because xylasine provide sedation and analgesia and ketamine itself not- it just make immobilistion of the muscles. You may use just xelasine by ruminants, if you will perforem short and simple procedure (like decornuation for example) but not ketamine alone

To get to the chirurgic tolerance stadium III for anesthesia only one of those will not fulfill the criteria  - you need to combine sedation with analgesia, like Małgorzata states before.

thank you Malgorzata madam

that means cocktail of these two provides such anesthetic  effect that i can use in less invasive procedure, 

the cocktail of both of them LETS you make an invasive procedure - one alone is simply not sufficient and  the animal will still feel pain.

I agree the explanations given by f the above observers viz. Małgorzata Raś-Noryńska and Dirk Kamin. Hopefully this will minimize your problem.

thank you Dirk sir, thank you jana sir 

Hello Alok, In addition to all this information, the recovery of an animal with this combination is very smooth as compared to other anaesthetics and/or their per se use.

i ll look forward...thank you Ignacio alvarez Gomez sir

I anaesthetize human patients. This can be accomplished with ketamine as a sole agent. It is a potent analgesic, also in subhypnotic doses. But I agree with Dr. Segura that an alpha-2 agonist like Xylazine may help preventing rigidity.

I would like to add up the information...Ketamine is known as dissociative anaesthesia so better to give with sedative..

because xylazine works as anaestesia and anaelgesia and ketamine itself have poor anaelgetic  properties and can cause convulsions when given alone

Follow the advice of Drs. Felsby and de Segura.

The other people should read more and have more experience. Yet some ignorance is simply shocking. Why don't you talk to some anesthesiologist before speculating? Ketamine has been and is still used in war surgery as almost perfect anesthetic and analgesic. Muscle (thorax) rigidity is a rare and not well documented condition. Addition of sedatives diminishes dissociative effects (hallucinations and similar) and "may" relax muscles. In rat anesthesia this is of little relevance if you are not measuring respiratory parameters - and hardly anybody does it in rats because rat is not very good model for respiratory mechanics measurements anyway. However, ketamine has relatively short action and addition of other long agents may mask fading away of its analgesic effects - what is the most frequent mistake in animal anesthesia when ketamine is used!