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Tardak, a drug traditionally used for cats and dogs, seems to be a possible alternative to castration, or at least a test to see if castration would help in the cases of aggressive bucks.

I first saw the idea of using Tardak posted on one of the egroups forums by Andy and Gwen Murray. I sent an e-mail privately asking more about it as at the time I had a buck that I was thinking about getting castrated and the reply was that the manufacturer, Pfizer had said ‘it’s not licensed for rats but it should work….’

Andy and Gwen sent me a mail which had come from their vet saying: - 

Tardak, 10mgs/ml injectable - made by Pfizer. Although not licensed for rats, the drug company advised that it could be used at the same dose rate and indication as for male dogs and cats:- i.e. 0.1ml subcut for average 500g rat, it can be repeated 10 days after the first injection if not apparently working or as needed - possibly after 3 - 4 weeks if the desired effect wears off. VET SHOULD FOLLOW INSTRUCTIONS AS ON DATA SHEET. Main indications are for certain forms of aggressiveness and nervousness in male rats. (A form of chemical castration) NB Changes in coat colour may occur so if this could be a problem e.g. in showing animals other areas of injection may need to be considered.

I took this information to my vet and they did a little more research themselves and were then happy to try Tardak out on my aggressive buck. Ben came to me at 7 weeks old and as he got older became very aggressive towards the other bucks in his cage. He tore a 1˝ inch gash in one of my buck’s sides on one occasion, so I had had him living alone for about a month by then, thinking along the lines of having him castrated. I also had a Siamese buck, Barney who was bullying other bucks as well. I took both along to the vet for the first Tardak injection and 10 days later the second. Barney was a different rat; he was so laid back on the Tardak, whereas it appeared to make absolutely no difference at all to Ben. I continued with the Tardak treatment on both bucks for a couple of months, and then stopped. Barney went back to being a bit aggressive, but seemed to be past the worst of his testosterone problems, whereas Ben hadn’t changed at any stage.

I had Ben castrated shortly after and it made absolutely no difference to his temperament at all. He lived alone for another couple of months, then I introduced a particularly stroppy doe to him and they settled well together. Ben lived out the remainder of his life with a harem and turned into a happy laid back rat, but I don’t think his problems were just testosterone, whereas Barney’s clearly were.

I have since done quite a bit more research on Tardak, and found that it is used in Holland to test for castration. Also Tardak should not be used for more than a few months (3-4) as it can cause mammary tumours in bucks. I feel that Tardak is a good test to find out whether castration would work in a buck or whether other methods of calming and aggressor need to be looked at. Tardak is not like the male pill, bucks are still capable, although usually lose interest. It is nicknamed chemical castration in dogs and cats.

In addition to this, Tardak can also be used to treat epileptic type seizures in dogs - something to do with the sedative effect on the brain. This has been tested with success on a rat that suffered seizures and aggression problems.

Article written by Estelle

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Last modified: February 08, 2017