Imaging

• location/position/alignment
• tissue characteristic
• size
• shape
• margin
• number
• function
• contrast enhancement

• radiography: opacity (increased or decreased)
• CT: attenuation (hyper or hypo)
• US: Echogenicity (hyper or hypo)
• MRI: signal intensity (hyper or hypo)
• Nuclear: uptake (increased or decreased)
• Radiographs and CT range: gas, fat, fluid/soft tissue, mineral/bone, metal

• iodinated contrast - all xray based modalities.  CT most common.
• DEHYDRATION IS ABSOLUTE CONTRAINDICATION
• vomiting, nausea etc.

• frequency: number of occurrences of a repeating event per unit time. Hertz = cycles per second. US can't travel through air. 
• Wavelength: distance over which the wave's shape repeats
• wavenumber: 
• Amplitude: 
• Intensity: 
• Speed: 
• Direction:

• constant velocity of sound (1540 m/sec)
• direction of returning US waves is from same sending angle relative to the probe
• All sound waves created by primary beam

• B mode = brightness mode.
• M-mode is motion, for cardio

• For all waves (sound or light), Doppler is the change in observed frequency because of motion of the source or observer.
• Continuous wave (can't calculate where the echo comes from) vs pulsed wave (can plot where the echo comes from)

• name of institution/practice
• Patient ID (name, number, etc)
• Date images acquired

• stochastic: severity independent of dose, probability increases with dose.  No threshold (fetal exposure, cancer, genetic damage)
• deterministic: severity increases with dose level.  Practical dose threshold (cataracts, skin damage)

5 REM (roentgen equivalent in man) = 50 mSv per year

• as low as reasonably achievable
• achieved with time, distance, shielding

• increased kVp
• increased field size
• Increased patient and/or body part size
• Restricted by collimators (limit field size), grids (absorb scatter)

• reduced serosal detail (brown fat is more opaque)
• unable to make out the margins of the organs

• Liver: gastric axis parallel to ribs
• spleen: variable in size (sedation), with smooth sharp margins
• kidneys: 2.5-3.5 x L2
• Urinary bladder: variable
• prostate: visible only in intact males.  Craniocaudal length should not exceed pelvic inlet. 
• Stomach: should only contain formed food or gas. Only liquid if JUST after a drink
• SI: <1.6x vertical body of L5. Loose loops, fluid or gas.  ANY formed material is indigestible. 
• Adrenals and pancreas usu not visible.  Sub-lumbar LN only visible when enlarged. Often incidental minerals, choleliths in GB

• retroperitoneal orgin
• caudal: sublumbar LN
• cranial: renal, adrenal
• diffuse: hemorrhage, effusion

• ventral abdominal origin
• splenic tail, intestine (gas), liver (pedunculated), ovarian/teste (large), mesenteric LN

• mid-abdominal origin
• spleen, intestine (gas), ovary/teste, mesenteric LN

• cranial abdominal origin
• Liver, stomach (gas)

• Caudal abdominal origin
• prostate, uterus, urinary, bladder

• used to gain a 3D overview of abdominal structures to aid in surgical and radiation planning
• mass lesions: origin, vascularity, margination, extents
• Vascular anomalies: PSS
• Urinary anomalies: ectopic ureters

• Dog rads: 2.5-3.5 the length of L2
• Cat rads: 2.4-3x the length of L2, as low as 2 in older cats
• US: cats = 3.0-4.3 cm in length. Dogs are hard to tell.

• smooth: lymphoma, FIP, bilateral hydronephrosis, amyloidosis, acute renal injury, bilateral perinephric pseudocysts, Hypertrophy (acromegaly)
• Irregular margins: pyelonephritis, polycystic kidney disease, FIP, lymphoma
• FIP or Lymphoma can be unilateral or bilateral, smooth or irregular

• diffuse with smooth (normal shape): ureteral obstruction, pyelonephritis, compensatory hyperplasia, FIP, neoplasia (lymphoma), renal vein thrombosis
• Focal with irregular margins (abnormal shape): neoplasia (adenocarcinoma, lymphoma), cyst, abscess, FIP

• Smooth/normal shape: chronic interstitial nephritis, renal dysplasia, congenital hypoplasia
• irregular (abnormal): chronic interstitial nephritis, infarcts, chronic pyelonephritis

• smooth: congenital hypoplasia, chronic interstitial nephritis
• irregular: chronic interstitial nephritis, chronic pyelonephritis, multiple infarcts

• Unilateral disease: pyelonephritis, congenital hypoplasia
• contralateral compensatory renomegaly

• Renal cortex is hypo- or isoechoic to the liver (can be hyper in obese cats because of fat accumulation)
• renal medulla is hypoechoic to the renal cortex, should be a clear demarcation.

• Helps show renal size and shape, masses around kidney, pyelonephritis, integrity of kidneys and ureters following trauma, renal pelvic or ureteral calculi, ureteral size, position and path. 
• Not great for function (50% still looks normal).  Not used as much now (US instead)
• IV iodinated contrast, then take rads at dif times after. 
• arteriogram immediately, nephrogram next (accumulates in renal tubules, homogenous kidney uptake, 5s to 5m), pyelogram in pelvis (10-20m), ureters (5-20m) and bladder (40min)
• CONTRAST-AGENT INDUCED RENAL FAILURE - don't use in dehydration, anuria, known sensitivity

• Hard to see on US, not usu seen on rads.  Ureteral jets may be visible with doppler US
• There is an end-on blood vessel, don't mistake it for a stone.

stricture, calculus, ectopic ureter, luminal/extraluminal mass, urinary bladder mass, inflammation

• R kidney at T12-L3, 18-25cm in length.  Percutaneous approach. 
• L kidney displaced medially by rumen, around L2-5, scanned rectally. Same size.
• Often indistinct corticomedullary definition. 
• Small ruminants: smooth outer margins, size varies based on animal size. Well defined corticomedullary. 
• disease: nephrolithiasis (obstructive or not, sm ruminant), hydronephrosis (sm ruminant), pyelonephritis (bovine), renal abscess (bovine), chronic renal disease (usu don't live long enough), congenital renal cysts (common)

• R: ventral to transverse spinous processes, 14-17th intercostal space
• L: 15th intercostal space to caudal border of the perilumbar fossa
• scan technique via both transabdominal and translumbar

• Wall thickness varies on degree of distension (distended = smooth and 1/2mm).
• can ID mural lesions and non-radioopaque calculi in lumen
• intraluminal echoes may be crystals, fat, cells (RBC, WBC).

thick irregular bladder wall, often worse cranioventrally

• Hyperechoic
• dependent (sink)
• strongly shadowing
• "twinkling" artifact with color doppler

• malignant: TCC most common. Also lymphoma, SCC and sarcomas.  Leiomyosarcoma is smooth luminal surface, rhabdomyosarcoma is seen in ,1yr and often botryoid (bunch of grapes)
• Benign: polypoid cystitis, leiomyoma, hematoma/hemorrhage/blood clot

• Broad-based, irregular margins, often at trigone. 
• Can be mineralized. 
• Commonly extends into cranial urethra

• homogenous soft tissue opacity, variably sized
• abnormal location suggests hernia or pelvic bladder
• abnormal opacity indicates mineral or gas

• Radiopaque: struvite, calcium oxalate
• Radiolucent: cystine, urate.  Visible if large enough
• add a flexed him view to check for urethral calculi
• don't forget to radiograph ALL the urethra!

