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ORIGINAL RESEARCH
published: 12 December 2018
doi: 10.3389/fnut.2018.00127
Frontiers in Nutrition | www.frontiersin.org 1December 2018 | Volume 5 | Article 127
Edited by:
Odile Viltart,
INSERM U894 Centre de Psychiatrie
et Neurosciences, France
Reviewed by:
María A. García,
Universidad de Concepción, Chile
Mercedes G. López,
Centro de Investigación y de Estudios
Avanzados (CINVESTAV), Mexico
*Correspondence:
Yuanlong Pan
yuanlong.pan@rd.nestle.com
Specialty section:
This article was submitted to
Neuroenergetics, Nutrition and Brain
Health,
a section of the journal
Frontiers in Nutrition
Received: 15 August 2018
Accepted: 28 November 2018
Published: 12 December 2018
Citation:
Pan Y, Landsberg G, Mougeot I,
Kelly S, Xu H, Bhatnagar S,
Gardner CL and Milgram NW (2018)
Efficacy of a Therapeutic Diet on Dogs
With Signs of Cognitive Dysfunction
Syndrome (CDS): A Prospective
Double Blinded Placebo Controlled
Clinical Study. Front. Nutr. 5:127.
doi: 10.3389/fnut.2018.00127
Efficacy of a Therapeutic Diet on
Dogs With Signs of Cognitive
Dysfunction Syndrome (CDS): A
Prospective Double Blinded Placebo
Controlled Clinical Study
Yuanlong Pan 1
*, Gary Landsberg 2, Isabelle Mougeot 2, Stephanie Kelly 3, Hui Xu 1,
Sandeep Bhatnagar 1, Cari L. Gardner 1and Norton W. Milgram 2
1Nestlé Purina Research, St. Louis, MO, United States, 2CanCog Technologies, Toronto, ON, Canada, 3Vivocore Inc.,
Toronto, ON, Canada
Cognitive dysfunction syndrome (CDS) is a common condition in senior dogs, which
may be analogous to dementia such as Alzheimer’s disease (AD) in people. In humans,
AD has been associated with many risk factors such as reduced cerebral glucose
metabolism, docosahexaenoic acid (DHA) deficiency, chronic oxidative stress, and
chronic inflammation. By targeting some of these risk factors, we have developed two
nutritional solutions (medium chain triglyceride, MCT and Brain Protection Blend, BPB)
to enhance cognitive function and slow aging-induced cognitive decline. These have
been positively evaluated in colony housed senior dogs and cats. The objective of this
clinical study was to evaluate the effects of diets with MCTs and the BPB on client-owned
dogs with CDS. Participating veterinary clinics screened senior dogs for signs of CDS as
determined by a Senior Canine Behavior Questionnaire and a Canine Medical Health
Questionnaire. Eighty-seven dogs were randomly enrolled into one of three diet groups
with 29 dogs per group: Control, 6.5% MCT oil +BPB (6.5% MCT diet), 9% MCT oil
+BPB (9% MCT diet). Diets were fed for a period of 90 days, and each dog’s CDS
signs were re-evaluated at day 30 and day 90. All 6 categories of the CDS signs were
significantly improved (p<0.05) in the dogs given the 6.5% MCT diet at the end of
the 90-day study. Control only improved in 4 out 6 categories. The 9% MCT diet only
improved in dogs that accepted the diet. The results from this dog study confirm the
benefits of MCT and BPB in managing clinical signs of CDS in dogs. The results support
our hypothesis that targeting known risk factors associated with brain aging and AD is
able to improve symptoms of CDS in dogs. These data may facilitate the development
of similar nutrient blends to manage MCI and AD.
