Do you mean to monitor vitals during anesthesia, or for a GPE?

Vitals have little importance in a physical exam. Pulse will vary with stress (and many species will undoubtedbly be stressed during an exam), as will respirations (smaller, more nervous species may become apneic if they suspect they are being watched by or are being handled by a "predator", normal weight ranges have not been standardized (and will vary seasonally- you are better off going with a BCS), and temperature is obviously not necessary to take because these animals are ectothermic...

For a GPE, focus more on the client's husbandry practices and a good once-over (or twice-over) of the patient's body. Husbandry questions include, but are not limited to:

Enclosure:
-Size and type of enclosure (including materials it is made out of, and proper attention to how the dimensions are oriented, i.e.: Tall vs. short and wide?).
-Substrate and cage furniture.
-Cagemates: Their size, sex and species.
-Other herps kept in the same house (same room? Order in which they are serviced and if a hand-washing regimen is followed?).
-Frequency of enclosure cleaning and products used.
-Time spent outside of the enclosure, handled by whom (children?) and at what time of day? Is free-roaming allowed?

Feeding:
-What type of diet?
-How is food kept alive or stored? If live food how are they gut-loaded? Are supplements used?
-Where is the food bought from? Is it bred and raised at home? How?
-Frequency of feeding? How is food presented?
-Does the owner re-use uneaten food items from other animals ("prey recycling" or from other days (ex: frozen mouse not eaten, refrozen then fed again)?
-Is live prey removed from the enclosure if uneaten? What is the animal's feeding response (ravenous, moderate or typically uninterested)?

Heating:
-What is the temperature gradient provided (day AND night)? How many thermometres are used to monitor the temps, and how often are the thermometres checked?
-What kind of heating device is used, and where is it located relative to the enclosure?
-Does the owner cycle the temperatures seasonally? How and when?

Humidity:
-Is humidity monitored?
-Are microenvironments provided to allow the reptile a choice of humidity ranges (ex: humid hides)?

Lighting:
-Is broad-spectrum lighting (including UV-B wavelengths) provided if this species needs it? Where is the light located, how far is it from the animal, and are there any barriers between the bulb and the animal (glass, plastic cover over bulb, screen from enclosure...)?
-What is the photoperiod? Is a timer used to control the lights? When the enclosure lights are off, are other room lights frequently left on?

For the GPE, examine everything! You can find thorough guides to examining herps if you look. Melissa Kaplan's "Picking a Healthy Reptile" (http://www.anapsid.org/pickingreps.html) provides some basics, and I have guides for both lizards (http://www.herptiles.net/lizardhealth.html) and amphibians (http://www.herptiles.net/amphibianhealth.html) on my site.

As for body condition scoring (BCS), this can be done similar to with dogs or cats, just there is no standard scale like the 1-5 or 1-10 in canine and feline patients. See the above links for ideas of what is important to look for: Muscle wasting and protruding bones are signs of being underweight; obesity may be spotted by large fatty swellings on limbs (not to be mistaken with fibrous osteodystrophy that accompanies nutritional secondary hyperparathyroidism (often ambiguously called MBD or metabolic bone disease)!), under arms and around the jaws. Personally I would like to see some more solid standards set for BCS's in reptiles, I may take this project on myself at some point.

Anesthetic monitoring of vitals is of course much more useful. Standards are not set in most species because of the infrequency of them being on the operating table.

During anesthesia, ectotherms should be kept within their optimal temperature zone, so the table or surrounding air should be monitored, and not so much the animal itself.

Most reptiles will cease respiration when at a surgical plane of anesthesia. One contributor to this could be the use of oxygen as a transport medium for the anesthetic: Unlike mammals whose respiratory drive is motivated by CO2 buildup, respiration in reptiles is stimulated by hypoxia. Since the anesthetic machine is delivering plenty of oxygen, the patient does not have the physiologic motivation to breathe. Manual ventilation becomes necessary to keep the herp anesthetized. In Green Iguanas, the normal respiratory rate at 24C (75F) is 15-30 beats/minute according to Jacobson's Biology, Husbandry and Medicine of the Green Iguana.

Heart function is difficult to monitor with a stethoscope because of the small size of the animal (usually) and the anatomy of the reptilian heart. An ECG, with alligator clips, hypodermic needles or stainless steel sutures attached like in mammals (or leads placed caudal and cranial to the heart in snakes) will allow you to visualize heart rate, and by establishing normals before anesthesia, you can monitor changes in the PQRST complex (standards for reptilian electrocardiography are not described); note that ECG in small species will not work. A Doppler may be used over a large artery to audibly monitor heartrate, and pulse oximetry works quite well with a rectal probe in the cloaca. According to Mader's Reptile Medicine and Surgery (I'm still stuck on the first edition), you can use the following formula to predict normal heartbeat frequency per minute:
hbf = 33.4 (W^-0.25)
Where hbf= heartbeats per minute, W = body weight in kilograms

Mader's book is an absolute must-have for anyone serious about reptile medicine, but the 1200-page second edition will set you back $130US (my reason for not purchasing it yet). My text for Exotic Animal Care was Exotic Animal Medicine for the Veterinary Technician by Ballard and Cheek, and I found it pale and basic in some aspects, and containing a few critical mistakes (let it be known that Green Iguanas are herbivores, NOT oppurtunistic omnivores, even as juveniles!). I'm currently waiting to receive a copy of the British Veterinary Nursing Association's Reptile Nursing review booklet, curious to see how good of a summary it is. I've heard good things about Veterinary Nursing of Exotic Pets by Girling, but have not seen it myself.

Feel free to ask more questions, of course. I'm sure others will also have some input.

Christina
www.herptiles.net