BEHAVIOR PROBLEMS IN GERIATRIC DOGS
Wayne Hunthausen, DVM

Pet owners are able to take advantage of better preventive care, medical care and premium nutrition.  The result is increased longevity and a larger population of elderly dogs.  For owners, the bond with their pets grows stronger and more special the longer it lasts.  This increases the importance of the geriatric pet’s health, quality of life and behavior.  We need to help owners anticipate behavior changes associated with old age and provide help as problems arise.  To accomplish this, good communication with our clients is very important.  Although many owners recognize problems associated with old age in their dogs, most do not bring them to the attention of the family veterinarian.  By asking pertinent questions during geriatric health exams and providing the necessary assistance, veterinarians can help preserve and strengthen the bond between the owner and pet.

Aging and Lifespan

We are learning more and more about the aging process in humans and animals.  While the ultimate answers remain elusive, there are many theories.  According to cumulative damage theories ionizing irradiation of genetic material or free radical damage to subcellular organelles underlies the aging process.1  Theories concentrating on waste product accumulation suggest that substances such as lipofuscin and advanced glycosylation compounds influence the aging process.1  The effects of immunologic events have also been suspected.  It has been suggested that acquired cellular changes might result in antigenic stimuli and prolonged antigen-antibody reactions, or that decreased immune surveillance and the emergence of forbidden clones promote the aging process.1

We know that longevity is in part determined by genetic influences.  Studies on human monozygotic twins support genetic influence in determining lifespan.1  It’s well known that small breeds of dogs outlive their larger counterparts.  Environmental influences also play a roll.  Medical care, nutrition, housing and stress are other important factors influencing longevity.  Physical insults such as trauma, infection and toxins can all have a deleterious effect on lifespan. 

Physical and Physiological Changes in the Older Dog

Older dogs have decreased total body water, decreased cell mass, an increase in body fat and a tendency towards obesity.  They have decreased capacity to compensate for changes in acid-base balance and hydration .  Renal function decreases along with a decease in the weight, number of nephrons, perfusion and concentrating ability of the kidneys.  Cell-mediated and humoral immunity systems are less effective.  A decline in respiratory and cardiac efficiency along with decreased cerebral blood vessel elasticity takes place.2  It’s possible that these changes may have a deleterious effect on cerebral O2 levels.  In the oral cavity, gum recession, loss of alveolar bone and loss of teeth occur.  Geriatric dogs have a decrease in gray and white matter volume in the central nervous system.3  This is accompanied by a deterioration of special senses, thickening of meninges and changes at the organelle and biochemical levels.  Extremes in heat or cold are tolerated less well.

Changes in the senses are obvious in most geriatric dogs.  Degeneration of peripheral acoustic structures such as cochlear ossicles, hair cells, ganglia and blood vessels, results in a decrease of high frequency hearing, as well as a general loss in hearing.4  The retina loses rods and cones and the and the lens tends to lose elasticity and clarity, resulting in loss of eyesight.2 Taste discrimination decreases along with the degeneration of taste papillae.1,25  The sense of smell lasts longest in dogs. 

Older dogs are less active, show less interest in the environment and have diminished interest in food.  They also have decreased alertness, exhibit less social interaction, are slower to obey, and learn more slowly.2  These changes likely reflect failing senses, decreased function and efficiency of the central nervous system, as well as decreased physical health and well being.

Behavior Problems of the Geriatric Dog

Geriatric dogs exhibit many of the same behavior problems that we see in younger dogs.  The major difference is that the senior age group has an increased incidence of cognitive and anxiety related disorders.  Older dogs are more likely to have problems with thunderstorm phobias, separation anxiety, generalized anxiety disorders, panic attacks and cognitive dysfunction.  It is likely that a number of the common behavior problems seen in older dogs result from degenerative, geriatric changes.5

