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Role of licking in drug exchange

Wednesday 29 June 2022

Is licking really a significant concern when selecting anthelmintics?

Social licking behaviour is observed in nearly all cattle, and it is an important aspect of their social structure and welfare. Pour-on formulations of macrocytic lactones (eprinomectin, doramectin, ivermectin and moxidectin) are commonly used to treat different parasitic infections. Can these friendly licks really impact pour-on drug exposure? Multiple studies have confirmed that licking has major consequences on the fate of pour-on anthelmintics in cattle and is partly responsible for interindividual variability of drug exposure seen with pour-ons which can impact efficacy and drive anthelmintic resistance.1,2

Licking has been proven to influence drug exchange

The extent of drug transfer from ā€˜lickedā€™ to ā€˜lickerā€™ animal has been investigated to establish the drawbacks of pour-on administration including the risk of sub-dosing and unpredictable residue levels.

Individual systemic exposures to doramectin, ivermectin, and moxidectin in eight cows. Each endectocide was administered as a pour-on treatment (500 mg/kg) in two cows. Areas under the plasma concentration-time curves (AUC) were calculated in treated (filled bars) and non-treated (open bars) cows. Cows 7 and 8 received no treatment (control).1Ā 
Holstein cows were housed on pasture and treated according to manufacturer recommendations with pour-on doramectin (2), ivermectin (2), moxidectin (2) or untreated (2). Blood samples were examined at timed intervals to 44 days post application in all animal.1 See the figure for individual systemic exposures (area of the curve, AUC) for treated and nontreated cows. These results demonstrate significant interindividual variability of drug exposure, resulting in underdosing based on previous studied efficacy levels for macrocytic lactones.1 In the case of doramectin, cow 2 received substantially less dose than the other treated cow and this raises substantial concerns for drug efficacy. The AUC of doramectin for cow 2 was below the established efficacy level previously published.3

Consequently, whatever the selected endectocide, one cannot guarantee that the nominal recommended dose (500 Āµg/kg) will actually be available on an individual animal basis when using a pour-on treatment. 1

Why choose injectable EprecisĀ® over a pour-on?

EprecisĀ® is the only injectable eprinomectin uniquely suited to be part of a sustainable anthelmintic strategy featuring zero milk withdrawal for the milking herd. Ā Sub-dosing anthelmintics is a primary driver of anthelmintic resistance. Ā Part of a responsible programme involves selecting products and practicing accurate dosing to reduce this risk. Subcutaneous macrocytic lactone treatment is associated with higher systemic exposure and much lower interindividual variability.4 Pour-ons have demonstrated large interindividual variability of drug exposure partly driven by the impact of licking with consequences of sub-dosing risks and efficacy impacts.1,2 This is further supported by the EMA Reflection paper on anthelmintic resistance stating ā€œpour-ons pose a particular riskā€ in the selection for resistance.5

As EU Reg 2019/6 is implemented in Ireland, remember to prescribe and sell anthelmintics responsibly. Choose EprecisĀ® as an accurate and sustainable part of your anthelmintic programme.

Ask your local vet or farm supplier about Eprecis today.

Use award-winning EprecisĀ®

EprecisĀ® won an innovation award at the National Millstreet Dairy Show in 2016. This award recognises a new product which has revolutionised an aspect of dairy farming.

Co. Mayo farmer Ronan Joyce milks 125 Jersey cross cows and uses EprecisĀ® due to itā€™s reliability, exact amount and that it can be administered in any weather.

The zero-milk withdrawal is a huge benefit to Ronan, as not withholding milk is worth between ā‚¬8-9/cow/day.

About EprecisĀ® Injection

EprecisĀ® (Eprinomectin 2%) is the only injectable endectocide for the treatment of common internal and external parasites in cattle, sheep, and goats with zero milk withdrawal.

Have confidence in your wormer with a precise, injectable treatment that is not impacted by licking or coat debris known to cause variability in drug exposure, has higher drug bioavailability, and is in line with responsible use guidelines to slow drug resistance.

EprecisĀ® is available in 50ml, 100ml and 250ml bottles.

Click here for more information on EprecisĀ®.

  1. Bousquet-MĆ©lou A, Mercadier S, Alvinerie M, Toutain PL. Endectocide exchanges between grazing cattle after pour-on administration of doramectin, ivermectin and moxidectin. Int J Parasitol. 2004 Oct;34(11):1299-307.
  2. Bousquet-MƩlou A, Jacquiet P, Hoste H, ClƩment J, Bergeaud J, Alvinerie M, Toutain P. Licking behaiour induces partial anthelmintic efficacy of ivermectin pour-on formation in untreated cattle. Int J Parasitol. 2011;41(5):563-569.
  3. Gayrard V, Alvinerie M, Toutain PL. Comparison of pharmacokinetic profiles of doramectin and ivermectin pour-on formulations in cattle. Vet Parasitol. 1999 Feb 1;81(1):47-55.
  4. Toutain PL, Upson DW, Terhune TN, McKenzie ME. Comparative pharmacokinetics of doramectin and ivermectin in cattle. Vet. Parasitol. 1997;72: 3ā€“8.
  5. European Medicines Agency. Reflection paper on anthelmintic resistance EMA/CVMP/EWP/573536/2013. 21 April 2017.

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