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Tuesday, December 18, 2007

The World of Epidurals

By Courtney L. Baetge, DVM

If I have learned anything during my time as an anesthesiologist, it is that for every topic there are a multitude of opinions. But I do believe most anesthesiologists are strong advocates of epidurals. The benefits of an improved anesthetic plane, smoother recovery and superior post-operative pain control well outweigh the additional time and effort involved in placing an epidural. However, for those who don’t do epidurals on a regular basis, they can seem a bit intimidating. I feel the skill is a small portion of this intimidation. Most practitioners with just a little practice become adept quite quickly. Most of our fourth year veterinary students can perfect the skill during the 2 week rotation. Having said this, why are they so scary? There are a lot of “other things” involved with an epidural than just the technique. Knowing when, where, who, and what are just a few. So let’s try and address a few of these (and how).

Most patients that will have a painful procedure done anywhere caudal to the umbilicus will appreciate an epidural. Obvious ones are rear limb surgeries and perineal hernias. But the less obvious cases include exploratory laparotomies, mastectomies, anal sac carcinomas, and preputial surgeries, just to name a few.

The subarachnoid space stops at L7 (can go further in young or very small dogs). So attempting epidurals at L7-S1, helps decrease the chance of causing damage to the spinal cord and performing a spinal rather than an epidural. However, if you end up getting CSF coming out of your needle simple reduce your dose by half and keep going. This will speed your onset of action but decrease your duration as well. There are times when the pelvis anatomy is not ideal and going to the L6-L7 space is easier. That’s fine!

More importantly is who NOT to give epidurals. Do not use an epidural if there is infection at the injection site, the patient is hypovolemic, the patient has a bleeding disorder or is on anticoagulants, axonal disease, severe anatomical abnormalities, or neurologic disorders. You do not want to spread any infections into or out of the spinal canal.

If there is a drug created, some researcher has tried putting it in some poor animal’s epidural space. BUT, there are a few drugs that most anesthesiologists consider staples. The drugs should be preservative free (the preservative in typical morphine is formaldehyde). The total volume should be less than 0.2 ml/kg [if the patient is very obese or pregnant the space will be smaller due to venous congestion and the dose should be reduced (0.15ml/kg)]. I tend to max out at 6 ml, especially if using a local, so there is less risk of respiratory or sympathetic blockade.

Opioids: Morphine [0.1 mg/kg] has a nice long duration of analgesia (12-24 hrs) without motor blockade or sympathetic nervous system blockade and will migrate well cranially to increase your area of analgesia. However, it can take up to 1 hr to begin working and can cause respiratory depression, urinary retention, decreased GI motility, vomiting and itching. Fentanyl is another opioid that can be used. It has a duration of 2-6 hrs, with a smaller area of analgesia and less systemic effects.

Local anesthetics: Lidocaine has a fast onset of action (10-15 minutes) but will only last about 60-120 minutes. Lidocaine can also cause respiratory depression and sympathetic nervous system blockade that can lead to hypotension. Bupivicaine has a longer onset of action (20-30 minutes) and a longer duration of action (4-6 hours).

Combining a local and opiod can give you the best of both worlds. I usually just reduce by opioid volume by 25% and replace that with local anesthetic. For instance, in a 10 kg dog at 0.1 mg/kg of morphine, you would use 1 mg of morphine which, if the 0.5 mg/ml Duramorph is used, equals 2 ml of morphine. Therefore, I would reduce my dose to 1.5 ml of morphine and add 0.5 ml of a preservative-free local anesthetic like bupivicaine for a total of 2 mL.

It is usually helpful for most people to have the patient in sternal recumbency with the rear legs pulled as far cranially as possible. This opens the L7-S1 space up and gives a larger target for your needle. The area is clipped and sterilely prepped. The thumb and middle finger rest on the wings of the pelvis which should direct the first finger to fall into the L7-S1 space directly between the thumb and middle finger. I tend to use a 20-22g 2 ½ to 3 ½ inch epidural needle, depending on the size and amount of fat at the injection site. An epidural needle is always preferred since the bevel is not a cutting edge and is less likely to damage the spinal cord if accidentally nicked. I turn the bevel to which ever direction needs the greatest analgesia (i.e. caudally for hernia repair, left for left stifle surgery, cranial for mastectomy). Once past the skin and majority of the fat, I remove the stylet and attach a test syringe of sterile saline or place a “hanging drop” so that I can see when I get negative pressure. The negative pressure may be gone in some patients but a test injection of saline should flow very easily (like an IV injection). Once in place, I inject my drug. If you get blood, stop and pull the needle out – it’s not the day for an epidural.

