Diabetes mellitus

Diabetes mellitus (DM) is a dysfunction of the pancreas. The pancreas is an endocrine organ that possesses clusters of cells known as islets of Langerhans. These secrete insulin in the blood circulatory system in order to control the glucose level in the blood and stimulate absorption of glucose into cells.

Diabetes mellitus is an entirely different condition to diabetes insipidus, which this article does not focus on.

Diabetes mellitus can be found in guinea pigs but is not common.

The most commonly seen symptoms that may indicate DM include:

• Excessive thirst.
• Excessive urination.
• Scurvy.
• Poor hair coat.
• Cataracts.

These symptoms can appear suddenly or have a slow onset and vary in severity from animal to animal. It is also important to remember that these symptoms can be attributed to many other disease processes that are more likely to affect guinea pigs, so although DM is always on the differential list of possible causes, it does not normally feature near the top of the list.

It is relatively easy to diagnose DM; a simple drop of blood on a glucometer (a device for determining the approximate concentration of glucose in the blood) showing a high blood glucose may indicated DM. This can be followed up by a glucose tolerance test where the guinea pig is fasted for 18 hours, blood glucose levels are checked and then a dose of glucose is given orally. Four hours later if the blood glucose levels are more than doubled this can confirm diabetes mellitus.

This needs to be completed with veterinary guidance as starving a guinea pig can cause gut stasis and can be fatal.

However, when guinea pigs are stressed their blood glucose can rise dramatically. Therefore, a high blood glucose in a guinea pig needs interpreting with care and alongside clinical signs.

Guinea pigs that indicate clinical signs and have high blood glucose levels may be suffering with DM.

Urine analysis to look for glucose in the urine is also advised alongside blood analysis. This is performed quickly and easily on a dipstick test.

If DM goes untreated then the guinea pig may become hypoglycemic, whereby there is not enough glucose in the blood. This is extremely dangerous and can be fatal. Symptoms include tremors, twitching, collapse, unconsciousness and death.

Diabetes mellitus can be spontaneous in guinea pigs but can also be caused by viral or hereditary factors. Congenital manganese deficiencies in young guinea pigs have also been reported. The most common reason is high carbohydrate diets, especially large amounts of fruit and sugary treats.

The treatment of choice with guinea pigs who do have true DM is often a healthy diet. Encouraging a healthy diet can reverse the process or at least control it.

All guinea pigs, including those with DM, should be fed a diet of the following:

• Unlimited, good quality hay, ie timothy hay – this should make up 80% of the diet.
• Fresh vegetables – this should make up 15% of the diet.
• A small amount of good quality pellets – approximately 1 egg cup full per guinea pig per day making up no more than 5% of the diet.
• No junk food, treats or fruit should be given as these are often rich in carbohydrates.

Insulin injections are not generally needed in a guinea pig with DM, since they do not metabolize insulin like cats, dogs and humans, but you should be guided by your veterinarian. Spontaneous recoveries have been reported.

If clinical signs are evident then these need appropriate management. Guinea pigs with excessive thirst and urination need their litter tray and environment cleaning more frequently. Those with an excessive appetite can be offered extra hay and grass, but this should be available ad lib regardless.

Guinea pigs that are fed a healthy diet, regardless of if they have DM, stand the best chance of a long and healthy life and the prognosis is good.