Clinical Data Gathering and Interpretation · 5 min read
History, Signalment and the Physical Examination
Signalment and History
Signalment (species, breed, age, sex, reproductive status) narrows the differential list before the animal is touched. A 10-year-old cat with weight loss and polyphagia points to hyperthyroidism; a young unvaccinated puppy with bloody diarrhea points to parvovirus; an intact bitch 4–8 weeks after estrus with polyuria and vomiting points to pyometra. NAVLE vignettes routinely hide the answer in the signalment, so read it first.
The history covers the chief complaint (onset, duration, progression, response to treatment), diet, medications and supplements, vaccination and parasite control, travel, toxin access, and in-contact animals. For herds and flocks, add morbidity and mortality, age groups affected, recent introductions, feed changes, stage of production, and biosecurity. A herd problem is defined by the population: ask how many are sick, how many have died, and what changed.
| Signalment | Think of |
|---|---|
| Large, deep-chested dog (Great Dane, Standard Poodle) | Gastric dilatation-volvulus |
| Doberman Pinscher | Dilated cardiomyopathy, von Willebrand disease |
| Cavalier King Charles Spaniel | Myxomatous mitral valve disease |
| Maine Coon, Ragdoll cat | Hypertrophic cardiomyopathy |
| Dalmatian, English Bulldog | Urate urolithiasis |
| Quarter Horse (Impressive line) | HYPP (hyperkalemic periodic paralysis) |
| Pony, Morgan, obese horse | Equine metabolic syndrome, laminitis |
| Older horse (>15 years) with hirsutism | PPID (equine Cushing's disease) |
| Fresh dairy cow, first month | Hypocalcemia, ketosis, displaced abomasum |
| Male cat, dysuria, straining | Urethral obstruction |
Vital Signs Across Species
| Species | Temperature | Heart rate (bpm) | Resp. rate (bpm) |
|---|---|---|---|
| Dog | 37.5–39.2°C (99.5–102.5°F) | 60–160 (small breeds higher) | 10–30 |
| Cat | 37.8–39.2°C (100–102.5°F) | 140–220 | 20–30 |
| Horse | 37.2–38.3°C (99–101°F) | 28–44 | 8–20 |
| Cow | 38.0–39.2°C (100.4–102.6°F) | 48–84 | 26–50 |
| Pig | 38.7–39.8°C (101.6–103.6°F) | 70–120 | 32–58 |
| Sheep/goat | 38.3–39.9°C (101–103.8°F) | 70–90 | 12–30 |
- Cattle: jugular distension and pulsation extending more than one-third up the neck, with brisket edema, suggests right heart failure (traumatic pericarditis, high-altitude disease).
- Horses: second-degree AV block and soft flow murmurs are common at rest in fit horses and disappear with exercise.
- Horses: take the rectal temperature before a rectal palpation, which lets air in and lowers the reading.
- Pigs: observe breathing, gait and behavior from a distance before restraint, which raises temperature and respiratory rate.
- Cats: palpate the ventral neck for a thyroid nodule ('slip') in older cats with weight loss.
The Systematic Examination
Observe before restraint: mentation, posture, gait, respiratory pattern and body condition. Then examine the same way every time. Mucous membranes and capillary refill time (normal < 2 seconds) assess perfusion. Pale membranes suggest anemia or vasoconstriction; brick-red suggests early sepsis or hyperdynamic shock; yellow means icterus; cyanosis means severe hypoxemia; chocolate-brown blood suggests methemoglobinemia (acetaminophen in cats, nitrate in ruminants, red maple in horses). A dark 'toxic line' at the gingival margin of a horse indicates endotoxemia.
| Deficit | Findings |
|---|---|
| < 5% | Not detectable on examination; history of losses only |
| 5–6% | Tacky mucous membranes |
| 6–8% | Mild skin tent delay, dry membranes |
| 8–10% | Marked skin tent, sunken eyes, prolonged CRT |
| 10–12% | Persistent skin tent, signs of shock |
| > 12% | Moribund; hypovolemic shock |
Auscultate the heart for rate, rhythm and murmurs (grade I–VI; a grade V murmur has a palpable thrill, grade VI is heard with the stethoscope off the chest). A gallop sound in a cat strongly suggests cardiomyopathy. Pulse deficits indicate arrhythmia (atrial fibrillation, ventricular premature complexes). Muffled heart sounds suggest pericardial or pleural effusion, or a diaphragmatic hernia.
Large Animal Examination Points
Finish with a problem list, then a ranked differential list for each problem using a system such as DAMNIT (degenerative, anomalous, metabolic, neoplastic, nutritional, inflammatory/infectious, idiopathic, immune, toxic, traumatic). Neurologic cases need an added step: localize the lesion (forebrain, brainstem, cerebellum, spinal segment C1–C5, C6–T2, T3–L3, L4–S3, or peripheral) before choosing a test. Pain scoring with validated scales, including feline and equine grimace scales, is part of every examination.
- Read the signalment first; NAVLE vignettes often hinge on breed, age and sex.
- Horse 28–44 bpm, cow 48–84 bpm, cat 140–220 bpm are the most tested vital ranges.
- Shocked cats are bradycardic and hypothermic; dogs and horses become tachycardic.
- Left-sided ping in a fresh cow: left displaced abomasum; right-sided ping: RDA/volvulus or cecum.
- Dehydration under 5% is clinically undetectable; skin tent and dry membranes appear at 6–8%.
- Build a problem list and localize neurologic lesions before choosing diagnostics.
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