Antibiotic treatment of calf diarrhea: survey in 4 European countries

Ricardo Bexiga - VetSalus Consultant

Neonatal calf diarrhea (NCD) is the most commonly treated disease in cattle. Any calf, which appears to be ill or injured, must be treated appropriately without delay, and veterinary advice must be obtained as soon as possible for any calf that is not responding to the stock keeper’s care. Choosing medical treatment is the responsibility of the attending veterinarian and, depending on the legal situation for each country, the responsibility of the farmer. To which extent farmers can get involved in the treatment of sick animals is regulated at country level.

There are several issues with the antibiotic treatment of calves with NCD, as the correct indication for treatment and choice of drug is often problematic. The etiological diagnosis is the first important pitfall. Viral and parasitic pathogens are more likely to be involved as primary causes of NCD than bacterial pathogens. Therefore, the majority of antibiotic treatments may not be justified. Aside from E. coli, treatment of NCD with antibiotics may only be necessary in cases where the calves show signs of systemic illness such as fever and depression or in calves that have blood or mucosal shreds in their feces, marking a breakdown of the blood-gut barrier.

Unfortunately, even in the absence of known disease, antibiotics are used extensively in calves for both therapeutic and prophylactic purposes worldwide. There is a potential misuse of antibiotics occurring in extra-label use, including with highest priority critically important antimicrobials (HPCIA). These HPCIA contain the antibiotic classes fluoroquinolones, cephalosporins (third and higher generations), macrolides and ketolides, glycopeptides, and polymyxin. Each antibiotic preparation is labeled for certain therapeutic indications. Any deviation and thus extra-label use has to be dictated by a veterinarian and must be justified. There is little information available about decision-making processes concerning the use of antibiotics in treating calves with diarrhea.

The aim of this study was to describe the treatment of neonatal calf diarrhea in four different European countries, Austria, Belgium, Portugal, and Scotland, (as part of the United Kingdom), using an online survey. A total of 873 questionnaires were included in the analysis. Of those, 597 were answered by farmers and 276 by veterinarians.

A total of 458 participants stated that they used antibiotics in calves suffering from NCD, therefore over 50% of respondents of the survey stated they used antibiotics in calves affected by NCD. Of the 458 respondents using antibiotics for the treatment of NCD, 404 provided more information regarding when they were using antibiotics: 30.7% (n = 124) stated that they used antibiotics always, and 69.3% (n = 277) in some situations. Most respondents stated that they would choose to administer antibiotics in calves with fever and bloody feces, which could be indicators for sepsis and indeed warrant antibiotic use. Country was the most important variable for the differentiation of antibiotic use in calves with NCD, followed by occupation and age (91.1% and 46.1%).

The probability of using an antibiotic for the treatment of NCD decreased with increasing age in veterinarians. The younger the veterinarians were, the higher the probability of using antibiotics. However, even in older veterinarians, the probability was still over 60%. One of the most important factors in veterinarians governing the selection of an antibiotic for treatment is their own experience. The lack of experience and confidence might be a reason for a higher amount of antibiotics used for the treatment of NCD carried out by younger colleagues. It is reasonable to assume that older veterinarians are more likely to follow treatment plans that they consider most appropriate. There are however other factors that may influence decision-making regarding antibiotic use in NCD: fear of unsuccessful treatment, lack of confidence in the diagnosis, or an increased workload, can also play an important role, as veterinarians fear to revisit when the animal did not improve after the first treatment, and they are called again.

When farmers and veterinarians were asked which antibiotic they used as 1st, 2nd and 3rd option for the treatment of calves with diarrhea, quinolones, sulphonamides and penicillins were the 3 most frequently cited classes. The majority (206 out of 291) of participants who answered questions on the type of antibiotic they were giving to calves with NCD named at least one class of HPCIA as their choice. Again, country was by far the most important factor for differentiating the use of HPCIA. Several antibiotics that are not licensed for use in NCD treatment were cited by veterinarians and farmers as 1st, 2nd or 3rd choice in this study. The reason for this is probably found in the lack of knowledge on licensed indications. This leads to extra-label use and treatment decisions, which are based on beliefs of efficacy rather than science. Many practices adopted in the field are not evidence-based. Among other measures, the use of HPCIA is only allowed as a last resort under veterinary direction, backed up by sensitivity or diagnostic testing.

It is likely that antibiotic use could be substantially decreased in the treatment of calves with NCD implementing specific guidelines and targeted training for veterinarians and farmers. Even without better scientific evidence, it is clear that many veterinarians and associated farmers are not applying best practice and agreed overall guidance. Continuing veterinary education of veterinarians, who are the first line of information to farmers, is key to reducing antibiotic use and, particularly, those HPCIA.

All antibiotics licensed for use in food-producing animals are prescription-only medicines that may only be administered following a clinical assessment. The veterinarian must weigh the benefits and risks for animals, humans, and the environment based on her or his knowledge and considering the current state of knowledge in veterinary medicine. The veterinarian can then recommend the most appropriate therapeutic treatment by use of the optimal drug, dosage, and duration of treatment. Ensuring responsible antibiotic use on-farm is an essential part of a veterinarian’s role, even though they may not be directly administering the medicines.

The link to the original paper is: https://www.mdpi.com/2079-6382/10/8/910

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