Grupos étnicos en el estado de Michoacán de Ocampo

I. General principles. Always take at least two orthogo- nal (i.e., lateral and dorsoventral [DV] or ventrodor- sal [VD] views). When checking for pulmonary meta- static disease, both lateral views and the DV or VD should be taken. This is because the nondependent lung will be better aerated

II. Upper respiratory A. Laryngeal

1. Laryngeal paralysis: Radiographs are usually normal

2. Laryngeal mass: Increased opacity in the laryn- geal region. Can be caused by neoplasia, in- fl ammatory disease, or foreign bodies B. Tracheal

1. Tracheal collapse: Narrowing of portions of the trachea. Most common in toy to small breeds. Collapse of the intrathoracic trachea and main- stem bronchi is best seen on expiratory fi lms. Fluoroscopy or endoscopy is useful for dynamic changes

2. Tracheal hypoplasia: Congenital narrowing of the entire trachea

44 SECTION I GENERAL DISCIPLINES IN VETERINARY MEDICINE

3. Tracheal stenosis: Focal persistent narrowing of the trachea, usually secondary to previous tracheal trauma

4. Tracheitis: Usually radiographs are normal. Occasionally irregularity or thickening of the tracheal wall is present in severe cases III. Pulmonary

A. Evaluate the overall pulmonary opacity. In- creased, decreased, or normal

B. Pay close attention to distribution and location of disease: Focal, multifocal, diffuse, perihilar, crani- oventral

C. Types of lung patterns (often combinations of the following patterns are present):

1. Interstitial: Can be divided into structured (nodular) or unstructured (results in diffuse in- crease opacity without nodular form)

2. Bronchial: Thickening of the bronchial walls and increased opacity within the lumen. De- fi ned on radiographs as donuts in cross-section and tram lines in longitudinal section

a. Bronchiectasis: Defi ned as lack of normal ta- pering of the bronchi

b. Bronchial pattern is typically seen with in- fl ammatory disease (either allergic or infec- tious). With feline lower airway disease, about 20% of patients will have collapse of the right middle lung lobe (right middle lung lobe syndrome)

3. Alveolar: More severe increase in pulmonary opacity than that seen with interstitial disease. Will cause border effacement (results in loss of visualization of the margin) of pulmonary ves- sels and structures adjacent to the affected lung (diaphragm, heart, etc.). Can occur with fl uid or cells. Distribution and duration of dis- ease are important as discussed with specifi c diseases listed below.

4. Vascular: An increase or decrease in the size of pulmonary arteries and veins. Most common abnormalities are listed below:

a. Heartworm disease: Increase in the size of the pulmonary arteries. Arteries become tortuous and blunted. Caudal lobar arteries are most commonly affected

b. Left-sided heart failure: Results in pulmo- nary venous distention; often concurrent pulmonary edema

c. Congenital diseases discussed below D. Patterns typical for specifi c disease

1. Benign disease or artifacts

a. Pulmonary microlithiasis (pulmonary osteo- mata, pulmonary osseous metaplasia, dys- trophic mineralization): Mineral opacities (smaller than 3 mm) throughout the lung b. Artifacts include structures on the surface

of the skin (e.g., debris, ticks), nipples, skin- fold artifact, and costochondral junctions 2. Pneumonia

a. Viral pneumonia: Normal to an unstructured interstitial pattern that is diffuse (some- times most easily seen dorsally in the cau- dal lung lobes)

b. Bacterial: Typical distribution is cranioven- tral alveolar disease

c. Fungal: Structured interstitial pattern (mili- ary to nodular) that is diffuse. May see concurrent lymphadenopathy

d. Parasitic: Multifocal ill-defi ned nodular opacities

3. Metastatic neoplasia: Most common pattern is a nodular pattern. Occasionally can see a somewhat unstructured interstitial pattern (lymphoma and mammary carcinoma) 4. Primary neoplasia: Solitary lung lobe mass or

diseased lung lobe. Caudal lung lobes most commonly affected but can occur anywhere 5. Pulmonary edema (cardiac): Left-sided heart

failure results in pulmonary edema that can have an interstitial to alveolar pattern. In dogs the distribution starts perihilar and spreads as severity increases. In cats there is no typical pattern of pulmonary edema 6. Pulmonary edema (noncardiac). There are

numerous causes, such as neurogenic (post- seizure), electric cord shock, chocolate toxic- ity, vasculitis

