Notebook: Equine Respiratory System 3

These are notes taken on cases presented by Dr. Rose Nolen-Walston.

Diagnostic plan fever and abnormal lung sounds: rads, ultrasound, sample.
Rads: miliary pattern. Only a few causes: cancer (metastases), sepsis, fungal dz, silicosis. Nothing good that looks like this on rads! Probably not viral or bacteria.

Plan at this point: How to sample? Use BAL (not trans trach) because it's diffuse. Get fungal hyphae, indicates fungal pneumonia, which is rare. Can be primary or secondary (usually secondary doesn't cause a problem). If suspect primary, get a travel history. Treat with systemic anti-fungals. Tends to be $, and prognosis is poor. Best treatment: Itraconazole. (Case study presented in class resulted in full recovery).

Up to 70% of trach washes have fungal hyphae; THIS IS NORMAL! Do not treat with anti-fungals unless you see evidence of fungal pneumonia: i.e., large numbers of intra and extracellular fungal elements, consistent rad changes, or history.

Pneumocystis (and others) is an opportunistic bug (i.e., SKID foals, recent GI dz, other reasons for immuosuppression). Exactly the same diagnostics, but also test for immune function. Prognosis is poor.

Other possibility for miliary pattern: Interstitial pneumonia (pretty rare)
- present with severe clinical signs, i.e. cyanosis, profound respiratory distress, wasting away, cough, fever, pretty hypoxemic
- diagnose with rads (parenchymal disease)
-- pattern must be diffuse. Do BAL.
- Interstitial pnuemonia may be associated w/ viral dz (like flu), systemic inflammation (ARDS), equine nodular pulmonary fibrosis (may be associated w/ EHV5, pattern looks more nodular than miliary), silicosis: granulomas form around silicon, or ideopathic
- treatment is often futile. Euthanasia often elected if owner decides not to treat. (If you sit and wait, the horse may be fine!)
- prognosis is guarded to poor.

Case presented: foals with puffy joints, no lameness
- if foal w/ puffy joints is lame: septic arthritis (EMERGENCY)
- on ultrasound, see what may be neoplasia/ abscess/ granuloma
- rads pathognomonic Rhodococcus equi.
- Rhodococcus equi causes abscess-forming pneumonia.
- puffy joints but not lame: don't tap
- diagnosis: use cytology (pleomorphic cocci), culture, PCR
- on PCR, only VapA is really bad
- transmission: shed in feces
- use macrolides to treat b/c they go into the cell. Azithromycin stays at effective levels in pulmonary macrophages for 30 days! Treat with macrolides + rifampin.

- Rhodococcus is not the only thing that causes pneumonia in foals: top cause is Strep. zooepidemicus. Diagnose with imaging (rads/ US), sampling (trach wash). Put on broad spectrum (but not penicillin).
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Notebook: Equine Respiratory System 2

Treating pleural pneumonia Start with broad spectrum antibiotics (4 quadrant coverage): penicillin, gentomycin, metronidazole. Gas specks in lungs (on ultrasound) probably indicate anaerobic infections; also brown or red nasal discharge and stinky breath. These horses need to be put on metronidazole. Strep. zooepidemicus is the number one isolate; enrofloxacin doesn't get it! Oral drugs: TMS (nice but a lot of resistance), doxycycline, rifampin (not rifampin by itself!).

Will often put on anti-inflammatories (NSAIDs) to increase patient's comfort level. Remember to consider effects on kidneys and stomach. Use thoracic drains if necessary (if there's a lot of fluid). Support with calories very very early.

Increased pleural effusion decreases lymphatic drainage, leading to edema.

When do you stop the antibiotics? Recheck frequently with US (consolidation and abscesses), check fibrinogen and WBC counts, make sure afebrile for 4-5 days afterwards. May also re-check the tracheal wash (though a bit invasive).

Can do rib resection if you encounter "pizza pleura."

Epidemiology: Young racehorses being shipped are at top risk. Next is esophogeal obstruction in older horses, then post-anesthesia and recent viral infection.

Aspiration: When horses aspirate, it goes to the "triangle of death."

Prognosis is good for pleural abscess; horses with pleuritis -- prognosis is a lot worse.

