If Your Guinea Pig is Anorexic, See a Vet Immediately!
Anorexia (not eating or eating very little) is extremely serious and requires veterinary diagnosis and treatment. A cavy you have just brought home that is not eating may have a respiratory or other bacterial infection.
If no feces or urine are being passed and your guinea pig is not eating, you must seek veterinary care immediately!
In addition, a pet that is losing weight (or if young, failing to gain) is also at great risk. Guinea pigs are especially vulnerable because of their need for vitamin C and tendency to develop ketosis.
"Irreversible ketosis may develop rapidly in guinea pigs despite a resumption of eating." -- Harkness and Wagner
Harkness and Wagner suggest a variety of causes for anorexia:
Changes in diet
Wide temperature swings
Loss of a cage mate
An aggressive cage mate preventing another's eating
Mechanical problems with feeders or sipper tubes
Food changes (too hard or unpalatable food or a poorly designed diet)
Loss of smell
Infectious diseases (such as pneumonia)
Metabolic disorders such as Vitamin C deficiency or renal failure
Analgesic use can cause anorexia
Some guinea pigs prescribed antibiotics, especially baytril, will stop eating. If this happens, the vet should be notified and consideration given to switching to a different drug. (See Antibiotic Intolerance)
The most common causes pet owners encounter for anorexia are illness (such as a bacterial respiratory infection), malocclusion, antibiotic intolerance, pain, and sometimes the loss of a cage mate.
The animal may seem hungry and would like to eat or may be "truly anorexic". Diagnosis will be based on information about diet, environment, recent changes, character of urine and feces; and on a physical examination of the respiratory and digestive tracts, head and mouth; and on the results of blood, fecal, and microbial tests. A urinalysis may be helpful. A full blood panel is best done before any medications are prescribed.
"A dental examination is mandatory in cases of anorexia." -- Harkness and Wagner.
It is vitally important to conduct a dental examination in all cases of anorexia. Foreign bodies, fractures, root abscesses, and most importantly dental malocclusion may be the cause. Excess saliva (also called "slobbers") and oral ulcers will indicate the need to check the premolar and molar teeth.
Skull radiographs are useful in determining the nature of a dental problem. A guinea pig with malocclusion may try to eat but be unsuccessful or extremely slow.
Read more about the signs and treatment of malocclusion.
Depending on the cause, treatment may be as simple as feeding palatable foods (calf manna, fresh greens, and vegetables), giving B vitamins (B vitamin complex at .20 ml/kg), or changing the environment to enable incompatible individuals to eat in peace. Infectious diseases and dental problems will need immediate veterinary treatment. Subcutaneous fluids will help restore hydration.
If the vet determines there is no bloat or blockage of the intestinal tract, hand feeding can keep your cavy alive. Be sure to read the hand feeding tips on this site.
Diazepam (given intravenously, intramuscularly, or by mouth according to Harkness and Wagner) is one of several drugs that can be used to stimulate the appetite. Diazepam (also known as Valium) can encourage eating within a few minutes and will last up to a half hour but also causes sedation and ataxia [loss of coordination of the muscles, especially of the extremities].
Cyproheptadine (Peri-Actin 4mg - 1/8 pill, twice a day) has been used as an appetite booster by some vets.
The Biology and Medicine of Rabbits and Rodents by J.Harkness DVM and J.Wagner DVM (publisher Williams & Wilkins - a Lea and Febiger Book)