Atypical Interstitial PneumoniaCade Moses, DVM

What is AIP?

• It is a cause for severe pulmonary symptoms that often end in death• It has a rapid onset• Cattle are often exhibit open mouth breathing

and stretched neck with an expiratory grunt.• This is due to air being physically pushed out of

lungs with abdominal press. Looks different than many typical pneumonias in which the effort is on the in-breath.

Heat Stress or AIP?

This posture can be heart failure, heat stress, chronic pneumonia, or AIP

Necropsy exam is a must!!

Pathology• Inflammation and widening of the connective tissue of the

lungs.• Widened septae

• Usually not a lot of fibrin and adhesions• Failure of lungs to collapse easily• May see large trapped air pockets (bulla) as well as smaller gas

bubbles in septae (emphysema)• Lungs are heavy and sometimes “wet”• The most affected areas are in the dorsal or higher portion of

the lung• The lower lung may be consolidated (no air) due to secondary

bacterial infection

What is the cause?

• We don’t really know!• The syndrome in cows is well understood.• Cows are transitioned rapidly to a high protein

diet (specifically high in the amino acid L-tryptophan)• The L-tryptophan metabolism in the rumen

releases 3-methylindole which is a lung toxin• The syndrome in feedlot cattle is not well

understood

AIP Syndrome in Cows

• The syndrome is also called “fog fever” in reference to dead cattle found in the lush mountain valleys where the fog settled. (high protein grass)• Rumensin has a protective effect in cows

possibly by reducing the number of Lactobacillus bacteria which convert L-tryptophan to 3-MI

AIP Syndrome in Feedlot Cattle

• Many possible triggers theorized• BRSV virus• Dust inhalation• Bacterial infection (lung or liver)• Protein rich diet• MGA• Inhalation of fungus• GI upset or acidosis• Heat• Feed Change

AIP Syndrome in Feedlot Cattle

•Cattle are usually affected later in the feeding period•Bigger economic loss for the producer

•Heifers seem to be more affected•Heavier cattle seem to be more affected

AIP cause definition

• “The disease is related to the interplay of feed intake, feed composition, sex and physiologic maturity, and possible environmental triggers”

Can it be Controlled?

• At this point best bet is to control the risk factors (remember none of these are proven)• BRSV virus• Ensure cattle are properly vaccinated, if using a 2 dose

product for BRSV, give the 2nd dose• Dust inhalation• Control dust with scaping/sprinking if possible

• Bacterial infection (lung or liver)• Medicated feed for liver abscess

• Protein rich diet• Protein usually not that high in finish rations

Can it be Controlled?• MGA• Ensure regular consumption. Theorized that heifers

fluctuate intake during weather or ration changes • Inhalation of fungus• Avoid moldy feedstuffs and hay dust

• GI upset or acidosis• Ration changes

• Heat• Heat stress protocol. Keep a sharp eye during hot

weather• Feed Change• Beware during times of changing rations and feedstuffs

Fog Fever?

Treatment Options

• Mostly supportive• Give a short withdrawl antibiotic that has good coverage

against lung pathogens• Treat with IV fluniximine for inflammation• Consider dexamethsone for inflammation• Some have tried furosemide in attempt to “dry out

lungs”• Reduce stress as much as possible• Shade, comfortable pen (move slow), easy access to

feed/water

AIP Diagnosis

•Clinical signs will give a pretty good determination•Necropsy all AIP deads to confirm that they are not being misdiagnosed and mistreated

Call for help before this happens!