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Pain Identification and Management in Pets

août 2, 2018

Based on physiological and neurological studies, it has been shown that animals feel pain in very much the same way we do. It is safe to assume if something causes discomfort in you, it will also cause discomfort in your pet. Untreated pain has many damaging system-wide repercussions.

Pain identification in animals is difficult. They cannot easily tell us where it hurts. There are many misconceptions regarding pain in animals. For example, a pet that is not moaning or crying out is not necessarily pain free. Most animals are not vocal about their pain, so subtle behaviour and physical changes must be noted. From a survival point of view, it was to an animal’s advantage to suffer quietly and not draw the attention of predators to themselves when still wild.

There are certain indications or signs that one can look for. An individual pet’s temperament may make these much more or less evident. Some pets, like some people, appear to be quite stoic, with apparent higher thresholds for pain tolerance. Hospitals use pain score systems to classify degree of pain, which helps provide objective assessments.

Certain signs may suggest pain:

• Vocalization (crying out, whimpering, howling, growling, hissing);
• Retreating from the family (to hide and be left alone);
• Appearing uncomfortable, which may manifest in pacing, restlessness, and repeatedly shifting into different positions [arched back, forelegs held out from chest wall, or sitting in a prayer position (posture of relief), poor sleep];
• Looking “anxious” (may be evident in the eyes and facial expression);
• Heavy panting;
• Snapping/biting/scratching if handled, while others may simply grunt;
• Reluctance to move, as if frozen;
• Decreased or lack of appetite;
• Listlessness or lethargy;
• Decreased grooming in cats leading to an unkempt look; 
• Licking or biting at a specific area if there is localized pain. The pet may try to hide injured legs or paws by tucking it underneath. These animals may also limp or not bear any weight on the affected limb;
• Dilated pupils;
• Increased heart and respiratory rate;
• Increased blood pressure and pulse intensity may be noted at the hospital.

Analgesics (i.e., painkillers) are used routinely in veterinary medicine for the comfort of the patient, but also to assist with reduced stress in handling the pet for examination and treatment at the hospital. Studies have shown that patients recover more rapidly from trauma or surgery if pain is alleviated. Chronic pain can be equally debilitating, leading to weight loss and poor thrift (poor overall health), poor immune system function, and even personality changes.

The greatest benefit arises when medication is given before the pain occurs. Providing analgesics prior to a painful event when possible reduces or prevents firing-up of the pain receptors, and allows control of pain using lower doses of medication, with much greater benefit. 

Pet owners should learn to recognize possible signs of pain in their pets. However, painkillers should never be administered without consulting a veterinarian first. Many human painkillers can be toxic to pets, require lower doses for animals than people, and need to be administered with extreme caution under veterinary supervision. See more on this below. Cats are very sensitive to human aspirin-type drugs and some are deadly for cats.

Human medications generally contain much more medicine per tablet than is safe for animals, so it is important that these medications be kept out of reach of pets at home. Bottles should not only be securely closed, but also kept in locked cupboards since pets have been known to chew the lids off of bottles left within their reach, resulting in poisoning.

Prescription medications of the narcotic class may be prescribed at the time of surgeries or painful procedures, including for the recovery phase. Your pet may need these to obtain sufficient comfort in chronic pain situations like cancer. These also must be stored and handled with care due to the potential for human abuse.

Comfort in Old Age or Chronic Illness

Pets, on average, are living longer and healthier lives due to medical and nutritional advances that have occurred in veterinary medicine. However, living longer means more pets are now experiencing more complications related to the aging process. More pets undergo cancer treatment which requires good analgesics to ensure quality of life.

Management Strategies

A common age-related problem is arthritis/osteoarthritis (OA), and degenerative joint disease (DJD) and is of great concern to pet owners because of the ongoing discomfort associated with changes. The good news is that animal-specific medications have been developed to safely deal with chronic pain in both dogs and cats, and nutraceuticals may be enough to support comfort in milder cases. The goal is to try and limit the need for medications by ensuring the joints are not overworked by being forced to carry too much weight (obesity). If the pet is obese, a professionally overseen prescription diet should be undertaken. Limiting heavy exercise may also be necessary. Complete or partial rest is sometimes needed to allow recovery of inflamed tissues, but not so much restriction should be done that muscle mass and tendon/ligament strength declines. Activity should be dialled down to avoid excess discomfort if signs of discomfort occur.

Rehabilitation can be a very important part of management for some conditions. Some localized problems or conditions may respond well to warm and/or cool compresses. Physiotherapy can help relax and soothe the pet, and keep the pet mobile. Examples of rehabilitation therapies include physiotherapy, massage, acupuncture, and hydrotherapy pools. Your veterinarian may need to refer your pet to an expert in this field if they are not comfortable with this area of veterinary medicine. There are certified experts in this field.

Dogs

The pet must be in the optimal weight range for a dog of its body size and conformation—be cautious of taking an out-of-condition or overweight dog on forced runs or playing a long game of fetch prior to consulting your veterinarian. Many dogs are so eager to please their caregiver or so excited in dog park play, they will overdo exercise to their detriment. Bursts of excessive exercise can put an arthritic and out-of-condition dog into a post-exercise pain episode, which may also include muscle cramps. It is best to take it easy and gradually increase the intensity of exercise. Swimming is an ideal exercise since it allows the muscles to get worked without the strain of putting full body weight on the joints.

Cats

Recent studies show that many senior cats are arthritic, which can be seen on X-rays, but frequently do not show any signs due to a stoic attitude and their highly flexible joints and back. Subtle changes like not jumping up on their favoured perch or excessive grooming over sore hips may be seen. Some may express sensitivity when petting over the spine or hips area. As with dogs, keeping a trim body weight will reduce wear and tear on joints.

