Licking induced changes to the pattern of moxidectin milk elimination after topical treatment in dairy cows

IMPERIALE, F.; SALLOVITZ, J.; FARIAS, C.; LIFSCHITZ, A.; LANUSSE, C.

JOURNAL OF VETERINARY PHARMACOLOGY AND THERAPEUTICS

Wiley-Blackwell

Lugar: Iowa; Año: 2009 vol. 32 p. 534 - 540

0140-7783

Pour-on administration of the macrocyclic lactones antiparasitic compounds in beef and dairy cattle is now worldwide accepted. However, the information available on their milk excretion pattern, after topical administration is rather limited. Additionally the cattle licking behaviour has been proven to affect the kinetics of these antiparasitic compounds. The purpose of the current study was to investigate the influence of the natural licking behaviour on the plasma and milk disposition of moxidectin (MXD), topically administered (500 mg/kg) in lactating dairy cows. Ten (10) lactating Holstein dairy cows (705 kg b.w) were allocated into two (2) experimental groups (n=5). The licking was prevented during 5 days post-administration in animals in Group I, and the remaining cows (Group II) were allow to lick freely. MXD concentrations profiles were measured in plasma and milk over 15 days post-treatment. The licking restriction period determined marked changes on MXD disposition kinetics both in plasma and milk. Both plasma and milk MXD concentrations (partial AUC 0-5 days) were significantly higher (P < 0.05) in licking-restricted cows. After the 5-day of restriction period the animals had access to lick freely, which permitted the oral ingestion of MXD, situation clearly reflected both in plasma profile and milk excretion pattern. In spite of the enhanced MXD milk concentrations measured in free-licking cows, drug levels did not reach the maximum MXD residues limit (MRL).