Keywords: dog, antioxidants, arginine, B vitamins, BPB, cognitive dysfunction syndrome, medium-chain
triglycerides, omega-3 PUFAs
Pan et al. A Therapeutic Diet for CDS in Dogs
INTRODUCTION
Cognitive dysfunction syndrome (CDS) is a major condition
affecting senior dogs (1,2) that has parallels to human
dementia. Both CDS in dogs and Alzheimer’s disease (AD)
in humans share similar neuropathological changes including
severe cortical atrophy, cerebral amyloid angiopathy and
ventricular enlargement (3–5). Multiple risk factors have been
associated with accelerated brain aging and higher risk of AD,
including DHA deficiency (6), elevated blood homocysteine (7),
low status of vitamin B6, vitamin B12, and folic acid (8), high
blood pressure (9), chronic oxidative stress (10), and chronic
low grade inflammation (11). Since it is impossible to address
the above-mentioned multiple risk factors with single nutrient,
we have selected a blend of nutrients (Brain Protection Blend,
BPB) which included enhanced levels of B vitamins, antioxidants,
omega-3 fatty acids and arginine based on their ability to prevent
or reduce these risk factors. We evaluated the effects of BPB on
cognitive function in healthy middle aged and senior cats, and
senior dogs with established cognitive test protocols including
landmark, egocentric and delayed-none-matching-to-position
tests, and the results confirmed that the BPB was able to enhance
cognitive function and retard aging-induced decline in learning,
memory, and executive function (12,13). A recent study showed
that in human subjects with mild cognitive impairment, dietary
supplementation of B vitamins was able to reduce cognitive
decline only in subjects with high levels of blood omega-3 fatty
acids (14).
Another common change associated with aging is the brain’s
ability to metabolize glucose. Cerebral glucose metabolism is
reduced in healthy old people (15) and healthy old animals
including rodents (16), dogs (17), and monkeys (18). Alexander
et al. (19) reported that cerebral glucose metabolism was
significantly lower in old patients with Alzheimer’s disease (AD)
than in age-matched healthy old subjects, which confirmed
a previous report that cerebral glucose utilization has been
significantly reduced in AD subjects (20). MCT supplementation
or exercise improved memory performance in AD patients by
providing the brain with ketone bodies as an alternative energy
source (21,22). Our study showed that dietary MCT was able
to improve learning, memory and executive function in senior
dogs (23). These data indicate that ketone bodies may play an
important role in supporting brain function by serving as an
energy source in both humans and dogs.
MCT and BPB enhance cognitive function with different
mechanisms of action, therefore we hypothesized that a
combination of MCT and BPB would deliver synergistic
beneficial effects on cognitive function in dogs with CDS. Since
cerebral glucose metabolism is significantly lower in old AD
patients compared to age-matched healthy old subjects (19), we
increased dietary MCT from the 5.5% level to 6.5% or 9% so that
more energy could be available to compensate for the marked
reduction in cerebral glucose metabolism in dogs with CDS.
Dogs with CDS present with clinical signs in a number
of behavioral domains including disorientation, altered social
interactions, sleep/wake disturbances, house soiling, anxiety
and activity, which may be referred to by the acronym
DISHAA (1,2,24–34). Therefore, for this clinical study we
used a questionnaire (35) that incorporated all 6 DISHAA
categories (Supplementary Table 1), including questions from
all previously validated questionnaires to have a complete and
sensitive screening tool for identifying dogs that had levels
ranging from mild to severe (27,36–39).
The objective of this clinical study was to evaluate the effects
of combinations of 6.5% MCT and BPB (6.5% MCT diet) or 9%
MCT and BPB (9% MCT diet) on signs of CDS in senior dogs.
EXPERIMENTAL METHODS
Study Design
The study was a randomized, double-blind, placebo-controlled,
multi-site study carried out at 24 different veterinary clinics
within the province of Ontario. The study protocol was
approved by the CanCog Technologies Institutional Animal Care
Committee (VRI5-15142-CC), and followed the guidelines of the
Ontario Ministry of Agriculture. Each pet owner was required
to sign an informed and written consent form prior to starting
his or her pet on the trial. Eligible dogs were >9 years of age
and exhibited signs associated with CDS. Upon enrollment, dogs
were randomly allocated to one of the following three groups of
29 dogs per group: Control diet, 6.5% MCT diet, and 9% MCT
diet.
At the pre-screening visit on day-8, a physical examination,
blood work and urinalysis were performed in addition to
completion of a Senior Canine Behavior Questionnaire and a
Canine Medical Health Questionnaire (Supplementary Tables 1,
2), to confirm eligibility of the subject. Following group
placement, appropriate food was distributed to pet owners and
feeding of the assigned diet continued for 90 days.
