Cats: Managing their Pain
David B. Brunson, DVM, MS, DACVA
Small Animal Track
2012 ISVMA Annual Conference Proceedings
Cats have been described as one of the most difficult species to assess both their level of pain
and the effectiveness of pain management. Pain evaluation and approaches to preventing and
treating pain are challenging.
Recent improvement in our understanding of how cats express pain coupled with safe and
effective analgesics have changed feline clinical pain management. Dogs and cats are different,
cats rarely vocalize when in pain. The lack of vocalizations to painful situations has been
misinterpreted to indicate that cats do not require analgesics as much as dogs. Pain
management is an important component of anesthesia for cats. Opioids, alpha-2 agonists, local
anesthetics and selective NSAIDs can minimize the severity of pain in cats.
Moaning, cries or whimpering are rarely observed from cats. They frequently suffer in silence,
crouched in the back of cages or hiding under cage papers. Many people believe that cats are
aloof and distant, uncooperative and combative, or overly reactive to minor injury or restraint.
This view may prevent us from detecting pain. Research on the attitudes of veterinarians
reflects this view. Cats receive: analgesics less often than dogs. Australian and Canadian
studies also confirm these biases. Although vocalization is not a reliable indicator, pain can be
detected by knowing what to look for. Several useful pain assessment tools have been
developed and should be incorporated into routine medical evaluations of cats
SIGNS OF PAIN
Traditionally, pain is recognized when animals vocalize or show aggressive responses to
handling of the injured area, Even though we now know that many cats do not vocalize, a 1996
survey of over 5000 veterinarians responded that vocalizations was the most commonly
reported sign of pain. In order to identify cats in pain it is important to look for behavioral
changes. Cats manifest depression by hiding, withdrawal and being less attentive to the
surrounding environment. Changes such as lameness, salivation, mydriasis, tachycardia and
tachypnea are also indicators of feline pain. Additional signs of pain included decreased
grooming, laying or sitting with limbs contracted and anorexia. A good approach is to use the
owners to detect abnormal behavior. They are often more aware of changes in behavior and
should be counseled in monitoring their cat's recovery.
Pain is recognized to be a cause of stress to cats and unrelenting pain can cause severe
disruptions in normal physiology. During severe stress, continued release of catecholamines will
result in protein catabolism, hypertension, cardiac arrhythmias, maldigestion and malabsorption.
Uncontrolled pain also results in the release of vasopression which can lead to abnormal renal
function and electrolyte shifts. As a part of the stress response, cortisone will be released from
the adrenal gland. Unless pain is alleviated, continued stimulation will result in protein
catabolism and immune suppression. Ultimately, adrenal exhaustion can occur resulting in an
inability to counterbalance stress. The result is increased morbidity and mortality.
Cats have been compared to human infants that lack the ability to verbally describe the quantity
and quality of the pain they experience. Pain evaluation of human infants is often performed by
assessing facial expressions and body position. Classical indication of pain in human infants is
performed by evaluating eye position and degree of opening of the eyes. Additionally, the angle
of the eyes and the shape of the face between and above the eyes provide indications of stress
and pain of both human infants and cats.
Assessing Pain - TWO ASPECTS OF PAIN
There are 2 major components to pain which must be separately evaluated. These are the
QUANTITY and the EFFECT of pain.
Preemptive pain management techniques are chosen by estimating the quantity of pain that will
likely be associated with the physical injury to tissues innervated with sensory (A-delta and C)
fibers. The magnitude of the pain is dependent upon the site of injury (periosteum, cornea, skin,
intestinal colic, or thoracotomy) and the extent of injury (surface area, number of bones, multiple
sites, etc.). Experience and research on the sensory innervation to tissue are the basis for the
“best guess” of the expected pain. The greater the quantity of pain expected the stronger the
pain management technique chosen for the patient.