7. Pulmonary hemorrhage

a. Contusions can occur with trauma. Distri- bution is highly variable with and intersti- tial to alveolar pattern. Usually most severe within 24 hours of trauma b. Anticoagulant toxicity: Distribution is

variable

8. Pulmonary abscess: Uncommon. May be focal or multifocal and either solid or cavitary 9. Cavitary lesions. Differentials should include

abscess, neoplasia, parasitic disease, and granulomas if the walls are thick and irregular. Smooth, thin-walled structures are cysts, bulla, blebs, or pneumatoceles. These are most commonly congenital or traumatic origin 10. Lung lobe torsion: Increased opacity of the

lung lobe with concurrent pleural effusion. May see abnormal location of the bronchus 11. Pulmonary thromboembolic disease: Variable

radiographic fi ndings (often normal). Very early may see hyperlucency and lack of termi- nal vessel. Much more common to see in- creased opacity (focal interstitial to alveolar disease in caudal dorsal lung)

12. Pulmonary infi ltrates with eosinophilia (PIE): Multifocal, patchy interstitial to alveolar dis- ease. Often seen with heartworm disease or other allergic or infectious causes

IV. Cardiac A. Congenital

1. Patent ductus arteriosus (PDA) (left-to-right shunt): Ductus bump (enlargement of the proximal portion of the descending aorta) is the classic fi nding. May also see enlargement of the main pulmonary artery and left atrium or left auricle. Left-sided to generalized car- diac enlargement with pulmonary overcircula- tion (enlarged arteries and veins) may be present

2. Reverse PDA (right-to-left shunt): Generalized or right-sided heart enlargement with promi- nent main pulmonary artery. May not see duc- tus bump. Differential cyanosis

3. Pulmonic stenosis: Enlargement of the main pulmonary artery and right ventricle. Pulmo- nary vessels are normal to decreased in size 4. Aortic stenosis: Elongation of the heart with

prominence of the aortic arch and left ventric- ular enlargement

5. Endocardial cushion defects (ventricular or atrial septal defects): Variable radiographic fi ndings dependent on size of shunt. May range from normal to severe cardiomegaly

6. Tetrology of Fallot. Combination of the four following abnormalities:

a. Pulmonic stenosis

b. Right ventricular hypertrophy c. Overriding aorta

d. Ventricular septal defect 7. Atrioventricular valve dysplasia

a. Moderate to severe cardiomegaly

b. Atrial enlargement: Left atrium is enlarged with mitral dysplasia; right atrial enlarge- ment with tricuspid dysplasia

8. Vascular ring anomalies: Most common is persistent right aortic arch.

a. Cardiac silhouette is normal

b. Segmental dilation of the esophagus cranial to the base of the heart

c. Barium esophagram may be needed for confi rmation

d. Aspiration pneumonia is often present (cranioventral alveolar pattern) B. Acquired

1. Canine heartworm disease (Figure 5-3) a. Prominent main pulmonary artery with

enlarged, tortuous, and blunted pulmonary arteries

b. Enlarged right ventricle (reverse D shape of heart on VD radiograph)

c. With or without patchy interstitial to alveo- lar pulmonary disease

2. Feline heartworm disease

a. Unstructured interstitial pattern is most common; however, alveolar disease may occur

b. Enlarged, tortuous pulmonary arteries may be present

c. Variable right ventricular enlargement 3. Valvular insuffi ciency

a. Mitral insuffi ciency: Enlarged left atrium in early disease. As duration and severity in- crease, left ventricular enlargement also oc- curs. The left-sided heart enlargement causes dorsal deviation of the trachea and mainstem bronchi (left mainstem bronchi may be compressed). If left-sided heart fail- ure occurs, pulmonary venous distention and pulmonary edema will occur

b. Tricuspid insuffi ciency: Usually does not oc- cur as the primary problem but concur- rently with mitral insuffi ciency

(1) Right atrial and ventricular enlargement (often see generalized cardiomegaly with both mitral and tricuspid valve in- suffi ciency)

(2) Right-sided heart failure leads to ascites and hepatic congestion and pleural effusion

4. Dilated cardiomyopathy

a. Variable degree of cardiac enlargement ranging from normal to severe. Left atrial dilation and generalized cardiomegaly can be seen. Left-sided or right-sided (or both) heart failure can be seen

b. Large to giant breeds, Doberman pin- schers, boxers, and cocker spaniels are commonly affected breeds

5. Feline hypertrophic cardiomyopathy: Cardiac size may be normal

a. Left ventricular enlargement

b. Left or biatrial enlargement with classic “valentine”-shaped heart on the VD view c. Left-sided and right-sided heart failure can

occur

d. Echocardiography often recommended 6. Feline restrictive cardiomyopathy

a. Mild to moderate cardiomegaly with left atrial dilation

b. Pulmonary edema and pleural effusion often seen

7. Feline dilated cardiomyopathy (due to taurine defi ciency). Generalized cardiac enlargement with right- or left-sided heart failure