• positive or double contrast cystography to eval bladder mucosa, cystic calculi, bladder masses.  Good for GP.  Iodinated contrast + room air
• Eval for filling defects, calculi, mural lesions

• castrated: not visible or small.  Fusiform, mildly hypoechoic
• intact: visible caudal to urinary bladder, intra-abdominal vs pelvic canal.  <70% distance from sacrum to pubis. Bilobed, medium-echoic. 
• cats: not seen.  Within pelvic canal.

• Symmetrical: BPH (intraprostatic cysts are common and incidental), prostatitis.
• Asymmetrical: abscess, paraprostatic cyst, neoplasia
• Castrated males: VERY suggestive of neoplasia, esp if mineralized

• irregular margins
• heteroechoic
• mineral foci
• often extend into urethra and urinary bladder

lumbar, sacral, pelvic bones

• ovoid, homogenous, medium echoic
• prominent, hyperechoic mediastinum
• epididymis
• pampiniform plexus (doppler)

• Cyst
• Hematoma
• Abscess
• Neoplasia
• Granuloma
•  neoplasia: leydig/interstitial cell tumor, sertoli cell tumor, seminoma

Not visible!

• pyometra (endometritis or metritis in mare/cow)
• hydrometra
• mucometra
• pregnancy

41-45d

• fetal gas
• mummified
• deformed skeleton
• abnormal position ("C-shaped", hyperextension)

• need to be 4x in size before seen radiographically, at which point they're in ventral abdomen. 
• Neoplasm can be bilateral
• ovarian cysts also a thing

• rads: reduces contrast/serosal detail. Can't see organ margins
• US: hypoechoic fluid (+/- particulate matter) around organs, a scant volume normal in neonates, LA
• ddx: transudate, modified transudate, exudate, hemorrhage, urine, bile, chyle (rare in abdomen)

• Rads: gas opacity outlines organs, causes increase in serosal detail, use horizontal beam to eval (gas floats up, so shoot from the side!)
• US: "Bright" shadowing gas external to viscera
• ddx: Previous laparotomy, ruptured GIT, external wound, ruptured abdominal abscess

• rads: mottled opacity within peritoneal fat, like a low-level effusion
• US: use this!  Peritoneal fat is hyperechoic. Stops deep penetration of US waves. 
• ddx: ruptured bowel, acute hepatitis / splenitis / nephritis / pancreatitis / prostatitis / enteritis, neoplasia, DIC, Sepsis, anaphylaxis

• rads: only visible via mass effect
• US: homogenous medium echogenicity. Oval or elongated shape with sharp margin.  Hilus visible with doppler.
• MUCH larger in pediatric. 
• adult canine: jejunal, medial iliac, superficial iliac
• juvenile canine: jejunal, medial iliac
• cat: pancreaticoduodenal, hepatic, jejunal, ileocecal, medial iliac

• rads: only mass effect
• US: reactive maintain smooth margin, oval shape, homogenous echogenicity and hilus structure.  Neoplastic can look like reactive but if they're ROUNDED, heterogenous, mineralized, loss of hilus or irregularly marginated, they're prob neoplastic
• CT/MR: best for deep LN metastasis.  Reactive are just bigger, neo are large, loss of hilus, mineralized.  Inflammatory have inflam peripheral to the node

• My (renal Medulla)
• Cat (renal Cortex)
• Loves (liver)
• Sunny (spleen)
• Places (prostate) 
• darker to lighter

• rads: increased size of hepatic silhouette with rounded lobe apices, caudodorsally displaced gastric axis.  
• US: increased parenchymal bulk, rounded lobe apices.  Could also have altered parenchyma
•       hyperechoic and dense = vacuolar hepatopathy, steroid hepatopathy, hepatic lipidosis
•       heterogenous or hypoechoic = infiltrative neoplasia, Acute hepatitis, congestion (right-sided CHF, Budd-Chiari = occlusion of CdVC between liver and heart)

• rads: reduced size of hepatic silhouette, cranial displacement of gastric axis.
• cirrhosis, PSS

• chronic hepatic insult/hepatitis causes microhepatia
• hyperechoic cirrhotic parenchyma with undulating margins
• causes portal hypertension, which causes acquired PSS and peritoneal effusion

• small liver with poorly visible vasculature on US.  Visible shunting vessel in abdomen (intrahepatic vs extrahepatic).
• Enlarged kidneys.  
• Sediment or uroliths in the urinary bladder
• CT for cross-sectional anatomy of anomylous vessel.  
• Nuclear to rule in/out a shunt, does not give info about morphology
• Fluoroscopy: IN SURGERY to confirm pre and post-ligation

• Rads: rounded cranial abdominal mass lesion visible extending from liver. Undulation of hepatic margin can suggest nodules
• US:
• nodules: benign (lymphoid hyperplasia is hypoechoic, myelolipoma is hyperechoic), malignant (metastasis is heterogenous/target),
• Mass lesions: Neoplasia (hepatocellular carcinoma, hepatoma, hemangiosarcoma, lymphoma, histiocytic sarcoma, biliary cystadenoma in cats), abscess, granuloma, torsion/infarction

• rads: ventral margin gallbladder occasionally seen
• US: GB on R side of liver, lumen contains anechoic or echogenic mobile bile, wall is thin and echogenic.  Intrahepatic ducts are not visible

• abnormal GB luminal contents
• static mucus in lumen, often has "kiwi fruit" appearance.  Gradually enlarges over time until wall rupture
• When ruptured, wall thickening and a bile peritonitis with bright peritoneal fat and fluid. 
• Doesn't move when P does

• visible on rads
• US: hyperechoic interface with dark shadowing. Observed in GB, common bile duct, intrahepatic ducts etc. Incidental unless obstructing

• commonly caused by choleliths, masses or cholangitis
• observe distension in common bile duct, GB and eventually intrahepatic ducts become visible
• "too many tubes" sign

• diffuse: cholangiocystitis, congestion, hepatitis, hypoalbuminemia
• focal: neoplasia, polyp, granuloma

• homogenous parenchyma
• vessels entering the hilus
• sharp apices

• rads: rounded lobe apices, increased bulk. 
• US: normal parenchyme indicates congestion or sedation.  Heterogenous parenchyma indicates splenitis/infiltrative neoplasia (lymphoma).  Hypoechoic hypovascular parenchyma with displacement indicates splenic torsion.

• rads: mid-abdominal mass lesion
• US: often heterogenous and rounded.  Distends splenic capsule. Assess for hemorrhage. 
• ddx: neoplasia (HSA, hemangioma, histiocytic sarcoma), hematoma, extramedullary hematopoiesis

• Hyperechoic = myelolipoma
• hypoechoic = extramedullary hematopoiesis, lymphoid hyperplasia, metastasis
• conforms to margin and hypovascular = infarct.

• rads: usu not visible unless mineralized
• US: canine between 5.4-8mm (based on size).  Feline 3.5-4.5mm

atrophy: addison's (bilateral), secondary to functional contralateral adrenopathy (unilateral), iatrogenic.

• hypertrophy: secondary to PDH, bilateral enlargement
• mass or nodular enlargement: >2cm = neoplasia.  >4cm = malignant. Vascular invasion is also likely malignant (adenocarcinoma, pheochromocytoma)

• Rads: not visible due to superimposition of larger soft tissue structures
• US: mottled medium echoic, looks like peritoneal fat.  Contains pancreatic duct and vessels, seeing these helps to ID.

• Rads: NOT SENSITIVE, use to r/o other causes of v and abd pain.
• US: MAINSTAY of dx. Hypoechoic pancreas, hyperechoic peritoneal fat.  Dark organ surrounded by bright. Scant effusion, duodenitis.

• rads: LARGE masses (rare) can be seen in cr. abd. Usu carcinoma. 
• US: cyst (rare), abscess (rare), neoplasia (rare), nodules (common in cats).

