Dehydration
Dehydration causes an abnormal reduction in the volume of circulating blood. This has a number of ramifications, many of which are related to imbalances in the levels of electrolytes in fluids that normally are contained inside and outside of cells (intracellular and extracellular fluids). Electrolytes are natural chemical substances which, when dissolved in water or melted, dissociate into electrically charged particles called “ions”. Ions can be negatively or positively charged and can conduct electrical currents. The key positively charged ions in a dog’s body fluids (“cations”) are calcium, magnesium, potassium and sodium. The primary negatively charged ions (“anions”) are bicarbonate, chloride and phosphate. The concentration of electrolytes is carefully regulated, because electrolytes are critical to the normal metabolic activities and functions of all cells in the body.
When a dog becomes dehydrated, the relative concentration of electrolytes in its cells, blood and other body fluids becomes imbalanced. This can affect virtually any organ or system, including the kidneys, bones, gastrointestinal tract, nerves, muscles, blood pressure, heart function and respiratory tract, among others.
Symptoms of Dehydration
The observable signs of dehydration in dogs can include one or more of the following:
Dogs at Increased Risk
Small dogs have an increased risk of becoming dehydrated, because they have a high body surface area-to-volume ratio. Anything that adversely affects thirst or appetite, or that diminishes water or food intake, can predispose a dog to dehydration. For example, dogs housed outdoors in exceptionally hot weather, and dogs whose water supply is frozen in the dead of winter, commonly have decreased water intake and become dehydrated. Dogs with some systemic diseases – especially those that cause vomiting, diarrhea, appetite loss or excessive urine production and output - are also predisposed to dehydration.
Dehydration
Dehydration is excessive loss of water from the body (typically through vomiting and/or diarrhoea, or inappropriate intake of water into the body (decreased thirst). The most common mistake with a vomiting dog is to encourage food and water intake whilst the dog is still vomiting. This actually makes matters worse by not allowing the stomach and intestinal tract time to rest and can cause additional vomiting and water loss. Removing access to food and water for a short period of time may seem like it would make dehydration worse, but it can help your dog avoid further dehydration.
What To Do
If moderate or sever dehydration, seek veterinary attention straight away. Intravenously fluids will be given by your vet and drugs to east the vomiting and diarrhoea.
If dehydration is mild and your dog is not vomiting, give frequent, small amounts of water by mouth, in the range of 1 teaspoon (2mls) – small dog, 1 tablespoon/ ¼ cum (5 – 10mls) – medium to large dog,
If your dog is lethargic, in pain, or has not eaten for 24 hours, seek veterinary attention straight away.
What Not To Do
Do not allow your dog to have immediate free access to large amounts of water or other liquids.
Do not feed your dog any dry food until directed by a vet, as this absorbs water in the stomach.
Easy Diagnostic Questions
Dehydration often accompanies symptoms like vomiting, diarrhoea, hypothermia (low body temperature), fever, no access to water and other conditions. It can be detected by several tests:
Mouth
Question: Are the tongue and gums moist or dry?
Answer: If they are dry, there is a chance your dog may be dehydrated.
Question: Is the saliva thick or ropey?
Answer: Normally saliva is quite watery and hardly noticeable.
Eyes
Question: Are they normal or do they sink into the sockets?
Answer: Sunken or dry eyes may indicate dehydration and warrant veterinary attention.
Skin
Do the skin turgor test outlined in the physical exam checklist.
If the skin is slow to return to position, your dog my well be moderately to severely dehydrated.
If the skin does not fully return to position, your dog may be severely dehydrated and possibly in a critical condition, you must then seek immediate veterinary attention.
The skin turgor test is not always accurate and several factors such as age, weight loss and condition of skin can give misleading results. A vet will be able to determine how dehydrated your dog is, what the cause may be and the best course of treatment.
Management of fluid and electrolyte abnormalities is a fundamental aspect of clinical medicine.
In health, fluid balance is maintained by:
Fluid therapy is an important supportive therapeutic measure in critically ill patients.
Before the initiation of fluid therapy, identification of the disease process involved will help in formulating an appropriate plan.