After completion of a mid-study (Day 30) cognitive and
behavioral assessment using the questionnaire, a Day 90 follow
up visit included repeat physical examinations, questionnaire,
blood work and urinalysis.
Dog Recruitment
One hundred dogs >9 years of age were screened for the
study. Of these, 13 were excluded from the study for abnormal
findings, including 1 dog with moderately elevated alanine
aminotransferase (ALT) and serum alkaline phosphatase (SAP)
that was also deaf; 3 dogs with renal disease; 2 dogs with persistent
urinary tract infections; 1 dog with hypercalcemia; 5 dogs with
markedly elevated SAP (1,500–4,000 U/L); and one dog with both
renal disease and moderately elevated ALT. Further diagnostics
were not performed within the study.
Eighty-seven dogs (48 males and 39 females) of various breeds
(52 different breeds) were enrolled with 29 animals assigned to
each treatment group. The ages of dogs ranged from 9 to 16 years.
Dogs were obtained from individual dog owners with signed
consent and were either intact or neutered.
Participating veterinary clinics performed pre-screening visit
procedures on potential dogs which were senior dogs with canine
cognitive dysfunction syndrome as determined by a Senior
Canine Behavior Questionnaire (Supplementary Table 1) and a
Canine Medical Health Questionnaire (Supplementary Table 2).
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Pan et al. A Therapeutic Diet for CDS in Dogs
The Study Coordinator in conjunction with the Principal
Investigator determined if the subject was suitable for enrollment
based on the Owner Informed Consent Form, physical
examination including body weight and body condition score,
blood results for CBC, clinical chemistry, urinalysis, and the
Senior Canine Behavior Questionnaire and the Canine Medical
Health Questionnaire.
For inclusion, dogs had to be 9 years or older, reside in their
current home for at least 24 months, and have a positive CDS
response on at least two of the categories on the Senior Canine
Behavior Questionnaire. Dogs treated with a calming product or
cognitive enhancing product within the previous 4 weeks could
be included if they were maintained on the product for the
duration of the study. Dogs that were on a diet meant to treat
cognitive decline were required to be off the diet for at least 30
days prior to enrollment.
Dogs were excluded if they had medical problems that
may have caused the behavioral signs, including dogs with
marked hearing loss, marked visual deficits, moderate to marked
osteoarthritis, or if medical problems precluded a change in diet.
Group Assignment
Cases that met inclusion criteria for enrollment were assigned
to one of three diet groups according to a random number
generated by randomization schedule. The three diet types were
provided in identical packaging and were pre-labeled as A, B, or
C to ensure double blinding. Twenty-nine dogs were assigned to
each group.
Dogs treated with a calming product or cognitive enhancing
medication for more than 4 weeks prior to study initiation were
spread evenly across groups to the extent possible. Of 10 dogs
that were being treated with these products, three dogs including
one on clomipramine, one on essential fatty acids (withdrew),
and one amitriptyline (withdrew) were assigned to diet A, three
dogs including two on an omega-3 supplement (both withdrew)
and one on an l-theanine, colostrum, valerian supplement were
assigned to Diet B and four dogs, two on gabapentin, and two on
omega-3 supplements were assigned to Diet C.
When multiple dogs from one household were enrolled in
the trial, all dogs in the home were assigned to the same group
in order to avoid cross contamination of the study diets. This
occurred for 2 pairs of dogs in 2 households assigned to diet C,
2 dogs in the same household assigned to diet B, and 4 dogs from
the same household in diet A.
Control and Test Diets
The control diet was an experimental diet for adult dogs
with all the essential nutrients exceeding the minimal nutrient
requirements for canine adult maintenance defined by the
Association of American Feed Control Officials (AAFCO). The
6.5% MCT diet was formulated by replacing 6.5% tallow with
6.5% MCT oil. The 9% MCT diet was formulated by adding 2.5%
more MCT oil to the 6.5% MCT diet by reducing carbohydrate
content by 2.5%. All diets were manufactured by Nestle Purina
PetCare, Inc., (Saint Louis, Missouri, USA), and contained
the same levels of protein, crude fiber and moisture. Dietary
ingredient and chemical composition are provided in Table 1.