• muscular tone, remain closed and not visible
• Some gas can be seen if swallowing air.  Mild dilation okay with sedation
• Brachycephalic can have redundant/too long, bows down in cranial mediastinum. 
• Contrast esophagram: fluoroscopy or rads.  <5s to LES.

FB/impacted material: ingestion of large FB or impaction of grass/feed. Distension of ST or mineral opacity FB.  May be gas distension. Look at mediastinal fluid/gas that could suggest perforation.

• esophageal mass: carcinoma, SCC, leiomyosarcoma.  Static body of ST. Distension of esophagus.  "bullet sign". Check for lung metastasis, aspiration pneumonia.
• Esophagitis: secondary to previous vomiting/doxy/FB.  Altered esophageal motility, gas distension on rads, abnormal bolus on fluoroscopy.  Look for strictures!
• Perforation: from FB, trauma, neoplasia, E-tube. Soft tissue swelling and gas, widening of mediastinum, pneumomediastinum, pleural effusion.  Can use contrast (NOT barium).
• Stricture: previous inflammation and scarring or vascular ring anomaly.  See esophageal distension with abrupt narrowing, accumulation of contrast.  Vascular ring anomalies ID'd when puppies/kittens move to hard food. Narrowing OVER HEART BASE. If caudal esophagus distended, POOR px.

• Hypomotility/megaesophagus
• usu an underlying cause (esophagitis, neuromuscular dz, myasthenia, SLE, dysautonomia, endocrinopathy, toxicity, thymoma).
• See gas distension of esophagus.  Barium accumulation and slow transit.  Uncoodinated or weak peristaltic waves. 
• Orad AND aborad movement of the bolus.

• thickening, hypoechoic/heterogenous, loss of wall layering, gas tracking, pedunculated.
• ddx: malignant = carcinoma, lymphoma, leiomyosarcoma.  Benign = leiomyoma, polyp

• thickening of the wall, maintenance of wall layering, reduced echogenicity, fluid-filled lumen.  
• Can lead to ulceration, perforation!
• ddx: dietary indiscretion, inflammatory, infectious, toxicity, drugs (NSAIDs), neoplasia.

• consequence of severe inflammation or neoplasia
• echoic gas tracking into wall. 
• Focal loss of layering. 
• Can lead to perforation and peritonitis!
• ddx: dietary indiscretion, inflammatory, infectious, toxicity, drugs (NSAIDs), neoplasia.

• rads: fluid distended stomach, free abdominal gas, reduction in serosal detail adjacent to stomach
• US: mural lesion, gas tracking through wall, hyeprechoic peritoneal fat, peritoneal effusion, free peritoneal gas (dark shadowing foci)

• single right lateral view.  Look for movement of pylorus dorsally, fundus ventrally, "double bubble", displaced and enlarged spleen, gastric pneumoatosis
• Look for pylorus to ID volvulus vs no volvulus

• Hiatal hernia: sliding vs static, common incidental in brachycephalics, lar pars and cats.  
• Diaphragmatic hernia: EMERGENCY if involves stomach
• Gastroesophageal intussusception: displacement of stomach into esophagus - can be lie-threatening.

• distension of the stomach with fluid (due to no mvmt) on rads and US. 
• caused by primary gastric diseases (gastritis, ulceration, neoplasia, dysautonomia), mechanical obstruction, iatrogenic, opioids, post-surgery, systemic disease processes, electrolyte imbalances.

>1.6x body of L5

• Digestible food should turn to fluid before entering duodenum, so ANY FORMED MATERIAL IS INDIGESTIBLE. Differentiate from fecal material in colon.
• Non-obstructive: chyme and fluid move past, will slowly move through intestine.  Does not cause significant luminal distension. 
• obstructive: chyme and fluid can't move past. Orad portion are distended, aborad non-distended and small.  TWO POPULATIONS.  Commonly at duodenal flexure or anywhere in jejunum (intestine fatigues).  Surgery!  Fluids and time if distal and no $. Warn O about perf. US: FB absorbs US waves = dark shadow.
• Linear: One end tethered in stomach/tongue, intestinal wall gathers, wall becomes perforated, maybe in multiple spots. Bunched on rads, angular gas opacity, material in pylorus/tongue. US - echogenic linear structure, loss of wall layering, effusion.  MOST perforate.

• rads: mid-abdominal mass that can contain gas. Reduction in serosal detail, obstruction.  Chronic partial "gravel sign" (big lumps of mineral opacity get stuck but fluid moves on).  Two populations. 
• US: loss of wall layering, circumferential hypoechoic/heteroechoic (lymphoma, carcinoma), peductulated or eccentric (leiomyosarcoma, GISTs), assess local LN

• rads show diffuse mild distension of SI or can be completely normal. Changes are diffuse. 
• US: acute enteritis shows reduced peristalsis, enlarged lumen, echogenic mucosa.  PLE show mucosal striations and lacteal duct distension. Chronic shows thickening of propria from IBD/lymphoma

• cause: FB, ulcer, neoplasia, trauma
• rads: effusion causing reduced serosal detail, pneumoperitoneum, tracking etallic body. 
• US: defect and gas tracking in intestinal wall, loss of wall layering, hypoechoic, local hyperechoic peritoneal fat, effusion, peritoneal gas

• Cause: previous trauma/obstruction/enterotomy.  May only cause obstruction with new FB, or cause chronic partial obstruction
• rads: gravel sign, variable patterns of distension.  Confusing!
• US: focal wall lesion with luminal narrowing.  
• May need sx to ID.

• telescoping of loops, commonly at ileocecocolic junction
• causes: parasites***, pedunculated mass, enteritis
• rads: mechanical obstruction (2 populations), bullet sign
• US: double layered region of intestine, hyperechoic fat centrally.  Orad to intussusception at the intestine is often distended.  Can form and unform between studies - dynamic.

• usu in large breed dogs
• rads: diffuse gas distension of SI
• US: often too much gas to see anything.

• body wall/diaphragm - congenital or trauma
• US: look for evidence of vascular compromise (color doppler).  Edematous thickened hypoechoic walls, loss of layering

• causes: primary intestinal (infectious/inflammatory, neuromuscular disease like dysautonomia, vascular compromise), Systemic disease (electrolytes), iatrogenic (surgery/medications)
• rads: diffuse distension of intestinal tract.  Fluid and gas-filled. Chronic disorders may have gravel accumulation. 
• US: lack of tone, fluid filled, reduced peristalsis, no aborad mvmt of content

• LI DOES NOT come ventrally in SA (so ventral fecal material is a FB).  LI is ventral in Equine. 
• US: thin-walled, layering.  Fecal material has dark shadow with bright surface interface.

opaque fecal content, distended colon, ratio of max diameter of colon to L5 length.  <1.28 is normal, >1.48 is megacolon

• rads: mineral opaque material accumulating in colon
• US: dark shadowing material in the lumen.

• causes: carcinoma, lymphoma, leiomyosarcoma, GISTs, polyp
• Rads: luminal narrowing
• US: wall thickening, loss of layering.

• Rads: fluid/gas filled lumen
• US: mild mucosal thickening and fluid feces

• Rads: diffuse thickening of colonic wall, if gas outlined
• US: variable degrees of mural thickening +/- loss of wall layering.

• Giant breed dogs.  Acute and chronic.  ONLY time you'll see displacement of colon
• rads: gas-distended colon, curled up, displaced.

comet tails.  Reverberation artifact caused by disruption of smooth gliding surface.