Natural Aids

If there is ongoing discomfort from OA, a simple assist for comfort is to provide deeply cushioned bedding with step up or ramps for areas where the pet might need aid in navigation.

Nutraceuticals are naturally occurring compounds taken orally to support joint function. Some have been shown to assist in the control of pain and inflammation associated with arthritis. One example is refined wild fish oils; those high in omega-3 fatty acid EPA and DHA, which can act as natural anti-inflammatory compounds.

Nutraceutical preparations employ glucosamine hydrochloride, chondroitin sulphate, avocado soybean unsaponifiable (ASU) extracts, green lipped mussels, MSM, eggshell membrane, glycosylated un-denatured collagen II (UCII), special milk protein concentrate (SMPC), and key minerals and vitamins alone or in combination. Some of these ingredients may make movement less painful and allow for comfortable moderate activity. There have been some recent studies evaluating these compounds in dogs, and this area shows promise for future research. Most evidence is anecdotal for now.

The form of some of these compounds can affect their safety and effectiveness. For example, glucosamine hydrochloride is preferred over the sulphate form. It is preferred to use a combined glucosamine-chondroitin-ASU product rather than one only, and a loading dose (a higher starting dose) is important for best effect.

Some prescription veterinary pet foods contain joint support compounds that may improve quality of life for a pet with OA. Your veterinarian may elect to prescribe these diets.

Your veterinarian is the most trusted source for advice—avoid using online testimonials or a friend’s suggestions, as there are a plethora of options available for purchase, and only a professional can help you sort the “wheat from the chaff”. Not all products are equal. Additionally, these types of products take time to produce effect, so allow about 8 to 12 weeks for the effects to become apparent.

Pharmacologic Treatments

Drug therapy may be used alone or in combination with one or more of the above-mentioned strategies. This method of providing analgesia is called multimodal therapy, and is often more effective than using a single drug to treat pain. It may also reduce cost and side effects.

Non-steroidal anti-inflammatory drugs (NSAIDs)

NSAIDs are pain control products familiar to most people, and they can be found in virtually everyone’s “human medicine” cabinet. Examples include acetylsalicylic acid (ASA or Aspirin™), acetaminophen (Tylenol®), naproxen (Aleve®), and ibuprofen (Motrin®).

ALWAYS get advice regarding the use of ANY human medication from your veterinarian before you administer it to your pet, otherwise your good intentions may lead to pet harm. 

Examples of NSAIDs specifically designed for animals and used to treat acute and or chronic pain include meloxicam (Metacam®), deracoxib (Deramaxx®), carprofen (Rimadyl®), and ketoprofen (Ketofen®). Your veterinarian may use an injectable form of one of these products and may prescribe an oral form for you to administer at home. Two different NSAIDs are not used together, as serious side effects, such as gastrointestinal bleeding, bleeding disorders, or kidney or liver damage will result. If your veterinarian advises that a different NSAID may provide superior analgesia for your pet, they will implement a period of time without any NSAIDs before the switch is made to the different drug.

NSAID use often results in pain symptoms subsiding within hours and these drugs have anti-inflammatory, as well as pain relieving, actions. NSAIDs have many uses in veterinary medicine, including providing analgesia for routine or emergency surgeries, for cases of trauma, and for longer term use for treating pain associated with OA in dogs and cats.

As stated above, NSAID medications may be given in conjunction with nutraceuticals, often reducing the amounts of NSAID needed to produce an effect. NSAIDs will not be given at the same time as steroid medications like dexamethasone, prednisone, or prednisolone.

As for other ”naturopathic” oral remedies, caution should be exercised, as some herbs designed for use in arthritis contain ingredients with NSAID-class action and they may create toxicities when used in conjunction with NSAID drugs. 

Baseline blood work for liver and kidney function will be recommended before starting these drugs, and if NSAIDs are used long-term, periodic testing will be done to ensure the pet is tolerating the NSAID well.

Like any drugs, there are potential side effects and a veterinarian assessment is required before these medications are prescribed. The results can be very good for those pets able to tolerate the NSAID medicines, with many bed-bound pets responding with significantly increased mobility.

Injectable Medications

Sometimes antiinflammatory steroids (triamcinolone, dexamethasone, and betamethasone) are used as direct joint injections (IA) in select cases.

Hyaluronic acid or HA (Legend ®), Polyglycan™ (mix of HA, chondroitin, glucosamine) may be injected directly into an affected joint (intra-articular or IA). 

Cartrophen Vet® is an injectable synthetic pentosan polysulphate. This product is not an analgesic, but instead supports joint fluid production, which may lessen the signs of OA in dogs.

Less Common Treatments

Other approaches include stem cell therapy, interleukin-1 receptor antagonist protein (IRAP-2), and platelet-rich plasma derived from the patient. These are costly options and are not widely available.

Surgery is an uncommon option for joint pain. If there is a damaged cruciate ligament in the back leg knees, or hip dysplasia, surgeries are definitive treatments. Some dogs even get artificial hips. Arthroscopy may be recommended to clear out damaged tissue or bone spurs. Rarely, severe arthritis in a joint may warrant fusing the joint to prevent it grinding bone-to-bone.

Talk to your veterinarian about designing a pain relief protocol that best suits your pet’s needs. Your pet will thank you!

Kathleen Cavanagh, BSc DVM MET
Consulting Online Editor CVMA

Cate Creighton DVM, MSc, DACVAA
Consulting Specialist Editor

June 9, 2018