Hand in Hand, Vol 1

From Trey’s Desk

Dear Colleague,

We are happy to move into 2012 having made it through our first year of multi-specialty existence.  Many changes have occurred following the move into our new location during September 2010.  We added a second internist (Dr. Shannon Flood) and a part-time dentist (Dr. Barden Greenfield), opened NVS – Animal Emergency, the IDEXX day lab is up and running next door and we welcomed our first intern class.  It makes my head spin just thinking about it.

Alas, 2012 brings more activities that we hope will be of value to your practice.  The first or second Tuesday of each month, we will hold a two-hour CE event for veterinarians. On January 10th, I will present on abdominal exploration considerations (i.e. when to cut, diagnostic evaluation, helpful instrumentation, important anatomy, etc) and review gastrointestinal surgical techniques (i.e. biopsy, enterotomy, resection-anastomosis, etc.)  Dinner will be provided at 6:30 p.m., followed at 7:00 by two hours of lectures and discussion.  Please join us in the IDEXX conference room.

The Spring CE schedule is included in this newsletter.  We welcome your suggestions on other discussion topics.  Please share your ideas about lecture subjects with any of our doctors or contact me directly.  We are so appreciative of the support of each referring veterinarian and are committed to continually improving the service we provide. We are here to support you in every capacity from providing emergency and specialty services, to telephone consultations, to being a back up for your hospital if you are out of something.  We can even send Dr. P.K. Hendrix to your hospital to talk about anesthesia.  Our doors are always open and we wish you the best in 2012.


Trey Calfee


Internal Medicine : Pancreatitis: a Pain in the Gut

Kelly Wang, DVM, MS
Diplomate American College of Veterinary Internal Medicine
Nashville Veterinary Specialists

Pancreatitis can range from mild to severe.  In the severe form, cellular necrosis is present, and morbidity and mortality significantly increases.  The treatment of pancreatitis has shifted from early surgical debridement to more aggressive intensive medical care.  Due to the advances in radiology and biochemical analysis, we are able to diagnose pancreatitis and institute treatment earlier since the PLI (pancreatic lipase immune reactivity test) is much more sensitive and specific compared to amylase and lipase.  Amylase and lipase are even more unreliable in cats.

The presentation signs of pancreatitis in dogs and cats vary depending on severity.  Mild cases are often subclinical.  Clinical signs include anorexia, vomiting, abdominal pain and/or diarrhea.  About 33% of dogs, however, don’t vomit and cats rarely vomit with pancreatitis.

The mainstays of therapy are intravenous fluid, support to help maintain adequate circulating volume and sometimes antibiotics.  This area can be a little controversial since most pancreatitis cases are considered an inflammatory process, rather than an infectious disease.  Fresh-frozen plasma is often used as a supplemental form of alpha-macroglobulin and as therapy for DIC, which is frequently seen with severe cases.  Delayed aggressive fluid support can worsen the prognosis with moderate to severe pancreatitis.

Pain management is an important treatment since abdominal discomfort is often associated with this disease.  Common drugs used include butorphanol, buprenorphine, morphine and fentanyl given parenterally.  Antiemetics (such as Cerenia) are used to help relieve nausea, and promotility agents (such as metoclopramide – ideally in CRI form since this drug has a very short half-life orally) can also help animals feel more comfortable.


Surgical Oncology: Management of Tumors of the Canine Oral Cavity

Earl F. Calfee, III (Trey), DVM, MS

Colorado State University Surgical Oncology Fellow
Diplomate American College of Veterinary Surgeons
Nashville Veterinary Specialists

Tumors of the oral cavity account for 6% of all canine tumors.  Affected animals will typically present with a history of dysphagia, halitosis, ptyalism or bleeding from the oral cavity.  An owner may describe facial asymmetry or observe “something” in the dog’s mouth.  Surgery is the preferred treatment for the following canine oral masses.

Melanoma accounts for 31% – 42% of canine oral tumors.  Two-thirds of melanomas are pigmented and these masses are typically ulcerated.  Non-pigmented or amelanotic melanomas are more difficult to diagnose and often require special histopathologic staining techniques.

Squamous cell carcinomas are typically raised, red, ulcerated and cauliflower shaped.  Those located at the base of the tongue or in the tonsillar crypts have a much more aggressive behavior than more rostrally located masses.

Fibrosarcomas typically occur in large-breed dogs and are firm, flat, broad-based and ulcerated on gross examination.  They infrequently metastasize but are typically locally aggressive.

Epulides arise from the periodontal ligament associated with the tooth root.  These tumors do not metastasize.

Cancer staging begins with a thorough physical examination and includes baseline blood work (i.e., CBC, serum chemistry), thoracic radiographs and regional lymph node aspiration.  Computed tomography is often needed to define the extent of disease.  Incisional biopsy is indicated prior to aggressive surgical treatment.

Mandibulectomy, maxillectomy and glossectomy are the most commonly performed surgeries for oral neoplasms.  All can be performed with good to excellent functional results.  Post-operative care involves pain management, assisted feeding and short-term prevention of oral trauma.