TABLE 1 | Ingredients and chemical composition of diets as fed.
Control 6.5% MCT diet 9% MCT diet
Crude Protein (%) 32.9 32.5 32.9
Crude Fat (%) 17.9 18.2 21.0
Moisture (%) 6.6 6.8 6.9
Crude Fiber (%) 1.70 1.57 1.27
Ash (%) 6.5 6.3 6.5
MCT (%)* 0 6.5 9
BPB INGREDIENTS
DHA (%) 0 0.23 0.22
EPA (%) 0 0.30 0.29
Arginine (%) 1.78 1.79 1.93
Thiamine (B1, mg/kg)* 8.16 58.68 56.57
Riboflavin (B2, mg/kg) 5.60 26.5 28.3
Niacin (B3, mg/kg)* 86.99 225.76 220.78
Pantothenic acid (B5, mg/kg) 19.20 77.3 83.2
Pyridoxine (B6, mg/kg) 4.39 17.8 18.5
Folic acid (B9, mg/kg) 1.64 8.39 9.32
Cobalamine(B12, mg/kg) 0.076 0.175 0.156
Vitamin E (IU/kg) 52.6 552.08 490.44
Vitamin C (mg/kg) 9.65 151 143
Selenium (mg/kg) 0.704 0.681 0.806
Calculated ME** (KJ/g) 15.67 15.66 16.26
Main ingredients Chicken, Rice, Corn Gluten Meal, Poultry
By-Product Meal, Dried Egg, Wheat Flour.
Medium Chain Triglyceride, Fish Meal, Soy
Protein Isolate, Tallow Edible w/Vitamin E.
*Based on formulation values. All other nutrients were the analytical values immediate after
production. **Calculated based on the predictive equation for metabolizable energy (ME)
in dog foods (40).
Diet samples were sent to Nestle Purina Analytical Laboratories
(Nestle Purina PetCare, St. Louis, Missouri, USA) for chemical
analyses. Ash, crude fat, crude fiber, crude protein, moisture,
fatty acid profile (linoleic acid, capric acid, caprylic acid) were
measured based on Association of Official Agricultural Chemists
(AOAC) Methods 942.05, 922.06, 962.09, 990.03, 930.15, and
996.06, respectively.
Both control and test diets had comparable macro and
micronutrient profiles except MCT levels and higher levels of
BPB nutrients (DHA, EPA, vitamin E, vitamin C, and B vitamins).
Ascorbyl-2-polyphosphate was used as the form of vitamin C
to ensure the stability of vitamin C in the test diet during the
clinical study. Arginine level was increased over control diet only
in the 9% MCT diet, but the arginine content in the control
and 6.5% MCT diets was three times higher than the AAFCO
minimum maintenance requirement (Table 1). In addition, fat
level was increased to 21% in the 9% MCT diet due to the addition
of higher level of MCT oil. Since many of the BPB nutrients
are components of the ingredients of the diet, most of the
BPB nutrients were several times over the AAFCO maintenance
requirements for dogs except DHA, EPA, vitamin C, and vitamin
E. In addition, Vitamin E in the control diet met the AAFCO
maintenance requirement. Higher levels of protein provided the
natural source of arginine so the levels were similar for control
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Pan et al. A Therapeutic Diet for CDS in Dogs
and 6.5% MCT diet. Therefore, it was possible that the control
diet also had positive effects on the brain health in dogs.
Administration of Test and Control Diets
After enrollment approval, bags of the assigned diet were shipped
to the corresponding veterinary clinic for pickup by the pet
owners. The assigned diet was to serve as the sole feed for a
period of 3 months (90 days). Feeding guidelines were included
with each diet and dogs were fed to maintain their body weight.
Owners were instructed to maintain the feeding regimen prior to
the trial. Assigned diets were introduced gradually over a 7-days
period.