Once the cat is painful the therapy is not based on the best guess of the amount of pain but on
the animal’s signs of pain. In other words this is where the pain management is selected by
looking at the animal’s reaction to the medical problem. Alleviation of pain improves patient
health. It is the aversive component of pain that we ethically must treat. Multiple factors must be
evaluated in order to determine how aversive (negative) the pain is to the animal. Cats should
be evaluated in the following areas for signs of pain.
Attitude - Evaluation of the response to its environment is a strong indicator of the effect pain.
Activity Level- Evaluation of spontaneous activity level can provide insights into the degree of
pain.
Appetite level - Food and water consumption can be used to measure the extent of dysfunction
associated with painful conditions. (Knowledge of the amounts of food and water which the
animal routinely consumes enables accurate evaluations).
Focal and/or regional pain level – can be assessed by the response to manipulation or
touching of the affected areas.
Physiological changes - Elevation of heartrate, blood pressure and alterations in ventilation
are frequently good indications of pain.
PAIN THERAPIES
Pain is easier to prevent than it is to alleviate, thus whenever possible use preemptive
approaches to pain management. The presence of pain changes the pain perception pathway.
Two mechanisms have been identified for this observation. Damaged cells release mediators
that change fine nerve endings into pain receptors. Subsequent stimulation to the area results
in a more vigorous and faster pain response. This is called hyperalgesia or wind-up. The second
change occurs at the spinal neurons. Dorsal spinal horn neurons become hypersensitized to
subsequent impulses resulting in an increased magnitude of stimuli to the central nervous
system. This is why preventing pain is more effective that treatment.
With the exception of local anesthetics, all of the anesthetic and analgesic drugs reduce the
aversive (reactions) to pain rather than blocking the perception of pain. The important goal of
the medical treatment of pain is oriented toward reducing the negative effects of pain.
Combinations of analgesic approaches are often advocated to both prevent and treat pain.
Local and general anesthetics plus systemic analgesics provide both approaches. Antiinflammatory drugs coupled with analgesics work at pain pathways in different locations and
result in better comfort for the animal. Techniques which rely on a single drug to provide the
right balance of effects invariably are inadequate in at least one of these areas.
Coccygeal-sacral block for urethral obstruction and castration
In 2011 a paper was published describing the use of a sacralcoccygeal local anesthetic block to
facilitate treatment of urethral obstruction in the cat. This is the same local/regional anesthetic
technique that had been taught for peritoneal surgery of cattle and horses. The authors indicate
that the use of this local anesthetic technique provided pain relief for the male cat during
recovery and seemed to aid in the removal of the urethral calculi.
The Sacralcoccygeal space is identified where the tail attaches to the sacrum. A 25G 1 inch
long needle is used to penetrate the skin on the midline. Ideally the needle is advanced and
penetrates the interarcuate ligament/ligamentum flavum. If no blood is aspirated, infuse 0.1–0.2
mL/kg of 2% lidocaine without epinephrine (average volume 0.5 mL/cat) into the epidural space.
(O’Hearn Wright J Vet Emerg Crit Care) doi: 10.1111/j.1476-4431)
SUMMARY
Improvement in the understanding of pain has resulted in efforts to prevent surgical pain rather
than treating pain. Preemptive analgesia has been demonstrated to be more effective. Clients
expect their cats will receive full medical care including the treatment of pain. As a society we
have been taught that pain should be minimized. For these reason, we as veterinarians need to
recognize the importance that our clients place on pain alleviation and the role of preemptive
analgesia on the recovery of our patients. The use of opioids is an important tool in decreasing
pain associated with declaws and ovariohysterectomy surgeries. Combined with local
anesthetics and anti-inflammatory drugs, this combination can effectively manage cat pain.
