Opioids

What are opioids?

Opioids are substances that bind to special receptors in the brain and spinal cord and thus reduce the sensation of pain. They are among the oldest known painkillers and are extracted from the milky sap of the opium poppy plant or produced synthetically. The best-known opioids include morphine, codeine, fentanyl, buprenorphine and tramadol.

How do opioids work in dogs?

Opioids have a similar effect on dogs as they do on humans. They bind to the opioid receptors in the central nervous system and inhibit the transmission of pain signals. As a result, they reduce the perception of pain and pain behavior in dogs. Opioids also have a calming, anxiolytic and euphoric effect, which can vary depending on the dose and type of opioid.

What side effects do opioids have in dogs?

Opioids also have some side effects in dogs that need to be considered. The most common are:

• Nausea and vomiting
• constipation
• respiratory depression
• sedation
• Changes in heart rate and blood pressure
• itching
• Miosis (constriction of the pupils)
• Hyperthermia (increase in body temperature)

The side effects are usually dose-dependent and can be alleviated by adjusting the dose or by administering other medications. In rare cases, opioids can also lead to hypersensitivity or an allergic reaction.

When are opioids indicated or contraindicated in dogs?

Opioids are primarily indicated in dogs when they are in severe pain that cannot be adequately relieved by other painkillers. This can be the case, for example, with severe injuries, operations, cancer or chronic pain. Opioids are often administered in combination with other painkillers such as non-steroidal anti-inflammatory drugs (NSAIDs) or local anesthetics to achieve better pain control.

Opioids are contraindicated in dogs if they have a known hypersensitivity or allergy to opioid drugs or if they have certain medical conditions that can be worsened by opioids. These include:

• Respiratory conditions such as asthma or pulmonary edema
• Cardiovascular diseases such as heart failure or cardiac arrhythmia
• Liver or kidney dysfunction
• Increased intracranial pressure
• Hypothyroidism (underactive thyroid gland)
• Hypoadrenocorticism (hypofunction of the adrenal cortex)

In addition, opioids should only be used with caution in pregnant or lactating bitches, as they can cross the placental barrier and pass into the mother's milk.

Conclusion

Opioids are effective painkillers for dogs that are indispensable in certain situations. However, they also have some side effects and contraindications that must be taken into account. Therefore, opioids should only be administered under veterinary supervision and the dosage should be adjusted individually.