing around it, the high fever, severe pain, sudden onset of swelling and lameness were most compatible with a diagnosis of cellulitis of unknown origin.

Cellulitis literally means inflammed cells.  It describes a condition where something - trauma, bacteria, virus, toxin, cancer - sets off a cellular reaction that causes the body to release fluid, white blood cells, and a wide variety of small chemical molecules into a region of the body in response to the insult.  This is the body going to war - these factors are the body's soldiers and weapons that it uses to kill invading organisms.  Unfortunately, as in any war, there is collateral damage, and the body not only attacks the enemy, it also attacks itself.  The result is swelling, heat, pain, and redness, the four classic signs of inflammation (rubor, calor, tumor & dolor in latin - these signs have been recognized since ancient times).

The yellow fluid leaking through Venus' skin was serum - as the cells in her skin and underlying interstitial tissues fell apart, the blood and lymph vessels in the area also lost their integrity, allowing the fluid that should be retained within the body's plumbing system to leak out.  The damage to Venus' leg was so severe that this liquid was exuding through her skin - the body's final and most important barrier to the big bad outside world.

Whatever the initiating cause of cellulitis, the destruction of the body's intricate array of barriers to the external environment allows immediate invasion of infectious organisms that always are lurking about- primarily bacteria.  In a barn setting, these bacteria are everywhere because they love to live in warm organic matter - manure, bedding, wet spots under water buckets - I'm sure you can  imagine many more if you look around your barn and paddocks.  Although to us hairless humans winter feels very cold, in our climate prolonged deep freeze is actually rare - and if you dig to the bottom of the manure that's been accumulating since November in the corner of a pen, you'll likely find some warm, wet spots that are the bacterial equivalent of our mid-winter Baha vacation haven.

So, let's take a step back and decide what to do for Venus.  Although at this point we have not determined the definitive cause of her clinical signs, we have put together the fever, painful swelling, and serum leakage as indicators of cellulitis as the most likely primary problem.  We have reasoned that cellulitis is associated with inflammation and infection, therefore our initial treatment should be directed against 1) pain 2) inflammation 3) infection.  On a scale of 1-10, I gave Venus' condition a clinical score of 8 - very severe.  When choosing medications, we must chose oral, intramuscular or intravenous routes of administration, and we must choose drugs according to their strength and spectrum of activity.  Venus needed the big guns - so she was given intravenous flunixin meglumine (Banamine - anti-inflammatory/analgesic), Gentocin (antibiotic) and Potassium Pencillin (antibiotic) as well as an intramuscular tetanus toxoid.

The next concern was hydration and nutrition.  I decided to monitor Venus' reponse to therapy for 24-48 hours.  She did improve, but it was not logistically possible to continue frequent intravenous antibiotic adminstration and Venus did not eat or drink well over the next 48 hours, so the decision was made to hospitalize her where she responded rapidly to intensive medical therapy.  She returned home a healthy, sound horse, although she continued to loose hair and some skin on the affected leg for 10 days after the initial insult.

What happened to Venus?  The owners reported finding a Black Widow spider in the tack room next to Venus' stall a few days before her adventure began.  They have had problems with these spiders in the past.  Although we cannot know for certain, I believe that Venus was bitten along the side of her cannon bone (the red spot leaking serum) by a Black Widow.

We have two spiders in our area that cause toxic bite reactions.  The picture at the top of the blog is a Brown Recluse.  The actual Brown Recluse species is rare in Northern Nevada, but we do have a closely related species.  The bite of the Brown Recluse and its relatives causes a severe, localized, necrotizing reaction, but not a generalized response. The site of brown recluse bites initially is warm and painful, and over the subsequent 3-7 days may develop into a deep, debilitating open wound with massive loss of tissue and secondary infection.

The Black Widow bite contains a neurotoxin.  It travels through the body and tends to cause more systemic signs which can range from muscle pain to neurologic signs, depending on the site of the bite and the size of the victim.  While dogs are quite resistant to the affects of Black Widow toxin, horses are very sensitive. To learn more about these two spiders, visit Slideshow: Black Widow Spider vs. Brown Recluse Spider on 

I believe that education is the key to evolution. I believe that animals are the key to compassion. I believe the learning never stops.

