Smallies Ddx by Clinical Sign

⭐Chronic cough

Chronic bronchitis

Bronchomalacia/bronchial collapse; tracheal collapse; Oslerus osleri; Crenosoma vulpis; eosinophilic bronchopneumopathy; feline asthma; bronchial foreign body; Angiostrongylus vasorum; Dirofilaria immitis; pulmonary neoplasia; pulmonary fibrosis; myxomatous degenerative valve disease with pulmonary oedema

⭐Acute cough

Bronchial foreign body or pneumonia

Pulmonary thromboembolism; Angiostrongylus vasorum; acute heart failure with pulmonary oedema

Productive cough

Pneumonia

Chronic bronchitis; lungworm infection; bronchiectasis

Non-productive cough

Feline asthma (cats) / bronchomalacia (dogs)

Pulmonary fibrosis; pulmonary neoplasia

Exercise-induced cough

Tracheal collapse

Chronic bronchitis; early heart disease; pulmonary hypertension

Coughing when drinking water

Tracheal collapse

Laryngeal dysfunction; oesophageal disease

Nocturnal cough

Left-sided congestive heart failure

Chronic bronchitis

Pink, frothy sputum

Cardiogenic pulmonary oedema (left CHF)

Acute volume overload

⭐Dyspnoea

Pulmonary oedema (CHF) or feline asthma

Pneumonia; pleural effusion; ARDS; pulmonary thromboembolism; pneumothorax; diaphragmatic rupture; idiopathic pulmonary fibrosis; metabolic acidosis

Tachypnoea

Pulmonary disease

Heart failure; pleural effusion; pain; stress; anaemia; metabolic acidosis

⭐Expiratory dyspnoea / wheeze

Feline asthma

Chronic bronchitis; bronchomalacia; allergic airway disease

⭐Inspiratory dyspnoea

Upper airway obstruction

Laryngeal paralysis; nasal disease; pharyngeal mass; tracheal collapse

Orthopnoea

Pulmonary oedema

Pleural effusion; heart failure; severe lung disease

⭐Cyanosis

Severe respiratory disease

Pulmonary thromboembolism; right-to-left cardiac shunt; severe heart failure

Paradoxical breathing

Diaphragmatic rupture

Severe pleural space disease; respiratory fatigue

Painful respiration

Pleuritis

Pleural effusion; pneumothorax; thoracic trauma

⭐Harsh lung sounds

Chronic bronchitis

Bronchopneumonia; pulmonary fibrosis; allergic airway disease

Lung Crackles

Pulmonary oedema

Pneumonia; pulmonary fibrosis; ARDS

Reduced lung sounds ventrally

Pleural effusion

Pneumothorax; lung lobe torsion; diaphragmatic hernia

⭐Nasal discharge

Upper respiratory infection

Nasal neoplasia; fungal rhinitis; foreign body; chronic rhinitis

Epistaxis

Nasal neoplasia or fungal infection

Coagulopathy; systemic hypertension; trauma

⭐Stertor

Brachycephalic obstructive airway syndrome

Nasopharyngeal disease; elongated soft palate

⭐Stridor

Laryngeal paralysis

Laryngeal mass; tracheal collapse; upper airway obstruction

⭐Exercise intolerance

Myxomatous degenerative valve disease

Dilated cardiomyopathy; hypertrophic cardiomyopathy (cats); pulmonary hypertension; heartworm disease; chronic bronchitis

⭐Lethargy

Congestive heart failure, CKD, anaemia

Pericardial effusion, acute pancreatitis, diaphragmatic hernia, mediastinal lymphoma, SRMA, glaucoma, hyperadrenocorticism, hypoadrenocorticism, hypothyroidism, hyponatraemia, hypercalcaemia, CKD, pyometra, hepatitis, pneumonia, systemic infection, endocarditis

Syncope

Cardiac arrhythmia (ventricular tachycardia; AV block)

Pulmonary hypertension; severe aortic stenosis; cardiac tamponade; congenital heart disease; pulmonary thromboembolism; pericardial effusion

