− | The spot-on canine preparations are often quite concentrated.<ref name="multiples"> '''BSAVA Manual of Canine and Feline Emergency and Critical Care''', Chapter 19, Second Edition, 2007 </ref>. | + | The spot-on canine preparations are often quite concentrated.<ref name="multiples"> '''BSAVA Manual of Canine and Feline Emergency and Critical Care''', Chapter 19, Second Edition, 2007 </ref>. Cats lack the enzyme glucuronidase transferase and is therefore unable to utilise the metabolic pathway that dogs and other animals use to break down permethrin into glucuronides and sulphates. |