Hopefully this will help anyone trying to ease into the epidural world. Practice, be sterile, and good luck!

Wednesday, November 28, 2007

Canine Adrenal Testing - Which Test Should I Run?

By Jennifer S. Fryer, DVM

Urine Cortisol:Creatinine Ratio:

· Screening test for Hyperadrenocorticism (Cushing’s or HAC)

· Low Cost, Easy to collect (voided morning urine at home)

· Normal value rules out Hyperadrenocorticism

· Elevated values can indicate stress or Hyperadrenocorticism & adrenal function testing is necessary.

Baseline Cortisol:

· Screening test for Hypoadrenocorticism (Addison’s)

· Values >2 mcg/dl rule out Hypoadrenocorticism (Addison’s)

· Cannot be used to diagnose Hyperadrenocorticism (Cushing’s)

ACTH Stimulation Test:

· Test of choice to diagnose Hypoadrenocorticism (Addison’s)

· Screening test for Hyperadrenocorticism (Cushing’s)

· Used to monitor Trilostane or Lysodren Therapy

· Can be used to differentiate spontaneous vs. iatrogenic HAC

· 60-85% of dogs with HAC will have a positive result on this test.

· 85-90% of dogs without HAC will have a negative result on this test.

· Advantages:

o Can be completed in 1 hour

o No special handling of samples

o Submit for extended Adrenal Panel to document Atypical HAC

· Disadvantages:

o High cost of Cosyntropin

o Low Sensitivity (false negatives are possible)

Low-Dose Dexamethasone Suppression Test:

· Screening test for Hyperadrenocorticism (Cushing’s)

· Helps differentiate pituitary vs. adrenal origin

· 85-95% of HAC dogs have a positive result.

· 70-75% of dogs without HAC have a negative result.

· 40% of dogs with PDH and all adrenal tumor dogs have dexamethasone resistance and will require another differentiating test.

· Advantages:

o Low cost

o Higher sensitivity than ACTH Stim

o No special handling of samples

· Disadvantages:

o All day test requiring three blood samples at 0, 4, 8 hours

o The dog should be kept as minimally stressed as possible during this 8 hour period

High-Dose Dexamethasone Suppression Test:

· Theoretically helps differentiate Hyperadrenocorticism of pituitary vs. adrenal origin.

· Similar results to Low-Dose Dexamethasone Suppression Test at 8 hours.

· Rarely performed.

Endogenous ACTH Measurement:

· Helps differentiate pituitary vs. adrenal HAC

· Single plasma sample required

· Sample handling is difficult & critical to accurate measurement.

· With proper sample handling, this test is very reliable at differentiating pituitary vs. adrenal HAC.

Abdominal Ultrasound:

· Helps differentiate pituitary vs. adrenal HAC.

· May identify adrenal tumor, local invasion or metastasis.

· High cost

· Adrenals can be normally sized in PDH

· Adrenals can be difficult to visualize in some animals

· Ultrasound does not always accurately identify extent of metastasis or local invasion of an adrenal tumor

Computed Tomography (CT Scan):

· Screening test for Pituitary Tumor or Primary Adrenal Tumor and abdominal metastasis &/or local invasion

· Brain CT is not indicated unless a macroadenoma is suspected.

· Very high cost.

· Requires anesthesia.

· Cannot detect 50% of pituitary masses.

· Cannot differentiate between functional and non-functional tumors. Adrenal function tests are still required.

Brain Magnetic Resonance Imagine (MRI):

· Screening test for Pituitary Tumor

· Brain MRI is not necessary unless a macroadenoma is suspected.

· More reliable than CT at detecting small pituitary masses.

· Very high cost.

· Requires anesthesia.

· Not indicated unless a macroadenoma is suspected.

· Cannot differentiate between functional and non-functional tumors. Adrenal function tests are still required.


Lennon EM, Boyle TE, Hutchins RG, et al. Use of basal serum or plasma cortisol concentrations to rule out a diagnosis of hypoadrenocorticism in dogs: 123 cases (2000-2005). J Am Vet Med Assoc 2007;231(3):413-6.

