Diabetes mellitus in birds.
“Has my Bird really got diabetes – Doc you must be joking? Why does a bird get Diabetes?”
Charlie was an 8-year-old male lutino cockatiel weighing 78.9 grams. He was a well loved pet that enjoyed freedom allowed out of his cage every day. He had a gutsy personality – and his owners told me how fussy Charlie was with his food. He refused everything except for his “nice” seed mix. That was the only thing he ate over the last few years. He presented at Highbury Veterinary clinic for assessment.
The following clinical signs typical of Diabetes were seen:
- Excessive thirst – called polydipsia. We measured his water consumption and found that Charlie drank more than half his body weight daily, about 55 ml of water a day. This is about 7 times more than normal.
- Excessive urine production – called polyuria. A bird passes droppings consisting of three separate entities – Firstly stool from the intestines -secondly urine from the kidneys – and lastly uric acid from the chalky white part also from the kidneys. There were large volumes of urine forming small puddles under his favourite perch.
- Excessive eating – called polyphagia – compared to the other cockatiel cage mate he was eating more than normal.
- Weight loss – over the last few weeks Charlie had gradually lost weight – even though he was eating well.
- Occasional bouts of sleepiness that had become more noticeable over the last few weeks.
The owner was informed of the necessity to diagnose the condition, and the various diagnostics testing available that would help us to manage the case. We elected to do laboratory blood testing – both haematology and biochemistry panel, urine testing and body radiographs and chlamydophilia testing.
“But doc how do you take blood from my bird? How much blood will you take? Will my bird survive the procedure?” Charlie’s concerned owner asked.
We took 0.14 millilites of blood (about 1 tenth of 1 ml). The bird tolerated the procedure well. See Pic 1.
Pic 1 – Taking a blood sample for laboratory testing. Blood is taken from the right jugular, as in the picture. The Conure above had 0.14 ml of blood taken.
The blood results confirmed our suspicions the blood glucose was high – much higher than normal and the liver enzymes were also elevated. The urine was analysed and found to contain lots of glucose. The abnormal tests results we repeated twice the next day, both tests results showed high glucose in both the blood and urine. It was important to repeat the tests, as a single elevated blood glucose sample is not diagnostic. The diagnosis was confirmed as Diabetes Mellitus.
Fig 3 a blood chemistry analyser that can run an avian biochemistry panel on 0.1 ml of blood. The tests are run at the veterinary clinic and results are available in less than 15 minutes.
What is the cause of this disease in birds?
Parrots have unique evolutionary adaptations. They have blood glucose levels about three times as high as mammals. Three hormones act together to maintain the high blood glucose level. The glucose lowering effects of insulin are much less important in birds than in mammals. The disease is caused only partly by an inulin deficiency. Often the glucose elevating hormones are also raised making therapy more challenging.
Parrots fed on an all seed diet are predisposed to metabolic diseases. Most readers will be aware of the vitamin A and calcium deficiency that is associated with all seed diets. In total 32 nutrients are lacking from the commonly fed seeds like oats, corn, sunflower, safflower and millet. The excess fat content and low nutrient content may results in all of the following to some extent: obesity, thyroid disease, fatty liver, renal disease, skin and feather disorders, pancreatic disease gastro intestinal disease and Diabetes mellitus. The diseases listed are all somewhat interrelated. In Charlie’s case we suspected that major contributing factors were underlying poor nutrition, liver disease and pancreatic disease.
Fig 2’All patients are weighed daily using a digital scale accurate to one tenth of a gram. Weight changes provide useful information about success of therapy and patient recovery.
There are three main treatments all resulting in a lowering of blood glucose and then a decrease in clinical signs.
- Oral glucose lowering drugs – The medication is added to the water and so the more the bird drinks the more it gets. The patient self regulates the dose. As the polydipsia resolves the amount of drug ingested decreases.
- Dietary therapy – to a complete formulated diet to replace the seeds. These diets are much lower in fat compared to seeds. They are also balanced in nutrients. This is often the most important part of the therapy.
- Insulin injections to help stabilise the patient. As Bird insulin is not commercially available we use mammalian insulin. It needs to be diluted which further affects its potency. It is different from mammalian inulin and there may be a reaction to it. So we only use insulin in birds when the glucose level does not normalise with diet and in water medications. Injecting insulin daily is often not practical or an option for many owners. Chicken insulin has been made, and it may be a better alternative.
These are generally treatments rather than cures, and used to stabilise our patients while the metabolic disease is corrected. Many birds respond so well to treatments 1 and 2 above that they often go into remission and require no further therapy