Lympadenopathy, fever and nasal discharge is strangles (Strep. equi equi) until proven otherwise! Gets submandibular and retropharyngeal lymph nodes. Let the dz run its course; treat symptomatically; may want to use NSAIDs; drain abscesses when they're "ripe"; more severe cases will need tracheostomy; put complicated cases on penicillin. Prevention: isolate effected horses until they have a negative culture. May need to identify carriers if barn problems persist. Rare to get strangles twice. 2 vaccines available: new intranasal modified live vaccine is much more effective than the other vaccine. Always give it as the last vaccine because it is a modified live vaccine!

Bastard strangles: metastatic strangles. Lymph nodes in any part of the body are affected; can end up with problems in brain, liver, kidney etc. Diagnose with a titer for Strep. M protein. Treatment: long-term antibiotics. Penicillin works well.

Immune-mediated problems associated with Strep:
Purpura hemorrhagica is a vasculitis associated with the body getting confused by the Strep. Results in severe edema. Penicillin and corticosteroids; good prognosis. If outbreak, don't vaccinate horses that have possibly been exposed! Greater chance that they will develop purpura. Only vaccinate horses that you are really sure have not been exposed.
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Notebook: Radiology of Lung Disease 3

INCREASED RADIOLUCENCY, cont'd.
- congenital emphysema is rare
- usually emphysema is correlated w/ lower airway dz
- asthma: difficulty exhaling leads to increased air retained in lungs
- very dark, black lungs may indicate emphysema.
- even if no bronchial pulmonary pattern, may still be feline asthma
- air in stomach: dyspnea has led patient to swallow air.

See focal increased radiolucency more commonly than diffuse.

Air filled structures in the lung
- cavity, cyst, bulla: Cysts are usually congenital with very thin walls. Bullae usually have no apparent walls.
- if related to the bronchi, called bronchiectasis
- term cavitary lesions: masses with air in the center. Differentials same for any other mass. This term can technically be used for any air-filled lesion within the lung. Typically used to describe a lesion with a very thick wall.

Increased radiolucency is less common than increased radiopacity. There are fewer differentials for increased radiolucency.

Why do we have a pleural space:
- main function: keep lungs attached to the chest wall
- small film of fluid creates a negative pressure.
- lubricates lungs (most animals have sm. amt. of fluid in this space)
Side note: elephants lack pleural space.

Pleural effusion
- as soon as we have dz in pleural space, negative pressure will be lost to some degree, causing lung to retract toward the center.
- usually we don't see the pleural space.
- if lungs pull away from chest wall and from each other, we see the pleural space (called pleural fissure line). Vessels taper and disappear; pleural fissure line does not.
- signs: pleural fissure lines, lung lobe retraction, silhouetting.
- bilateral pleural effusion: More common. Top differentials: congestive heart failure, neoplasia, trauma.
- unilateral pleural effusion: Top differential = inflammatory dz

Note to self: see Dr. Seiler's slides for more info.
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Notebook: Radiology of Lung Disease 2

ALVEOLAR PULMONARY PATTERN, cont'd.
Atelectasis vs. pneumonia: You may have difficulty discerning the two on laterally projected rads, because both problems present in the ventral lung field. Take an orthogonal view; if you see a mediastinal shift on the VD or DV projection, this indicates atelectasis. If not, pneumonia may be indicated.

Remember: After looking at rads and coming up with differentials, ALWAYS check to see if your problem list matches the clinical signs! (for any rads, any case)

BRONCHIAL PULMONARY PATTERN
- indicates bronchial disease.
- results in thickened appearance of bronchi
- overall pulmonary pattern/ opacity is not that different
- typically all bronchi are affected.
- bronchiectasis: widened bronchi. A sign of chronicity.
- in older animals, bronchi are often mineralized.

Side note: right middle lung lobe is often collapsed in cats with asthma.

INTERSTITIAL PULMONARY PATTERN
- This pattern is usually diffuse.
- interstitial space: connective tissue that makes up the alveolar walls and the connective tissue around the big vessels and bronchi.
- interstitial pulmonary dz: on rads, everything is a little blurred.
- generalized increased opacity in the lungs. Still see all the structures, but they're not as sharp anymore.
- Since this is a hazy pattern by definition, it may be difficult to distinguish interstitial pulmonary pattern from poor radiograph quality. Check for good contrast between trachea, soft tissue and bone. Make sure that outlines of vertebrae are visible; check if you can see the dorsal spinous processes.