Behavior problems may be primary problems or may occur as signs of underlying medical problems.  Older pets have a relatively high frequency of medical problems and this makes the medical workup for a geriatric dog very important.  This should include a thorough physical exam, neurological evaluation, serum chemistries, CBC, thyroid evaluation and urinalysis.  Once medical problems have been taken into consideration and ruled out or corrected, attention may be given to treating the behavior problems.  Therapy for many of the behavior problems exhibited by geriatric pets is basically the same as treatment of similar problems occurring in younger dogs.  But there are some special considerations when working with geriatric patients.  Learning and behavior modification may be slowed due to degenerative CNS changes.  Pharmacologic choices may be narrowed due to underlying organic disease.  There may also be some physical constraints on what the pet can be taught to do depending on its general state health.

Cognitive Dysfunction

Some dogs exhibit rather severe signs of mental deterioration as they grow older.  These may include problems with recognizing familiar places or people, spatial disorientation and confusion.  Loss of learned behaviors is common, a common sign of which is housesoiling.  There may be problems with the sleep-wake cycle, inappropriate or excessive vocalization, and nonproductive, repetitive behaviors such as licking, circling or pacing.  Signs of apathy, irritability, decreased awareness of the environment, and a reduction in social interaction with family members are common.  In the absence of other disease processes, these changes are representative of cognitive dysfunction.  This syndrome involves the loss of intellectual and integrative functions of the brain.19,23  In humans, severe cognitive dysfunction or dementia can result from cerebral hypoxia due to vascular disease or neurodegenerative lesions such as with Alzheimer’s disease.20  In dogs, hypothyroidism, chronic epilepsy, encephalitis, tumors and other structural diseases have been suggested to cause these types of severe behavior changes.3  Dogs with cognitive dysfunction appear to have underlying pathological CNS changes including amyloidosis, meningeal fibrosis and accumulation of ubiquitin-protein conjugates.21  These are some of the same changes seen in Alzheimer’s patients.21  Physiologically, these changes are thought to be associated with decreases in activity of the cholinergic or dopaminergic neurotransmitter system and increases in levels of monoamine oxidase.3

As the pet gets older, preventive measures such as providing a consistent, moderate amount of mental stimulation and exercise may help.  Owners should review obedience commands and tricks with the pet as well as frequently engaging it in simple games of fetch, “find the biscuit,” round robin, etc.  Treatment for cognitive dysfunction has traditionally been palliative involving changes in management, controlling the pet’s environment and nursing care.  Anipryl® a (selegiline hydrochloride) is a selective monoamine oxidase-B inhibitor which shows great promise in alleviating signs of cognitive dysfunction in elderly dogs.22  While the exact mode of action of Anipryl® has not been demonstrated, suggested modalities include enhanced dopaminergic cell function, decreased dopamine catabolism by monoamine oxidase B inhibition, and reduction as well as increased removal of toxic free radical production. It also appears to be neuroprotective with apparent positive effects in decreasing programmed cell death of injured neurons and promotion of resynthesis of nerve growth factors.26

Miscellaneous Anxiety Disorders

There are some senior dogs that begin showing anxiety disorders of unknown origin.  They may manifest signs of generalized anxiety or have actual panic attacks.  Dogs with generalized anxiety problems may exhibit persistent, anxious vocalizing, trembling and hiding.  They frequently seek the owner’s attention, act nervous and are easily startled.  A variety of medical problems can contribute to this type of behavior, so a good medical work up is very important.  With time the behaviors may also develop a conditioned component, since attention from the owner may serve as a reinforcement.  Although the pathophysiology of these disorders is poorly understood at this time, there may be physiologic problems in the brain involving changes in neurotransmitter activity and receptor sensitivity.

A more intense manifestation of anxiety disorder in the older pet occurs in the form of panic attacks.  Dogs with this condition may have acute episodes of intense anxiety involving severe panting, shaking and trembling.  Rapid heart rate, respiratory rate and mydriasis are typically seen.  The pet may suddenly run through the home in a frantic manner or seek a hiding area.  The episodes usually occur in the evening or during the night.  Psychomotor seizures may be an explanation for this behavior, or it may be an intense form of generalized anxiety disorder.

