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Crack the Code

Just about everything you need to solve a medical mystery is within your reach. A logical, methodical and evidence-based approach goes a long way.

Crack the Code
You can tap into many diagnostic tools, but remember that each test you run must have a diagnostic value to the pet and client.

I learned during my years in veterinary school and practice that my eyes can’t take radiographs, my hands can’t perform cytology or histopathology, my ears can’t conduct an ultrasound, my mouth isn’t a diagnostic laboratory, and my nose isn’t an MRI. So, I must supplement my mind and senses with one of a plethora of diagnostic tools to help me shrink my list of rule-outs and determine a treatment plan.

With the increasing number of adjunctive resources available, where do you start? Hopefully, the physical examination shrinks the rule-out list from the table of contents in Ettinger’s Textbook of Veterinary Internal Medicine to a single chapter. And then, your decision-making might be influenced by the following.

Standards of Care

Community standards of care most often determine liability in a malpractice situation. And then there are hospital standards of care. More a legal term than a medical term, standard of care usually means the degree of care and skill of the average health care provider in a particular specialty, taking into account the field’s available medical knowledge. So, standard of care typically is based on the hypothetical practices of a reasonably competent health care professional in the same or similar community.

When applied in a veterinary practice setting, the standard of care is a set of guidelines adopted by the health care team. The guidelines help deliver a consistent level of basic care for each pet each time all the time. Common standards of care cover everything from pain management and puppy vaccinations to deworming, pre-anesthetic testing and intraoperative IV fluids.

Cost of Care

When used in conjunction with our minds, diagnostic testing is the epitome of what we went to veterinary school for. Together, they are Sherlock Holmes’ magnifying glass. In the eyes of pet owners, radiographs, blood tests and CT scans have huge perceived value. People understand the importance of these tests, which dominate TV medical shows. People also see the tests as expensive.

Veterinary practice profitability requires balancing a multitude of expenses and income streams. All the diagnostic tools we use or outsource come with associated costs. Thus, we have to determine fee structures to make each tool profitable to the practice. Additionally, many of the workups require human resources to achieve. Take this into consideration.

Depending on client demographics, your ability to use all the diagnostics at your fingertips must be balanced with the workup that provides the most information at the most affordable cost to the pet owner. This situation can create a balancing act between what your practice has as a standard of care and what is within the pet owner’s financial wherewithal.

The Deeper Dive

You can tap into many diagnostic tools, but remember that each test you run must have a diagnostic value to the pet and client. Thus, start with the basics and get more complex as you peel the layers off the proverbial onion.

No matter the diagnostic workup you perform, the ultimate goal is to go beyond the physical exam and patient history and either confirm your hunch or direct you to something you hadn’t considered. Plenty of times, I walked into an examination room and diagnosed hypothyroidism in a middle-aged golden retriever or hyperthyroidism in a cachectic old cat. Laboratory testing was required to confirm the diagnosis and the condition’s severity and guide the treatment plan. In most cases, the workup supports your premonition. At times, though, you’ll find that hypothyroidism was actually Cushing’s disease and hyperthyroidism was diabetes mellitus.

For most situations where a pet presents with a condition deemed to be systemic, a complete blood count, total body function, urinalysis and other laboratory testing are warranted. This first round of testing might be performed using in-house laboratory equipment or sent to a reference lab. Follow-up testing, endocrine stimulation testing or another nontraditional test might be needed to confirm a diagnosis.

With a laboratory profile in hand, you next might add imaging —radiograph or ultrasound — to look for neoplasia, organ changes and other conditions that might be deduced from the laboratory testing. For example, in cases of anemia and no obvious bleeding, looking for blood in the chest or abdomen would need imaging.

In musculoskeletal or neurological situations, the nature of the diagnostic workup might be more imaging-based. Radiographs of joints, bones and spines can help validate a diagnosis of arthritis, cruciate tear or intervertebral disk disease. Young large-breed dogs that present with lameness might require radiographs of the hips or other joints. With a diagnosis in hand, you might order laboratory testing to gauge the safety of certain prescribed medications.

