
Taken from an earlier thread
Special Precautions and Warnings
Studies with milbemycin oxime indicate that the margin of safety in certain dogs of Collie or related breeds is less than in other breeds. In these dogs, the recommended dose should be strictly observed.
The tolerance of MILBEMAX in young puppies from these breeds has not been investigated.
During treatment with MILBEMAX, no other macrocyclic lactones should be administered.
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The other contraindications are:
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The product should be administered with or after some food.
Treatment of dogs with a high number of circulating microfilariae can sometimes lead to the appearance of hypersensitivity reactions, such as pale mucous membranes, vomiting, trembling, laboured breathing or excessive salivation. These reactions are associated with the release of proteins from dead or dying microfilariae and are not a direct toxic effect of the product. The use in dogs suffering from microfilaremia is thus not recommended.
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Like most things this is probably something your vet may not mention when you buy them and it is worth knowing in case your dogs shows the above symptoms.
I would rather not take any risks and so would not use this product on my collies