• down side gets smooshed!  What you're seeing is the up side.  
• Cardio loves the DV but VD better for lungs.
• Take at peak of inhalation for thoracic (on exhalation for abdominal)

• black
• air
• fat
• soft tissue
• bone
• metal
• white

• further away from the plate/closer to the beam = larger.  
• works the opposite in lungs as others--put the lesion up in lungs, down in everything else

• Two structures of same opacity in contact (margins cannot be distinguished)
• To differentiate, structures of same opacity must be separated by substance of differing opacity
• = border effacement.

cardiomegaly (or poor positioning)

• usually benign in dogs and cats.  Rarely metastatic, usually indicates chronic inflammation
• horses and cows have more fibrin in lungs

• unstructured is patterns
• don't forget lucent lesions (bulla, pneumatohemocoeles)
• structured is focal vs multifocal (mass and nodules easiest to detect.  Tiny minerals can be pulmonary osteomas.  Tiny soft tissue is miliary.
• Abscess has a thick wall, bulla has a thin wall often incidental, post-traumatic, or congenital in Huskies. Rupture causes spontaneous pneumothorax.

• bulla, pneumatohemocoeles
• Abscess has a thick wall, bulla has a thin wall
• often incidental, post-traumatic, or congenital in Huskies.
• Rupture causes spontaneous pneumothorax.

• rare
• tiny nodules
• dogs: fungal (blastomycosis), lymphoma
• cats: mycobacterium
• mineralization, less opaque than ribs, usually diffuse, very rare

• increased size: round or displaced (mediastinal shift).  Pulmonary or bronchoalveolar carcinoma is primary diagnosis for single large mass in a dog
• decreased size: Always a reason.  "triangle" displacement vs technical or pathologic (scarring? Plugging?)

• lobar
• cranioventral: infection (or hemorrhage - rodenticide)
• caudodorsal: edema (cardiogenic or non-cardiogenic)
• peri-hilar: edema (cardiogenic)
• mid-zone: transitional disease
• peripheral: PTE
• diffuse or generalized: bad news.

• uniform soft tissue opacity
• air bronchograms
• lobar sign
• border effacement of large structures (cardiac silhouette and diaphragm, adjacent to abnormal lobe)
• border effacement of small structures (outer airway wall and vessels, within abnormal lobe)
• ddx: blood, pus, edema, neoplasia (classic pneumonia)

• disease of small airways.
• Look for lines and rings within periphery of lobes= thickening of lower airways (peripheral).  Always generalized
• caused by wall infiltrate, luminal fluid or peri-bronchial change. 
• R/O infectious (parasitic, bacterial), inflammatory (chronic bronchitis), allergic (irritants).  Rarely, neoplastic spread along airways (carcinoma in cats).

• arteries: enlarged, tortuous, blunted = canine or feline heartworm disease.  Or could be thrombo-embolism
• veins: venous congestion secondary to elevated left atrial or ventricular filling pressures (diastolic pressures)
• Arteries and Veins: left to right shunt, AV fistula, fluid overload (renal insufficiency cases with fluid overload), or left heart failure (cardiomyopathy) in cats.

• metastatic disease
• granulomatous disease

2-3mm, irregular shape, ventral distribution

• generalized, 2mm size, round
• carcinoma, lymphoma, fungal disease

• vague increase in overall background opacity (you know it's real because one side is normal)
• results in decreased sharpness to vascular lines
• never MILD
• Can accentuate airways (rings and lines will not be present in the periphery)
• On an continuum with alveolar pulmonary pattern (airspace disease rather than airway).  Like alveolar but less severe

• Spongy lobe (miliary is diffuse)
• Pleural fusion is common
• sight hounds in right middle
• Pugs in left cranial

• agenesis or hypoplasia of ribs
• only important when needed as a surgical landmark
• often accompanied by butterfly or hemivertebrae

• pectus excavatum: dorsal displacement of caudal sternebrae.  Can cause resp distress. 
• Short sternum: can be seen with PPDH

• rare
• tumors: primary mesenchymal tumors such as chondrosarcoma.  Local extension. 
• Infection: discospondylitis.  Bacterial, aspergillosis

• common
• acute: history of recent trauma, sharp margins.  May have underlying pulmonary and pleural abnormalities
• chronic
• healing fractures can be lucent at fracture due to respiratory motion.  
• Expanded trabecula and smooth margins when healed.  
• Adjacent fractures make you more sure
• repeat rads - could be expansile metastasis

• air accumulation in extra-thoracic soft tissues
• may mimic and/or obscure lung disease.  Bite wounds, penetrating FB (bullet), trauma. ET tube from ruptured trachea, sucking neck wound, sinus?  BDLD.

• uncommon
• often only a small portion visible externally
• concurrent pleural fluid common
• look for rib osteolysis or osteoproduction
• "extrapleural sign": medial extension of mass causing intra-thoracic mass effect.  Broad-based concave displacement of medial parietal pleura.  "Cat under a rug". 
• Must differentiate lung from chest wall mass. May require oblique projections since best visualized with tangential beam. Concurrent pleural fluid is common. 
• tumor: most common.  Osteosarcoma, chondrosarcoma (better px), fibrosarcoma.
• Trauma: hematoma
• Infection: migrating FB, bite wound abscess
• Carcinomas classically met to ribs

• common site in skeleton for metastasis
• hematogenous spread
• totally lytic
• easily overlooked
• local extension very uncommon

• loss of outline visualization: bilateral pleural fluid, severe generalized pulmonary disease
• caudal displacement: severe respiratory distress, tension pneumothorax, caudal cupula displacement due to severe cardiomegaly

• abdominal viscera within pleural space
• gas- or fluid-filled bowel or stomach
• solid soft tissue organs (liver, spleen)
• mottled fat opacity = omentum
• look for cranial displacement of abdominal organs - cranial displacement of falciform fat. Organs not visible in normal abdominal location
• caused by trauma.  Only 1/2 had KNOWN trauma hisotry. Usu in MUSCULAR portion
• commonly also have pleural effusion
• organs most frequently herniated are liver, small bowel, stomach, spleen, omentum
• Wait for 24h and stabilize UNLESS left sided hernia with displaced gas distended stomach (life-threatening because of tamponade) or dilated small bowel.

• Failure of tendinous portion of diaphram and pericardial sac to separate
• congenital (rare).  Can be incidental. 
• rads: large, round cardiac silhouette. Rounded dorsal margins. Indistinguishable borders of caudal heart and ventral diaphragm.  Abdominal organs may be ID'd within pericardial sac (caudal or caudo-lateral to heart)

• positive contrast
• obtain survey radiographs, inject warmed iodinated contrast medium into mid dorsal right abdominal wall (avoid the spleen).  Roll/tip the head down.
• Small holes or those with omental plugs may not be visible

• hiatal hernias: esophageal hiatus (shar pei)
• gastroesophageal intussusception: rare, may be fatal

• rare
• diaphragm is innervated by phrenic nerve. Not well documented (clinically silent?). Suspect with cranial displacement of one or both crura. 
• Confirm with fluoroscopy

• not large enough to absorb sufficient xrays
• insufficient fat to outline
• border effacement if in contact with structures of same radiopacity

• Left subclavian artery
• brachiocephalic trunk
• cranial VC
• normal mediastinal LN
• Thymus in young animals

• should be superimposed on spine
• 1-2x width of spine normal in dogs
• 1x width of spine normal in cats
• fat accumulation can widen

• cranioventral
• caudoventral
• plica vena cava
• thickness depends on amount of fat accumulation.  If it's parallel with no bulging, probably fat.