Treatment involves counseling the owner to avoid reinforcing the behaviors, increased physical and mental stimulation and medication.  I have used benzodiazepines such as alprazolam and clorazepate successfully.  Anipryl® might also be helpful since it has been used with reported success in Europe for anxiety problems such as separation anxiety.  Phenobarbital may help the pet with panic attacks if the underlying problem is a seizure disorder.

Housesoiling Problems

The geriatric pet usually requires more frequent access to the outdoors.  This may result from a decrease in bladder capacity due to obesity, reduced elasticity or prostatic enlargement.  Medical problems seen in older pets that cause polyuria will increase the need to void more frequently.  The frequency of defecation may increase when the overweight pet is changed to a diet that is high in fiber.  If the owners are unable to change their schedule to accommodate the pet’s needs, a doggie door or paper training may be necessary.

Any problem that makes it difficult for the pet to get outdoors, such as weakness, muscular atrophy and arthritis, can lead to housesoiling.  If it’s painful for the pet to get up or down stairs to eliminate, it may choose to avoid the discomfort and eliminate indoors.  Medication to control pain, carpet runners on stairs for traction and control of obesity should help.  Intolerance to adverse weather may also cause the pet to choose to eliminate indoors.  This may be seen in hypothyroid patients during cold weather.

Treatment for housesoiling involves accompanying the pet outdoors as often as possible so that elimination in a desired location may be reinforced, consistent supervision/confinement, and a regular feeding schedule.7  Punishment should be avoided since it will likely make the problem worse or create other problems, such as social avoidance or fear aggression.  However, it must be discussed with owners since harsh or delayed punishment is often used in an attempt to correct housesoiling.8  A sharp noise given during the act to interrupt the behavior is the only interactive correction that is acceptable.

Social Problems with Other Dogs in the Home

There are two types of social problems that might occur as the dog ages.  The first occurs with the addition of a puppy to the home, and  the second involves hierarchy problems with other adult dogs in the home.

Young puppies are full of energy and engage in assertive play involving chasing, attacking and biting.  If the older dog is strong enough and has had adequate intracanine socialization, it will usually control the exuberant pup with threats and inhibited bites.  If the pet is weak, passive or fearful it may withdraw and hide.  Some dogs will become exceptionally anxious about having an active, young pup in the home.  This may lead to housesoiling, excessive vocalizing, destructive problems and anorexia.  If an older dog appears to be overwhelmed by a young puppy, the two should be separated whenever the owner is not around to supervise.  Before allowing the pup and older dog to interact, the owner should provide enough exercise or play to fatigue the puppy.  This will help ensure desirable interactions.  All gentle play should be rewarded.  The noise of a squeak toy may help distract the pup from engaging in play attacks.  A long lead on the pup can be used for control and to apply a light correction.  Attaching a head halter, such as the Gentle Leader® b will give the owner even more control.  Occasionally, a timely squirt from a water gun or a toy tossed near the puppy will prevent or stop rough play.

Problems between adult dogs can occur between dogs who have lived together for years when the older, dominant dog becomes weaker and less assertive.  The older dog may be challenged by a younger, confident dog in competitive or social situations.  Problem situations may include soliciting attention from the owner, greeting visitors, exhibiting territorial displays, and guarding food or toys.  The owners may make the situation worse by trying to protect and maintain the older pet’s dominant position.  Theoretically, the owner might consider supporting a dominant roll for the younger pet by allowing it to have what it wants such as receiving treats and attention first from the owner, giving  it access to desired sleeping areas, etc.  But, in reality, it is very difficult for most owners to force the older dog to defer to a younger pet who has been a member of the family for a shorter period of time.  A better solution is for the owners to reaffirm the family’s dominant roll in respect to both dogs.  Obedience commands should be taught or reviewed. Both dogs should then be taught that the owners have complete control over anything that the pets desire.  The owner can do this by requiring a response to a command before either pet receives anything (food, treats, play, a walk outdoors, and, especially, social attention).  Whenever the dogs start to approach the owner, a guest, doorway, food bowl, etc., they should both be commanded to stay and, then, released, one at a time.  The order in which the pets are released or receive attention, should vary each time.  Establishing a strong dominant roll for the owners tends to reduce aggressive tension between the pets.  In some cases, muzzles or head halters may be necessary for control and safety.