Nelson RW, Turnwald GH, Willard MD. Endocrine, Metabolic, and Lipid Disorders. In: Willard MD and Tvedten H, eds. Small Animal Clinical Diagnosis by Laboratory Methods. 4th edition. St. Louis: Elsevier Saunders, 2004:165-207.

Reusch, CE. Hyperadrenocorticism. In: Ettinger SJ and Feldman EC, eds. Textbook of Veterinary Internal Medicine. 6th edition. St. Louis: Elsevier Saunders, 2005:1592-1611.

Thursday, November 15, 2007

Severe DKA and Severe Financial Constraints - What are the Options?


Ms. Smith brings in her 14 year old cat Mama Cat. The cat is a diabetic who receives twice daily insulin. Ms. Smith tells you that she hasn’t come back for a glucose curve for the last year because she couldn’t afford it. She thought Mama Cat was doing OK on her dose of insulin. The cat started vomiting a few days ago. Ms. Smith came home from work today to find that Mama Cat can’t get up. She wants to do everything possible for Mama Cat, but wants to do it inexpensively. And she promises to heed your advice on follow-up visits in the future.Mama Cat is hypothermic and obtunded. A blood glucose is >600 and the cat has 1+ ketones in her urine. Ms. Smith has declined referral to the local 24 hour clinic. You are uncomfortable managing such a sick cat. But Ms. Smith really wants you to treat her. You look in the fridge. Your bottle of Regular Insulin expired a month ago - a testament to the fact that it has been a long time since you have treated a DKA. What should you do now?

First of all, don’t worry. If you can get an IV catheter & fluids in Mama Cat, you have made huge progress towards saving her. The first thing Mama Cat needs is fluid resuscitation. You can worry about the insulin later, once she is better hydrated. That gives you plenty of time to send your assistant to the drug store to get some more Humulin R. Once you have that insulin, you can use the IM technique, which requires less monitoring for you & your staff and less expense for the owner. It works just as well as a CRI of insulin. Control her nausea with metoclopramide to get her eating (or put an NE tube in). You will find that her glucose, potassium, and phosphorus will regulate faster and with less need for monitoring.

We frequently receive calls like this at Veterinary Answers. We will talk you through the steps you need to take and send you a written report to use as your guide. We want Mama Cat to pull through just as much as you do. And we will be there for you every step of the way.

Wednesday, November 14, 2007

Focus on Referral Issues

This article in the recent issue of Trends Magazine, highlights many of the issues that prompted me to found Veterinary Answers. AAHA held forums to promote better relationships between general practitioners and specialists. The forums were held in Denver, CO; Orange County & Fremont, CA; Houston, TX; Chicago, IL; Boston, MA; and Washington, DC and were attended by 121 specialists & 74 general practitioners. Unfortunately, specialists were overrepresented. But I think the results are pertinent.

Please add your perspective on these issues, too.

The Referring Veterinarian’s Perspective

  • They would like “mutual respect and a non-judgmental attitude” in communications with specialists.
  • They prefer that their calls be returned during business hours.
  • They would like to have a specialist give due to consideration to consultations and advice on cases that cannot be referred.

The Specialist’s Perspective

  • Because of busy schedules, they return most calls after hours.
  • Most specialists return consult calls last.
  • Specialists are hesitant to discuss advice when a case is not going to be referred.
  • They are also hesitant to give advice on cases they have not seen for a long time.

I have been on both sides here. It is so frustrating to have a difficult case that cannot be referred, yet you and owner desperately want to help the animal. I have also been the busy specialist who didn’t see her less urgent messages until she could finally sit down at her desk at 8:30 in the evening, long after most veterinarians (hopefully) have gone home. I can’t tell you how many consults I gave on the fly to a vet who needed help. I gave the best advice I could while juggling several issues at once (an occasionally with an ultrasound probe in my hand). It wasn’t fair to anyone. My advice wasn’t as well reasoned as it should have been, I probably sounded stressed, and the veterinarian at the other end of the phone did not receive any documentation of our conversation. While doing referral work, most of my time was spent talking with owners and RDVMs about hospitalized cases, doing ultrasound, and SOAPing patients. Everything else developed a low priority so that my patients could receive the best care. Something had to give, and unfortunately, it was often the referring veterinarians who paid the price.

