Diabetes in dogs: symptoms, treatment and home monitoring

Overview

Pancreatic beta cells make insulin; their permanent loss can cause marked insulin deficiency. Without enough insulin, cells take up glucose from blood less effectively. As blood glucose rises, glucose enters urine and increases water loss. Increased drinking can replace water lost in urine.

A Swedish study published in 2007 followed insured dogs aged five to 12. Diabetes was identified in 860 dogs through insurance claims. Average age at the first diabetes-related claim was 8.6 years.

High glucose and severe insulin deficiency can persist for a while before owners notice clear symptoms. With good control, a dog drinks and urinates normally and is not constantly hungry.

Causes

Insulin deficiency and resistance

Insulin-producing pancreatic cells often decline gradually in canine diabetes. Repeated pancreatitis can damage beta cells. Immune-mediated destruction is one possible mechanism of damage. In insulin resistance, tissues respond less effectively than normal.

The reproductive cycle and other diseases

The luteal phase after oestrus lasts around nine weeks regardless of pregnancy. Progesterone increases growth hormone secretion from mammary tissue. Growth hormone can reduce tissue response to insulin. Excess cortisol in Cushing's disease can also reduce insulin effectiveness.

Post-oestrus insulin resistance can cause diabetes even in a non-pregnant bitch.

Reproductive hormone effects may be stronger in genetically predisposed dogs.

Risk factors

Diabetes is most often diagnosed in middle-aged or elderly dogs. Long-term glucocorticoid or progestogen medication can increase insulin resistance. Excess weight can reduce tissue insulin sensitivity. Pregnancy can also predispose an entire bitch to diabetes.

In the Swedish insured-dog study, females accounted for 72% of diabetic dogs. Samoyeds and Australian Terriers were among breeds with the highest incidence relative to follow-up time. One Finnish Lapphund breeding committee knew of 113 dogs with diabetes by August 2023.

Ketoacidosis can develop even in a dog already receiving insulin. Concurrent urinary tract infection can predispose a diabetic dog to it.

Dental disease can increase insulin resistance in an already diabetic dog. After pancreatitis episodes, insulin requirements can vary as inflammatory activity changes.

Typical symptoms

Early in diabetes, a dog may appear reasonably healthy on general examination. Weight can fall despite increased food intake.

• Increased drinking.
• Increased urine volume.
• Markedly increased appetite.
• Muscle loss as disease progresses.
• Poor coat condition.
• A cloudy lens from cataract.

Ketoacidosis can cause loss of appetite. Ketone accumulation may give breath a sweet smell.

Unintentional diabetic weight loss may become apparent within weeks. Ketoacidosis can cause apathy, with markedly reduced interest in the surroundings.

A diabetic dog may be weaker despite still eating well. The liver may feel enlarged because fat accumulates in liver cells.

Complications and consequences

In ketoacidosis, the body uses more fatty acids for energy, producing ketones in the liver. Ketone accumulation can acidify blood. Excessive urination can cause substantial dehydration. Potassium and phosphate can also be lost in urine during ketoacidosis.

Sorbitol accumulating in the lens draws in water and can promote diabetic cataracts. Cataracts can rapidly cloud the lens. Blood glucose below 3.3 millimoles per litre is considered hypoglycaemia. Severe hypoglycaemia can cause seizures.

Very severe fluid and glucose disturbances can cause loss of consciousness. In one hospital study of 127 dogs with ketoacidosis, 65% were first diagnosed with diabetes during that episode.

Diabetic dogs can develop persistent or recurrent bladder infections. Considerable sodium can be lost in urine during ketoacidosis as high glucose increases urine volume.

Diagnosis at the vet

Blood glucose, urinary glucose and symptoms

In a symptomatic dog, diabetes is diagnosed by combining high blood glucose with glucose in urine. Blood glucose of at least 11.1 millimoles per litre supports diagnosis with typical symptoms and no other likely explanation. If symptoms are unclear, glucose testing may be repeated. Fructosamine forms when glucose binds to blood proteins, particularly albumin.

History includes medicines, concurrent diseases and, when relevant, the last season. Blood testing may show increased lipid concentrations as the body uses more fat for energy. Urinary tract symptoms may warrant bacterial urine culture.

Fructosamine reflects glucose levels over the preceding seven to ten days. Low blood protein, for example with protein-losing intestinal disease, can produce a falsely low result. Elevated nitrogenous waste concentrations may suggest dehydration or concurrent kidney disease. A pancreas-specific lipase test may be taken if symptoms suggest concurrent pancreatitis.