Drug
Amantidine
Atipamezole
Bupivicaine
Buprenorphine
BuprenorphineS
R
Butorphanol
Carprofen
Codeine
Fentanyl
Fentanyl
Transdermal
Patches
Gabapentin
Hydromorphone
Ketamine
premed
as induction
gent
Dose
NOTES and/or Major Side Effects
3-5 mg/kg
anticancer drug for chronic pain
ug dosing
approved for
rapid rough recovery
5:1 to
dogs only
following IV
agonist
1.0ml/4.5kg for Epidural
1.0mg/kg for Intraplural
takes 20-30minutes
(Chest tube)
for
1.0mg/kg maximum for local
full effect
block
5-40mcg/kg
difficult to reverse due to high receptor
affinity
Duration
24 hours
longer
than
agonist
3-8 hrs
3-8 hrs
Route
PO
IM
3-5 hrs
SQ
6-8 hrs
IM,IV, buccal
3 day
???
0.2-0.5mg/kg provides mild
blocks/reverses mu
analgesia
opioids
1.0-4.4
not to be used with corticosteroids
mg/kg
0.1-1.0
DO NOT USE w/acetaminophen for
mg/kg -->
feline patients
felines
3used as intra or post-op CRI for
25mcg/kg/hr analgesia
2.0used as premed immediately prior to
5.0mcg/kg
induction
<10kgs --> 25mcg patch 21-30kg --> 75mcg patch
action onset time
11-20kg --> 50mcg patch
31-50kg --> 100mcg
patch
can not be used w/agonist/antagonists
heat may
increase administration rate
2-10 mg/kg
Neuropathic pain, spinal pain and
windup
0.05tachycardia
0.1mg/kg --> similar to Morphine but usually ↓
felines
vomiting
5-11 mg/kg - stings when administered IM ataxic
-> felines
recovery
2.0-6.0mg/kg used in equal volume of
benzodiazepine
0.5mg/kg loading dose then 2-10 mcg/kg/minute
dysphoria, CNS ↓
1-2 hrs
SQ,IM,IV,PO
12-24 hrs
SQ,IM,IV,PO
4-8 hrs
PO
20-30 min
IV, CRI
20 min
IV
Max volume 1ml/4.5kg for Epidural use
1.0mg/kg for Intraplural (Chest tube) use
4.0mg/kg maximum for local block techniques
4-8 hrs
1-2 hrs
1-2 hrs
Epidural
Intraplural
12-24hrs
Trans-dermal
72 hrs
12-24 hrs
PO
3-4 hrs
SQ, IM, IV
1-2 hrs
SQ, IM
IV, IM
IV, CRI
as CRI
Lidocaine
Epidural
Intra-plural
SQ
1-2mg/kg loading dose THEN 25-50mcg/kg/min CRI
Dexmedetomidi
ne
Meloxicam
Morphine
Naloxone
Oxymorphone
Prenisilone
Robinacoxib
Tiletamine
/zolazepam
Tramadol
cat 40 ug/kg
IM
“Kitty Magic”
bradycardia/vasoconstriction reversible
.1mls K/.1 mls Torb/.1mls Dexd per 10
lbs
recovery rescue doses 1-2 ug/kg/hr
*microdosin
g*
0.1-0.2mg/kg not to be used with corticosteroids
0.2mg/kg --> long lasting sedation, excitation due to
felines
Mu
vomiting, tachypnea, emesis
0.1mg/kg
Must be preservative free for epidural
epidural
use
0.04mg/kg
opioid reversal antagonist
0.05-0.1
mg/kg
1 mg/kg
2.0 mg/kg
Not to be used with corticosteroids
2.0-5.0
excellent for fractious patients
mg/kg
5-10 mg/kg
more effective with Rimadyl (NSAIDs)
60
minutes
1-3 hrs
IV CRI
1.5-2.5 hrs
SQ, IM, IV,
PO
SQ, IM, IV
20-40
minutes
24 hrs
8-12 hrs
IM
IM
IM
8-12 hrs
Epidural
0.5-1 hrs
3-4 hrs
SQ, IM, IV
SQ, IM, IV
24 hours
4-8 hours
PO
IM
SQ, IM, IV
8-12 hours
PO