Collapse

Cardiac arrhythmia

Hypoxia; heart failure; hypoglycaemia; pulmonary thromboembolism; heat stroke

Heart murmur

Myxomatous degenerative valve disease

Dilated cardiomyopathy; hypertrophic cardiomyopathy (cats); congenital heart disease; endocarditis; neoplasia

Gallop heart rhythm

Hypertrophic cardiomyopathy

Restrictive cardiomyopathy; myocarditis

⭐Ascites

Right-sided congestive heart failure

Pericardial effusion; portal hypertension secondary to chronic hepatitis; hypoalbuminaemia

Sudden onset ascites

Pericardial effusion

Right-sided heart failure; cardiac tamponade

Acute hindlimb paralysis (painful)

Feline arterial thromboembolism (FATE)

Aortic thromboembolism

⭐Vomiting

Pancreatitis

Gastrointestinal obstruction; GDV; gastritis; CKD; hepatitis or liver failure; hypoadrenocorticism; septic peritonitis

Chronic vomiting

Inflammatory bowel disease

Gastrointestinal neoplasia; CKD; chronic hepatitis; food-responsive enteropathy

⭐Chronic diarrhoea

Inflammatory bowel disease

Adverse food reaction; intestinal lymphoma; lymphangiectasia; EPI; endocrine disease

⭐Weight loss

Inflammatory bowel disease or intestinal lymphoma

Exocrine pancreatic insufficiency; chronic kidney disease; hyperthyroidism; congestive heart failure

⭐Weight loss with polyphagia

Exocrine pancreatic insufficiency

Hyperthyroidism; diabetes mellitus

Greasy, pale faeces

Exocrine pancreatic insufficiency

Intestinal lymphangiectasia; severe small intestinal malabsorption

⭐Regurgitation

Acquired megaoesophagus

Oesophagitis; oesophageal obstruction/stricture; vascular ring anomaly

⭐Icterus

Hepatitis or cholangiohepatitis

Pre-hepatic haemolysis; post-hepatic biliary obstruction; hepatic neoplasia; hepatic lipidosis (cats)

⭐Hepatic encephalopathy

Portosystemic shunt

Severe hepatic failure; acute hepatitis; gastrointestinal bleeding

Seizures (systemic illness)

Hypoglycaemia or hepatic encephalopathy

Metaldehyde toxicity; organophosphate toxicity; lead toxicity

Seizures in young small-breed dog

Congenital portosystemic shunt

Hypoglycaemia; congenital brain malformation

⭐Pyrexia

Bacterial infection (e.g. pneumonia, septic peritonitis)

Pancreatitis; bacterial endocarditis; immune-mediated disease

⭐Pale mucous membranes

Anaemia (IMHA, chronic blood loss)

Hypovolaemic shock; poor perfusion due to CHF

Petechiae / ecchymoses

Immune-mediated thrombocytopenia

DIC; vasculitis; anticoagulant rodenticide toxicity; tick-borne disease (Ehrlichiosis)

Failure to thrive (young animals)

Congenital heart disease

Portosystemic shunt; chronic infection; immunodeficiency

Recurrent infections

Primary immunodeficiency

Chronic steroid use; endocrine disease

⭐Bradycardia

High vagal tone

AV block; hypothermia; drug effects

⭐Tachycardia

Pain or hypovolaemia

Anaemia; heart disease; hyperthyroidism

Muffled heart sounds

Pericardial effusion with cardiac tamponade

Pleural effusion

Borborygmi in thorax

Diaphragmatic rupture

Peritoneopericardial diaphragmatic hernia

Cough + weight loss

Pulmonary neoplasia

Lungworm infection; tuberculosis (rare); fungal pneumonia; chronic bronchitis

Cough refractory to antibiotics

Chronic bronchitis

Neoplasia; eosinophilic bronchopneumopathy; fungal disease

Acute dyspnoea after surgery / immobilisation

Pulmonary thromboembolism

Aspiration pneumonia; pneumothorax; acute heart failure

Acute onset tachypnoea with normal lung sounds

Pulmonary thromboembolism

Metabolic acidosis; pain; early heart failure

Pleural effusion

Congestive heart failure (cats)