8. Hyperthyroid cardiomyopathy

Figure 5-3 Dorsoventral thoracic radiograph obtained from a dog with chronic heartworm disease (HWD). Reader should note the enlarged main pulmonary artery, right ventricular enlargement, and enlarged, tortuous caudal lobar pulmonary arteries. (From Ettinger SJ, Feldman EC. Textbook

46 SECTION I GENERAL DISCIPLINES IN VETERINARY MEDICINE

a. Ranges from normal to moderate cardiac enlargement

b. Heart failure can occur 9. Heart-base tumors

a. Focal enlargement at the base of the heart is often masked by pericardial effusion b. Focal deviation of the terminal trachea

over the base of the heart 10. Pericardial disease

a. Pericardial effusion results in an enlarged, globoid shape of the cardiac silhouette. Type of effusion cannot be determined on radiographs (cytology is needed). Idio- pathic effusion is most common. Masses may also be present so echocardiography is recommended (Figure 5-4)

b. Peritoneopericardial diaphragmatic hernia

(1) Inability to separate the apex of the heart and the diaphragm

(2) Globoid enlargement of the cardiac sil- houette

(3) Cardiac silhouette may be inhomoge- nous opacity

V. Mediastinal

A. Mediastinal shift refers to leftward or rightward shift of the cardiac silhouette on the VD or DV radiograph. Results from the following:

1. Volume loss of lung (atelectasis); heart shifts

toward the affected side

2. Volume increase caused by intrathoracic or pulmonary mass; heart will shift away from affected side

3. Obliquity of the patient can mimic a mediasti- nal shift

B. Mediastinal masses

1. The cranial mediastinum should be less than twice the width of the thoracic vertebrae on

the DV or VD fi lm in dogs. Symmetrical widen- ing can be seen in fat animals

2. The most common cause of a mass is lymph node enlargement (often secondary to lym- phoma, other neoplasia, or fungal disease) a. On radiographs, cranial mediastinal lymph

node enlargement causes widening of the cranial mediastinum and dorsal deviation of the trachea on the lateral view

b. Perihilar (or tracheobronchial) lymphade- nopathy is characterized by widening and bowing of the mainstem bronchi on the VD view and increased perihilar opacity on the lateral

c. Sternal lymphadenopathy results in soft tis- sue opacity dorsal to the 2nd and 3rd ster- nebrae. These nodes drain portions of the mammary glands and cranial peritoneal cavity, so a cause for abdominal disease should be sought

C. Pneumomediastium refers to the presence of gas in the mediastinal space. Radiographs are vari- able dependent on the amount of gas present. Patchy radiolucency and outlining of mediastinal structures with gas opacity may occur. Pneumo- mediastinum may lead to pneumothorax

D. Mediastinal fl uid results in symmetrical widening of the mediastinum. Positional radiographs may be helpful in determining if fl uid is present VI. Pleural

A. Pleural effusion

1. Overall increased thoracic opacity (variable dependent on the amount of fl uid present) with border effacement of the cardiac silhou- ette and diaphragm (again degree is dependent on amount of fl uid)

2. Pleural fi ssure lines between lung lobes 3. Separation of the lung from the thoracic wall

with fl uid opacity in the pleural space

4. Differences between the VD and DV view occur. Heart is more readily apparent on a VD radio- graph if fl uid is present

5. Differentials for fl uid include transudates, mod- ifi ed transudates, exudates. These have numer- ous causes such as right-sided heart failure, chylous effusion, pyothorax, hemorrhage, neo- plastic effusion.

B. Pneumothorax

1. Air within the pleural space results in separa- tion of lungs from the thoracic wall

2. The heart will appear dorsally elevated, with gas lucency below on the lateral radiograph 3. Lack of visualization of vessels beyond the

margin of the lungs

4. Variable collapse and increased opacity of the lung lobes. If lung lobes are collapsed, a ten- sion pneumothorax is present. This is an emer- gency situation

VII. Thoracic wall: Abnormalities involve the ribs or soft tissues

A. Masses may be neoplastic or infectious (abscess or granuloma). Hemorrhage secondary to trauma is generally more diffuse

Figure 5-4 Lateral thoracic radiograph of a dog with severe, chronic pericardial effusion. Cardiac silhouette is globoid and overlaps diaphragm,

and trachea is elevated. A total of 1600 mL of pericardial effusion was re- moved by pericardiocentesis. Histopathology of the pericardium disclosed pericardial mesothelioma. (From Ettinger SJ, Feldman EC. Textbook of Vet-

B. Rib fractures are commonly overlooked

C. Congenital pectus excavatum is seen as dorsal el- evation of the caudal sternebrae. This results in a shift of the cardiac silhouette. Clinical signifi - cance is variable

SMALL ANIMAL ABDOMINAL

In document MICHOACÁN DE OCAMPO Su origen, relaciones fitogeográficas y filogenéticas (página 81-91)