Low blood sugar in puppies – hypoglycaemia signs and first aid

Overview

Blood glucose is an energy source, and the brain needs a continuous supply to function normally. Hypoglycaemia is a finding or sign with several possible causes.

A blood glucose level below 3.3 mmol/l is used as a general threshold for hypoglycaemia in dogs. Newborn puppy results are interpreted separately because metabolism and reference values differ from those of older dogs.

Even a short fast can cause a dangerous energy shortage in a small puppy. The outlook is often good with early treatment, but prolonged seizures or coma worsen it.

Causes

A puppy has limited energy reserves and glucose production

The liver stores glucose as glycogen, from which sugar can be released between feeds. Glucagon is a pancreatic hormone that promotes glucose release from liver glycogen stores when blood sugar falls.

Before birth, a puppy receives glucose through the placenta, but afterwards energy must come from milk and its own reserves. A newborn has small liver glycogen stores and an immature ability to make new glucose.

Low muscle mass and limited fat reserves reduce a puppy's ability to cope without food. A cold environment increases energy expenditure, which can worsen the effects of insufficient feeding.

Vomiting, diarrhoea and intestinal parasites can interfere with nutrition and predispose to falling blood sugar. Systemic bacterial infection, or sepsis, can increase glucose use and disrupt liver glucose production.

A congenital liver shunt can be associated with low blood sugar in a young dog. A rare glycogen storage disease can prevent normal use of stored energy.

Xylitol can trigger insulin release in a dog and rapidly lower blood sugar. Access to human glucose-lowering medicines can also cause dangerous poisoning.

Excessive insulin activity removes too much glucose from the blood and can cause hypoglycaemia.

Risk factors

In puppies under 3 months old, blood sugar regulation has not yet developed to an adult level. Small breeds' increased susceptibility may continue to around 3–4 months of age.

Risk groups include Chihuahuas, Yorkshire Terriers, Maltese, Toy Poodles and Pomeranians. In Chihuahuas, the problem can also occur in young adulthood and sometimes later in life.

Among newborns, premature, low-birthweight, orphaned and already ill puppies are particularly vulnerable. A small puppy may not get enough milk if it cannot compete with larger littermates for a teat.

Low milk production or unsuccessful nursing can interrupt a newborn's energy supply. After a caesarean section, waiting for the dam to recover may prolong the puppy's time without feeding.

A cleft palate or another oral structural abnormality can prevent adequate suckling even when milk is available.

Typical symptoms

Signs may initially look like unusually marked tiredness or odd behaviour.

• Your puppy is weak or becomes unusually sleepy.

• Walking is unsteady and control of movement looks clearly impaired.

• Your puppy trembles, shakes or has muscle twitches.

• The eyes look glazed and your puppy does not seem to focus normally on its surroundings.

• A newborn does not suckle normally or repeatedly stops feeding.

• In severe cases, your puppy has seizures or loses consciousness.

A newborn may also vocalise more than usual, seem irritable and eventually become apathetic. A combination of hypoglycaemia, hypothermia and dehydration can develop when nursing fails.

An absence of signs does not always mean a newborn's glucose balance is normal.

Complications and consequences

A serious glucose shortage can impair brain function and cause seizures or coma. Severe hypoglycaemia may also be accompanied by a slow heart rate and bluish mucous membranes.

Untreated hypoglycaemia can cause a puppy's death. A glucose concentration below 92 milligrams per decilitre during the first 24 hours of life has been associated with increased risk of death during the first 21 days.

This is a prognostic observation in newborns, rather than a basis for setting the same threshold in older puppies. An episode recognised and treated quickly has a better outlook than prolonged seizures or coma.

Diagnosis at the vet

Blood glucose is measured promptly and checked if needed

The vet measures glucose promptly from a blood sample, often with a point-of-care meter. A low meter reading may be confirmed by a laboratory method before extensive further investigations.

Sample handling can lower the measured glucose even when the dog's actual blood sugar is not low. Blood cells continue consuming glucose in the tube if plasma or serum is not separated from them promptly.

An unexpectedly low result in a well dog without symptoms may therefore be investigated using a new blood sample. Symptomatic hypoglycaemia is treated urgently, so help for a seriously ill puppy is not delayed for an extensive investigation.

In a newborn, blood glucose is assessed alongside the suckling reflex, body temperature and general condition.

Tests investigate feeding problems, infection and underlying disease

The history reviews recent meals and changes in alertness, appetite, drinking and bowel function. The examination also assesses signs of infection or liver disease.

In a newborn, the palate and suckling reflex are checked to identify possible barriers to milk intake. A blood count, blood biochemistry and urinalysis help assess general health.

White blood cell changes may direct investigation towards a serious bacterial infection. Low albumin, cholesterol and urea alongside hypoglycaemia may suggest liver dysfunction or a shunt.

A suspected liver shunt can be investigated with bile acid testing and abdominal imaging. Ammonium urate crystals in urine may support suspicion of a shunt or other severe liver disease.

