The effect of meloxicam at the time of treatment of hoof-horn lameness in pasture-grazing dairy cattle on time to lameness soundness, pregnancy risk, and time to conception: A randomized control trial

Abstract

The aims of this study were to assess the effect of meloxicam at the time of lameness treatment for hoof-horn (HH) lesions in dairy cattle on (1) time to lameness soundness after trimming and block application and (2) reproductive success. Five seasonal-calving pasture-based dairy farms located in the Waikato region of New Zealand were enrolled into a randomized clinical interventional trial. Farmers were tasked with identifying lame animals over a period of approximately −4 to 6 wk relative to the herd start of mating (HSM), with lameness subsequently confirmed with lameness score (LS) by trained technicians (0–3 scale, where ≥2 are considered lame). Animals with a LS ≥2 were examined by a veterinarian who then enrolled animals if they presented lame with HH (white line or sole) lesions. This same veterinarian then provided therapeutic hoof trimming, and application of wooden blocks, to the enrolled lame animals. Randomization into either meloxicam (0.5 mg/kg s.c.) or negative control groups was conducted after trimming, with animals blocked by farm and lesion. Following lameness treatment, animals were lameness scored at a median interval of every 4 d until sound (LS = 0), with scoring occurring regardless of block retention status; blocks were not removed at any stage. Animals had conception date and pregnancy status confirmed via rectal ultrasound. Outcomes were number of days to soundness (animals may still have block on) and number of days from HSM to conception, and binary outcomes of pregnant within 6 wk of the breeding period and final pregnancy status. Cox proportional-hazard methods were used to analyze the time-to-event outcomes, with binary outcomes analyzed using multivariable logistic regression methods. A total of 241 animals were enrolled, 123 into the meloxicam group and 118 into the control group. The majority of lesions were described as white line (225; 93%), with 207 (86%) animals receiving wooden blocks on the nonlame hoof. No improvement in the time to soundness was reported between animals in the 2 treatment groups (hazard ratio 0.78; 95% CI 0.56–1.03 for meloxicam-treated animals compared with control animals), with most scoring events occurring with a block present. From the 229 animals with reproductive outcome data (117 meloxicam treated and 112 control treated), the hazards of conception in meloxicam-treated animals were 1.42 (95% CI 1.06–1.90) times that for the control animals. Meloxicam-treated lame animals had 15% greater predicted probabilities of conceiving within the first 6 wk of the breeding period and final pregnancy status, respectively, compared with control lame animals. The addition of meloxicam to the treatment regimen of lame dairy cattle with HH lesions can significantly improve reproductive outcomes, despite no apparent difference in time to soundness.