• young animals (~6mo)
• best seen on VD, not usu on lateral
• "sail sign"

• unilateral decrease in lung volume: atelectasis (recumbency, collapsed lobe)
• VD or DV radiographs. Not apparent on laterals. Note the position of visible organs (esp heart). 
• Unilateral decrease in lung volume
• unilateral increase in lung volume: hyper-inflation (pneumothorax)
• presence of intrathoracic mass
• presence of non-mediastinal intrathoracic mass: lung mass, extra-pleural mass

• common
• have to differentiate lung from mediastinum - on or adjacent to midline, mediastinal reflection, deviates mediastinal structures (trachea). 
• cranial mediastinal mass: widening or elevation of trachea. Trachea may float iwth moderate volume of pleural fluid. Displacement of carina only reliable indicator of cranial mediastinal mass if pleural fluid is present. Ddx = lymphoma (LN), Thymoma or thymic lymphoma, ectopic thyroid carcinoma, abscess or granuloma
• most common is mediastinal lymphadenopathy (lymphoma, lymphoid granulomatosis, malignant histiocytosis, pulmonary mycoses)

• most common mediastinal mass
• ddx: lymphoma, lymphoid granulomatosis, malignant histiocytosis, pulmonary mycoses
• cranial mediastinal LN: drains cranial 1/2 of thorax, axillary region
• Tracheobronchial LN: drains lungs and bronchi.  Metastasis from primary lung tumor.  Mass is a prognostic factor.
• Sternal: drains cranial abdominal serosal surfaces, spread of peritoneal inflammation or neoplasia

• has a soft tissue opacity
• silhouettes appear as cardiomegaly or mass. Consider horizontal beam. 
• Causes: FIP, trauma, coagulopathy, esophageal perforation

• free gas in mediastinum.  May progress to pneumothorax but not vice versa.  Can spread to retroperitoneum and fascial planes of the neck (or vice versa)
• causes (6): retrograde migration of air from alveolar or bronchiole rupture (trauma, iatrogenic overinflation), caudal extension of gas in neck or head fascial planes (bite wounds, common cause), hole in trachea (trauma due to TTW or over-distension of ET tube, jugular venipuncture, or erosion). 
• Esophageal perforation (emergency, trauma (FB), inflammation, neoplasia, cranial extension of retroperitoneal air (rare), gas-producing organism (very rare)

• retrograde migration of air from alveolar or bronchiole rupture: trauma, iatrogenic overinflation
• caudal extension of gas in neck or head fascial planes: bite wounds, common cause
• hole in trachea: trauma due to TTW or over-distension of ET tube, jugular venipuncture, or erosion
• Esophageal perforation: emergency, trauma (FB), inflammation, neoplasia,
• cranial extension of retroperitoneal air: rare
• gas-producing organism: very rare

• free: distribution dependent on gravity and lung compliance. Obscures heart and diaphragm (silhouette sign), diffuse increase in opacity. May see "floating" trachea. Widened interlobar fissures.  Increased soft tissue dorsal to sternum, silhouetting ventral margin of heart. Scalloped lung margins on lat. Blunting of costophrenic angles on ventrodorsal radiograph, decreased heart on DV, obscured diaphragm on DV and lat. 
• Unilateral: anatomically complete mediastinum, plugged microscopic fenestrations, prolonged recumbency, content too large or viscous (pyothorax). 
• Loculated

• all accumulation is clinically significant.  Usu sign of dz elsewhere.  Less likely primary. Impossible to determine cause from rads. 
• exudate: septic, non-septic (FIP), chylous, hemorrhagic. 
• modified transudate: right heart failure, pericardial effusion, diaphragmatic hernia, neoplasia (lymphoma)
• Transudate: hypoproteinemia

• thoracocentesis (no need for US)
• Re-rad after draining (look for rib tumor, pulmonary mass, etc)
• CT for SA
• a thickened pleura, mineralized costal cartilages and thoracic wall deformities (brachycephalic) may be problems

• peritoneal and pleural fluid
• indicator of severe disease (neoplastic, CV)

• Retraction of lungs from chest wall (radiolucent)
• vessels and lung margins do not extend to chest wall
• increased lung opacity.
• dorsal displacement of heart on lateral

• trauma - most common
• lung rupture/bulla (serious, spontaneous)
• chest wall rent
• extension of pneumomediastinum

• Emergency!
• pressure in pleural space exceeds atmospheric pressure.  "ball-valve" at origin of air leak. Potentially fatal
• rads: lung collapse (amorphous opacity on midline), contralateral mediastinal shift, caudal displacement of diaphragm, costal attachments may become visible.

• foal hearts appear larger (5.5-6.5 vertebrae)
• adult hearts cross films

• complete inflation by 12 hours
• re-evaluate in 24-48h

• dorsocaudal (unilateral vs bilateral)
• look for cause if not from a penetrating wound (FB, bulla, trauma (bilateral, like rib fractures), pleuropneumonia (unilateral).

may extend into pleural cavity (but not vice versa).  Increased intra-thoracic pressure with pneumothorax prevents entrance of air into the potential mediastinal space.  If concurrent, usu secondary to trauma

Lymphoma in cranial mediastinum

• collapse/stenosis: dynamic or static
• luminal masses are usually expectorant

• stricture from choke
• intra-mural mass (abscess)
• extra-mural mass
• megaesophagus
• Tx with Esophogram (normal survey rads, barium suspension)

• Obscured heart and diaphragm (silhouette)
• diffuse increase in opacity
• elevation/floating trachea
• increase soft tissue dorsal to sternum (scalloped lung margin)
• widened interlobar fissures
• decreased visualization of heart on DV
• obscured diaphram outline on DV and lat
• blunting of costophrenic angles on VD

• prolonged recumbency
• mediastinum not fenestrated (plugged by inflammation)
• content too large or too viscous to pass through fenestrations (pyothorax)

• in the chest of a dog is a thoracic duct rupture
• in the thorax of a cat, heart disease
• in the abdomen of a cat or dog, neoplasia

• nasopharyngeal polyps: cats. Sequel to URIs.  Soft tissue mass in ear canal, bullae or nasopharynx.  Originate in bullae or auditory tube (associated otitis media)
• Neoplasms and granulomas are rare.  Carcinoma and osteochondroma in a dog, lymphoma in a cat.

• reliable sign of mass in surrounding soft tissues
• caudally (5th IC space) or laterally.  
• Cr. mediastinal mass = thymoma or lymphoma

• edema: collapsing trachea, post anesthesia
• hemorrhage: rodenticide toxicity
• tracheitis: not a radiographic diagnosis

• common
• dynamic.  Related to resp cycle. Weakness in structural rigidity (collagen) of tracheal rings or redundant dorsal tracheal membrane
• occurs in toy breeds (yorkie, poodle, maltese, bichon, chihuahua, etc). 
• rads: inspiratory and expiratory films, fluoroscopic eval, brochoscopy is gold standard.
• Inspiration: cervical trachea (thoracic inlet). Negative intrathoracic and intraluminal pressures.
• expiration: thoracic trachea. Main stem bronchi. Due to positive intrathoracic pressure.  Severe collapse occurs regardless of phase of respiration.

• short circumferential narrowing
• may not be visible on rads (endoscopy!)
• result of tracheal lacerations (BDLD or ET tube overinflation)

• signs consistent with airway obstruction
• FB
• Granuloma (oserlus oserli)
• Tumors rare (carcinoma in dog, lymphoma in cat)

• diameter varies between breeds
• EBD have small diameters naturally, prone to hypoplasia
• careful with pneumonia puppies - they can have concurrent tracheitis rather than hypoplasia
• measure via radio of tracheal to thoracic inlet diameter in lateral

• bronchial dilation: loss of normal tapering and branching (tubular, saccular)
• single or multifocal (congenital, secondary to chronic inflammation)

• dog: 2.3-3.5 intercostal spaces wide on lat.  1/2 to 2/3 width on DV/VD
• Cat: 2-3 intercostal spaces.