Veterinary Answers gives calling veterinarians their undivided attention. Every call is followed with a written report that is faxed or emailed to the veterinarian to document the conversation. We work together with veterinarians to advance the level of care they give all of their patients. We understand the limitations veterinarians face, from owner financial constraints to limited resources. Together, we will work with you to help your patients despite these obstacles.

Thursday, November 1, 2007

Veterinary Answers Services

Advice on diagnosis and management of difficult cases

Veterinary Answers understands the difficulties you face in your practice - from an animal owner’s financial limitations, to staff and equipment availability, and the reality that you will never have enough time in the day to do everything. Our goal is to work with you to find the next step in diagnosis or treatment of your patients under these circumstances.

Answers to general questions
- Call us when you have a question related to a patient, recent veterinary news, new products, etc. We will research the answer and provide written follow up.

Article Search - Once you leave academia, it is difficult to find the latest information from every journal. We have access to a large number of veterinary and scientific journals. If you are looking for a particular article or the most recent information on a given topic, we can find it for you.

Set Up Protocols
Your clients appreciate it when all doctors in a practice work in similar ways to treat their pets. Catch chronic diseases early, prevent transmission of infectious diseases inside and outside of your clinic, give your patients the best quality of life by managing their chronic diseases based on the latest research. Veterinary Answers will work with you to develop protocols that fit your practice.

    • Vaccination
      • Which core vaccines should your clinic use?
      • How often should you vaccinate?
      • What are the alternative options?
    • Infection Control
      • Isolation Protocols
      • Protocols for Feline Upper Respiratory Infection Management
      • Protocols for Parvovirus Management
      • Protocols for Antibiotic Resistant Infection Management & Prevention
    • Infectious Disease Testing
      • FeLV/FIV
      • Lyme/E. canis/A. phagocytophilum/Heartworm
      • Parvovirus
      • Intestinal parasites

Internal Medicine

      • Geriatric screening
      • Chronic Vomiting/Diarrhea
      • Chronic Diabetes mellitus
      • DKA & Hypoglycemic Crisis Management
      • Hyperadrenocorticism
      • Hypoadrenocorticism
      • Refractory hypothyroidism
      • Hyperthyroidism and Chronic Renal Failure
      • Chronic Renal Failure management in cats and dogs
      • Chronic Urinary Tract Infections
      • Urolithiasis
      • PU/PD Workup
      • Feline Idiopathic Cystitis
      • Hypertension
      • Immune-mediated diseases
      • Inflammatory bowel disease
      • Chronic Rhinitis
      • Hepatopathies


      • Staging for Common Neoplastic Diseases
      • Cancer treatment protocols and response rates
      • Discussion of best treatment options
      • Palliative treatment options


      • Pre-anesthetic screening protocols
      • Anesthesia protocols for all life stages and underlying disease conditions
      • Prepare a protocol for a high risk patient
      • Prepare a protocol for a patient with previous anesthetic complications

Emergency Medicine

      • Emergency Treatment & Diagnosis of the Dyspneic Patient
      • Hit By Car
      • Hemoabdomen
      • Stabilization of congestive heart failure
      • Acute Renal Failure
      • Diabetic ketoacidosis
      • Urethral obstruction
      • Paresis: evaluation and next steps
      • Talk through procedures: pericardiocentesis, thoracocentesis, chest tube, tracheostomy
      • Head Trauma: drugs, nursing care, ventilation
      • Dystocia
      • Cluster seizures, Status Epilepticus
      • Pain control
      • Snake bite and envenomation
      • Saddle thrombus management and important points of discussion with owners
      • Heat stroke
      • Common toxicities
      • Transfusion medicine


Veterinary Answers Partners with Diagnostic Vet Labs

In the Los Angeles metropolitan area, Veterinary Answers has partnered with Diagnostic Vet Labs to offer internal medicine consultations through the lab on their lab work.

We also offer a 20% discount on our services directly to DVL clients.

Contact DVL at (800) 247-8621 to set up a DVL account.

The Future of Veterinary Answers

What’s In Store For Veterinary Answers?
  • More Consultants! Tell us which specialties you would like us to add
  • Continuing education seminars - We can provide a speaker for your next event or staff meeting.
  • Research - As veterinarians on the front line, you are the first to see cases of emerging diseases, trends in antibiotic resistance, clusters of immune-mediated or neoplastic diseases. We can work together to address trends more quickly.

Tell us what else you would like to see.