Clinical Signs of Diabetes Mellitus in Dogs and Cats
Clinical signs
are useful in the diagnosis and monitoring of canine and feline
diabetes. Other laboratory tests are also necessary for diagnosis
of diabetes mellitus and the monitoring of treated diabetic pets.
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There are three distinct clinical pictures in diabetes mellitus:
Uncomplicated diabetes mellitus
The classical signs are:
- Polyuria /Polydipsia
- Polyphagia
- Cachexia
- increased susceptibility to infections (e.g. urinary tract infections)
In long term diabetes, effects due to protein glycosylation can be seen:
- cataracts (mainly in dogs)
- peripheral neuropathy (mainly in cats)
Diabeties complicated by ketoacidosis
Diabetic ketoacidosis (DKA) is a serious metabolic emergency.
DKA develops due to:
- Long standing undiagnosed diabetes mellitus
- Insufficient insulin dose in treated diabetics
- Impaired insulin action and/or resistance, caused by obesity, concurrent illness or drugs. This is the cause of more than two thirds of cases of DKA.
Due to the lack of insulin, glucose cannot be used as an energy source. Fats are broken down to provide energy. During lipolysis, high levels of ketones are produced. Ketosis and acidosis develop and are accompanied by electrolyte imbalances. Ketosis causes anorexia, nausea and lethargy.
Diagnosis
The diagnosis of DKA is based on the presence of
ketonuria
along with signs of systemic illness.
Treatment
DKA is an emergency and treatment must be started as soon as possible.
The goals of treatment are:
- Correction of fluid deficits, acid-base balance and electrolyte balance
- Lowering blood glucose and ketone concentrations
- Recognition and correction of underlying and precipitating factors
Correction of fluid deficits, acid-base balance and electrolyte balance
- Intravenous fluid therapy with isotonic fluids, e.g. 0.9% saline.
- If possible the electrolyte concentrations and acid-base balance should be measured and corrected.
Blood glucose and ketones can be reduced by
- Intravenous administration of rapid-acting insulin. Intervet's intermediate-acting insulin is not suitable for intravenous administration.
- The use of low dose intermittent intramuscular injections of intermediate-acting insulin.
When blood glucose is lowered and maintained between 11 and 14 mmol/L (198 and 252 mg/dl) for at least 4 hours, insulin therapy with intermediate-acting insulin administered subcutaneously can be initiated.
Hyperglycaemic, hyperosmolar syndrome
Hyperglycaemic, hyperosmolar syndrome or hyperosmolar non-ketotic syndrome (HHS) is an uncommon complication of untreated diabetes mellitus. It is an emergency and has an extremely guarded prognosis.
HHS is characterized by very marked hyperglycaemia (e.g. >36 mmol/l or >650 mg/dL) and osmolality (>380 mOsm/L). Blood glucose concentrations as high as this shift water from brain cells by osmosis and result in coma.
Diagnosis
Initially, before HHS develops, the typical clinical signs of diabetes
mellitus will have been seen:
- polyuria
- polydipsia
- polyphagia
These animals become progressively weaker, anorexic, and lethargic and drink less.
Physical examination often reveals:
- Profound dehydration
- Lethargy
- Severe depression or coma
As described, there appears to be a direct relationship between the severity of the hyperosmolality and the severity of the clinical signs.
Differentiation from diabetes ketoacidosis:
- there is no ketoacidosis in HHS
- Plasma glucose concentrations are much higher (>36 mmol/l) in HHS
Treatment
The goal of treatment is correction of the hyperglycaemic, hyperosmolar
state. This is achieved by aggressive intravenous fluid therapy
and reduction of the blood glucose concentration.
Prognosis
The prognosis for full recovery is extremely guarded. Even with
appropriate treatment, many animals die within the first 24 hours.