The first questions the clinician should ask when deciding if fluid therapy is indicated are:
Once the decision to institute fluid therapy has been made, the following questions should be addressed:
Body Fluid Compartments
Total body water (TBW) represents 60% of the body weight of adult dogs.
2/3 of TBW is located within the cells (intracellular).
1/3 is located extracellular.
Extracellular fluids (ECF) is further divided into interstitial fluid (75% ECF) and intravascular fluid (25% ECF).
Maintenance Fluid Requirements
Normal sources of water are those consumed directly or in food and those produced in the body through medication.
Maintenance requirements are defined as the volume of fluids or electrolytes that are required on a daily basis to keep TBW and electrolyte content normal.
In a healthy dog, water input = water output loss.
Daily water loss (loss not readily measurable from evaporation and faeces) – estimated at 22mls/kg per day.
Sensible fluid volume is calculated by adding sensible and insensible water losses.
Maintenance volume required for small dogs 66ml/kg per day
Maintenance volume for large dogs is 44ml/kg per day.
Physical Examination In /Helping To Assess The Degree Of Dehydration
The use of physical examination to detect the degree of dehydration is helpful, but somewhat limited in it’s sensitivity.
Dehydration is not detected by clinical examination until at least 5% of body water has been lost.
Hydration status of a dog is estimated by evaluating:
Skin turgor is dependant upon subcutaneous fat and elastin as well as fluid content.
Obese Dogs – because of subcutaneous fat, may appear well hydrated even if they are not.
Emaciated and Older Dogs – may appear less hydrated than they are because of the loss of skin elastin and fat.
Initial Database Of Patients Requiring Fluid Therapy
History to include information of water and food intake, gastrointestinal losses, urinary output, exposure to heat, trauma, haemorrhage, excessive panting fever and diuretic use.
Physical examination findings:
<5% Dehydration = Not detectable
5% - 6% Dehydration = Subtle loss of skin turgor
7% - 8% Dehydration = Delay in skin returning to normal position.
Prolonged capillary refill time.
Tacky mucous membranes of mouth.
Eyes may appear to be sunken in orbit,
10% - 15% Dehydration = Tented skin.
Prolonged capillary refill time.
Eyes sunken in orbit.
Dry mucous membrane.
Signs of shock (↑ HR = Tachycardia weak peripheral pulses collapse of peripheral veins).
12% - 15% Dehydration = Shock/collapse → Death
Determine body WT = Acute decrease in body weight may be due to fluid
loss 1kg = 1000mls fluid
Assessment Of Patient Requiring Fluid Therapy
History: The first step in formulating a fluid therapy plan is to assess the degree of dehydration and electrolyte in the patient.
Historical information about the dog’s disease and route of fluid loss will help in deciding on the type of electrolyte and acid-base changes present. The length of time over which fluid loss has occurred, an estimate of the magnitude of loss and information about water and food consumption can be obtained by asking owner. Assessments about the source of fluid loss, such as gastrointestinal, urinary or traumatic (haemorrhage) are also helpful.
Technically, dehydration refers to loss of pure water from the body. In the clinical setting, most water loss is accompanied by electrolyte loss.
Increased fluid loss can result in:
Dehydration causes an abnormal reduction in the volume of circulating blood. This has a number of ramifications, many of which are related to imbalances in the levels of electrolytes in fluids that normally are contained inside and outside of cells (intracellular and extracellular fluids). Electrolytes are natural chemical substances which, when dissolved in water or melted, dissociate into electrically charged particles called “ions”. Ions can be negatively or positively charged and can conduct electrical currents. The key positively charged ions in a dog’s body fluids (“cations”) are calcium, magnesium, potassium and sodium. The primary negatively charged ions (“anions”) are bicarbonate, chloride and phosphate. The concentration of electrolytes is carefully regulated, because electrolytes are critical to the normal metabolic activities and functions of all cells in the body.
When a dog becomes dehydrated, the relative concentration of electrolytes in its cells, blood and other body fluids becomes imbalanced. This can affect virtually any organ or system, including the kidneys, bones, gastrointestinal tract, nerves, muscles, blood pressure, heart function and respiratory tract, among others.
