Common Method for Veterinary Clinical Diagnostic Approach for Disease Diagnosis in Animals
The clinical examination consists of three parts: (1) obtaining a meaningful history, (2) performing a thorough physical examination including observations of the environment, and (3) selecting appropriate ancillary tests when necessary.
The goal of the clinical examination is to determine the organ systems involved, differential diagnoses, and, ideally, a diagnosis. In most cases, an accurate diagnosis will be reached by an experienced clinician. In difficult cases, the clinician, even when experienced, may formulate only a differential diagnosis that requires further information before an accurate diagnosis can be made.
The clinical examination is an art, not a science. The basic structure of the clinical examination can be taught, but the actual performance and interpretation involved require practice and experience. Clinicians who are lazy, who are poor observers, or who fail to interact well with clients will never develop good clinical skills.
The clinical examination is a search for clues in an attempt to solve the mystery of a patient’s illness. These clues are found usually in the form of “signs” that are demonstrated to the examiner through inspection, palpation, percussion, and auscultation. Signs are the veterinary counterpart to the symptoms possessed by human patients. Stedman’s Medical Dictionary defines a symptom as “any morbid phenomenon or departure from the normal in function, appearance, or sensation experienced by the patient and indicative of a disease.” A sign is defined in the same source as “any abnormality indicative of disease, discoverable by the physician during the examination of the patient.” Although somewhat pedantic, the veterinary interpretation of these terms has evolved to connotate that animals cannot have symptoms, only signs. We cannot help but believe that sick cattle “experience” departures from normal and indicate that to experienced clinical examiners. However, we shall evade this pedantry and use the idiomatic “sign” throughout this text.
Signs are not the only clues that contribute to a diagnosis. Knowledge of the normal behavior of cattle, an accurate assessment of the patient’s environment, the possible relationship of that environment to the patient’s problems, and ancillary tests or data all may figure into the final diagnosis. A “tentative” diagnosis may be reached after the history is taken and physical examination is performed, but ancillary data are required to translate the “tentative” into the “final” diagnosis.
The major stumbling block for neophytic clinicians remains the integration of information and signs into a diagnosis or differential diagnosis. The inexperienced clinician often focuses so hard on a single sign or a piece of historical data that the clinician “loses the forest for the trees.” These same “trainees” in medicine are frustrated when a cow has two or more concurrent diseases. In such situations, the signs fail to add up to a textbook description of either disease, and the examiner becomes frustrated. A cow with severe metritis and a left abomasal displacement (LDA), for example, may have fever and complete anorexia. Such signs are not typical for LDA, so the inexperienced clinician may want to rule out LDA. The clinician must recognize that concurrent disease may additively or exponentially affect the clinical signs present. The clinical signs may cancel each other out, as may be seen in a recumbent hypocalcemic (subnormal temperature) cow affected with coliform mastitis (fever) that has a normal body temperature at the time of clinical examination.
Much is made of “problems” possessed by sick animals and people. These problems constitute the basis of the Problem-Oriented Medical Record. We do not disagree with this thought process, but in fact it adds nothing to the skill or integration ability of a good diagnostician. It is longhand logic that allows other clinicians or students to follow the thought processes of the clinician writing the problem-oriented record. Therefore it may be valuable in communications among clinicians concerning a patient. The major “problem” with the problem-oriented approach is that it does not make a bad diagnostician a good one. The clinician who cannot integrate data or recognize signs cannot recognize problems and will not formulate accurate plans. Therefore the problem-oriented approach is not a panacea and in fact is merely an offshoot of the thought processes that a skilled diagnostician practices on a regular basis.
