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Various treatments for calf diphtheria

Animal Health: Injury to mouth or throat can allow bacteria to set in

I am sure most producers over the years have had calves (on a sporadic basis) develop a throat infection. These are the calves which have an extremely loud inspiratory and expiratory sound which can be heard, across the pen. They generally have extended neck breathing 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, which can often cause foot rot. Technically it is called necrotic laryngitis or calf diphtheria, sometimes referred to as “barker calves.” The initiating cause is usually an abrasion to the throat caused by rough feed or an oral ulcer. Seldom do we see these cases in outbreak form. Sporadic cases are the norm and can occur from young calves right up until cattle are in the feedlot. The younger cattle having a soft oral lining are therefore most susceptible to these abrasions.

The oral ulcerative lesion could have even started from sharp teeth and them inadvertently biting the inside of their cheeks. I am sure we have all done this from time to time or bitten our tongue so we all know how these injuries could occur.

The organism gains entry this way and over time an abscess is formed around the laryngeal cartilages. This combined with the surrounding swelling significantly reducing the respiratory passage. In a sense, what you are hearing is like a whistle when the calf is breathing.

Various treatment approaches

Over the years veterinarians have used various treatments 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 the potentiated sulphonamides to penicillin and more recently drugs such as the macrolides (Zuprevo and Draxxin) or florphenicol (Resflor) have been tried. If you have a calf with symptoms, make sure to get your vet’s advice as to what drugs have worked the best and for what length of time as they are all prescription drugs.

Veterinarians will often recommend a 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 why you need your herd veterinarian involved.

Response is favourable if caught early and treated aggressively. I have found in numerous cases where the producer notices the condition early, but stops treatment too early, that a relapse occurs. In my experience even if clinical signs have subsided substantially I continue treatment for several more days. The NSAIDs 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. You will have such a restriction that the eyes seem bugged out from straining to breathe.

Calving injury similar symptoms

There is only one other condition I know of that mimics necrotic laryngitis. Large calves that are born backward and have had a hard pull may break some ribs. The first few ribs as they heal it causes a restriction on the windpipe resulting in 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 always ask with these affected calves was it a hard-pull backward calf. If the answer was yes then the prognosis is much much worse and treatment does nothing to alleviate the clinical signs.

Cattle are valuable so keep in mind something can be done or at least tried on these calf diphtheria cases. Try to not wait too long before treatment is initiated and remember to finish the course of antibiotics your veterinarian recommends. Laryngeal surgery can be done as a salvage operation but most cases will clear up with good sound medical treatment. A few will recover but will still have a distinctive whistle especially if they breathe heavy after running a bit. This will be a permanent condition 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. Watch for these calves both this fall as they go on feed and in spring as young calves run the risk of developing this condition.

About the author

Columnist

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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