Metastatic nodule vs. end-on vessel: End-on vessel will always be brighter than a nodule, because it is a cylindrical structure. Also, it must sit on top of another vessel, which you sould be able to see as well.

Metastatic nodule vs. heterotopic bone: The smaller and the brighter the structure is, the less you have to worry. Heterotopic bone is very small and very bright.

If you are unsure if it's a nodule or not, ask the owner to come back in a week or so for more rads.

IF YOU CAN'T DECIDE ON A PATTERN
- i.e., if characterisitcs of multiple patterns are present
- just call the pattern a mixed pulmonary pattern
- these rads may not help reach a definitive diagnosis.

If lungs are too black: again, rule out artifact first (just as was discussed for whiteness in Radiology of Lung Disease 1).

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Notebook: Radiology of Lung Disease 1

Radiographic technique: pull legs forward in left lateral position so that they're not super-imposed on the thorax. For VD projection, make sure the animal is straight. Exposure: use high KVP (reduces contrast, gives a lot of grayscale). Also, use a grid and try to take rads on full inspiration. This is important because we need something that contrasts the structures in the thorax. Also, always take 2 projections of each patient. This is important for best possible assessment because the recumbent lung will be collapsed.

- Anatomy: caudal vena cava is always on the right side.
- When evaulating chest rads: look at extra-thoracic structures first!

Now to the meat of the lecture: Pulmonary parynchema: pleural space, mediastinum, heart, vessels. In normal small animal lungs, the right lung is a bit bigger. Lumen of bronchi will always be black with very thin wall; mainly seen in perihylar area. Vessels are filled with blood. Connective/ interstitial tissue around big vessels and bronchi. Black lung with white lines, white vessels, thin parallel branching lines are the bronchi.

If there's a problem with the radiograph, rule out artifacts or extra-pulmonary diseases. Artifact: It may be that the rads weren't taken at full peak inspiration. Think of the animal's fat content. Legs may not be pulled fully forward.

Alveolar, bronchial, interstitial, vascular patterns and combinations of them.

Alveolar pulmonary pattern: fluid and cells on rad are white. So if all those alveoli are filled with fluid and the round structures are filled with soft tissue opacity, we don't see the difference between the vessels and the lung parynchema anymore. All we see is the air within the bronchi (black outline of bronchial tree). List things that indicate alveolar pulmonary pattern: soft tissue opacity, silhouetting with other soft tissue structures, air bronchograms, lobar sign. May indicate: pneumonia, edema, hemorrhage, atelectasis, neoplasia, torsion, infarct.

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Sapna: new, improved, more efficient

As yet another way of evolving to accomodate our audience, we at Sapna Magazine have begun blogging it up, WordPress style. And it was super-easy to implement! Once WordPress was installed on our site, I created some beautiful graphics to go with our new, modern and more mature image.

Not only is the new site prettier, but it's easier for our writers and editors to upload articles. (They love how user-friendly it is!) And our design has already gotten rave reviews from an expert in WordPress theme development. Please contact me [mariamkamal@gmail.com] if you are interested in joining the creative team.



Visit the new site to explore our new issue! The issue features stunning fashion photography done by Billy Rood of Fig Media in Chicago and an interview with Freida Pinto, the gorgeous feature actress in Slumdog Millionaire, which is a favorite for this year's Oscars. Writer Tirusha Dave includes an important factoid at the end of her article: The young kids who play the orphans in Slumdog were actually rescued from the slums of Mumbai. Please read the conclusion of the Freida feature to find out what organizations to support.
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a cyber-sample of Sapna

Our new site is launching this week! Check out the Sapna Magazine website this Friday, January 23, to admire our new look.


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almost time for a fresh start

Okay, so usually I just write my notes in this blog... But it hasn't been updated in some time, so I thought I'd do a quick traditional blog entry! I've been working to jump-start a project in tiger conservation over break, and I'm very excited, as I think it shows promise. I've also been working on Sapna (sapnamagazine.com) -- I did not design the current site, but we're relaunching our site on January 11th, and I'm working on that design. It's powered by Wordpress, and it'll be much more dynamic than our current site! The excitement is building...
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