Health Observations and Physical
Examinations
Dog health observations were performed daily over the course
of the study by the dog owner. Any serious, prolonged, and/or
life threatening health observations were to be reported to
the participating veterinarian and Principal Investigator to
determine if removal from study was warranted.
Physical examinations were carried out by the site veterinarian
according to industry standard and included an assessment of
all body systems. Exams occurred at baseline (study Day-8) and
again at study conclusion (Day 90 ±10 days).
Behavioral and Cognitive Assessment
The pet owner was required to complete a Senior Canine
Behavior Questionnaire (Supplementary Table 1) and a Canine
Medical Health Questionnaire (Supplementary Table 2), which
assessed cognitive function, and behavioral health status. The
questionnaire was completed as part of the initial baseline visit,
on Day 30 (±5 days) and again on Day 90 (±10 days). Scoring
scale of the questionnaire for the CDS signs had four scores (0
=none or no change, 1 =mild, 2 =moderate, 3 =severe).
The maximal scores for DISHAA are 21, 21, 15, 18, 21, and 18,
respectively. Scores for enrolled dogs ranged from 6 to 85. Of
the 74 dogs that completed the trial, 41 dogs had scores <30
indicating a milder dysfunction and 33 had scores ≥30 indicating
a more severe dysfunction.
Blood Sample Collection
At the time of the initial veterinary examination and again on Day
90 (±10 days), a blood sample was collected from each animal
for the purpose of complete blood count, clinical chemistry
and β-hydroxybutyrate (BHB) analysis. Approximately 10 ml of
whole blood was collected from a suitable vein. Of the 10 ml
collected, 2 ml was placed into a K2EDTA tube, and 8 ml was
placed into two separated 4 ml serum separator tubes. Tubes were
refrigerated until sent to Antech Diagnostics for analyses.
Urine Sample Collection
A urine sample was collected from each dog during the Day-
8 visit and again on Day 90 (±10 days) for the purpose of
urinalysis. If a sample could not be obtained at the initial visit,
it was required within 7 days for the animal to be considered for
enrollment. A minimum of 5 ml of urine was collected according
to industry standard practices by natural voiding, cystocentesis,
or catheterization. Samples were placed in a sterile container and
refrigerated until sent to Antech Diagnostics for analysis.
Blinding
The study was double-blinded to the pet owner, study
veterinarian, study coordinator, and clinical laboratory staff.
Therefore, all people collecting data were blinded to the
treatment of each dog.
Statistical Analysis
Statistical analyses were carried out using StatSoft, Inc. (2012).
STATISTICA (data analysis software system), version 11, www.
statsoft.com. Each subtest of the questionnaire data was initially
analyzed using a repeated measures ANOVA with Group as
between subject variable and age at test (baseline, 30 and 90
days) as a within subject variable. Although none of the analyses
revealed statistically significant age by treatment interaction, the
analyses did yield significant age at test effects. In instances where
there were significant age-at-test effects, we used the Fisher Exact
Probability test for multiple comparisons to determine which of
the differences achieved statistical significance. The sample size
was determined by the feasibility of recruitment.
One dog in group B (Case 67) was removed from the data
analysis, as the dog was enrolled in error as it had been fed a diet
(Royal Canin Mature Consult) that was on the exclusion list.
For the analysis of blood chemical and CBC data, a linear
mixed effects model was run where ID was entered in as a random
effect and Time (initial/baseline vs. final/90 days), Diet (A, B,
and C), and Time∗Diet were entered as fixed effects. A mixed
effect model was run because it allows for control for the repeated
nature of the data. LS means and differences in LS means are also
provided.
A retrospective power analysis was conducted to determine
the sample size for each of the six subsets of CDS signs within
each dietary group, using the data collected from this study and a
power of 0.80 and a significance level of 0.05. The results showed
that the sample sizes for the control group, 6.5% MCT diet group
and 9% MCT diet group ranged from 17 to 232, 7 to 30, and 31
to 372, respectively, depending on the subset differences between
the baseline and end of the study. These data indicated that we
had adequate power mostly in the 6.5% MCT diet group.
