Nexgard

Olá Leonor,
Aparentemente, o Nexgad (afoxolaner) pode ser administrado a Collies sem perigo. Mesmo em tratamentos 5x acima da dose recomendada, os animais apenas apresentaram sintomas ligeiros de toxicidade, consistindo em vómitos e diarreia. Aconselhamos então que siga as indicações de dosagem na embalagem. Deixamos também aqui as citações de duas fontes que demonstrar a utilização segura deste composto em Collies:
 

In an exploratory pharmacokinetic/safety study, Collies sensitive to ivermectin (MDR1-Collies) were treated orally with 25 mg afoxolaner/kg bw. Afoxolaner was generally well tolerated confirming that Pglycoprotein does not play a role in afoxolaner transport. One treated animal had diarrhoea and one animal vomited 6 hours after administration. (fonte)
In general dogs tolerate very well afoxolaner at the therapeutic dose range (3 to 6.8 mg/kg) apart from sporadic vomiting and diarrhea reported in a number of studies and more notably at higher dose rates: diarrhoea and vomiting was observed at approximately 5x overdose (25 mg/kg bw) in Collies (…) Half-life was higher in Collies than in Beagles, but no serious adverse effects were observed after treatment of Collies at 25 mg/kg bw (i.e. ~10x the therapeutic dose). (fonte)

 
Abraços,
Joana Prata