“Pain” is a perception that the brain creates from input called “nociception” (pronounced no-si-sep-tion). This is the physiology term to describe the chemical processes that are at work in the body that receive a stimulus, modify it, and transfer it to the brain for interpretation and reaction. The stimulus can be physical, temperature, chemical or inflammatory damage to tissues. The brain processes this nociceptive input, mixes it with other data, and creates the perception we call pain. Everyone’s pain perception and reaction to it may be different.
Not all pain is bad—pain lets us know that something may be harming our bodies that we need to stop. But “pathologic pain” is a type of pain that is no longer serving this helpful purpose. Most of the pain issues we are likely to encounter with our pets in the medical situation are examples of pathologic pain.
Pain can be caused by many things:
- physical trauma, such as falling down or being hit by something
- internal organ problems, such as intestinal upset or kidney blockage
- surgical procedures, such as abdominal surgery or bone surgery
- brain or spine problems, such as a slipped disc, pinched nerve or headache
- degenerative changes, such as arthritis and joint damage
Common pain behaviors are:
- growling and/or purring (cats)
- not grooming (cats)
- not moving from one spot (cats)
- squinting (cats)
- crying and/or whining (dogs)
- glassy-eyed, vacant look (dogs)
- hunched up body (cats and dogs)
- restlessness and changing positions a lot (dogs)
- shaking and trembling (dogs)
- hiding (cats and dogs)
- irritable or aggressive (cats and dogs)
- no appetite (cats and dogs)
- protecting the hurting body part (cats and dogs)
During and right after a painful injury or other illness, the body responds in several ways; the heart and breathing rate go up, muscles tense, endorphins (natural pain killers) are released internally. But after awhile, other stress hormones are released as the pain continues. This is when the down side of pain starts to outweigh the earlier benefits. The bad effects of pain include:
- no eating or drinking
- poor intestinal function, poor nutrient uptake
- increased risk of infection or delayed wound healing
- poor hygiene and ability to move around
- inability to sleep
- irritable or aggressive behavior, preventing nursing care or therapy
Any one or all of these complications may be present and may risk the recovery of your pet. Sometimes it means your pet does not recover; sometimes it means treatment is more prolonged, intensive, invasive, ineffective or costly. Painful illnesses in a pet’s life may make future illness or injuries more difficult to treat. Your pet may have a bad memory of veterinary care he/she received, and be fearful or aggressive the next time they need treatment.
Not all pain is created equal. Some is short-lived (like an injection), some is manageable w/ accommodation (like limping to relieve a sore ankle), and some is incredibly severe (like a broken back that makes a pet bite their owner when being helped). If pain goes away quickly and is minor enough, the negative impact is slight. As the duration and/or severity of pain rises, all of the negative impacts start to add up, and pets need our help.