Neurology: Cerebrovascular Disease in Dogs

Rossi House, DVM
Diplomate American College of Veterinary Internal Medicine (Neurology)
Nashville Veterinary Specialists

Strokes are reported infrequently in dogs, but with advances in technology, they are being identified more often.  There are two main types of stroke: ischemic and hemorrhagic.

Ischemic strokes are more common, and an underlying cause is found in about 50% of cases.  The most common concurrent medical conditions found in dogs are hyperadrenocorticism, chronic kidney disease, hypothyroidism and hypertension.

Hemorrhagic strokes are rare and have been reported secondary to rupture of congenital vascular abnormalities, brain tumors, intravascular lymphoma, cerebral amyloid angiopathy and impaired coagulation.  Signs are typically peracute in onset, and then they plateau.  Worsening edema can sometimes lead to progression of neurologic signs

MRI is the imaging modality of choice.  CT can detect hemorrhage and is useful for ruling out mimics of stroke, but it is not very sensitive in detecting ischemic changes.  Ancillary diagnostic tests for ischemic strokes include CBC, chemistry, UA, serial blood pressure measurements, urine protein/creatinine ratio, d-dimers, endocrine testing, thoracic radiographs, abdominal ultrasound and echocardiography.

Ancillary diagnostic tests for hemorrhagic stroke include serial blood pressure measurement, CBC, chemistry, BMBT, PT/PTT, thoracic radiographs and abdominal ultrasound.  Treatment, regardless of type, includes supportive care and management of neurologic and nonneurologic complications, as well as treating any underlying causes.

Most cases of ischemic stroke recover within a few weeks with just supportive care.  Hemorrhagic stroke is far less common, but associated with higher mortality.  The risk of neurologic deterioration is highest in the first 24 hours.  Dogs with concurrent medical conditions have significantly shorter survival times and are more likely to suffer from subsequent infarcts.


Surgery: Excessive Tibial Plateau Angle (eTPA)

Wesley Roach, DVM, DACVS
Nashville Veterinary  Specialists

Cranial cruciate ligament (CCL) disease is the most common reason dogs present to our surgery department.  Surgery (TPLO, TTA, Lateral Suture) is typically recommended to stabilize the stifle, and the prognosis is generally good.

Most dogs have a tibial plateau angle (TPA) between 20-30 degrees.  Occasionally dogs will have an excessive tibial plateau angle (eTPA), which is an angle greater than 34 degrees.  eTPA can be unilateral or bilateral and is most likely associated with a caudal deformity of the proximal tibia.  Excessive stress on the CCL as a consequence of the altered conformation has been postulated as the mechanism of ligament injury.

Recognizing this abnormality before surgery with radiographs (lateral view of entire tibia) is important because the typical surgeries for CCL rupture may not be appropriate.  The theory behind the Lateral Suture is to replace the CCL.  If the CCL ruptured because of the excessive stress from the eTPA, then the Lateral Suture will likely fail as well.  Therefore surgeries that level the tibia plateau are generally recommended for dogs with eTPA.

Sometimes the eTPA can be corrected with a TPLO or TTA alone.  The tibial plateau, however, can be rotated only so far with a TPLO, and the tibial crest can be advanced only so far with a TTA.  The current recommendations are to combine a TPLO with a cranial closing wedge osteotomy (CCWO) to achieve a level tibial plateau in dogs with eTPA.  This procedure requires additional pre-operative planning and a has a complication rate approaching 25% rather than the traditional 10% with a TPLO alone.


Anesthesia: Carbon Dioxide Monitoring in Anesthetized Animals

P.K. Hendrix, DVM, PhD
Diplomate American College of Veterinary Anesthesiologists
Nashville Veterinary Specialists

While pulse oximeters monitor oxygen saturation in anesthetized animals, hypercapnia occurs more commonly than hypoxemia.  Affordable, portable monitors are available to measure exhaled CO2.  These units consist of a monitor with a pump (to obtain respiratory gases), and a sampling line with an adaptor that attaches between the endotracheal tube and the breathing hose.

Capnometers are available as either mainstream or sidestream devices.  Mainstream devices sample the gas at the airway without diverting it into a monitoring unit while sidestream devices divert gas from the airway into a monitoring unit for sampling. Although mainstream devices are somewhat bulky at the ET tube connection, sidestream devices have a slight delay between the actual and displayed readouts.

Normal ETCO2 levels are 35-45 mmHg.  The most common cause of increased ETCO2 is hypercapnia secondary to anesthetic-induced hypoventilation.  Normal healthy animals can tolerate some increase in carbon dioxide levels (up to 60-70 mmHg) without suffering detrimental effects.  Extremely high carbon dioxide levels (> 100 mmHg) can cause narcosis and exacerbate deep levels of anesthesia.  The simplest way to correct high ETCO2 is to simply ventilate (“bag”) the animal more frequently.

Low ETCO2 levels are most commonly a result of hyperventilation or diluted exhaled carbon dioxide caused by high oxygen flow rates such as those used with non-rebreathing systems.  Sudden significant reductions in ETCO2 can be due to airway occlusion, ET tube dislodgement, disconnection or cardiac arrest.  Capnometers are also useful during CPR to determine ETCO2 production as an indicator of return of CO2  production and blood flow through the lungs.