Most any organ system and presenting complaint can benefit from a diagnostic workup. For example:

  • Don’t cubbyhole skin cases into a flea infestation or atopy. Diagnostic testing for secondary bacterial or yeast infections or ringworm might identify primary, secondary or tertiary conditions that must be treated along with the allergic condition. The allergic condition can benefit from allergy testing or food sensitivity testing.
  • Ear infections beyond a relationship to an allergic skin disease almost always will warrant cytology to look for bacteria, yeast or mites. Subsequently, a culture and sensitivity or microbiome testing will direct the appropriate treatment. Laboratory testing might be warranted if the possibility of endocrine or other disease conditions is indicated.
  • “Ain’t Doin’ Right,” a catch-all phrase for nondescript findings, could set off a diagnostic cascade that starts with basic laboratory testing and imaging and is followed by tick-borne disease assessments, clotting profiles and endocrine studies. These challenging presentations can get very expensive very fast as you try to determine a treatment plan.
  • Weight loss, another challenging presentation, might be a reason for the additional testing of blood or urine, an ultrasound, an endoscopy, or specialized pancreatic or renal tests. The list goes on.
  • In cases of lumps and bumps, your fingers are the starting tool. Still, a fine needle aspirate is warranted virtually every time to get a preliminary reading through a stain and microscope in your practice, a virtual consultation, or referral to a pathologist at a reference lab. And, of course, all this could lead to a biopsy.
  • When a patient hesitates to jump onto a couch, the physical examination might help you isolate the problem to the back, hip, neck or other location. Imaging, with or without sedation, is the first step in working up an undetermined pain source. Subsequent diagnostics might include a myelogram, spinal tap, MRI or CT to determine the best course of treatment.
  • Many drugs get lifetime use and might require therapeutic level testing, effectiveness testing or a side-effects assessment. Whether the pet has seizures, thyroid or adrenal conditions or is on long-term NSAIDs, a diagnostic monitoring program should be established when a chronic medication is prescribed.

Coming Full Circle

For the benefit of the patient and client, a logical, methodical and evidence-based approach to the diagnostic workup must be part of your standard of care. Although a shotgun blast usually hits the target, peripheral damage is frequently done. A rifle can more easily hit the target without damaging other areas. This metaphor has more to do with the cost of care. Do you go right to the MRI, or can you perform less expensive imaging? By forgetting to do something as simple as a urinalysis, what might you miss?

The diagnostic workup system is a series of tests run after a thorough physical exam and patient history. A logical and scientific approach allows you to choose tests that will guide you sequentially to the diagnosis and treatment plan.

Diagnostic workups are invaluable to a clinician. They help patients who can’t verbalize how they feel or where it hurts. In conjunction with the physical exam and history, they help solve the mysteries we encounter every day.

I enjoyed the TV series “House” for its approach to diagnosing some of the more obtuse conditions of human patients. “House” always looked for the zebra. As veterinarians, we know how a horse looks. Our job is to listen to the hoofbeats and use testing to find the horse. But of course, every once in a while, the tests reveal a zebra. We must be ready to treat it.

Dr. Peter Weinstein owns PAW Consulting and is the executive director of the Southern California Veterinary Medical Association. He serves as chair of the American Veterinary Medical Association’s Veterinary Economics Strategy Committee. The podcast “Peter & Phil’s Courageous Conversations,” a dialog between Dr. Weinstein and Dr. Phillip Nelson, is available through all major podcast providers.


In the general practice setting, the results of a diagnostic workup sometimes are confusing. The clinician might benefit from someone else’s opinion. For example, the practitioner might want to contact a:

  • Teleradiology or teledental expert
  • Teleultrasound service
  • Virtual cytology company
  • Teleconsultant such as an internal medicine specialist, pathologist, cardiologist or behaviorist
  • Specialist for high-end diagnostic workups such as a CT or MRI


Some veterinary hospitals create minimum databases and add them to protocols for certain presenting complaints to ensure that cases are managed similarly. Doing this ensures that services, tests and medications are not forgotten. In the average general practice, a minimum database might include:

  • Complete blood count
  • Total body function
  • Electrolytes
  • Urinalysis
  • Thyroid levels
  • Chest radiographs
  • Abdominal radiographs
  • Spine radiographs
  • Limb and joint radiographs
  • Dental radiographs
  • Clotting profile
  • Contrast studies
  • Tonometry
  • Tear testing
  • EKG
  • Pulse oximetry
  • Ultrasound

A specialty practice might include the above list and a:

  • CT scan
  • MRI
  • Spinal tap
  • Myelogram
  • Fluoroscopy