HISTORY
Obtaining an accurate and meaningful history or anamnesis is an essential aid to diagnosis. History may be accurate but not meaningful or may be misleading in some instances. The clinician must work to ask questions that do not verbally bias the owner’s or caretaker’s answers. When obtaining the history, the clinician also has the opportunity to display knowledge or ignorance regarding the specific patient’s breed, age, use, and conformation. When the clinician appears knowledgeable concerning the patient, the owner is favorably impressed and often will volunteer more historical information. When the clinician appears ignorant of the patient and dairy husbandry in general, the owner often withdraws, answers questions tersely, and loses faith in the clinician’s ability to diagnose the cause of the cow’s illness. Therefore part of the art of history taking is to communicate as well as possible with each owner. Bear in mind that owners are proud of their cattle, care for them, and have large economic investments in them. The clinician enhances credibility with dairy farmers by displaying knowledge and concern regarding the sick cow, the herd, and the dairy economy.
Other information may be necessary. In most instances, the experienced clinician already will know breed, sex, approximate age, use, and other husbandry information. However, in some instances, specific age information may be necessary. The clinician can appear very observant by asking question three regarding treatments by the owner when it is obvious that the cow has had injections. Question eight is open-ended and may yield valuable information from an observant owner or totally useless information from an unobservant owner. The clinician should be as complete as necessary in obtaining information but should avoid asking meaningless questions because they may annoy or confuse the owner. Frequently when students are first gaining experience, they ask impertinent questions of owners; imagine the concerned owner, whose cow has an obvious dystocia, being asked what he feeds the cow. In such instances, the inexperienced clinician or student is trying to be thorough but has upset the owner, who usually will reply, “What difference does that make? She’s trying to have a calf!”
Another important aspect of history is to determine the duration of the disease. The general terms used to distinguish duration include peracute, acute, subacute, and chronic, although various experts disagree on the exact length of illness to define each category. Rosenberger suggests the following:
Peracute = 0 to 2 days
Acute = 3 to 14 days
Subacute = 14 to 28 days
Chronic ≥ 28 days
These durations are somewhat longer than those commonly used in the United States, and in general we would suggest:
Peracute = 0 to 24 hours
Acute = 24 to 96 hours
Subacute = 4 to 14 days
Chronic ≥ 14 days
The interpersonal skills necessary for effective history taking and “bedside manner” in a veterinarian are similar to those used by physicians. The veterinary clinician, however, has to establish a doctor-client relationship, whereas the physician must foster a more direct doctor-patient relationship. A good relationship, together with the skills and interactions that create a good one, is the secret to acceptance by the human client just as for a human patient.
Experienced clinicians adjust to the owner’s personality. Highly knowledgeable and educated clients require a much different use of language and grammar than do poorly educated clients who may be confused by or misunderstand scientific terms and excessive vocabulary.
The history also should clarify any questions regarding the signalment that the clinician cannot ascertain by inspection alone. Because we are concerned with the bovine species only, the use (dairy), sex, color, breed, size, and often age of the animal are apparent by inspection. It may be important to determine whether valuable cattle would be retained only for breeding use if production should decrease drastically. The various components of the signalment are important to recognize because certain diseases occur more commonly in some breeds, colors, ages, and sex than in others.
PHYSICAL EXAMINATION
The physical examination begins as soon as the bovine patient comes into the clinician’s view.
General Examination
A general examination consisting of inspection and observation is performed. The experienced clinician often makes this general examination quickly and sometimes while simultaneously obtaining verbal history from the owner. The general examination may be as short as 30 seconds or as long as 5 minutes, should further observation be necessary. As part of the general examination, the clinician needs to establish the habitus—the attitude, condition, conformation, and temperament—of the sick animal.
