Hypoglycemia Symptoms in Dogs to WATCH Out For

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Did you know hypoglycemia symptoms in dogs are the same as in humans? Have you ever felt dizzy, started seeing stars, and felt your brain wasn’t functioning when extremely hungry? You are not alone, and that is your brain’s way of telling your body, “we need to eat now!”

Dogs, too, go through the same process of hypoglycemia. So what is hypoglycemia in dogs? And how would we get to know dog hypoglycemia symptoms? Let’s dive in. 

White and Red Cavalier King Charles Spaniel Puppy

What is Hypoglycemia in Dogs?

Hypoglycemia in dogs can be broken down into: hypo (low) + gly (glucose) + cemia (blood) = low glucose in the blood. In much simpler terms, hypoglycemia in dogs refers to low blood sugar. The normal blood glucose concentration for a healthy, non-diabetic dog is 3.3 – 6.1 mmol/L (60 mg/dL – 110 mg/dL).

Glucose is the primary source of energy for the body. Excess glucose is converted to glycogen and stored in the liver and muscles. In days of fasting, lack of appetite, etc., the body uses up the glycogen and turns it into glucose. Thus, hypoglycemia occurs when glucose levels reach an abnormally low concentration in the blood, and the body has used up its stored glucose or can’t get it released.

Hypoglycemia can be grouped into two main types – juvenile hypoglycemia and adult hypoglycemia. 

Juvenile hypoglycemia occurs in puppies less than three months of age. Puppies are especially vulnerable to hypoglycemia because they have not fully developed the ability to regulate blood sugar concentrations and need a higher amount of glucose for growth purposes. Hypoglycemia in puppies can be deadly, and one shouldn’t joke with it. 

Adult hypoglycemia occurs when older dogs fast, lack appetite, or have a severe underlying disease that affects glucose regulation.

Hypoglycemia is one of the most common emergencies seen in veterinary hospitals. Dog hypoglycemia is a severe medical condition that needs to be treated urgently. If left unchecked, it affects brain function in the end, leading to coma and death. 

What are the Causes of Hypoglycemia in Dogs?

Hypoglycemia occurs from many causes, both physical activities and internal conditions. Most of these physical causes include the direct issues we can see and address, such as fasting, exertion from extreme activities, etc. In contrast, internal conditions include certain health conditions that require a diagnosis to detect, such as liver and pancreatic issues. 

The causes of dog hypoglycemia can be grouped into four main factors:

  1. Eating a diet with fewer amounts of glucose.
  2. Glucose is removed from the bloodstream faster than usual.
  3. Glycogen stores not being able to release glucose when needed.
  4. Endocrine abnormalities.

Some known causes of hypoglycemia include:

  • Increasing time between feeding for puppies
  • Excessive use of glucose by the body during pregnancy
  • Giving an overdose of insulin to a dog, diabetic or not
  • Starvation / malnutrition / poor diet
  • Abnormal growth of cells of the pancreas
  • Disease / inflammation / cancer of the liver
  • Glycogen storage disease
  • Cancer of the GIT
  • Portosystemic shunt 
  • Toxicity from eating artificial sweeteners such as xylitol
  • Excessive, strenuous exercise
  • Taking antifreeze
  • Hypocorticism/ hypocortisolism/ Addison’s disease
  • Leukemia
  • Sepsis
  • Malignant melanoma
  • Intestinal parasites
  • Specific drug toxicity such as with beta-blockers and sulfonylureas
  • Hypopituitarism
  • Chronic kidney failure
  • Pancreatitis
  • Severe canine babesiosis

Pathophysiology and Mechanisms of Low Blood Sugar in Dogs

Before we get to how hypoglycemia comes about in the body, let us know the pathways of glucose and its absorption first. The body obtains glucose from three primary sources: 

  1. Absorption of glucose in the intestines from digested carbohydrates.
  2. Breaking down glycogen into glucose (glycogenolysis) in the liver and, at times, the muscles.
  3. Creating new glucose from noncarbohydrate sources such as fats, proteins, lactate, and pyruvate (gluconeogenesis) in the liver and, sometimes, the kidneys.

In a healthy animal, the body maintains average glucose concentrations in the blood by balancing the hormone responsible for lowering blood glucose, insulin, and hormones. Conversely, these hormones are responsible for elevating blood glucose, glucagon, epinephrine (adrenaline), norepinephrine (noradrenaline), cortisol, and growth hormone.

After your dog eats a meal, glucose levels rise in the blood. The pancreas secretes insulin when the blood sugar level is more than > 6 mmol/L (106 mg/dL). Insulin will temporarily stop gluconeogenesis and glycogenolysis. It will increase glucose uptake and use by cells sensitive to insulin. 

Insulin release will boost the production and storage of glycogen and prevent glucagon from being secreted. In effect, this reduces hyperglycemia (high blood sugar). 

After a while, the body releases an inhibitory mechanism that regulates insulin secretion and excretes insulin to prevent the body from going into hypoglycemia. This occurs when the blood glucose levels are <3.3 mmol/L (<106 mg/dL). 

The decrease in the blood glucose level leads to the release of counter-regulatory hormones to keep the blood sugar level stable.

The first hormones released are glucagon from the pancreas and epinephrine from the adrenal gland on top of the kidneys. These hormones are short-acting and counteract the effect of insulin physiologically. Therefore, these hormones restart gluconeogenesis and glycogenolysis. As a result, they reduce glucose uptake and stop insulin secretion. 

Cortisol and growth hormone are released one to two hours after hypoglycemia is detected. These have a prolonged effect on raising blood sugar levels. This is also achieved through gluconeogenesis, reducing glucose use in the body, and promoting lipolysis (breakdown of lipids/fat).

