Lack of efficacy of homeopathic therapy against post-calving clinical mastitis in dairy herds in the Waikato region of New Zealand.

AIM

To compare clinical and bacteriological cure rates of clinical mastitis following treatment with either antimicrobials or homeopathic preparations.

METHODS

Seven spring-calving herds from the Waikato region of New Zealand were used to source cases of clinical mastitis (n = 263 glands) during the first 90 days following calving. Duplicate milk samples were collected for bacteriology from each clinically infected gland at diagnosis and 25 (SD 5.3) days after initial treatment. Affected glands were treated with either an antimicrobial formulation or a homeopathic remedy. Generalised linear models with binomial error distribution and logit link were used to analyse the proportion of cows that were clinical treatment cures and the proportion of glands that were classified as bacteriological cures, based on initial and post-treatment milk samples.

RESULTS

Mean cumulative incidence of clinical mastitis was 7% (range 2-13% across herds) of cows. Streptococcus uberis was the most common pathogen isolated from culture-positive samples from affected glands (140/209; 67%). The clinical cure rate was higher for cows treated with antimicrobials (107/113; 95%) than for cows treated with homeopathic remedies (72/114; 63%) (p < 0.001) based on the observance of clinical signs following initial treatment. Across all pathogen types bacteriological cure rate at gland level was higher for those cows treated with antimicrobials (75/102; 74%) than for those treated with a homeopathic preparation (39/107; 36%) (p < 0.001).

CONCLUSIONS AND CLINICAL RELEVANCE

Using herds located in the Waikato region of New Zealand, homeopathic remedies had significantly lower clinical and bacteriological cure rates compared with antimicrobials when used to treat post-calving clinical mastitis where S. uberis was the most common pathogen. The proportion of cows that needed retreatment was significantly higher for the homeopathic treated cows. This, combined with lower bacteriological cure rates, has implications for duration of infection, individual cow somatic cell count, costs associated with treatment and animal welfare.