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Necrotic laryngitis or calf diphtheria (barker calves)

Veterinarians use various treatments depending on what they've found is most effective

I am sure most producers over the years have had calves develop a throat infection on a sporadic basis. These are the calves which have an extremely loud, inspiratory and expiratory sound which can be heard across the pen. They generally extended their neck to breathe and are in various forms of respiratory distress.

The cause of these signs is generally an infection of the throat or larynx area caused by the same bacteria that often causes foot rot. The initiating cause is usually an abrasion to the throat caused by rough feed or an oral ulcer. This is why we seldom see an outbreak of these cases. Sporadic cases are the norm and can occur from young calves right up to cattle in the feedlot. Younger cattle have a soft oral lining and are therefore most susceptible to these abrasions.

An oral ulcerative lesion can be started by a calf inadvertently biting the inside of its cheek, something I’m sure we’ve all done from time to time so we know how these injuries can occur.

The organism gains entry this way and over time an abscess forms around the laryngeal cartilages and when combined with the surrounding swelling significantly reduces the respiratory passage. What you hear, in a sense is like a whistle as the calf struggles to breathe.

Veterinarians have used various treatments for this condition over the years depending on what they have found to be most effective. The larynx is mostly cartilage and as a result the blood supply and hence the ability to get antibiotics to the site of the infection is not good. Drugs from potentiated sulphonamides to penicillin and more recently macrolides like Zuprevo and Draxxin or florphenicol (Resflor) have been tried. Make sure if you have a case to get the advice of your veterinarian as to what drugs have worked best in his or her experience and for how long.

Veterinarians will often recommend an NSAID (non-steroidal anti-inflammatory drug) such as Banamine, Anafen or Metacam to name a few. These and the antibiotics are all prescription drugs, which is another reason why you need your herd veterinarian involved.

If caught early and treated aggressively the response is often favourable. I have found in numerous cases the producer notices it quick enough but stops treatment too early and a relapse occurs. Even if clinical signs have subsided substantially I continue the treatment for several more days. The NSAID may be stopped after a few days but the antibiotics are kept on board for the duration.

In chronic cases or those unresolvable with drugs, some can be saved with an emergency tracheotomy and laryngeal surgery, where the abscess is peeled out and the proper diameter to the wind passage is re-established. These cases of course carry a guarded prognosis but leaving these calves and doing nothing is grave indeed. It will have such a restriction that the eyes seem bugged out from straining to breathe.

There is only one other condition I know of that mimics necrotic laryngitis. Large calves that are born backwards and have had a hard pull may break some ribs.

As the first few ribs heal it can cause a restriction on the windpipe and the same clinical signs. These generally cannot be helped and although a tracheotomy may provide temporary relief, the actual problem cannot be corrected as the restriction is lower down the wind passage. This is why one question I would always ask with these affected calves if they experienced a hard pull backwards at birth. If the answer was yes then the prognosis was much, much worse.

With the price of cattle ever rising keep in mind something can be done, or at least tried, on these calf diphtheria cases. Try to not wait too long before initiating treatment and remember to finish the course of antibiotics your veterinarian recommends.

As a salvage operation laryngeal surgery can be done but most of these cases will clear up with good sound medical treatment. A few will recover but still have a distinctive whistle, especially when run a bit. This will remain for the rest of their life but they still will do well enough in the feedlot. Extra attention to a few of these calves can save them so do your due diligence and treat where appropriate on advice from your vet on what has been successful for them.

Roy Lewis is a Westlock, Alta.-based veterinarian specializing in large-animal practice. He is also a part-time technical services vet for Merck Animal Health.

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Roy Lewis is an Alberta-based veterinarian specializing in large-animal practice. He is also a part-time technical services vet for Merck Animal Health.

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