Be Prepared To Care For Your Cavy Following Any Surgery
Some cavies seem to recover well from surgery and are up and eating right away. Recovery takes more time for other animals. A cavy in pain may not eat. Food is extremely important to any recovery so hand feeding a cavy that is not eating is vital.It is not unusual for cavies to be more quiet, less active than usual for the first 24 hours after surgery. Appetite is often down, but you should syringe feed to keep digestion moving properly. Often a cavy hasn't eaten since early morning so there may be little stool. Fluids given SQ post operatively should carry hydration over just fine until the next day. Look for pee stains on the bedding to ensure fluids are moving through.
HAND FEEDING
Make absolutely sure your guinea pig begins eating as soon as possible after surgery. If your guinea pig is not eating that evening (following surgery earlier in the day), be sure to hand feed. Read the information on Hand Feeding at this site.
Food and water should be available at all times.
Provide extra vitamin C (perhaps 50mg/day).
Supplement your ill or recovering cavy with Oxbow Critical Care if you have access to this product. Vicki of JPGPR is convinced that Critical Care has pulled through many of her cavies: it is an appetite stimulant, with probiotics and needed fiber (to keep things moving through the digestive system).
Have a scale handy and monitor weight at least a couple times during the day.
Note: If your cavy is receiving post-surgery antibiotics, watch for antibiotic intolerance which may also result in anorexia. 
HOUSING
Towels. Keep the cavy on towels, change as needed. This helps monitor pee and poop output and bleeding more easily -- white towels work best.
Temperature. Keep your cavy warm. The room should be comfortable. Use a wrapped water bottle or light (for its radiant warmth) at one end of a cage. Any heat source should be positioned so the cavy can move away from it if uncomfortable. Thermacare wraps (See:
www.thermacare.com) can provide additional heat for up to 8 hours. WARNING: Children and pets should not ingest this product as it may be poisonous when consumed.
Space. Place the guinea pig in a confined area to restrict movement and avoid creating adhesions (scar tissue) at the incision site, especially important if your cavy has had abdominal surgery.
HANDLING
Picking up your cavy. Handle carefully. The author's pig struggled terribly when she would pick her up and so to avoid her pet tearing the incision, the author devised a kind of open sided drawer from a couple of boxes. Once she would walk in, the entire box could be picked up, later sliding out the drawer on a counter where she could be hand fed. A box with a side that could be lowered to allow the pig to walk in and raised to secure it would also work.
Feeding your cavy. Vicki of JPGPR finds pigs feel more secure when they have their feet on a hard surface. The author used this technique of placing the pig on a towel on the counter, corralled in the crook of the arm when feeding and administering antibiotics.
BEHAVIOR
Pain. Observe your cavy for signs of pain. Ideally, your vet will have provided you with post surgery pain medication. If not and your cavy is in apparent pain, call your vet.
Few or no droppings. Some pet owners report seeing few if any droppings in the cage all day. This may be caused by your cavy eating almost all of them as a way of returning needed nutrients to their system. Observe your pet to see if this is the case. Your veterinarian may prescribe motility drugs like (reglan and propulsid) if your pet is not passing droppings normally.
PROBLEMS WITH THE INCISION
The incision is opening up: contact your vet. Incisions are typically closed with sutures, surgical adhesive, or staples. Staples seem to be the most secure. Some pigs will pull out external sutures. View the detailed photos of Snowflake's incision (closed using surgical adhesive) as it healed. Some inexperienced vets who neuter boars do not suture the inguinal ring: a rupture is very serious and requires emergency treatment.
A lump is forming in the incision area: contact your vet. The swelling may be a seroma (a collection of fluid at the incision site which is basically harmless), an infection, or a hernia (sudden and extreme swelling). Visible pus and inflammation (hot to the touch) are signs of infection.
An internal dissolvable suture is visible: contact your vet. Some guinea pigs may have a reaction to the suture material. Trimming the suture material may be sufficient to allow it to heal.
SUTURE TIPS
Occasionally a cavy will bother an incision -- and in rare cases, even rip out its sutures. Kleenmama was able to fashion a collar, stapled together, to prevent one of her pigs from chewing on an injury. Vicki of JPGPR has coated incisions with Preparation H (her vet's advice) - which was supposed to help soothe and heal. Then dabbed an evil tasting veterinary lotion called Banquard around the incision, to further discouraged licking and chewing. She has mentioned that the incision heals quicker if it is exposed to air and unless absolutely necessary, one would not wrap it.The list on this page is primarily based on advice the author was given during Snowflake's recovery from a spay. See the spay page for photos showing incision granulation and healing. Thanks to Carol and other members of Guinea Lynx Forums for additional suggestions.
See also: Cavy Spirit's page on Postoperative Care.