Dealing with Diphtheria in Calves

by Heather Smith Thomas of Salmon, ID

Upper respiratory problems in cattle include diphtheria — infection/inflammation of the vocal folds of the larynx (voice box) at the back of the throat. This infection (necrotic laryngitis) and swelling from inflammation can be serious and even fatal if it restricts the airways and makes breathing difficult. Air must travel through the larynx to go into the windpipe and down to the lungs. Swelling or trauma to this area makes it difficult for the animal to breathe.

Dr. Lee Meyring, a veterinarian in cow/calf practice near Steamboat Springs, Colorado says the main thing with diphtheria is to identify it early. “If you don’t halt the infection and inflammation soon enough, the scarring it causes in the larynx can be a serious problem.”

Many people don’t know what diphtheria is and may have a hard time telling the difference between diphtheria and pneumonia. In both situations the calf has trouble breathing, but with pneumonia the difficulty is forcing the air out of the impaired lungs. The calf may make a grunting sound with every forced exhalation and is often making little short breaths.

By contrast, a calf with diphtheria has a hard time drawing air in through the narrowed airway at the larynx. The greatest respiratory effort is when inhaling. “The calf will have his head and neck extended, trying to open that airway a little more because he can’t get enough air,” Meyring explains.

Another sign of diphtheria is drooling and slobbering — or foaming from the mouth because the throat is swollen and it’s difficult to swallow. The calf may still be bright and alert because this is not a systemic infection like pneumonia (at least not at first), but he may not be nursing. Even if he’s hungry he may just stand by his mama fiddling with her teats but not actually suckling because it is difficult to swallow — or to try to breathe at the same time he’s trying to suckle. “The calf with diphtheria usually doesn’t have a fever, and often the main clue is noisy breathing,” says Meyring.

Cases of diphtheria are sporadic. “We may have several years in which we don’t have much problem with it and then there’s a year we see more cases. It may be related to weather and other factors. It is the same bacterium that causes foot rot in cattle, and the incidence of diphtheria is a lot like foot rot; some years it’s not very bad and other years we have a lot more foot rot. When it’s wet and muddy and the ground is churned up and there’s a lot of wet soil, the pathogen is more accessible,” says Meyring.

Calves might be nibbling more dirt and mud and also chewing on things — as calves always do. If they are trying to eat coarse feeds, nibbling on straw or chewing on anything that’s abrasive, this may scrape the lining of the mouth and throat and open the way for infection. Just like with foot rot, the pathogen can’t enter unless there’s a nick or scrape or some kind of break in the skin.

“I tell people that if they see a case of diphtheria they should be prepared to see a few more. I’ve gone to some ranches to treat 3 or 4 calves over the course of a spring, and sometimes these ranchers have never seen a case before. Some years seem to have ideal conditions for these infections,” he says.

It’s important to monitor young calves and check them often, and closely. You might not notice that one of them has diphtheria until the cattle are moving — and then you can see that one of them is slow and having trouble breathing. You can also hear the wheezing sound, as he struggles to get enough air.

For diagnosis, if a person is not really sure, but suspects diphtheria, Meyring suggests putting a little pressure over the larynx (voice box). “If you press on the outside of the throat with your fingers of a calf with diphtheria, you can shut off the airway completely. Then you realize it’s really swollen because it only takes a external pressure to close it off. In a normal calf you can’t press hard enough on the larynx to shut off the airway, but if it’s swollen there isn’t much opening at all and it’s easy to shut it off.”

TREATMENT — The sooner you treat a calf, the better, to minimize damage and scarring in the airway. In an acute case, the calf may have so much trouble drawing air into the windpipe that he suffocates. “The swelling can shut the airway off quickly. So an anti-inflammatory medication such as dexamethasone (to reduce the swelling that’s shutting off the airway) is very important for the diphtheria calf, even more than it is for a calf with pneumonia. They both need antibiotics, but with a pneumonia calf I generally don’t use the dexamethasone,” says Meyring.

In an emergency, when the calf is unable to breathe, a tracheostomy can be done, slicing through the windpipe below the larynx (carefully cutting between the ribs of cartilage surrounding the windpipe — with a very clean, sharp knife), for the calf to breathe through. “This enables the calf to breathe immediately (incoming air bypasses the swollen-shut larynx) but sometimes after we take the tracheostomy tubes out there may be so much scarring of the vocal cords that the calf still wheezes.” The tracheostomy enabled the calf to survive, however, and it can do well otherwise.

Today there is a stainless steel tracheostomy insert that can be used to keep the incision open and continue to by-pass the swollen, irritated larynx and allow the calf to breathe through a hole in his windpipe. This insert comes in two pieces, and your veterinarian can place it into the calf’s windpipe below the larynx.