Aggressive Behavior

Pain can lower the threshold for aggressive behavior, so all pets with aggression problems should be carefully screened for signs of pain.  Look for signs of arthritis, dental disease and otitis.  Sensory deficits can also contribute to aggressive behavior.  Fearful pets usually learn to avoid  interactions that make them nervous by simply moving away from people that approach.  When the pet loses its hearing or sight, it is more likely to be startled and display defensive or fearful aggression.  Avoidance is usually the best way to handle this type of problem.  Visitors should always be advised about approaching the pet with sensory deficits.  In some cases it may be prudent to simply confine the pet to a safe, quiet area when visitors are in the home. 

Although, cerebral vascular disorders are frequently blamed for apparent sudden onset of aggression, they are quite rare in the dog.  A good medical and behavioral workup will usually uncover more common etiologies such as pain-elicited aggression, fear aggression or dominance aggression.  The importance of ruling out and treating painful problems cannot be stressed enough.  Failure to treat these will likely prevent successful resolution of the aggression problem.  The treatment for fear aggression involves desensitization and counterconditioning.9,10,11  The owners of dominant dogs need to establish a dominant role for themselves in respect to their pet.  This involves obedience training, control of resources, counterconditioning and desensitization exercises.12,13,14

Environmental and Social Stress

The elderly pet has a more difficult time dealing with stress.  Stressful situation have the potential for triggering anorexia, destructive behaviors, excessive vocalization, housesoiling, displacement behaviors and stereotypical behavior.  Changes in the owner’s schedule or in the amount of time the owner spends with the pet can be very unsettling.  In Chapman and Voith’s study of older dogs referred for behavior problems,6 separation anxiety was the most common cause of destructive behavior and excessive vocalization.  The majority of dogs over ten years of age that I have seen for destructive behavior have had separation anxiety as the underlying etiology.  Treatment for separation anxiety has been described15,16,17 and involves changing the way the owner interacts with the pet so that it is not always getting attention on demand, gradually accustoming the pet to absences by the owner and, in some cases,  prescribing anxiolytic medication such as tricyclic antidepressants, benzodiazepines and selegiline.  It is helpful to reward play with toys when the owner is present and to provide food-laced toys at departure.18  Taste-aversive sprays can be used on objects around the house to teach the pet to avoid them.

Long trips and boarding should probably be limited or carefully thought out.  If major changes in the pet’s life are anticipated, some care should be taken to gradually introduce the pet to these.  If sudden, major changes are unavoidable and the pet responds very anxiously, anxiolytic medication may be helpful.

DRUG DOSES:

Anipryl® (selegiline hydrochloride):

 Uses:

            a.  Canine cognitive dysfunction

            b.  Sleep disorders

            c.  Neurodegenerative disorders

            d.  Geriatric housesoiling problems related to cognitive dysfunction

            e.  Pituitary dependent Cushing’s disease

            f.   Separation anxiety

DOGS:      0.5 – 1.0 mg/kg q 24 hrs

Mode of action: MAOB inhibitor

Comments:

-Avoid concurrent treatment with other MAOIs (eg. amitraz) , selective serotonin reuptake inhibitors (eg. fluoxetine), tricyclic antidepressants (e.g. amitriptyline, clomipramine) and ephedrine.