Neoplasia; pyothorax; chylothorax; hypoalbuminaemia; diaphragmatic rupture

Chylous pleural effusion

Idiopathic chylothorax

Cardiac disease; mediastinal mass; heartworm disease; trauma

Pyothorax

Bacterial infection

Bite wounds; migrating foreign body; pneumonia extension

Sudden respiratory distress in cat with murmur

Congestive heart failure (HCM)

Feline asthma; pleural effusion; pulmonary thromboembolism

Bounding pulses + continuous murmur

Patent ductus arteriosus

Anaemia; hyperthyroidism; sepsis

⭐Vomiting + icterus

Hepatobiliary disease

Pancreatitis; haemolysis; biliary obstruction

⭐PU/PD + weight loss

Diabetes mellitus

CKD; hyperadrenocorticism; hyperthyroidism

⭐PU/PD

CKD

Diabetes mellitus; hyperadrenocorticism; pyometra; hepatic insufficiency

⭐Muscle wasting + pot belly

Hyperadrenocorticism

Protein losing enteropathy; chronic malnutrition

Behavioural changes + GI signs

Hepatic encephalopathy (secondary to portosystemic shunt or liver failure)

Hypoglycaemia; electrolyte disturbances; metaldehyde toxicity; lead toxicity

Petechiae + pyrexia

Immune-mediated thrombocytopenia

Infectious thrombocytopenia; DIC; drug reaction

Neurological toxins

• Metaldehyde (slug bait)
• Organophosphate
• Ethylene glycol
• Lead

GI +/- systemic toxins

• Xylitol
• NSAIDs
• Rodenticide
• Mycotoxin

Coagulopathy / bleeding toxins

• Anticoagulant rodenticide
• Zinc phosphide

Renal toxins

• Ethylene glycol
• NSAIDs
• Leptospirosis

⭐Hyponatraemia

Iatrogenic - diuretics, hypotonic fluids, mannitol

Volume overload - CHF, hepatic disease, renal disease, effusions, ascites

Losses - hypoadrenocorticism, Diabetes mellitus, vomiting, diarrhoea

⭐Hypernatraemia

Iatrogenic - hypertonic fluids

Water deficit - dehydration, water depriviation, renal (PUPD), vomiting, diarrhoea, Diabetes mellitus

Salt gain/retention - salt poisoning, Diabetes insipidus

⭐Hypokalaemia

Decreased intake - anorexia, malnutrition

Increased loss - GI (vomiting, gastric outflow obstruction), renal (CKD, hyperaldosteronism, renal tubular disease)

Transcellular shift - metabolic alkalosis, insulinoma, endotoxaemia

Iatrogenic - diuretics, insulin overdose

⭐Hyperkalaemia

Iatrogenic - IV fluids with potassium, potassium-sparing diuretics

Transcellular shifts - tissue necrosis, DIabetes Mellitus, uroperitoneum, metabolic acidosis

Decreased renal excretion - AKI, CKD, uroabdomen, hypoaldosteronism, urinary obstruction

Pseudohyperkalaemia (sample haemolysis)

⭐Hypochloraemia

Iatrogenic - fluids with high bicarbonate, diuretics

Primary metabolic alkalosis - vomiting, gastric reflux, gastric rupture, GDV

Secondary metabolic alkalosis - compensation from respiratory acidosis by increasing renal excretion

• Most likely: Gastric outflow obstruction
• Other ddx: Prolonged vomiting; Diuretic therapy; Metabolic alkalosis; CHF; Third-space losses

⭐Hyperchloraemia

Iatrogenic - hypertonic saline, ammonium choride fluids, anticonvulsants

Bicarbonate loss - vomiting (biliary, pancreatic), diarrhoea, renal loss

Chloride gain - renal tubular acidosis, AKI, hyperaldosteronism

⭐Hypocalcaemia

Hypoparathyroidism, vitamin D deficiency

Eclampsia (lactational hypocalcaemia)

Hypoalbuminaemia (low total ca)

Ethylene glycol toxicity

Acute pancreatitis; Sepsis; CKD

⭐Hypercalcaemia

Primary hyperparathyroidism, vitamin D toxicity

Paraneoplastic (lymphoma, anal sac adenocarcinoma);