To sum the mechanism up, after feeding, glucose is gotten directly from outside sources, while in the fasting period or hypoglycemia state, glucose is obtained from internal sources.

Now back to the pathophysiology of hypoglycemia. Pathophysiology means a deviation from the normal mechanism or running of the body, usually associated with disease or injury. 

Pathophysiology of hypoglycemia comes about when glucose utilization exceeds the production of glucose and glucose circulation. Hence, low glucose in dogs. 

Most of the causes of hypoglycemia are multifactorial and can result from poor diet, dysfunctioning gluconeogenesis or glycogenolysis pathway, increased glucose uptake without replacement, and abnormalities in the endocrine system.

Even though hypoglycemia occurs when the blood sugar levels are less than 3.3 mmol/L (60mg/dL), clinical signs are not detected until the blood sugar levels drop between 2.8 mmol/L – 2.2 mmol/L (50 mg/dL – 40 mg/dL) or less. 

Tan and White Short Coat Dog Laying Down

Hypoglycemia Symptoms in Dogs (With Clinical Signs)

Hypoglycemia symptoms can be summarized into just one sentence; the dog will usually feel weak and seem to be in a daze. Clinical signs, however, vary with the severity of hypoglycemia and don’t follow a required pattern. It ebbs and flows. 

Symptoms of low blood sugar in dogs vary based on the duration. It begins mildly and progresses with time. Thus, the farther the time from the onset of being hypoglycemic, the severity of the symptoms. If left untreated and unattended, it can lead to unconsciousness and death. 

Most of the signs of hypoglycemia in dogs are associated with the brain’s function (neuroglycopenia). This is because the brain has a high requirement for glucose, which is its only energy source. It cannot store nor create glucose, leading to most signs being neurological since the brain is affected first. 

Here are some of the symptoms of hypoglycemia in dogs, in no particular order:

  • Trembling
  • Intolerance for exercise
  • Unconsciousness
  • Lack of coordination 
  • Change in behavior
  • Slow responses
  • Lethargy or low energy
  • Loss of appetite
  • Increased thirst (polydipsia)
  • Increased urination (polyuria)
  • Weakness
  • Seizures
  • Partial paralysis, especially at the hind limbs. 
  • Involuntary twitching or muscle spasms
  • Irregular heart rate
  • Blindness
  • Irregular breathing
  • Discoloration of skin and gums
  • Dilated pupils
  • Sleepiness or drowsiness

Available Treatments for Canine Hypoglycemia

The first line of treatment is to get the blood glucose level back to normal. If the hypoglycemia is not severe, corn syrup, glucose/sugar, honey, or fruit juice can be rubbed on the gum or under the tongue of the dog. If the hypoglycemia is severe, the pet may be put on a concentrated dextrose (glucose) intravenous fluid. 

In seizures, the dog is given a small meal after the episodes cease. 

The blood sugar levels would be reassessed after a while to ensure it is back to normal before the dog is discharged. Hypoglycemia in small dogs requires the owner to feed it at short intervals.  

If the hypoglycemia is due to fasting or strenuous exercise, the dog would be discharged after the vet carefully monitors it and advises the owner.  If the hypoglycemia is due to an underlying disease, treatment for that condition would be started once the blood sugar level is stable. 

If hypoglycemia is due to a poor diet, your veterinarian would recommend feeding your dog meals high in complex carbohydrates, fats, and proteins. This is especially important in small breed dogs as they are prone to frequent hypoglycemia.  

How is Low Blood Sugar in Dogs Diagnosed?

The veterinarian will ask you about your dog’s medical history and perform a complete physical exam. Next, they will measure your pet’s blood sugar/glucose level using a blood glucose meter. This test is rapid and does not require a lot of samples. A small drop of blood is all that it takes. Hypoglycemia is detected if the reading on the meter is less or below 3.3 mmol/L (60 mg/dL). 

Additional tests such as blood biochemistry, complete/total blood count, urinalysis, and blood insulin concentration would be conducted to test for organ functioning, thyroid function, electrolyte balance, toxicity, and other blood tests. In addition, an ultrasound or x-ray can be done when cancer is suspected. 

The Outcome and Prognosis of Canine Hypoglycemia

The outcome and prognosis of low glucose in dogs are good when detected early, and treatment is carried on without a severe underlying condition. On the other hand, hypoglycemia becomes deadly when it is not seen early or not treated on time. 

It is essential to monitor your dog for possible signs of recurrence and note what triggers hypoglycemia in your dog.

Person Holding White and Black Puppy

Final Thoughts

Hypoglycemia is pretty severe and should be treated with utmost urgency. Special care should be given to small breeds, especially puppies of those breeds. Highly active dogs must be monitored carefully. Dogs about to undergo a surgical procedure and need to fast should also be watched. 

Instead of feeding one big meal for puppies and small breed dogs at the end of the day, space out those meals into smaller quantities twice or thrice a day. Keep a snack handy for hyperactive dogs. Be sure to feed a moderate amount of food before any strenuous activity.

Owners of small dogs should have glucose available at home as those types of breeds are most prone to hypoglycemia. During emergencies, put a sugar/glucose water solution on or under your dog’s tongue for it to be absorbed immediately.

With that, you are on the road to a hypoglycemic-free life with your dog.

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Currently a Veterinary House Officer at the University of Ghana, Akosua plays a pivotal role in disease diagnosis, treatment, and student supervision. Akosua's educational journey in veterinary medicine has been instrumental in shaping her commitment to public education and awareness. Her veterinary training equips her to communicate complex topics for public understanding. Her online presence on Instagram reaches a wider audience. She actively engages in public speaking, inspiring a deeper understanding of responsible pet care and the role of veterinary professionals in fostering a healthier coexistence between humans and animals.