Fructosamine trends usually provide more information than one result. Urine specific gravity in a diabetic dog is often below 1.030.

If fructosamine is below the reference range, a glucose curve or sensor can investigate prolonged hypoglycaemia.

Investigating ketoacidosis

The vet assesses whether both ketone accumulation and abnormal acidity have developed. Blood beta-hydroxybutyrate can detect ketone accumulation earlier than a urine strip. The acidosis criterion includes blood pH below 7.35 together with reduced bicarbonate. Urinary ketones can occur without confirmed ketoacidosis.

A urine ketone strip measures acetoacetate.

Treatment

Insulin and feeding

Canine diabetes is treated with subcutaneous insulin, which most dogs need for life. The vet selects a suitable insulin preparation. Treatment aims to reduce thirst and excessive urination and maintain an appropriate weight. Regular feeding in suitable portions helps keep appetite and nutrient intake consistent.

A high-fibre diet can reduce the rise in glucose after meals. An underweight dog needs sufficient energy to regain weight. Planned weight loss in an overweight diabetic dog should not exceed 2% weekly.

If acute pancreatitis worsens diabetic control, it may need separate supportive treatment.

Daily treats count towards total energy intake. A dog with concurrent chronic kidney disease needs a diet addressing renal requirements too.

Monitoring and hospital care

A glucose curve monitors several blood glucose measurements. A skin-mounted sensor tracks interstitial glucose over several days. An unexpectedly low sensor reading in a symptom-free dog should be checked with a blood glucose meter. The first glucose monitoring period often falls 5–14 days after insulin starts.

Ketoacidosis treatment starts in hospital by correcting dehydration. Insulin reduces ketosis during hospital care. It moves potassium into cells, so circulating potassium is monitored.

In the 2007 Swedish study, median survival after the first diabetes insurance claim was 57 days. Excluding dogs dying during the first day, median survival was two years.

A glucose curve for a dog receiving intermediate-acting insulin may span up to 12 hours. Monitoring is repeated if previously controlled thirst, excessive urination or weight loss returns.

Curves can vary between days, and altered feeding or exercise routines can affect measurements. Blood phosphate is also corrected during ketoacidosis care when needed. A study comparing two approaches treated 24 ketoacidosis episodes in 23 dogs. Twenty episodes ended in discharge. Median time to resolve severe hyperglycaemia was five hours in both groups.

Ketosis and acidosis resolved in 22 episodes. A concurrent infection is treated if it contributed to triggering ketoacidosis.

Prevention

Maintaining appropriate weight supports insulin sensitivity because obesity can increase resistance. Consistent gentle exercise can support weight control and reduce post-meal glucose rises. Dental and gum care can help maintain diabetic control. For diabetes associated with the post-oestrus hormonal phase, removing the ovaries can reduce insulin resistance.

Keeping food, treats and exercise reasonably consistent each day helps control.

Insulin sensitivity can change with weight loss, so treatment is monitored as weight changes.

Important for dog owners

Record drinking, urination and appetite. Weigh regularly because weight trends help assess treatment effectiveness. Learn to use the specific prescribed insulin device under veterinary guidance. Follow written instructions for a missed meal. Do not increase insulin on your own because of a high reading.

Insulin preparations differ in handling, so store and handle yours according to its instructions.

Record daily feeding and exercise deviations because they help identify problems.

Follow the specified storage temperature, as excessive cold or heat can damage insulin.

Frequently asked questions

Why does a diabetic dog drink so much?

Once blood glucose is high enough, glucose enters urine. It increases water excretion, causing more urination and thirst. Changes in drinking and urination are monitored at home after insulin starts too.

Can canine diabetes go away?

Most dogs need lifelong insulin. In some bitches with post-oestrus hormone-associated diabetes, ovarian removal can reduce the disease enough to remove insulin requirements. Glucose must then be monitored closely to avoid low levels.

What if my dog refuses food?

Follow the treating vet's written instructions because a missed meal can affect insulin safety. Contact a vet immediately if weakness, vomiting or deteriorating general health also occurs.

How do I recognise low blood glucose?

Signs include trembling, weakness and unsteadiness. An awake dog with mild signs can be offered a little food before leaving for the vet. Seizures require immediate emergency care.

What does a glucose sensor show?

It tracks changes in interstitial glucose over several days. It can detect night-time changes missed by an ordinary glucose curve. A very low sensor result in a symptom-free dog can be confirmed with a blood glucose meter.