RESULTS
Effects of the Test Diets on Clinical Signs
of Dogs With CDS
Dogs fed the 6.5% MCT diet showed significant improvement
over baseline in all 6 categories of CDS signs including three
categories related to brain cognitive functions (disorientation,
altered social interaction, and loss of house training) at day
90, and most of the improvements (5 out of the 6 categories)
were observed as early as day 30 during the study (Figure 1).
Of the dogs on 6.5% MCT diet that completed the study, 23/26
dogs were responders (improvement or no further progression)
and 3 were worse. The greatest number of dogs improved in
the category of social interactions in which 24/26 dogs were
responders (improvement or no further progression) and 2
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Pan et al. A Therapeutic Diet for CDS in Dogs
worse. For disorientation, 19 dogs were responders and 4 dogs
were worse. Comparing dogs with low and high CDS scores, for
dogs with CDS scores <30, 10 dogs improved, 2 worsened and 1
had not change, while for dogs with CDS scores 30 and over, 11
dogs improved, 1 worsened, and 1 was the same.
Dogs fed the 9% MCT diet failed to significantly improve in
most of the signs over baseline because of smaller sample size
due to larger dropout rate. However, the signs in 5 out of 6
categories were numerically reduced in the dogs fed 9% MCT diet
(Figure 2). Further analysis showed that dog owners’ attitudes
about the 9% MCT diet determined the outcome of this group.
Dogs from owners who would not continue to feed their dogs the
diet after the clinical study did not show significant improvement
at the end of the study. On the contrary, dogs from owners
who would continue to feed their dogs the diet after the clinical
study showed significant improvements at the end of the study
(Figure 3).
Effect of Control Diet on Clinical Signs of
Dogs With CDS
At day 30, control diet significantly improved 3 (Sleep-wake
cycle, house training and altered activity) out of 6 categories of
CDS symptoms. Dogs in the control group showed significant
improvement in 4 out of the 6 categories of CDS symptoms at
day 90. But the control diet failed to significantly improve two
out of the three categories of CDS symptoms related to brain
cognitive function (disorientation, and altered social interaction)
(Figure 4).
Effects of the Diets on Blood Lipid Profiles
Both test diets significantly increased blood levels of DHA, EPA,
DHA, and EPA, total omega-3 PUFAs, and omega-3/omega-6
ratios compared with the control diet (Table 2). However, even
though both test diets had the same inclusion rate of DHA and
EPA (Table 1), dogs fed the 9% MCT diet had significantly lower
blood EPA, DHA, and EPA, total omega-3 PUFAs, and omega-
3/omega-6 ratio than the dogs fed the 6.5% MCT diet (Table 2).
These data indicated that pet owners might have mixed the 9%
diet with other diets, which diluted the intake of DHA and EPA.
Effects of the Diets on Complete Blood
Count (CBC)
All the CBC parameters were within the normal range for
adult dogs (data not shown). No significant differences were
observed at both baseline and end of the study between control
and either of the two test groups in WBC, RBC, hemoglobin,
hematocrit, platelet count, neutrophils, lymphocytes, monocytes,
eosinophils, and MCH (data not shown). MCV in control dogs
was significantly higher than the 9% MCT group at the end
of the study (71.71 ±0.89 vs. 68.96 ±0.91), and MCHC was
significantly lower in the control dogs than in dogs from both
test groups at the end of the study (326.96 ±3.21 vs. 336.35 ±
3.10 or 337.59 ±3.35).
Effects of the Diets on Blood Chemical
Parameters
All the blood chemical parameters were within the normal
range (data not shown). No significant differences at both
baseline and end of the study between control and either
of the two test groups was observed for globulin, A:G
ratio, alkaline phosphatase, total bilirubin, glucose (Table 3),
calcium, sodium, potassium, sodium:potassium ratio, chloride,
bicarbonate, cholesterol (Table 3), triglycerides (Table 3), and
fasting BHB (Table 3). Total protein and albumin differed
between control and the 6.5% MCT diet at the end of the study
(68.24 ±0.93 vs. 64.71 ±0.88, 37.66 ±0.76 vs. 35.44 ±0.73,
respectively). Serum ALT and BUN differed between control and
6.5% MCT diet at baseline (58.14 ±5.31 vs. 41.80 ±5.49, 5.48 ±
0.37 vs. 6.76 ±0.36, respectively). Additionally, creatinine, and
anion gap differed between the control and 6.5% MCT diet at
the end of the study (74.21 ±3.96 vs. 88.35 ±3.91, 21.38 ±0.60
vs. 19.45 ±0.64, respectively). Finally, both cholesterol and BHB
were significantly higher at the end of the study than the baseline
in dogs fed the 9% MCT diet.