Buspirone: (non-sedative anxiolytic)

Uses: a.  Feline urine marking

           b.  Antianxiety

            c.  Aggression
DOGS: 1-2 mg/kg PO SID-TID

Comments: Wide margin of safety

Benzodiazepines

Uses:   a. Urine marking in cats

             b. Fear induced behavior problems

Mode of Action:  Acts on limbic system and reticular formation

                                 -Potentiates GABA, an inhibitory neurotransmitter

Comments:

-Long term use may produce habituation

-May be withdrawal signs

-May cause hyperphagia, ataxia, depression, and sometimes a paradoxical increase in activity and fear aggression (which may subside after a few days)

-May release inhibitions in fear aggression and disinhibit attack behavior.

-May interfere with learning.

-Contraindicated: Impaired liver function

Clorazepate:

    DOGS: 0.55-2.2 mg/kg PO SID-BID

Alprazolam: 

    DOGS: 0.25-2.0 mg po BID-TID

Tricyclic Antidepressants:

Uses:  a.  Antidepressant - Antianxiety

            b.  Aggressive disorders

            c.  Feline urine spraying

            d.  Stereotypic, obsessive compulsive, acral lick dermatitis

            e.  Separation anxiety

            f.  Narcolepsy

            g.  Enuresis

Mode of action:

 -Mildly sedating

 -Block serotonin reuptake at receptor sites; serotonergic

 -Peripheral and central anticholinergic action

 -Variable degree of antihistaminic activity

Caution:

  -Side effects (anticholinergic) include dry mouth/constipation/urine retention/inappetence/disorientation/depression/ataxia

 -May interfere with thyroid replacement medications

 -Must have normal hepatic and renal function

 -May alter liver enzymes

 -Cardiotoxic:  Possible arrhythmias in cats and dogs.  May cause tachycardia / syncope.

Amitriptyline:

DOGS: 1.0-6.0 mg/kg bid

Clomipramine:

CLOMICALM™   (Novartis)

  DOGS:  2-4 mg/kg PO per day     SID or split BID

Doxepin:

  DOGS: 3-5 mg/kg PO q 12 hr

Summary

Owners should be advised to keep stress to a minimum, offer moderate exercise and provide environmental stimulation for older dogs.  The importance of environmental stimulation certainly should not be overlooked.  Studies have shown that when fat, inactive rats are moved to an enriched environment, they become more active, lose weight and have an increased number of cerebellar synapses compared to control groups.2   Good geriatric programs should include a sound nutrition plan, frequent health exams, appropriate laboratory testing, as well as behavior counseling.  Behavior issues should be brought up by the family veterinarian and discussed during health exams since owners typically don’t bring up geriatric behavior concerns on their own.  They need to know that solutions are available for behavior problems and that they do not necessarily have to live with undesirable behavior just because the pet is old.  Discussion of potential problems and prevention is important.  Topics that may be helpful include adding a new pet to the home, hierarchy problems, cognitive dysfunction and sensory loss.  The geriatric exam may also provide the time to discuss the eventual loss of the pet.   As primary caregivers, we need to help ensure the physical as well as the mental well being of our older patients and attend to the bond between the pet and the owner.

a   Anipryl® Pfizer Animal Health, Exton, PA
b   Gentle Leader: Premier Pet Products, 527 Branchway Rd., Richmond, VA, 23236, 800-933-5595,

REFERENCES

1.     Allen TA. Geriatric Internal Medicine. In Proceedings of AAHA/Midwest Small Animal Assoc. Meeting Proceedings, Davenport, Iowa, November 1988

2.     Fogle B.  The Dog’s Mind. Viking Penguin, Inc, NY, 1990

3.      Fenner WR. Neurology of the Geriatric Patient, Vet Clin of No Amer: Small Anim Pract. Vol. 118, No 3, May 1988, p711-724

4.      Sorjonen DC. Neurologic and Otologic Disorders of Geriatric Patients, Vet Clin of No Amer: Small Anim Pract. Vol. 19, No. 1, Jan 1989. p125-135

5.      Houpt KA and Beaver B. Behavioral Problems of Geriatric Dogs and Cats, Veterinary Clinics of North America: Small Animal Practice, Vol. 11, No. 4, Nov 1981