• horizontal - heart lays down on sternum, hard to measure
• redundant aorta in 30-40% of 10-15 year old cats, not sure why. 
• cat heart disease is usually inward at expense of chamber, so hard to ID on rads

• variable generalized cardiomegaly - globoid.  
• Featureless, curved caudodorsal border on left lateral.  Dep on volume of fluid. Can be obscured by pleural effusion due to RHF
• caused by HSA, trauma, myocardial dz

• left ventricular enlargement: tall, hard to ID
• Left atrial enlargement: dilation only.  Divergence of principle bronchi ("bowlegged cowboy") on DV/VD.  Summation dilated LA on heart.  Fairly reliable and common. On lat, straightening of cardiac waist. May compress left main stem bronchus

• Fairly reliable and common
• dilation only
• lateral: straightening of caudodorsal border/loss of cardiac waist, dorsal deviation of mainstem bronchus
• DV/VD: divergence of principle bronchi. "bowlegged cowboy".

• disease progression.  Happens after left atrium is severely dilated. 
• Focal bulging between 2-3 on VD

• over-diagnosed, rare. 
• Hypertrophy most common.  Sternal contact?  Elevation of apex from sternum on left lateral (most specific - like a ball, back end comes up).  "reverse D". 
• rarely an isolated lesion.  usu concurrent with LV dilation in DCM

• rare
• dilation only, can be from tricuspid dysplasia or severe pulmonic stenosis.  
• ddx be aortic root, pulmonary trunk, heart base mass

• much more common than real disease
• positioning artifact
• fat accumulation in pericardium of obese dogs (pointed in RA region)

• window on cardiac function
• cranial lobar vessels: artery dorsal, bronchus, vein ventral. All should be same size.  0.5-1 x width of 4th rib proximally on the lateral. TAPER as move to periphery
• caudal lobar vessels: artery lateral, bronchus in middle, vein medial. 0.5-1 x width of 9th rib as they intersect on VD.

• subjectively too small for thoracic cavity (<0.5 width of thorax on VD)
• evaluate size of caudal VC and pulm vessels
• causes: hypovelemia.  Maybe atrophic myopathy like Addison's.

• eccentric: volume overload, chamber enlargement.  DCM
• concentric: pressure overload.  Great vessel change, chamber enlargement only when very severe. HCM

• usu valvular disease (mitral, aka endocardosis)
• cough from bronchial compression, decompensation.  Resp distress in CHF

• most common disease of dog (small breed), degenerative. 
• LOOK FOR LEFT ATRIAL ENLARGEMENT
• progresses to include left ventricular enlargement (generalized cardiomegaly)

• young is infectious
• middle aged is tracheal collapse
• old is heart disease

• pulmonary venous congestion: veins dilated, larger than corresponding artery
• Pulmonary edema: hilar to caudodorsal distribution

• myocardial disease more common than valvular disease.  Cockers are only small-ish dogs that get DCM
• Right sided disease is more common but still rare.  DCM, pericardial effusion

• acquired
• large breed dogs (relatively common)
• normal to severe cardiomegaly
• left atrial enlargement may be only visible change. Rads vary between breeds
• Dobermans: round, upright heart normally.  Left atrial and ventricular enlargement.  May be normal size with apparent pulmonary edema.  Better to get an echo!
• giant breeds: generalized to globoid cardiomegaly.  All chambers grossly dilated. Concurrent left and right failure. 
• Boxer: normal rads vs cardiomegaly (left atrial and ventricular enlargement). 
• Cocker: generalized cardiomegaly
• heart failure: evidence of left heart failure (pulmonary edema) or right heart failure (pleural/peritoneal effusion).  Typically left, but can become/start biventricular.  See venous congestion, pulmonary edema (caudodorsal distribution, airspace patterns in dobermans.

• neoplasia
• idiopathic hemorrhage
• cardiac
• traumatic
• uremic
• infectious

usu lg dogs. Globoid heart without features

• usu LHF.  Don't usually cough
• may have gallop, may not have murmur
• concurrent hyperthyroid common

• relatively common in cats
• mild t severe LA enlargement
• Apex can be displaced to the right. "valentine" or "kidney-shaped" heart.
• Hypertrophy at expense of chamber, may not be visible on rads.
• Rads: patchy pulmonary pattern (airway to asymmetric), pulmonary veins dilated, may fail to taper.  Pleural effusion. Confusing.

• top 3 of congenital lesions.
• Often normal on rads.  May be enlargement of aortic arch due to turbulent flow.
• Elongation of left ventricle due to hypertrophy.  Left atrial dilation if secondary mitral insufficiency develops

• Top 3 of congenital lesions
• dilated pulmonary trunk (bulge at 1-2 on VD clock face)
• Enlargement of R ventricle secondary to hypertrophy
• Pulmonary undercirculation

• congenital
• tricuspid or mitral
• less common in large breed dogs
• right sided disease and enlargement

• top 3 congenital lesions
• mild right ventricular enlargement to generalized cardiomegaly (dep on location and size of shunt. Heart may appear normal with small shunts)
• mild pulmonary overcirculation

• top 3 congenital lesions
• "three knuckles" sign: rare. Segmental enlargement of proximal descending aorta, pulmonary trunk, left auricle. 
• Left sided enlargement
• enlarged pulmonary arteries and veins from pulmonary overcirculation (too many little vessels)

• rare other than HWD (which is 5-10%, 50% in the south)
• can be confusing
• wide variety of rads signs, multi-organ involvement

• Southeast esp
• radiographic changes dep on worm burden
• R sided enlargement
• Main pulmonary artery enlargement (1:00 on DV clock face)
• Reverse D
• Pulmonary artery abnormalities: dilation, blunting, tortuous. Appears before cardiac changes. Looks the same as cor pulmonale (lung dz causes pulm hypertension, then R heart enlargement)

• endemic regions.  
• Signs: anorexia, vomiting, dyspnea.
• Cardiac changes uncommon. Mild to severe arterial enlargement (like dogs)
• Diffuse airway/broncho-interstitial pattern (looks like asthma)

• infection of valves. 
• rare signs: anorexia, lethargy, fever, shifting-leg lameness, failure. 
• Aortic and mitral valves. May not have structural disease.  >50% staph and strep
• often normal radiographically.
• Clinical/radiographic signs from valvular destruction, embolism and immune-complex disease

• Heart base mass: brachycephalic, neuroendocrine
• Myocardium: rare, LSA
• Pericardium: mesothelioma
• Intra-luminal: right atrial HSA

• dogs: depends on etiology.
•    Mitral valve: hilar to peripheral distribution. Could involve right caudal lung lobe
•    Cardiomyopathy: hilar distribution with pleural effusion (RHF and LHF). Dobermans have accessory lung lobe distribution
•    Shunts - left to right. Generalized. 
• Cats: NO RULES. Multifocal. Hilar and peripheral. Pleural effusion common (+/- pulmonary edema)

• allergic lung disease, parasitic (HWD), chronic bronchitis/pneumonia +/- bronchiectasis or smoke inhalation.
• generalized.  Look in the periphery. 
• Next steps: blood work, baerman fecal eval for HW, TTW/BAL with cytology and C/S

• Typically inflammatory (fungal, parasitic)
• but don't rule out primary lung tumor (carcinoma)
• lipid pneumonia
• chronic obstructive pulmonary disease (severe, chronic feline asthma)