Drop-Out
At the end of the study, four dogs in the control group, 2 dogs
in the 6.5% MCT diet group and 6 dogs in the 9% MCT diet
group failed to complete the study. At 30 days 2 dogs in the 9%
MCT diet dropped out, one due to owner non-compliance and
one due to an abdominal tumor, while at 90 days 4 more dogs
were dropped due to owner non-compliance, gastrointestinal
upset, disinterest in the diet and vestibular disease. In the control
group at 30 days, 3 dogs were dropped, one due to owner non-
compliance, one due to illness and one that could not transition
to diet, and 1 dog was dropped at 90 days due to owner non-
compliance. In the 6.5% MCT group at 30 days two dogs had been
unable to be transitioned onto the diet.
DISCUSSION
The main objective of this study was to test the hypothesis
that a combination of MCT and BPB will improve clinical
signs of dogs with CDS. In this clinical study, we have used
a questionnaire including all six categories of CDS symptoms
referred to as DISHAA to assess dogs with CDS and evaluate
the effects of diet on these CDS signs. The results showed that
the 6.5% MCT diet was able to significantly improve five out of
the six categories of clinical signs of CDS at day 30 and all six
categories of clinical signs of CDS in pet dogs at the end of the
3-months clinical study. This is in comparison to the control diet
in which disorientation and social interactions did not improve
significantly. As pet owners are particularly sensitive to changes
in social interactions, it is perhaps not surprising that they are
the most frequently reported signs in mild cognitive decline and
amongst the most commonly reported signs (1,27). Additionally,
signs of disorientation are indicative of more advanced stages of
dementia and amongst the most common signs in severe CDS
(1,27,28,36).
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Pan et al. A Therapeutic Diet for CDS in Dogs
FIGURE 1 | Effects of 6.5% MCT diet on CDS signs at day 30 and day 90. Twenty-nine client owned dogs were assessed for six different behavioral signs of cognitive
dysfunction syndrome (CDS) and then placed on the 6.5% MCT diet. The dogs were re-assessed after 30 days and again after 90 days. The bars illustrate Means ±
SEM for each of the measures at baseline, 30 days and 90 days. Fisher Exact Probability test for multiple comparisons was used to compare baseline with day 30 and
day 90. The asterisks indicate statistically significant differences (p<0.05) from baseline. Two dogs dropped out of the study, and one dog was removed from the
study due to enrollment error.
FIGURE 2 | Effects of 9% MCT diet on CDS signs at day 30 and day 90. Twenty-nine client owned dogs were assessed for six different behavioral signs of cognitive
dysfunction syndrome (CDS) and then placed on the 9% MCT diet. The dogs were re-assessed after 30 days and again after 90 days. The bars illustrate Means ±
SEM for each of the measures at baseline, 30 days and 90 days. Fisher Exact Probability test for multiple comparisons was used to compare baseline with day 30 and
day 90. The asterisks indicate statistically significant differences (p<0.05) from baseline. Six dogs dropped out of the study.
In evaluating individual dogs, 88% improved or did not
progress, with an approximately equal number of dogs improving
that had high scores ≥30 indicative of more marked dysfunction
as those with lower scores <30 (mild dysfunction). Taken
together this supports the findings that the diet was effective
in improving signs from mild to severe CDS. These results are
further supported by the reports showing that in human subjects
with mild cognitive impairment, dietary supplementation of B
vitamins was able to reduce cognitive decline only in subjects
with high levels of blood omega-3 fatty acids (14), and dietary
MCT supplementation improved memory performance in AD
patients by providing the brain with ketone bodies as an
alternative energy source (21).