Symptoms of Dehydration
The observable signs of dehydration in dogs can include one or more of the following:
- Excessive skin tenting/decreased skin turgor (the skin stays “stuck together” for a prolonged period of time after being gently lifted and pressed between two fingers. Normal skin pliability depends in large part upon hydration status. Obesity and emaciation can alter the results of this test.)
- Loose skin (loss of elasticity)
- Wrinkled skin (due to dryness)
- Vomiting
- Diarrhea
- Lack of appetite (inappetance; anorexia)
- Weight loss (may be rapid in onset)
- Excessive volume of urine production and output (polyuria)
- Lethargy; listlessness
- Weakness
- Depression
- Panting
- Excessive drooling/salivation (ptyalism)
- Tacky, dry gums and other mucous membranes
- Elevated heart rate (tachycardia)
- Weak pulse quality/strength
- Prolonged capillary refill time (this is a simple test done by pressing on the dog’s gums with a fingertip and assessing how long it takes for the spot to return to its normal pink color; the normal canine capillary refill time is less than 2 minutes.)
- Sunken eyes (enophthalmos; usually bilaterally symmetrical/affecting both eyes equally)
- Collapse
Dogs at Increased Risk
Small dogs have an increased risk of becoming dehydrated, because they have a high body surface area-to-volume ratio. Anything that adversely affects thirst or appetite, or that diminishes water or food intake, can predispose a dog to dehydration. For example, dogs housed outdoors in exceptionally hot weather, and dogs whose water supply is frozen in the dead of winter, commonly have decreased water intake and become dehydrated. Dogs with some systemic diseases – especially those that cause vomiting, diarrhea, appetite loss or excessive urine production and output - are also predisposed to dehydration.
Dehydration
Dehydration is excessive loss of water from the body (typically through vomiting and/or diarrhoea, or inappropriate intake of water into the body (decreased thirst). The most common mistake with a vomiting dog is to encourage food and water intake whilst the dog is still vomiting. This actually makes matters worse by not allowing the stomach and intestinal tract time to rest and can cause additional vomiting and water loss. Removing access to food and water for a short period of time may seem like it would make dehydration worse, but it can help your dog avoid further dehydration.
What To Do
If moderate or sever dehydration, seek veterinary attention straight away. Intravenously fluids will be given by your vet and drugs to east the vomiting and diarrhoea.
If dehydration is mild and your dog is not vomiting, give frequent, small amounts of water by mouth, in the range of 1 teaspoon (2mls) – small dog, 1 tablespoon/ ¼ cum (5 – 10mls) – medium to large dog,
If your dog is lethargic, in pain, or has not eaten for 24 hours, seek veterinary attention straight away.
What Not To Do
Do not allow your dog to have immediate free access to large amounts of water or other liquids.
Do not feed your dog any dry food until directed by a vet, as this absorbs water in the stomach.
Easy Diagnostic Questions
Dehydration often accompanies symptoms like vomiting, diarrhoea, hypothermia (low body temperature), fever, no access to water and other conditions. It can be detected by several tests:
Mouth
Question: Are the tongue and gums moist or dry?
Answer: If they are dry, there is a chance your dog may be dehydrated.
Question: Is the saliva thick or ropey?
Answer: Normally saliva is quite watery and hardly noticeable.
Eyes
Question: Are they normal or do they sink into the sockets?
Answer: Sunken or dry eyes may indicate dehydration and warrant veterinary attention.
Skin
Do the skin turgor test outlined in the physical exam checklist.
If the skin is slow to return to position, your dog my well be moderately to severely dehydrated.
If the skin does not fully return to position, your dog may be severely dehydrated and possibly in a critical condition, you must then seek immediate veterinary attention.
The skin turgor test is not always accurate and several factors such as age, weight loss and condition of skin can give misleading results. A vet will be able to determine how dehydrated your dog is, what the cause may be and the best course of treatment.
Management of fluid and electrolyte abnormalities is a fundamental aspect of clinical medicine.
