Ferrets are much larger than rodents and serve as an example of both a larger Helicobacter animal model and a naturally occurring model using an indigenous organism. Unlike cats, another relatively large H. pylori animal model, which must be anesthetized for almost any experimental manipulation, ferrets are much easier to handle and do not require anesthesia for oral immunization or inoculation. The biggest drawback to the ferret as an animal model is the paucity of immunologic reagents available.
Culture of H. mustelae prepared as above (Basic Protocol 1 or 2). Young adult ferrets (see Critical Parameters)
16-G ball-tipped feeding needles: 3-inch curved needle with 3-mm ball tip (e.g.,
Perfectum, Popper and Sons, or equivalent) Padded gloves
1. Draw 2 to 3 ml of H. mustelae inoculum containing 107 to 108 cfu into a 5-ml syringe fitted with a ball-tipped feeding needle.
2. Using a padded glove, grasp the ferret behind the neck using the left hand (grasp ferret with the right hand if left-handed). Gently but firmly extend the thumb and two fingers around the neck of the ferret and while removing the animal from its cage, swing the ferret up under the left armpit (right if left-handed), using the other hand to boost it into position, being careful not to choke it.
The ferret will now be in a position where its head is slightly elevated from the rest of its body, and if one keeps a firm but gentle grip around its neck, it will be possible to hold its head relatively motionless. The remainder of the ferret's body is immobilized under the armpit. It is only necessary to use a grip firm enough to prevent it from escaping one's hold on it.
Ferrets are generally quite playful and do not usually bite, but padded gloves should be used as a precaution.
3. In much the same manner as for oral gavage of a mouse (unit 15.11), use the right hand (left if left-handed) to slide the feeding needle behind the ferret's tongue, along its palate and into its stomach.
It should be possible to "feel" a slight resistance, and then no further resistance, as the inoculating needle moves past the upper esophageal sphincter into the esophagus and then into the stomach. See Figure 19.8.1 for demonstration of how to hold and orally inoculate a ferret. Do not "force" the inoculating needle past the oropharynx. If the resistance does not decrease or even increases, the needle may be in the trachea instead of the esophagus, in which case completely withdraw the needle and start over again.
Animal Models for Infectious Diseases
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