Diabetes in rabbits

 

 

Esther van Praag, Ph.D.

 

 

Diabetes is caused by a dysfunction of the pancreas, an endocrine organ that possesses islets of Langerhans. Those islets secrete insulin in the blood circulatory system in order to control the glucose level in the blood and stimulate absorption of glucose into cells. In experiments where the pancreas of rabbits was ligated, a strong decrease of insulin secretion (hypoinsulinemia) was observed, accompanied by an increase of glucagon (hyperglucagonemia). As a consequence the glucose level in the blood increased considerably.

DW ductus, V pylorus, Vf, gall bladder with ductus) from: “Das Kaninchen”, by Dr. U. Gerhardt, 1909

 

Pancreas of the rabbit

In human medicine, there are several types of diabetes:

•     Type 1 diabetes (or I, or juvenile) and is characterized by a destruction of the islets of Langerhans. There is still speculation about the cause: autoimmune, or viral, or viral that triggers an autoimmune reaction against the virus and the cells of the islets due to mimicry of surface proteins. An individual suffering from diabetes 1 needs regular injection of insulin.

•     Type 2 diabetes is observed mainly in obese persons. Insulin production remains normal in the beginning, but cells have developed a mechanism of resistance to the hormone and fail to respond. Consequently the level of sugar remains high in the blood. An individual suffering from diabetes 2 will take medication to reduce the level in the blood.

True diabetes is a rare to inexistent condition in rabbits, and is barely described in the literature, with the exception of obese rabbits and experimentally drug-induced diabetes (e.g., alloxan or streptozotin induced diabetes). Both type 1, and type 2 have been observed; the symptoms of the latter being more common in obese rabbits.

During the onset phase of the disease, rabbits were able to compensate for the lack of insulin production in the pancreas. This led to conclude that insulin may play a less important role in rabbits and herbivores sugar metabolism, than in carnivores. Many plants have furthermore hypoglycemic properties and, when ingested, may help the rabbit adjust its glucose level. A corrected diet, with a great variety of fresh vegetables and hay would help correct true diabetes or diabetes-like symptoms in a rabbit, without a need to inject insulin on a daily basis. 

Clinical signs

In cases of experimentally induced diabetes, hyperglycemia is accompanied by polydipsia (excessive thirst), polyuria (excessive urination) and polyphagia (strong desire to eat).

Pathology

In New-Zealand rabbits suffering from type 1 diabetes, endocrine cells of the Langerhans islets were affected and hypergranulation was observed, unlike healthy non-diabetic rabbits. In other animals, there is usually degranulation. The lack of insulin production was accompanied by glycosylation of the hemoglobin (attachment of glucose molecules to hemoglobin, the protein that is involved in oxygen transport in the red blood cells). When the diabetes was left untreated, diabetic rabbits suffered the same ill effects than humans: mineralization of the kidneys, eye trouble and blood vessel problems, independently from a corrected diet.

Medirabbit

Obese rabbits are more prone to develop diabetes-like symptoms

Diagnosis

Manipulation of a rabbit can lead to an increase of the glucose level in the blood to the order of 8.6 mmol/l and higher, and will misrepresent the actual level. This phenomenon is triggered by the release of adrenaline (epinephrine), a molecule that counters the effect of insulin and enables a raise in the blood glucose. Knudtzon J. reports about this phenomenon in his papers about diabetes in rabbits.

Consequently, diabetes cannot be diagnosed by one simple blood test; a series of blood and urine tests must be done over a period of time to confirm the disease.

Blood chemistry tests should include:

- blood glucose;

- serum osmolarity;

- elevated BUN;

- electrolytes disbalance (sodium and potassium);

- glucose in urine;

- glycosylation of protein (fructosamine test);

- glycosylated hemoglobin (HbAc1).

Hyperglycemia (overload of glucose in the blood) has been linked to stasis, with poor prognosis for rabbit; seems to relate to fatty degeneration of the liver. If the rabbit survives, the glucose level that can be as high as 25 mmol/l, will return to normal.

Differential

Diabetes must be differentiated from:

•          endocrine disorders, e.g. overproduction of cortisol or glucagon, Cushing disease;

•          disorders of the target organs (liver, fat tissue, muscle);

•          pancreatitis (inflammation of the pancreas);

•          renal glycosuria.

Treatment

The treatment of choice a healthy diet:

•          hay;

•          fresh vegetables;

•          good quality pellets;

•          no "junk" food, treats, rich in carbohydrates.

If the rabbit is overweight, a weight-reduction plan must be organized. This should be done slowly, over weeks, rather than days. Insulin injections are not needed in a rabbit with diabetes. They live well with a healthy diet and no insulin injections, on the contrary to dogs and cats.

Further Information

Catala J, Daumas M, Chanh AP, Lasserre B, Hollande E. Insulin and glucagon impairments in relation with islet cells morphological modifications following long term pancreatic duct ligation in the rabbit--a model of non-insulin-dependent diabetes. Int J Exp Diabetes Res. 2001; 2(2):101-12.

Conaway HH, Faas FH, Smith SD, Sanders LL. Spontaneous diabetes mellitus in the New Zealand white rabbit: physiologic characteristics. Metabolism. 1981; 30(1):50-6.

Roman-Ramos R, Flores-Saenz JL, Alarcon-Aguilar FJ. Anti-hyperglycemic effect of some edible plants. J Ethnopharmacol 1995; 48(1):25-32

Roth SI, Conaway HH, Sanders LL, Casali RE, Boyd AE 3rd. Spontaneous diabetes mellitus in the New Zealand white rabbit: preliminary morphologic characterization. Lab Invest. 1980; 42(5):571-9.

 

  

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