Monday, January 17, 2011

The Will to LIve

The Will to Live
     Three years ago, Angel was born dysmature and septic.  Angel could not stand, could not suckle, and had a bacterial infection (neonatal septicemia) affecting her entire body.  Hospitalization in a neonatal intensive care unit was not an option due to financial constraints.  Under the best of circumstances the likliehood of survival in this situation is 20%.  In an at home care setting, it is drastically reduced.  Somebody forgot to tell Angel.
We set up a MASH unit in the outdoor paddock where Angel and her dam lived.  Angel’s human family basically stopped eating or sleeping for the next 10 days.  I provided Angel with an intravenous catheter and a nasogastric feeding tube, and administered initial aggressive treatment to address the immediate issues of failure of passive transfer, sepsis, inadequate caloric intake, toxemia, and possible cerebral anoxia, and gave the owners a crash course on IV medication and fluid administration, feeding tube maintenance, and neonatal foal nursing care.  Remember, Angel couldn’t stand  – she could barely lift her head.
     Angel required around the clock care and she got it.  As day 1 became day 2, then 3…6…10 I watched amazed as Angel’s owners gave life to this gritty little filly.  As the caregivers began to look increasingly weak and exhausted, Angel did just the opposite – by 2 weeks of age she was a bouncing, active, clinically normal foal.  We all danced for joy (well, her owners watched with bleary eyes while I danced – they were just too wooped to jump around) and Angel set off to live a normal life.
     Turn the clock ahead to late summer, 2010.  Angel is now 3, and has been sent off to spend some time with a cowboy trainer.  She went on a slow cattle drive and had some great experience just learning to be out and about with other horses.  Unfortunately, there was an outbreak of Strangles on the ranch while she was there.  Strangles is a strep bacteria: Streptococcus equi sp. equi.  It is highly contagious.  A typical case of Strangle goes like this: the horse is exposed to the bacteria.  Three to five days later the horse is depressed and has a fever.  This may go unnoticed.  By day seven the horse has a thick yellow nasal discharge.  Over the next week to ten days, the horse develops swelling just behind the cheek bones (retropharyngeal) or between the jaw bones (submandibular) caused by lymph node abscessation.  These abscesses break open and drain, the horse recovers and that’s that.  An uncomplicated case of Strangles is not treated with antibiotics, and has no long lasting consequences for the horse.
     Complications occur in about 10% of horses with Strangles.  These include abscesses that compress the airway and interfere with breathing or swallowing, pneumonia, formation of internal abscesses within the abdominal cavity, and an uncommon immune mediated disease called purpura hemorrhagica.  All complicated cases of Strangles require intensive medical treatment and are potentially fatal.
     Angel didn’t handle her Strangles well.  By the time her owner was notified and came to see Angel she had been sick for 3 weeks.  She had multiple abscesses on the left side of her face and neck, she had pneumonia, she was suffering from severe malnutrition, and to top things off, she had multiple foxtail abscesses under her tongue and in her throat.  This picture was taken the day Angel came home.  She was weak, staggered as she unloaded from the trailer, had long strings of saliva falling from her mouth, and stood with her head extended, her eyes half closed.  Her heart rate, respiratory rate and temperature were elevated and she had difficulty breathing.  Her hip bones and back bone were prominent – I estimated her weight loss over the 3 weeks at over 100 pounds.
      Once again, the MASH unit was organized.  However, instead of a 65 pound neonate, the owners were now trying to manage a critically ill adult.  I placed an intravenous catheter and we began intensive antibiotic, anti-inflammatory and fluid treatment, but when Angel’s initial blood work came back from the lab, it was obvious that we were not going to able to provide adequate care at home.  She was suffering not only from a critical bacterial infection, but also from severe cachexia.  Our bodies burn many additional calories when we are ill.  Angel’s ability to prehend, chew and swallow had been compromised for 3 weeks, and to compound this problem, she had been competing for food in a group of horses.  In her increasingly weakened condition she had been left with the poorest quality hay to try and consume.  Her blood protein levels were alarmingly low – her body was consuming itself in an effort to fight the infectious process and it was losing the battle. 
     Angel’s owners and I sat down and had a heart to heart.  None of us were willing to give up on Angel, even though it was clear that she once again was facing an immediately life-threatening situation with a guarded prognosis for recovery.  I called UC Davis and arranged for an emergency referral.  Angel’s owners loaded her up and off she went.  Angel , whose normal body weight is 950-1000 pounds, weighed 760 pounds on arrival at the University hospital .  Diagnostic testing including ultrasound and endoscopy confirmed the presence of pneumonia and multiple upper airway abscesses.  Under the excellent care of Dr. Dawson, a senior medicine clinician and her staff, Angel once again defied the odds.  She was in the hospital for close to 3 weeks, and continued her treatment at home for another month.  By Christmas Angel had recovered completely from her second brush with death.  Here she is, head up, bright eyed, and round barrelled.
     It takes a village.  Angel has a tremendous will to live.  She also has a family who loves her and doesn’t hesitate in the face of adversity.  Grandma, grandpa, grand-daughter, the entire medicine staff at UC Davis, the benefactors who support the UC Davis Emergency fund, the Care Credit organization, myself and my assistants, all played roles in Angel’s survival. 
     These days we see and hear a lot of stories of loss, of animals suffering because the money isn’t there, because people give up.  Angel’s owners are not wealthy, but they were willing to look for help when they needed it, and to roll up their sleeves and work themselves to the point of exhaustion to care for their horse.  Their dedication and Angel’s desire to survive are insipirational.
I believe that education is the key to evolution. I believe that animals are the key to compassion. I believe the learning never stops.

Thursday, January 6, 2011

Go to Facebook

Hi there.  I haven't been blogging through the busy warm seasons and suddenly it is 2011 and I have NO EXCUSES.

I have found that sometimes it is more convenient to post short educational pieces or links to informative articles directly on our Facebook Page.  Therefore, if you don't see fresh info on this blog, be sure and check out the HighDesertEquine Facebook page, or just click on the Facebook link on our website home page at

If I haven't seen you recently, feel free to comment here or on our Facebook page - and as always, let me know what you want to hear about and I will try to address your topic of interest quickly!

Please become a fan or friend of the Facebook page  - it helps it circulate to more people.

Take care,
Dr. C

I believe that education is the key to evolution. I believe that animals are the key to compassion. I believe that learning never stops.

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