Ask the Vet

Grazing Cautions to Avoid Atypical Pneumonia

(Troy Salzer)

READER: We found one of our cows slobbering and struggling to breathe. We got her up and gave her Draxxin and Banamine, but the next day she died. We took her to our state diagnostic lab, which said she had atypical pneumonia, and antibiotics would not have helped.

Can you explain what is going on and how we can control this in the rest of the herd?

DR. McMILLAN: This was probably a case of what I call atypical interstitial pneumonia. It has a lot of other names, way too many -- acute bovine pulmonary emphysema and edema, fog fever, pulmonary emphysema, acute bovine respiratory distress syndrome and bovine asthma. Adult cattle are typically affected.

In the Southeast, it's most commonly caused by consumption of perilla mint. In the West and Canada, it occurs when cattle are turned onto lush pastures in late fall and winter. It's also common in feedlots during the finishing period. Consumption of moldy sweet potatoes can also cause it.

When the condition is linked to lush pastures, the cause is thought to be breakdown products from an amino acid (tryptophan) that leads to severe cellular injury in the lung. Perilla mint (also known as purple mint, wild coleus and beefsteak plant) is an invasive species that thrives in late summer and fall in the Southeast, when pastures are often dry, short and dormant. This is also when these plants are most toxic. Cattle typically avoid these if adequate forages are available. If they ingest them, however, a toxic ketone is absorbed from the rumen and carried to the lungs, where it damages the lung tissue.

Signs come on suddenly with severe respiratory distress and minimal coughing. Antibiotics are of no benefit and many animals die even with supportive care.

You ask about control, and that really depends on the cause of the disease. A good management practice is to avoid any sudden change in nutrition in the herd, and certainly to gradually introduce lush forages. There is evidence that ionophores and, especially, monensin (Rumensin) are beneficial if the cattle are on it prior to going onto lush pastures. Moldy sweet potato control is easy -- don't feed moldy sweet potatoes. With perilla mint, making sure cattle have adequate forage, hay or feed helps to prevent problems, but perilla mint is easily killed with a variety of herbicides.

READER: We just got a new dog, and now we have dead spots in our yard where she urinates. We never had this problem with our other dogs. Why is this happening, and is there any way to prevent it?

DR. McMILLAN: This is a common problem with a really simple answer as to the why, but a more difficult solution.

First the why. Dog urine contains high levels of urea, the same urea that is a common nitrogen source in many fertilizers. If you've ever spilled a little fertilizer in your yard, pasture or hayfield, you've probably noticed brown spots. These circles often have a deep green ring around them. The center received too much nitrogen and was killed while only enough nitrogen seeped into the ring to stimulate rapid growth.

Female dogs are more likely to create this problem than males, but not always. Any dog who squats to urinate and stays in one place is more likely to damage your lawn. Most male dogs hike their leg to urinate on a vertical surface like a tree, tire or shrubbery. They often go in several places to mark territory, so they tend to spread the love.

There are products advertised to prevent urine damage. I know of no scientific evidence that these products are effective or, more importantly, safe for our pets. Messing with the pH of urine or adding something to bind nitrogen sounds a little sketchy to me and could cause long-term health problems.

So what can you do? Create a bathroom area that is mulched, and train your dog to go there. Also, watering the area where she urinates immediately afterward will dilute the urine and protect the lawn. Just like a pasture or hayfield, soil test and correct any deficiencies to make your lawn as healthy and resistant to damage as possible.

Proper watering of the whole lawn is also important to lawn health. Cutting the grass to the maximum recommended height can also prevent damage or, at least, make damage less visible. Some grasses are more tolerant of nitrogen damage than others, including tall fescue, bermudagrass, Kentucky bluegrass, zoysia grass or perennial ryegrass.


-- Please contact your veterinarian with questions pertaining to the health of your herd. Every operation is unique, and the information in this column does not pertain to all situations. This is not intended as medical advice but is purely for informational purposes.

-- Write Dr. Ken McMillan at Ask The Vet, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email