• not a specific lobe predilection
• Invasion of a central bronchus - results in atelectasis, ipsilateral mediastinal shift of cardiac silhouette
• Lung-digit syndrome - bronchogenic carcinoma with mets to digits (third phalanx

• DCM (rarely anything else)
• Accessory lung lobe predilection (flow dynamics to right caudal?)
• Unstructured interstitial pattern and in some cases a bronchocentric interstitial distribution (accentuation of airways without thickening of the airway walls)

• lung less opaque than normal (diffuse vs focal)
• may be artifactual
• diffuse: non-pulmonary factors (hypovolemia) vs hyperinflation (increased tidal volume (metabolic acidosis), air trapping, emphysema.  Inspiratory and expiratory films appear similar. 
• focal: localized breakdown of parenchyma (emphysema, pneumatocoele, traumatic bulla), cavitary nodule or mass (congenital bronchogenic cyst, neoplasm), reduced blood flow (reducing circulating volume, pulmonary thromboembolism)

• normal
• hyperlucent lung
• absent vessles (pruned, truncated)
• peripheral to lobar alveolar patterns

• is the P stable?  
• PE to check physiological status, localize sites of trauma
• recognize potentially life-threatening injuries
• provide analgesia
• take rads (take normal side too?)

• Geographic (bone cyst)
• Moth-eaten (big holes)
• permeative (edges have tiny holes)

• solid continuous: non-aggressive. smooth, regular. Healed trauma, degeneration
• thick brush-like: moderate. Big thick columns
• thin brush-like: moderate. Spicules into reactive tissue
• sunburst: aggressive. Just what it sounds like.
• amorphous: aggressive. Fuzzy halo.

• well demarcated with sclerotic rim.  Narrow zone of transition
• Well demarcated. Intermediate zone of transmission
• poorly defined. Wide zone of transition

• none
• mild
• marked

• bones look like they exploded.
• proximal humerus, distal radius/ulna, distal femur, proximal tibia or axial

• Odontoma
• Odontogenic fibroma
• amyloblastoma

• hypertrophic osteopathy
• sublumbar periosteal reaction

• infection: localized spread to bone (sequestrum, from abscess, cellulitis, etc), dental associated infection, hematogenously spread infection (disseminated bacterial or fungal - blasto, coccidiomycosis, asper)
• Inflammation: panosteitis

• small fragments of bone that devitalize and becomes a FB. Bone remodels around it. Often there's a pocket of fluid (involucrum) to draining tract (cloaca)
• common in equine, rare in d/c

• early: widening of periodontal space, sclerosis of adjacent alveolar bone
• late: abscess or sinus formation

• shifting-leg lameness in GROWING large breed dogs.  
• Region of sclerosis in medullary cavity.

• loss of mineralization due to age-related change
• stress guard - loss due to plate, no need for cortex if stabilized otherwise
• disuse.  Also see loss of muscle

• normal balance of bone production and resorption is out of balance
• diffuse changes in bone opacity, cortical thickness, bone fragility, physeal and metaphyseal appearance
• HYPERPARATHYROIDISM (nutritional vs renal)

• causes: low Ca diet vs husbandry issues (lack of UVB in reptiles, low cage temp in reptiles, parasitism)
• diffuse osteopenia, thinned cortices, folding fractures (often multiple)

• most marked in renal dysplasia cases (young growing animals).
• More rarely in CRD
• changes most severe in the skull - may see so much osteopenia that you get "floating teeth". Rubberjaw.

• incomplete ossification of the humeral condyle  (IOHC)
• ununited anconeal process
• if you see a fx on one side, radiograph the other!

• Metaphyseal osteopathy / hypertrophic osteodystrophy
• double physeal lines

• craniomandibular osteopathy
• westies and cairns <1yr
• super weird and super rare

• incomplete ossification of the humeral condyle (IOHC)
• Spaniels!

• ununited anconeal process
• can be from radius and ulna not lining up

• greenstick
• stress
• pathologic

• don't see a fracture so much as 
• Periosteitis
• endostitis
• sclerosis

• longitudinal incomplete fracture within bone
• in young animals
• bones are still bendy, so can partially fracture.  
• "fissure fracture"

• incomplete fracture, often with increased cortex formation in racehorses (saucer).  
• Can see intermittent lameness, bilateral vs shifting or just decreased performance
• Also see in racing greyhounds

• can be incomplete, due to pathology in bone
• mild/intermittant lameness, then suddenly severe.

• bone edges become less sharp over time, fx often widens. 
• Can AGE fx for cruelty cases, etc.

• Physeal
• Straight through physis.  Simplest type. ONLY goes through physis.

• physeal and metaphyseal
• goes away from the joint

• Physeal and epiphyseal
• toward/through the joint
• more severe/significant than I, II

• Epiphysis, Physis, Metaphysis
• Goes across all of bone but diaphysis and into joint

• Physeal compression injury
• not a fracture, just causes early closing of physis
• biggest issue in radius or ulna, leads to severe elbow issues

• Simple: 2
• communuted: many
• segmental: 3 pieces not in contact

• straight
• oblique
• spiral

• compression
• depression
• avulsion: pull bits of bone off by their tendon/ligament attachments
• folding: from metabolic/nutritional
• slab fracture: articular to articular
• chip fracture

Look for connection between outside and fx - bubbles of gas!!  skin wounds may be hidden

secondary is actually faster, primary often with a plate -- no incentive for bone to heal

• non-union/delayed union: atrophic (less bone formation) vs hypertrophic (lots of bone formation)
• mal-union: healing wrong
• angular limb deformities: often from salter harris fx (early physis closure)
• avascular necrosis of the femoral head
• implant failure: instability and infection look the same (bone loss)
• implant impingement: always take orthogonal views post-op!
• implant associated infection: body thinks it's a FB
• Implant-associated neoplasia

• often in equine
• marked radiopharmaceutical uptake in areas of NEW BONE
• highly sensitive
• Can't see it?  rest for 48h and retake.  Will open up

• complex fx in complex anatomy
• good for surgical planning

• Inflammation
• joint distension
• synovial thickening
• (soft tissue opacity expanding around joint, widened joint space)
• NO LYSIS

• osteophyte formation
• cartilage loss
• subchondral bone sclerosis
• NO LYSIS

joint-associated malignant neoplasia (not necessarily subchondral bone lysis)

• synovial osteochrondromatosis
• well-marginated osseus bodies associated with synovium
• commonly observed incidentally in cats

• most commonly observed in dog
• soft tissue mass causing aggressive bone lesion and erosive arthropathy
• most common is synovial cell sarcoma (lysis, multiple bones involved, rapid progression)

• penetrating injury vs hematogenous spread of bacteria vs systemic infections (CAE)
• Lameness often severe and associated with pyrexia
• rapid progression of radiographic changes.  Initial effusion progresses to subchondral bone lysis and erosion rapidly.  Can result in joint instability

• severe lameness with wound close to a joint. 
• Initial effusion, rapid progression to subchondral lysis. 
• try shooting contrast into wound to see where it goes

• foals and calves via failure of passive transfer or primary infection (omphalophlebitis)
• or older animals with DJD - bacteria seeds to these joints.
• DISCOSPONDYLITIS happens via hematogenous spread, causes serious pain (rads least sensitive for detecting)

• Caprine Arthritis encephalitis (CAE)
• polyarthritis, effusion and swelling, synovial mineralization

• non-erosive: rads normal or show effusion. Subchondral bone smooth
• Erosive: rheumatoid.  Multiple distal limb joints. Causes subchondral erosion and joint instability

• ligamentous trauma to joint
• Some joints that have destabilizing ligamentous injury do not appear displaced. 
• Stressed view will show. 
• Stressed views have risks!!! (spine)
• Could be caused by underlying malformation (atlanto-axial)
• look for fractures, too!