Attitude
The attitude or posture may suggest a specific diagnosis or a specific system disorder. The clinician must have basic knowledge of the normal attitude of dairy cattle, calves, and bulls before interpreting abnormal attitudes. The arched stance and reluctance of the animal to move as observed in peritonitis may indicate hardware disease, perforating abomasal ulcers, or merely a musculoskeletal injury to the back. A cow observed to be constantly leaning into her stanchion may have either nervous ketosis or listeriosis. A cow standing with her head extended, eyes partially closed, and exhibiting marked depression could have encephalitis or frontal sinusitis. A bull lying down with a stargazing attitude may have a pituitary abscess. A periparturient recumbent cow with an “S” curve in her neck is probably hypocalcemic. All of the attitudes in the above examples are abnormal and indicative of disease. Many attitudes are not specific, however. A cow affected with hypocalcemia, for example, will often open her mouth and stick out her tongue when stimulated or approached, but some nervous cattle assume this attitude even when healthy. An arched stance with tenesmus may be observed in simple vaginitis, coccidiosis, or rectal irritation but may be observed occasionally with liver disease, bovine virus diarrhea, and rabies.
Cattle stand typically by elevating their rear quarters while resting on their carpal areas, then rising to their forelegs. It is unusual for cattle to get up on their front legs first as do horses, but some cattle, especially Brown Swiss cows, cows with front limb lameness, or late pregnant cattle, do this normally. Therefore once again, it is important to be familiar with normal variations. It is impossible to enumerate all the possible abnormal attitudes assumed by cattle, but Table 1-1 is a partial list.
TABLE 1-1 Some Examples of Abnormal Attitudes Assumed by Cattle
| Arched back, anorexia, abducted elbows (“Painful stance”) | Peritonitis, pleuritis | |
| Arched back, anorexia, limbs placed further under body than normal, reluctance to stand | Polyarthritis | |
| Arched back, normal appetite, legs placed further ahead (front) and behind (back) body than normal | Musculoskeletal back injury | |
| Bloat, elevated tail head, weather vane head and neck, legs placed further ahead and behind body than normal, anxious expression, ears erect, nictitans protruding | Tetanus | |
| Recumbent with forelegs extended | Musculoskeletal injuring to forelegs—usually carpus | |
| Lateral recumbency but alert and responsive | Occasionally normal for brief time | |
| Usually indicative of musculoskeletal pain causing reluctance to flex one or more limbs | ||
| Ventral abdominal pain caused by udder swelling, udder hematoma, ventral abdominal hernia, or cellulitis | ||
| Recumbency with “S” curve neck, depressed, or comatose | Hypocalcemia | |
| Lateral recumbency, opisthotonos, depression | ||
| Calves | Polioencephalomalacia or other central nervous system (CNS) diseases | |
| Cows | Occasional hypomagnesemia or CNS disease or other CNS diseases | |
| Recumbency, hyperexcitability | Hypomagnesemia, occasional hypocalcemia | |
| Grinding teeth, blindness with intact pupillary responses, depression | Lead poisoning, polioencephalomalacia | |
| Grinding teeth, pushing nose against objects | Chronic abdominal pain, sinusitis, musculoskeletal pain | |
| Colic | Indigestion with small intestinal gas and fluid accumulation | |
| Small intestinal obstruction | ||
| Pyelonephritis or other urinary tract abnormality | ||
| Cecal distention or volvulus | ||
| “Praying position” with rear raised but resting on carpi | Laminitis | |
| Tenesmus | Vaginitis, rectal irritation, coccidiosis, rabies, hepatic failure, BVD | |
| Dog-sitting position | May be normal before raising rear quarters in some Brown | |
| Swiss and occasionally in other late pregnant cattle, some lamenesses | ||
| If cow cannot raise rear quarters but can raise front end, it may indicate a thoracolumbar spinal cord lesion | ||
| Hind feet under body, forefeet in front of body, reluctance to stand or move | Acute laminitis or severe forelimb lameness | |
| Hind feet standing on edge of platform with heels non weight-bearing | Sore heels, overgrowth of claws, sole ulcers | |
| Hind feet in gutter with rear legs extended behind body | Spastic syndrome, too short a platform for cow, heel pain | |
| Hind feet in gutter with rear legs extended behind body and lordosis | Chronic renal pain, chronic pyelonephritis, other causes of colic | |
| Forelimbs crossed, reluctance to move | Bilateral lameness of medial claws | |
| Chewing on objects, biting water cup, licking pipes, licking and chewing skin, aggressive behavior, collapse | Nervous ketosis or organic CNS disease | |
Condition
The condition of the animal is another component of the habitus that is assessed during the general examination. Condition is judged both subjectively and experientially in most instances. The clinician may assess the condition of a calf or an adult cow in comparison with the animal’s herdmates, as well as with the bovine population in general. Excessively fat cattle are predisposed to metabolic diseases during the periparturient period and, when suffering musculoskeletal injuries, may become recumbent more easily than leaner cattle.
