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Old Dog Resources
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BEHAVIOR PROBLEMS IN GERIATRIC DOGS
by 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 O
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.
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EFFECTS/CHANGES DUE TO AGING
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METABOLIC EFFECTS OF AGING
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BEHAVIORAL IMPLICATIONS |
Decreased metabolic rate - increased obesity
Thermoregulation capacity reduced
Decreased immune competence
Increase in autoimmune diseases
Less sensitive to thirst - tissue dehydration
Decreased ability to metabolize, or excrete drugs
Increase in metabolic disorders affecting nervous system-hypothyroid, hypoglycemia (insulinoma),
hepatic disorders, hyperlipidemia (Schnauzers)
Decrease REM sleep, intermittent sleep
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Decreased activity; obesity may affect locomotion, elimination, and other systems
May affect any organ system
Decreased tolerance of temperature changes, seeks warmth, avoids cold
Constipation - stool housesoiling
Caution with all forms of drug therapy!
Pacing - seizures - restlessness - decreased mental alertness - geriatric onset behavior changes -
Increased waking, appearance of restlessness |
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GASTROINTESTINAL |
Increase in dental disease - can increase incidence of disease of other internal organs
Decreased nutrient absorption
Decreased colonic motility
Liver function decreases
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Pain - Increased irritability - Aggression?
Nutritional effects on behavior? - Changes in stool consistency leading to housesoiling?
Hepatic encephalopathy & associated behavior
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RESPIRATORY |
Decreased respiratory capacity, reduced efficiency
Decreased oxygen at the cellular level |
Hypoxemia: Nocturnal confusion?, signs of senility? Decreased ability to do work |
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URINARY |
Decreased renal function-decreased blood flow
Anemia due to erythropoietin decrease and uremia- hypertension -
Prostatic hypertrophy
Incontinence due to urethral incompetence, urinary tract infections and conditions leading to polyuria /polydypsia
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Polyuria - decreased control. Housesoiling
Behavior changes associated with uremia
CNS hypoxia? - confusion - restlessness
Pollakiuria/incontinence
Housesoiling due to decreased control or incontinence
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ENDOCRINE |
Decreased hormone production by thyroid, testis, ovary, and pituitary - may also be overproduction due to functional tumors (see below)
Testicular tumors (60% of older dogs):
Sertoli cell-estrogen increase/androgen decrease
Interstitial cell tumors - increased androgens
Prostatic hypertrophy
Dysregulation of hypothalamic-pituitary-adrenal axis
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Decreased activity level - increased irritability or aggression - Decreased tolerance to cold
Medical/behavioral effects of increased estrogens
Medical/behavioral effects of testosterone increase
Pollakiuria/Incontinence
Polyuria/ polydypsia/ panting/polyphagia/ increased restlessness / housesoiling?
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MUSCULOSKELETAL |
Loss of bone and muscle mass
Neuromuscular function deteriorates
Cartilage degenerates/arthritis |
Weakness - decreased mobility - housesoiling?
Decreased mobility/activity - Incontinence - Housesoiling?
Increased pain/irritability
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CARDIOVASCULAR AND HEMATOLOGIC |
Heart disease in 33% of dogs over 13 years old
Tissue and cellular anoxia leading to dysfunction or deterioration of other organs
Propensity toward anemia
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Decreased exercise tolerance
Brain hypoxia leading to signs of senility?
Brain hypoxia - signs of senility? |
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NERVOUS SYSTEM |
Increasing hypoxia due to anemia, cardiovascular disease, respiratory deterioration
Tumor formation - primary or secondary
Neurotransmitter changes:
Increase in MAOB - decrease in dopamine
Decrease in cholinergic system, decrease serotonin
Cell numbers decrease: Neurons of the locus ceruleus and substantia nigra most affected
Thickening of meninges
Amyloidosis - Lipofuscinosis - gliosis - meningial fibrosis - Alzheimer like pathology
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Senility?, Cognitive decline? Effects on memory and previous learning
Cerebral: Abnormal sleep, change in eating, loss of housetraining, aggression, docility, visual
deficits, circling, weakness
Cerebellar: ataxia, tremor, head tilt, circling
Brain stem: state of consciousness, cranial nerve deficits
Cognitive dysfunction, tremors?, pituitary dependent Cushing’s syndrome?
Depression, sleep, and neuromuscular disorders
Reduced reaction to stimuli
Irritable when disturbed, slow to obey commands, problems with orientation and learned behavior
Cognitive decline? Senility? - Urinary incontinence, disorientation - alteration of sleep-wake cycles -
geriatric onset behavioral problems
Decreased performance in recognition/memory
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SPECIAL SENSES |
Decreased sight, smell, hearing
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Hypersensitive to stimuli with less affected senses (e.g. sensitive to noise if blind) -
Less responsive and alert to stimuli with affected senses
Increased irritability? - Increased fear ? Changes in sleep-wake cycle - aggression - decreased appetite
Increased vocalization |
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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. might also be helpful
since it has been used with reported success in
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®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.
MEDICATION:
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
Mode of action: MAOB inhibitor
Comments:
- Avoid concurrent treatment with other MAOIs (e.g.. amitraz) , selective serotonin reuptake inhibitors (e.g..
fluoxetine), tricyclic antidepressants (e.g. amitriptyline, clomipramine) and ephedrine.
Buspirone:(non-sedative anxiolytic)
Uses:
a.Feline urine marking
b.Antianxiety
c.Aggression
Comments:- Wide margin of safety
Benzodiazepines
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:
Alprazolam:
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
Clomipramine
CLOMICALM #8482; (Novartis)
Doxepin
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
Permission to reprint from Dr. Wayne Hunthausen
Westwood Animal Hospital
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