Beitrag zur Verbesserung des Tierschutzes und der Tiergesundheit in der Milchviehhaltung durch Untersuchungen zu Prävalenz und Ätiologie von Schwanzspitzenveränderungen bei Milchkühen

In fattening bulls tail tip alterations are described as health issues associated with (sub)acute rumen acidosis and lameness. Investigations of dairy cows’ tail tips are scarce; however, there is evidence that tail tip alterations occur as a result of intensive feeding management and metabolic imbalance. In June 2020, we investigated 68 German Holstein cows for tail tip alterations using a handheld thermal camera (FLIR® T1030). Thermal images of the shaved tail tip were taken from two different perspectives: (p1) tail in front of the udder and (p2) held tail in front of the ground. Additionally, all cows were evaluated for any kind of tail tip alterations, body condition score (BCS), and locomotion score (LMS). Milk yield data, resulting from latest performance testing were collected, too. Images were analysed using FLIR Tool+ and a generalised linear model was used to correct measured temperatures for fixed effects. The prevalence of tail tip alterations, regardless the findings, was 94%. Raw temperature data showed high correlations of r² = 0.79 for maximum and average temperature and r² = 0.70 for minimum temperature between p1 and p2 (P < 0.001). Tail tip necroses and BCS > 3 decreased the tail’s temperature, while swelling of the tail tip increased its temperature. Average, maximum and minimum temperatures for perspective 1 and 2 were 34.05 (±0.16) and 33.78 (±0.20) °C, 35.46 (±0.11) and 35.52 (±0.11) °C, and 30.30 (±0.30) and 29.22 (±0.38) °C, respectively. Temperatures of necrotic tissues (n = 4) decreased on average by 8.38 °C compared to the average temperature and were close to the minimum. We concluded thermal imaging can be used for the detection of alterations regarding the tail’s temperature, which could allow an early-warning system for swellings, probably caused by inflammation and possibly resulting in necroses. Further studies are needed to evaluate the praevalence of tail tip alterations in dairy cows on larger samples and to clarify their etiology. However, thermal imaging can be used as an early-warning system for tail alterations. Each early-warning system regarding health issues, improves animal welfare as it allows adapting management strategies early.

Research investigating necrotic tail tips in dairy cows resulting in necrotic tissues is scarce. However, there is evidence that in dairy cattle tail tip necroses exist with high prevalence. In piglets, the latest research described tail and ear necroses not because of tail and ear biting only, but because of swine inflammation and necrosis syndrome (SINS). Besides tails and ears, SINS includes inflammation of claws, heels, and teats. In cattle, tail tip necroses are described mainly in fattening bulls. As known so far, these findings are often discussed related to slatted flooring, intensive housing systems and management strategies. However, an association with subacute rumen acidosis and laminitis is described.

In order to investigate what kind of and how often tail tip alterations appear in dairy cattle, data of 87 German Holstein dairy cows were collected over a period of 12 months. All cows were evaluated for tail tip alterations, body condition score (BCS), and locomotion score (LMS) every two weeks. In addition, milk yield data resulting from performance testing were included. Thermographic images of the tails were taken once. Firstly, all kind of tail tip alterations were described and collected. After 6 months, we categorized the observed alterations and developed a tail scoring system. The scoring for each specified trait (tail tip, tail ring) ranged from 0 to 4.

The overall prevalence for tail alterations was 94%. Especially tail tip alterations had a constantly high prevalence of 56%. Cows affected by an increased average tail tip score, showed higher locomotion scores compared to others (P = 0.02). The prevalence of ring-like tail alterations increased from first to second lactation cows from 9 to 46%. Regarding the BCS, lighter cows showed higher scores due to ring-like alterations than heavier cows (P = 0.054). The most often occurring anomalies of the tail were sports or scurf (21.6%), followed by verruca-like mass (10.2%), swelling (8.4%), and thinning (4.3%).

The results and especially the scoring system can serve as a template for further studies considering larger samples sizes, to investigate prevalence for tail necroses and other tail anomalies in different herds and management systems. It was hypothesized, that an inflammatory condition in dairy cows showing up in altered/necrotic tail tips or rings exists, which is in relationship with claw disorders indicated by lameness. If so, the tail score of a cow could be used as health indicator to evaluate the health status in dairy production systems.