Cattle may be thin yet perfectly healthy. When a cow loses weight and is thin because of illness, she generally appears much different than her herdmates. Healthy, thin cattle have normal hair coats and hydration status, appear bright, and possess normal appetites. Emaciated cattle that have lost weight because of chronic illness have coarse, dry hair coats, leathery dehydrated skin, and appear dull. The clinician must remember that severe acute disease may cause weight loss of 50 pounds or more per day. The condition of the animal correlates largely with the duration of the illness. Extreme emaciation is associated with chronic problems such as parasitism, chronic abscessation, chronic musculoskeletal pain, Johne’s disease, advanced neoplasia, and malnutrition.
The body score of dairy cattle is a system designed to add some objectivity to the subjective determination of condition. Body score is used in herd management to assess the nutritional plane of the cattle and to correlate this to milk production, relative energy intake, and stage of lactation. Body score is arrived at subjectively by observation and palpation of the cow’s loin, transverse processes of the lumbar vertebrae, and tail head area from the rear of the animal. Scores are recorded in half point gradations from 0 to 5 with 0 being very poor and 5 being grossly fat. Ideal scores have been suggested as 3.5 for calving cows, 2.0 to 2.5 for first service, and 3.0 for drying off (see Chapter 14).
Conformation
The conformation of the animal is the third component of the habitus to be assessed during the general examination. Familiarity with normal conformation is an obvious asset when observing conformational defects that may predispose to or indicate specific diseases. For example, udder conformation in the dairy cow is extremely important, and cattle with suspensory ligament laxity are prone to teat injuries and mastitis. Calves with kyphosis may have vertebral abnormalities such as hemivertebrae. Splayed toes may predispose to interdigital fibromas, and weak pasterns often lead to chronic foot problems. A crushed tail head allows chronic fecal contamination of the perineum and vulva, with the potential for reproductive failure or ascending urinary tract infection. Chronic cystic ovaries may change the conformation appearance of many cows so that they display thickened necks, prominent tail head, relaxed sacrosciatic ligaments, and flaccid perineum.
Temperament
Temperament is the fourth component of habitus and should be evaluated from a distance in addition to when the animal is approached during general examination. From practical and medicolegal standpoints, it is imperative that the clinician anticipates unpredictable or aggressive patient behavior whenever possible, lest caretakers, the clinician, or the animal itself be injured. Dairy bulls should never be trusted, even when they appear docile. Dairy cattle with newborn calves should be approached cautiously because many people have been injured or killed by apparently quiet cows that suddenly became aggressive to protect a calf. Some dairy cattle are naturally wild and vicious. They should be approached with extreme care or restrained in a chute if possible. Fortunately, most dairy cattle are rather docile and, unless startled or approached without warning, may be examined thoroughly without excessive restraint.
As a general rule, free-stall cattle are wilder than cattle housed in conventional barns, but there are exceptions. The manners and nature of the owner (or herdsperson) are directly reflected in the contentment or lack thereof observed in the herd. Some herds consist of truly quiet and contented cows, whereas in other herds all cattle will act apprehensive, jumpy, and fear all human contact. These latter herds, without exception, are handled roughly and loudly and frequently are mistreated. The veterinarian will quickly learn to adjust to the variable husbandry of herds within the practice. The increase in size of herds coupled with the impersonal nature of free-stall housing has decreased the family farm husbandry that had allowed more human/cow contact.
Physical restraint