In health, fluid balance is maintained by:
- Oral intake
- Renal
- Gastrointestinal
- Insensible losses
Fluid therapy is an important supportive therapeutic measure in critically ill patients.
Before the initiation of fluid therapy, identification of the disease process involved will help in formulating an appropriate plan.
The first questions the clinician should ask when deciding if fluid therapy is indicated are:
- Is the patient dehydrated?
- Are there serious acid-base changes?
- Are there significant electrolyte disturbances?
- Are there ongoing fluid losses, such as vomiting that must be accounted for?
Once the decision to institute fluid therapy has been made, the following questions should be addressed:
- By what route should fluids be given?
- What volume of fluid needs to be administered?
- What type of fluid should be used?
- How fast should fluids be given?
- What supplements should be added to the standard fluid?
- How will hydration status be monitored?
Body Fluid Compartments
Total body water (TBW) represents 60% of the body weight of adult dogs.
2/3 of TBW is located within the cells (intracellular).
1/3 is located extracellular.
Extracellular fluids (ECF) is further divided into interstitial fluid (75% ECF) and intravascular fluid (25% ECF).
Maintenance Fluid Requirements
Normal sources of water are those consumed directly or in food and those produced in the body through medication.
Maintenance requirements are defined as the volume of fluids or electrolytes that are required on a daily basis to keep TBW and electrolyte content normal.
In a healthy dog, water input = water output loss.
Daily water loss (loss not readily measurable from evaporation and faeces) – estimated at 22mls/kg per day.
Sensible fluid volume is calculated by adding sensible and insensible water losses.
Maintenance volume required for small dogs 66ml/kg per day
Maintenance volume for large dogs is 44ml/kg per day.
Physical Examination In /Helping To Assess The Degree Of Dehydration
The use of physical examination to detect the degree of dehydration is helpful, but somewhat limited in it’s sensitivity.
Dehydration is not detected by clinical examination until at least 5% of body water has been lost.
Hydration status of a dog is estimated by evaluating:
- Skin turgor or pliability
- Moistness of mucous membrane
- Position of eyes
- Heart rate
- Character of peripheral pulses
- Capillary refill time
- Jugular venous distension
Skin turgor is dependant upon subcutaneous fat and elastin as well as fluid content.
Obese Dogs – because of subcutaneous fat, may appear well hydrated even if they are not.
Emaciated and Older Dogs – may appear less hydrated than they are because of the loss of skin elastin and fat.
Initial Database Of Patients Requiring Fluid Therapy
History to include information of water and food intake, gastrointestinal losses, urinary output, exposure to heat, trauma, haemorrhage, excessive panting fever and diuretic use.
Physical examination findings:
<5% Dehydration = Not detectable
5% - 6% Dehydration = Subtle loss of skin turgor
7% - 8% Dehydration = Delay in skin returning to normal position.
Prolonged capillary refill time.
Tacky mucous membranes of mouth.
Eyes may appear to be sunken in orbit,
10% - 15% Dehydration = Tented skin.
Prolonged capillary refill time.
Eyes sunken in orbit.
Dry mucous membrane.
Signs of shock (↑ HR = Tachycardia weak peripheral pulses collapse of peripheral veins).
12% - 15% Dehydration = Shock/collapse → Death
Determine body WT = Acute decrease in body weight may be due to fluid
loss 1kg = 1000mls fluid
Assessment Of Patient Requiring Fluid Therapy
History: The first step in formulating a fluid therapy plan is to assess the degree of dehydration and electrolyte in the patient.
Historical information about the dog’s disease and route of fluid loss will help in deciding on the type of electrolyte and acid-base changes present. The length of time over which fluid loss has occurred, an estimate of the magnitude of loss and information about water and food consumption can be obtained by asking owner. Assessments about the source of fluid loss, such as gastrointestinal, urinary or traumatic (haemorrhage) are also helpful.
Technically, dehydration refers to loss of pure water from the body. In the clinical setting, most water loss is accompanied by electrolyte loss.
Increased fluid loss can result in:
- Increased urination (Poluura)
- Vomiting and diarrhoea (common)
- Fever, panting
- Large burn wounds
- Excessive salivation
- Haemorrhage