• require careful surgical reduction to prevent arthritis
• make sure dislocated joints don't have fractures somewhere!
• femoral head has a tenuous blood supply, can cause necrosis

Tibial condyle should be in middle 1/3 of femur in flexed view - may slide back if CCL is ruptured.

• dachshunds
• dehydration of the nucleus pulposis (first)
• thickening of the annulus fibrosis and longitudinal ligaments
• rads show disc space narrowing, spondylosis deformans
• Then discs are prone to protrusion and extrusion. May not be visible on rads, but could observe narrowing of disc space and (if mineralized) disc material in vertebral canal

• Wear and tear on the joint causes cartilage erosion and chronic joint inflammation (older or overworked animals)
• Rads: effusion and synovial thickening, osteophyte formation, subchondral bone sclerosis, joint space narrowing, subchondral erosion or cyst in severe.
• Early onset and severe may have underlying cause or predisposing factor (dysplasia, OCD, CCL)
• Equine: spavin or navicular disease. Common in horses. May be mild radiographic changes with severe disease.

equine DJD of the tarsus.  Common cause of pelvic limb lameness, secondary to chronic joint wear. Most in quarter horses

• degeneration of the navicular bone cartilage resulting in deep digital flexor tendon injury and navicular bursitis
• rads: increased size and number of synovial invaginations along distal border of bone; sclerosis causing loss of corticomedullary definition; cyst formation; exostosis at ligament insertion

• Often incongruent growth of the radius and ulna, due to fragmented medial coronoid process or ununited anconeal process (or trauma = early closure).  look at medial coronoid first.
• That and/or OCD lead to osteoarthritis/DJD
• Elbow incongruency = inconsistent joint space due to different length of ulna and radius.  Longer bone gets increased pressure, then sclerosis, then fragmentation.

• flattened subchondral bone where cartilage dissects off. Lucent areas surrounded by a ring of sclerosis
• growing animals
• avascular necrosis of subchondral bone
• cartilage and bone dissection and fragmentation
• chronic lesions form joint mice and bone cysts
• common in horse: elbow, shoulder, tarsus, stifle, fetlock (DIRT)
• common in dog: medial humeral epicondyle, caudal humeral head, medial and lateral trochlear ridges of the talus, lateral and medial femoral condyles

• tarsal OCD - distal intermediate ridge of the tibia
• fragment adjacent to the intermediate ridge
• most visible on PLDMO
• Tiny round bone fragment along ball joint line below talus
• Can use US to evaluate equine OCD

• disc-associated: Disc pushes up, flattening spinal cord (increased horizontal, decreased vertical).  Dobermans.
• Osseus-associated: bone pushes in, narrowing spinal cord (thin and tall). Large heavy dogs like great dane, rottweiler.  Equine.

• young dobermans
• angulation and stepping of the vertebral bodies
• disc degeneration
• multiple sites of vertebral canal compression
• disc pushes on cord, spinal cord is wide and short. Many indentations on MRI

• Giant breed canines: Great dane, mastiff, rottweiler
• enlargement and remodeling of articular process joints
• bone presses in on spinal cord, makes it thin and tall.

• large rapidly growing horses (warmbloods)
• enlargement and remodeling of articular process joints causing cord and nerve-root compression
• hard to draw clinical conclusions from rads, may need a myelogram

• abnormal joint laxity.  Straight femur rad shows wide 
• Excellent, good and fair: okay to have a little incongruently wide joint space as long as >50% covered. 
• abnormal mild, moderate, severe: Morgan's line, OA and <50% coverage.

• Premature foals with incompletely ossified cuboidal bones in the tarsus
• too structurally weak to bear weight without deformation
• results in tarsal bone collapse, wedge-shaped, early DJD

• skeletal muscle: rhabdomyosarcoma, rhabdomyoma
• CT: soft tissue sarcoma, fibrosarcoma, fibroma
• Hoof and horn: keratoma (horse)
• nasal cavity: carcinoma, lymphoma, ethmoid hematoma (vascular tumor of horse)
• tendons, ligaments, discs: none

• soft tissue opacity mass lesion
• may contain mineralization
• if invading bone: Benign = SMOOTH periosteal reaction and geographic osteolysis.  Malignant = irregular periosteal reaction and moth-eaten osteolysis
• Benign example: keratoma (horse)
• Malignant example: soft tissue sarcoma (soft tissue thickening, irregular periosteal reaction)

• normal air-filled nasal or sinus structures become soft tissue opaque
• Loss of normal detail of osseus nasal structures
• mass effect
• Possible fluid filling or FLUID LINES (equine) if bleeding or obstruction of drainage
• canine carcinoma, equine ethmoid hematoma

• rads: soft tissue thickening, able to assess for osseous remodeling (osteomyelitis)
• US: Can see lesions better.  Fluid-filled cavity (may contain gas), localized fluid in tissues (cellulitis)

• rads: soft tissue swelling, irregular periosteal reaction
• US: fluid tracking through the soft tissues
• Can try injection of iodinated contrast (dilute 1:1 with H2O

• infection: extend from otitis externa
• secretion: obstruction of eustachian tube (brachycephalics, CKCS have so much pharyngeal tissue)
• presents: fluid-filled tympanic cavity, thickened bulla wall.  
• Take rads with the mouth open

• loss of conchal detail
• "empty nose" esp in fungal (asper)

• FLUID LINES from fluid accumulation
• often associated with caudal maxillary dental disease

• inflammation of the lamina connecting the hoof to the pedal bone. 
• Inflammation leads to a loss of connection between the sensitive and insensitive laminae
• Results in instability of connection between hoof and pedal bone
• severe foot pain
• Acute/early show no changes on rads
• Then, pedal bone rotation and sinking. 
• Chronic causes gas opacity within widened white line (WHITE LINE DISEASE aka "seedy toe"), osseous remodeling and hoof changes
• Normal: Dorsal margin of hoof and bone should be parallel (<2 degrees), bottom of bone and ground <8 degrees.  Coronary band to extensor process <15mm, sole depth >11mm to lowest point of bone.
• abnormal: changes in above measurements, remodeling of distal tip of P3 ("ski jump" tip), ridges along hoof wall (from inflammation)

• white line disease.  Chronic laminitis causes separation from pedal bone from hoof
• gas, dirt and bacteria can get into space, predispose to infections that break out a coronary band.

Calcium:Phosphorus imbalance results in soft tissue deposition of mineral

• variable causes, common in canine hyperadrenocorticism and on steroids
• mineral opacity within skin and soft tissues

• mineralization of tissues secondary to previous tissue injury
• rads: mineral opacity within tissues
• US: dark shadowing structures

• rads: thickening of tissues, dystrophic mineralization, associated osseus remodeling (enthesiophytosis).  POOR imaging of ST trauma
• US: much better. Cavitation, effusion, loss of tendon/ligament fiber pattern, enlargement of structures, synovial thickening

• COMMON cause of lameness
• rads to help r/o underlying bone or joint changes
• US required to examine. 
• Normal: smooth margins, medium grey echogenicity, homogenous fiber pattern. 
• Abnormal: enlargement and swelling, hypoechogenicity, loss of normal fiber pattern, irregular margination and increased vascularity
• become more echogenic as they heal

• inflammation of the biceps tendon
• observe osseous remodeling in the intertubercular groove
• associate with shoulder OA

• rads: thickening of the tendon, enthesopathy, dysptrophic mineralization, avulsion fracture
• US: loss of fiber pattern, hypoechoic, thickening, effusion, mineralization

• Common with TPLO
• thickening and irregular margin