Just as there are a wide variety of manifestations of pain in humans, so are there for animals. Not all humans feel pain the same way; pain is likely not felt the same way by every animal either.
Some people tolerate dental work very stoically and honestly don’t mind it that much while the same procedure is unadulterated torture for others. Similarly, we have observed that if you cut a toe nail too short on one dog, he might simply pull his paw away while another dog might shriek so loud that an entire block will wonder what animal abuse has just taken place!
Animals do feel pain in similar ways as humans do, but they display it in much more subtle ways. Their emotions and behavior vary depending on the mount of pain they feel, but we must be very alert because they try their very best to hide pain. 
If we could measure pain in similar terms as we measure red blood cells, calcium levels or blood pressure, it would indeed make things much easier in evaluating pet pain! The idea of measuring the amount of pain a person feels by blood tests is rather irrelevant because people can voice their pain and discomfort and we can tell if a pain medication is working or not. But when it comes to pets, it would be such a wonderful tool to have. Unfortunately, this is not possible at this time. We can measure inflammatory factors, but not the pain sensation itself. So we have to play pet detective when it comes to "sniffing out" pet pain and it makes it very important for a pet owner to learn how to recognize pain in their pet.
The first thing to know is that pets, particularly when the pain is chronic (as is the case in old arthritic dogs), do not cry, moan or complain unless the pain becomes pretty unbearable.
With the creation of the IVAPM (International association of Veterinary Pain Management), there has been much progress made in the field of veterinary pain management. We are somewhat out of the stone age when it comes to pain management in pets. Twenty-five years ago, the practice of giving pain medication to a dog or cat after a spay or any major abdominal surgery was not widespread. We thought that dogs are tougher and that they don’t feel post-op pain. Since then, we have discovered that this is not true. We have found out that they do feel pain, that healing is delayed when pain is not controlled properly and that we were just not trained to recognize HOW pets manifest pain, and this particular point still vastly leaves to be desired. What is the use of advancement of pain management in veterinary medicine if pet owners are not aware of their pets’ pain and don’t know to seek help because they don’t think that their pet is in pain when he actually is?
This subject is particularly dear to me when it comes to End of Life patients. How do you know if your old arthritic dog needs pain medication? How do you know if the pain medication is working? How do you know if the dosage or kind of medication used needs to be adjusted?
We will expand on these questions in the next installment of my newsletter. We will list many of the signs of pet pain and discuss them. Stay tuned!
In the meantime, visit our website! It has all the detailed information: www.homepeteuthanasia.com. Also the pet pain page: http://www.homepeteuthanasia.com/end-of-life-care/understanding-pain.