Blood sodium and potassium changes may prompt investigation for hypoadrenocorticism. If sepsis is suspected, blood culture may help identify the bacterium and an appropriate antibiotic.

With repeated unexplained hypoglycaemia, insulin may be measured at the same time as a documented low glucose level.

Treatment

The vet corrects blood glucose while investigating the cause of the energy shortage.

Prompt glucose treatment and correction of temperature imbalance

In severe hypoglycaemia, glucose is given intravenously in a controlled manner at the veterinary practice. A very small newborn may instead receive treatment through the bone marrow cavity if needed.

Glucose may be continued as an infusion if blood sugar does not remain stable after the initial correction. Excessively rapid or excessive correction is avoided to prevent another fluctuation.

Fluid therapy and other supportive care are selected according to dehydration, temperature and the underlying disease. Oral sugar alone is too slow a treatment for severe neonatal hypoglycaemia.

A hypothermic newborn is warmed gradually over around 30–60 minutes. An excessively hot warming pad can burn a puppy that cannot yet move away from the heat source.

Tube feeding a cold newborn is delayed until body temperature has recovered. Hypothermia suppresses gut function and increases the risk of regurgitation and food entering the airways.

First aid on the way does not replace examination

A conscious puppy swallowing normally may be offered food according to the veterinary practice's advice. Sugar-containing syrup rubbed on the gums may be used as temporary first aid.

Do not pour liquid into the mouth of a puppy that cannot swallow well or has reduced consciousness. Keep your puppy warm during transport, for example wrapped in a blanket.

An early response to oral energy may be visible within 5–10 minutes. The puppy is still taken to a vet because stabilisation is needed after a severe episode.

Resuming suckling or adequate eating helps maintain the corrected glucose balance. Glucose is not given routinely to newborns just in case, as it can raise blood sugar excessively.

Prevention

After weaning, a small puppy is offered 3–4 regular meals daily. Use a complete food designed for a growing puppy's nutritional needs.

A newborn's energy intake depends on successful nursing and adequate milk production. Colostrum supplies dietary fats and carbohydrates that are important energy sources for newborns.

If the dam's milk is unavailable, a puppy milk replacer is a better option than a homemade mixture. Adequate maternal nutrition during pregnancy also influences puppies' energy reserves.

Vomiting, diarrhoea, poor appetite or unusual tiredness are investigated promptly to prevent declining energy intake. Newborns cannot regulate temperature like adults, and this ability remains immature until around 4 weeks of age.

During the first week of life, the puppies' environmental temperature is usually around 28.9–31.7°C. A healthy newborn is expected to gain around 5–10% of its bodyweight daily.

A halt in weight gain can reveal a nursing problem before visible hypoglycaemia signs begin.

Important for dog owners

Record meals, the time of the last substantial feed, vomiting and diarrhoea. Tell the vet about chilling, medicines and possible access to xylitol-containing products. Bring the packaging of a suspected product. Check that your puppy actually eats enough, rather than simply that food has been in the bowl.

Record a newborn's weight daily for the first 2 weeks, then around every 3 days until 1 month of age.

Before any planned fast or investigation, agree on feeding instructions appropriate to your puppy's age and size. Make sure an emergency contact number and transport arrangements are available beforehand. If blood sugar has fallen previously, ask for an individual first-aid and monitoring plan. Do not manage recurrent episodes with sugar alone.

Investigating the underlying cause may require further tests even if blood glucose is corrected quickly.

Frequently asked questions

Is hypoglycaemia the same as diabetes?

Hypoglycaemia means blood sugar is too low; in a puppy, insufficient energy intake is one possible cause. Excessive insulin activity during diabetes treatment can also cause hypoglycaemia. A trembling puppy's problem is investigated by a vet so treatment targets the correct cause.

What should I do if my puppy is unsteady and trembling?

Keep your puppy warm and seek urgent veterinary care. If it is awake and swallowing normally, food may be offered. Do not pour liquid into the mouth of a puppy that cannot swallow well. A puppy with severe symptoms may need intravenous glucose at the veterinary practice.

Is it enough if sugar makes my puppy brighter?

Oral energy can improve condition quickly, but a puppy that has had severe symptoms still needs veterinary treatment. An infection or liver dysfunction may underlie the problem as well as insufficient nutrition. Recurrent signs require further investigation.

Can a puppy that looks healthy have low blood sugar?

A newborn may have hypoglycaemia without clear outward signs. Conversely, a single low laboratory result may be caused by sample handling. The vet assesses the situation using the puppy's condition and a fresh repeat sample if needed. Failure to gain weight can also reveal a nutritional problem early.

How often should a small puppy eat?

After weaning, 3–4 meals daily are generally recommended for a small puppy. A newborn's nutrition instead relies on repeated suckling and adequate milk intake. If weight does not increase, nursing success and the puppy's health must be investigated.