Hypoadrenocorticism

CKD

Granulomatous disease

Idiopathic hypercalcaemia (cats)

⭐Hypophosphataemia

Hyperparathyroidism

Diabetic ketoacidosis, insulin administration

Respiratory alkalosis

Malnutrition

⭐Hyperphosphataemia

CKD, AKI, tumour lysis syndrome

Hypoparathyroidism, vitamin D toxicity

⭐High TP

Dehydration

Chronic antigenic stimulation (e.g. feline infectious peritonitis)

Neoplasia (e.g. multiple myeloma, lymphoma)

Chronic inflammatory disease

⭐Low TP

Protein-losing enteropathy

Protein-losing nephropathy

Severe haemorrhage

Hepatic failure

⭐High albumin

Dehydration (only true cause)

⭐Low albumin

Protein-losing enteropathy

Protein-losing nephropathy

Reduced hepatic synthesis (end-stage liver failure)

Severe inflammation / sepsis

Overhydration

⭐High globulin

Chronic inflammation

FIP

Lymphoma

Multiple myeloma

Chronic infectious disease

⭐Low globulin

Failure of passive transfer (neonates)

Immunodeficiency, immunosuppressive therapy

Protein-losing enteropathy

⭐High urea

Increased protein catabolism - pyrexia, Cushings, starvation

Increased protein digestion - GI haemorrhage, high protein diet

Decreased GFR - AKI, CKD, dehydration

⭐Low urea

Decreased protein intake - low protein diet, young animals

Decreased production - hepatic disease

Increased excretion - Cushings, Diabetes Mellitus, PUPD

Increased GFR - portosystemic shunts, overhydration

⭐High creatinine

Greyhounds

Decreased GFR - dehydration, AKI, CKD

Decreased excretion - urinary obstruction, urethral rupture

⭐Low creatinine

Decreased production/intake - starvation, cachexia, reduced muscle mass

Increased GFR - portosystemic shunts, overhydration

⭐ High CK

Young animals

Anorexia

Muscle injury - myopathies, trauma

Toxins - monensin, doxorubicin

Cerebrocortical necrosis

⭐High cholesterol

• Hypothyroidism
• Hyperadrenocorticism
• Diabetes mellitus
• Nephrotic syndrome
• Cholestasis

⭐Low cholesterol

• Portosystemic shunt
• End-stage liver failure
• Protein-losing enteropathy
• Malabsorption / malnutrition

⭐High ALP

Iatrogenic - anticonvulsants, thyroxine, steroids

Cholestasis

Endocrine - Cushings, hyperthyroidism, chronic stress

Increased bone activity - growing animals, hyperparathyroidism, fracture healing, osteosarcoma

Mammary tumours

⭐High ALT

Iatrogenic - anticonvulsants, steroids, cephalosporin, cyclosporin

Hepatocellular injury, hepatitis, hepatic hypoxia (shock), hepatic neoplasia

Severe muscle injury - FATE, myopathies, trauma

⭐High AST

Iatrogenic - anticonvulsants

Hepatocellular injury - hepatitis, hepatic failure, neoplasia

Skeletal muscles - myopathies, trauma

⭐High bilirubin

Pre-hepatic: immune-mediated haemolytic anaemia

Hepatic: hepatitis, hepatic lipidosis

Post-hepatic: extrahepatic biliary obstruction, cholestasis

Bacterial sepsis, severe inflammation

⭐High glucose

Post-prandial

Pregnancy (progesterone)

Iatrogenic - xylazine, detomidine, propanalol, ketamine)

Lack of insulin / insulin resistance - Diabetes Mellitus, Cushings, acromegaly, pheochromocytoma, pancreatitis

⭐Low glucose

Iatrogenic - insulin administration, xylitol

Decreased production - portosystemic shunt, juvenile toy breed hypoglycaemia

Decreased intake - starvation

Increased usage - sepsis, idiopathic hypoglycaemia, exercise, Addison’s

Increased insulin - insulinoma, paraneoplasia