General Anaesthesia in Dogs
General anaesthesia is a controlled state of unconsciousness in which a dog does not feel pain and cannot deliberately move. It allows veterinary procedures to be carried out safely, but no anaesthetic is entirely without risk.
An Individual Anaesthetic Plan
There is no single anaesthetic drug or combination that is safest for every dog. The veterinary team selects medication according to the dog's health, age, weight, temperament, breed, previous reactions and the procedure being performed.
Propofol is one of several drugs that may be injected to induce anaesthesia. Isoflurane and sevoflurane are inhaled anaesthetic gases commonly used to maintain it. Other drugs or techniques may be more suitable for an individual patient.
Safety depends on the complete process: assessment, appropriate drug selection, airway management, monitoring, temperature control, pain relief and careful recovery.
Before the Anaesthetic
The vet will review the dog's history and perform a physical examination. Tell the practice about:
- Any previous anaesthetic or medication reaction
- Heart, breathing, liver, kidney or neurological disease
- Recent coughing, vomiting, diarrhoea or loss of appetite
- All prescribed medicines
- Over-the-counter medicines, supplements and herbal products
- Possible pregnancy
- The dog's MDR1 status, if known
Blood tests may be recommended to look for anaemia, dehydration, infection or problems affecting organs such as the liver and kidneys. Depending on the dog and procedure, urine tests, blood pressure, heart tests or diagnostic imaging may also be advised.
Follow the Fasting Instructions
Follow the veterinary practice's instructions about food and water exactly. Fasting reduces the risk of vomiting and inhaling stomach contents while normal swallowing reflexes are reduced.
Fasting times are not identical for every patient. Puppies, very small dogs, diabetic dogs and emergency patients may require a different plan. Do not extend the fasting period without asking the practice.
If the dog accidentally eats, vomits, develops diarrhoea or becomes unwell before admission, telephone the practice. Do not conceal it, as the anaesthetic plan or procedure time may need to change.
What Is Premedication?
Premedication is given before general anaesthesia and often includes a sedative and pain-relieving medication. It can:
- Reduce fear and anxiety
- Make induction smoother
- Reduce the amount of general anaesthetic required
- Provide pain relief before the procedure begins
- Help produce a calmer recovery
The choice and dose are tailored to the individual dog. For Collies, an alternative to acepromazine—often called ACP—should be selected.
Collies and ACP
Acepromazine, commonly known as ACP, should be avoided in Rough and Smooth Collies. Some Collies carry the ABCB1 gene mutation, usually called MDR1, which can make them unusually sensitive to this medication and may result in deeper or prolonged sedation.
Collielife recommends that owners request a suitable alternative premedication. Always provide the dog's MDR1 DNA result if it is known.
During General Anaesthesia
An intravenous catheter is commonly placed so that anaesthetic medication, fluids and emergency drugs can be given promptly. After anaesthesia is induced, a breathing tube is usually placed in the windpipe to protect the airway and deliver oxygen and anaesthetic gas.
A trained member of the veterinary team should monitor the dog throughout the procedure. Monitoring may include:
- Heart rate and rhythm
- Breathing rate and ventilation
- Oxygen level
- Carbon dioxide level
- Blood pressure
- Body temperature
- Anaesthetic depth
The team responds to changes by adjusting the anaesthetic, oxygen, fluids, warming and other treatment.
Are Some Breeds at Greater Risk?
Breed alone does not determine whether anaesthesia is safe, but anatomy, genetics and body type can influence the plan.
- Flat-faced breeds may have an increased risk of airway obstruction and require particularly careful airway management and recovery.
- Sighthounds can respond differently to some drugs and are more vulnerable to becoming cold.
- Toy breeds and puppies can develop low body temperature or low blood glucose more quickly.
- Giant breeds require accurate weighing and carefully calculated doses rather than estimates based only on size.
- Dogs with an MDR1 mutation may need dose changes for specific medicines.
Every patient should be weighed accurately before medication is calculated. A thick or long coat can make visual estimates particularly unreliable.
Is a Dog Too Old for Anaesthesia?
Age alone is not a reason to refuse a necessary anaesthetic. Older dogs are more likely to have heart, kidney, liver, hormonal or other disease, so they may require additional assessment and adjustments to the anaesthetic plan.
The vet weighs the likely benefit of the procedure against the individual risk. In some cases treatment is needed to stabilise a medical problem before proceeding. A healthy older dog may be a better anaesthetic candidate than a younger dog with significant illness.
Pain Relief
Pain relief is normally planned before the procedure begins and continued during recovery and at home where necessary. Several methods may be combined, including injectable medicines, local anaesthetic blocks and tablets.
Good pain control improves comfort and can reduce the amount of general anaesthetic required. Tell the practice if the dog has reacted badly to pain medication or has liver, kidney, digestive or bleeding problems.
Never give a human painkiller unless the veterinary surgeon has specifically prescribed it for that dog. Ibuprofen, naproxen and paracetamol can cause serious poisoning when used incorrectly.
Recovery at the Veterinary Practice
Recovery is a critical part of anaesthesia. The dog should be monitored while waking until its airway, breathing, circulation, temperature, comfort and level of alertness are satisfactory.
Do not rush to collect a dog before the veterinary team considers it safe to leave. Some procedures and medical conditions require a longer stay or overnight monitoring.
After Your Dog Comes Home
Mild sleepiness and reduced coordination may occur for several hours. Keep the dog warm, quiet and supervised. Prevent access to stairs, furniture, slippery floors and other places where a drowsy dog could fall.
Follow the discharge instructions about food, water, medication, wound care and exercise. A smaller meal may be recommended because nausea can occur after anaesthesia.
Contact the practice promptly if the dog:
- Has difficulty breathing
- Collapses or cannot stand when expected
- Has very pale, blue or grey gums
- Vomits repeatedly
- Appears to be in significant pain
- Bleeds from the wound
- Becomes increasingly sleepy instead of gradually improving
- Has any other sign specifically mentioned in the discharge advice