6.     Chapman BL and Voith VL, Behavioral problems in old dogs: 26 cases (1984-1987), JAVMA, Vol 196, No. 6, March 15, 1990

7.      Voith VL and Borchelt Peter, Elimination Behavior and Related Problems in Dogs, Comp Cont Ed, vol 7, no 7, Jul 1985, p 537-544

8.      Voith VL, Treating elimination behavior problems in dogs and cats:  The roll of punishment, Mod Vet Pract, p 951, Dec, 1981

9.      Young MS, Treatment of fear-induced aggression in dogs, Vet Clin North Am (Small Anim Pract) 1982; 12:645-653

10.    Voith VL and Borchelt, PL, Fears and phobias in companion animals, Compend Contin Educ Pract Vet 7(3):209-221, 1985

11.    Voith VL, Fear-induced aggressive behavior, In Hart BJ:  Canine Behavior, Vet Pract Pub Co, 1980

12.    Borchelt PL and Voith VL, Dominance aggression in dogs, Comp on Cont Ed, Vol 8, No 1, Jan 1986, pp.3 6-43

13.    Voith VL and Borchelt PL, Diagnosis and treatment of dominance aggression in dogs, Veterinary Clinics of North America: Small Animal Practice 12(4):655-663, 1982

14.    Landsberg GM, Diagnosing Dominance Aggression, Canadian Vet Journal, Vol 31, Jan 1990, pp. 45-46

15.    Voith VL and Borchelt, PL. Separation anxiety in dogs, Compend Cont Educ Pract Vet 7(1):42-53, 1985

16.    Borchelt PL, Voith VL. Diagnosis and treatment of separation-related behavior problems in dogs, Vet Clin North Am (Small Anim Pract), vol. 12, no. 4, Nov, 1982, pp. 625-636

17.    McCrave EA. Diagnostic criteria for separation anxiety in the dog, Veterinary Clinics of North America: Small Animal Practice 21(2) 1991 Mar:247-55

18.   Hunthausen WL. The causes, treatment, and prevention of canine destructive chewing, Veterinary Medicine, Oct 1991, 1007-1010

19.    Berg L. Aging and Dementia.  In Pearlman AL, Collins RC (eds): Neurologic Pathophysiology. New York, Oxford Univ. Press 1984

20.    Skoog I, Nilsson L, Palmertz B, Andreasson L and Svanborg A.  A population-based study of dementia in 85-year-olds, New England Journal of Medicine, Vol. 328, No. 3, January 1993, pp. 153-158

21.    Ferrer I, Purarola M, Rivera R, Zujar MJ, et.al., Primary central white matter degeneration in old dogs, Acta Neuropathologica Berl., 1993, vol. 86, No. 2, pp. 172-175

22.    Ruehl WW, DePaoli AC and Bruyette DS. L-deprenyl for treatment of behavioral and cognitive problems in dogs: preliminary report of an open label trial, Applied Animal Behavior Science, Vol 39, February 1994, p. 191

23.   Ruehl WR, Bruyette D, DePaoli A, Cotman CW et al. Canine cognitive dysfunction as a model for human age-related cognitive decline, dementia, and Alzheimer’s disease: clinical presentation, cognitive, testing, pathology and response to l-deprenyl therapy.  Progress in Brain Research, volume 106, chapter 21, 217-225, 1995

24.    Landsberg GL, Hunthausen WL, Ackerman L.  1997.  Handbook of Canine and Feline Behaviour, Butterworth-Heinemann.  Oxford, England

25.    Markham RW. Hodgkins EM.  Geriatric Nutrition. Vet. Clin. North Am. (Small Anim. Pract.) 19(1):165-185; 1989

26.    Ruehl WW, Hart BL.  Canine cognitive dysfunction.  In: Psychopharmacology of Animal Behavior disorders.  NH Dodman, L Shuster (eds).  Blackwell Science Inc., Boston 1998; pp. 283-304