“I have also used the handle of a plastic milk jug to act as a tube that fits into the trachea pretty well. It goes down into the windpipe, and you can suture the plastic to the skin, to hold it in there for several days and hope the swelling in the vocal cords will subside enough to allow the calf to breathe normally again. The commercial inserts have a rounded tube you insert in there, and a flat edge that you can use for suturing to the skin and hold it open. We can use a piece of gauze to serve as an air filter to make sure no fiber or foreign material goes into that breathing hole,” Meyring explains.

By bypassing the larynx and allowing the calf to breathe through the hole in his trachea, you take the constant irritation away (air being forced past the swollen folds of the larynx with every breath). You still need to keep treating with antibiotics until the infection is gone, but even in stubborn cases, within a couple weeks or a month the calf has healed and you don’t need to keep treating him with antibiotics. Usually the infection is already gone after a couple weeks’ treatment and the breathing by-pass takes away the irritation so the larynx can heal.

Early intervention is best because you can reduce the swelling (resulting in easier breathing and less irritation of the vocal cords) and address the infection before it creates much damage and scar tissue. If you get started too late with treatment, some of these calves can be hard to save, or may take many weeks of treatment.

“If they have impaired breathing, they can’t keep up with the herd for summer grazing and you have to keep them in a small pen. They are eating and doing ok but have no endurance — they can’t get enough air for exertion,” he says. If you don’t treat diligently, or if you quit too soon, they may relapse and be harder to treat — with a longer course of antibiotics and anti-inflammatory medications.

“Many people use oxytetracycline (which works well against this bacterium) or penicillin, but I’ve had good luck with Nuflor if you catch it early. I have the rancher give the antibiotic several times, because sometimes when you think the calf is recovered and stop the medication, he relapses. The problem with penicillin is that you have to give it twice a day, whereas some of the other drugs can be given every other day. Nuflor has been labeled for some of the tougher foot rot cases, and I’ve had good luck with that for foot rot, and the same is true when using it for diphtheria,” says Meyring.

“It’s usually not hard to resolve the infection if you start treatment quick enough. The key is early intervention and making sure you treat more than once. You need to stay with it for multiple treatments. I usually use dexamethasone daily for 3 days and keep using the longer-acting antibiotics at least 3 times — giving at least a week’s coverage and sometimes longer,” he says.

You should not keep giving dexamethasone (no longer than 3 days) because it starts to inhibit the immune system. If the calf is still having trouble breathing you can use a little DMSO (dimethyl sulfoxide) mixed with a little warm water as a drench after you stop giving dexamethasone. DMSO is a good anti-inflammatory that reduces swelling but does not hinder the immune system, and can be given for as many days as needed. Use of DMSO in food animals is controversial and some veterinarians will not prescribe it. Others, like Meyring, recognize its value and will use it, especially in a young calf that isn’t going to enter the food chain for a long time and DMSO might be a factor in saving its life.

“The key to resolving diphtheria in calves is early detection and diligence. If you are not out there looking at those calves frequently, you might not pick it up early, and if you treat for just a few days and quit, they relapse. People have told me they had to treat some of these calves for a long time and the calves finally get over it, and it may be partly due to the fact that the calf is getting older and bigger, and the airway is getting larger.” Expansion of the airway as the calf grows may enable him to breathe better in spite of some remaining scar tissue.

OUR EXPERIENCE WITH DIPHTHERIA — Raising cattle for more than 50 years, my husband and I have experienced numerous cases of diphtheria in calves. The first one we encountered, we thought was pneumonia, but our vet told us how to tell the difference and also recommended DMSO to relieve the swelling in the throat so the calf could breathe. Over the years we had great success treating calves this way, using 2 or 3cc of liquid DMSO mixed with warm water — squirted into the back of the mouth with a dose syringe (or any syringe without a needle on it) so it contacts the throat and the calf has to swallow it. Then the swelling resolves quickly and the calf can breathe. In severe cases this can be repeated daily for a few days.

We also made sure we didn’t quit on the antibiotics too soon. We made that mistake early on, with a calf we thought was recovered. He relapsed and was harder to save the second time around; we had to keep him on antibiotics for more than a month.

Older animals can also get diphtheria but you generally don’t notice it because the windpipe is larger and the swelling doesn’t close it off to where they could suffocate. They usually get better on their own. You might simply hear them wheezing. Sometimes their vocal cords are damaged, however, and they can’t moo as loudly.

We experienced one serious case in a two-year-old cow and were lucky to find her in time to save her. I was riding to check cattle on our range pasture and when I rode by a grove of trees and brush I heard her wheezing. She was deep in the brush, struggling to breathe. I brought her out of the brush and very slowly brought her and her calf home to the ranch. It took several hours because she was too short of breath to travel and could only go a few steps at a time and had to stop and gasp for air. But I got her home and we treated her and she survived.