Higher antioxidants in the BPB of the test diet may be
able to further enhance the therapeutic benefit of the diet by
attenuating chronic oxidative stress associated with subjects with
dementia (10). Higher omega-3 PUFAs of BPB in the test diet
resulted in higher blood omega-3 PUFAs which can correct
DHA deficiency and lead to better management of chronic low
grade inflammation in dementia subjects (11). An optimal level
of dietary arginine is able to enhance fasting blood arginine
and nitric oxide production in senior dogs, which, in turn,
improves blood circulation and cognitive function (13). MCT
may potentiate the BPB effects by improving cognitive function
through enhanced energy supply to the brain in forms of ketone
bodies in dogs with CDS. Therefore, in the current study, the
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Pan et al. A Therapeutic Diet for CDS in Dogs
FIGURE 3 | Effects of owners’ comments on 9% MCT diet on the outcome of the diet. Twenty-nine client owned dogs were assessed for six different behavioral signs
of cognitive dysfunction syndrome (CDS) and then placed on the 9% MCT diet. The dogs were re-assessed after 30 days and again after 90 days. The bars illustrate
Means ±SEM for the mean score of six different behavioral signs at baseline, 30 days and 90 days. Six dogs dropped out of the study. Out of the 23 dogs remaining
at the end of the study, 12 dog owners answered that they do not want to continue to feed their dogs with the diet, and 9 dog owners answered that they want to
continue to feed their dogs with the diet. Fisher LSD test was used to analyze the data between the baseline and day 30 or baseline and day 90. The asterisks
indicate statistically significant differences (p<0.05) from baseline.
FIGURE 4 | Effects of Control diet on CDS signs at day 30 and day 90. Twenty-nine client owned dogs were assessed for six different behavioral signs of cognitive
dysfunction syndrome (CDS) and then placed on the control diet. The dogs were re-assessed after 30 days and again after 90 days. The bars illustrate Means ±SEM
for each of the measures at baseline, 30 days and 90 days. Fisher Exact Probability test for multiple comparisons was used to compare baseline with day 30 and day
90. The asterisks indicate statistically significant differences (p<0.05) from baseline. Four dogs dropped out of the study.
benefits of the test diet containing MCT and BPB on CDS signs
come from multiple nutrients working synergistically to enhance
cognitive function by eliminating or reducing multiple known
risk factors for dementia.
Dogs fed the 9% MCT diet didn’t significantly improve most
of the signs compared with baseline due to a high drop-out rate
(6 out of 29 dogs). Another primary suspected reason for the
failure of the 9% MCT test diet to improve CDS signs was poor
acceptance of the diet by the dogs, which was confirmed by dog
owners’ attitudes toward the 9% MCT diet and blood omega-3
PUFA enrichment in the dogs. Even though both test diets had
the same inclusion levels of DHA and EPA, dogs fed the 9% MCT
diet had significantly lower blood EPA, DHA, and EPA, total
omega-3 PUFAs and the ratio of omega-3 and omega-6 PUFAs
than the 6.5% MCT diet. These data indicated that some owners
did not feed their dog exclusively with the 9% test diet and likely
added in other diets, which resulted in lower daily intake of both
MCT and BPB nutrients.
Our previous studies have demonstrated that a MCT
supplemented diet or the BPB diet was able to enhance cognitive
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Pan et al. A Therapeutic Diet for CDS in Dogs
TABLE 2 | Effects of the diets on blood omage-3 and omega-6 levels.
Diets DHA (%) EPA (%) DHA+EPA (%) AA (%) Total N-3 PUFAs (%) Total N-6 PUFAs (%) N-3/N6 ratio
Control (n= 12) 1.03 ±0.17 0.49 ±0.12 1.53 ±0.17 16.93 ±1.74 3.09 ±0.43 42.79 ±2.22 0.071 ±0.01
6.5% MCT diet (n= 9) 3.00 ±0.36* 3.31 ±0.42*# 6.31 ±0.76*# 14.70 ±0.61 8.85 ±0.86*# 42.23 ±1.06 0.212 ±0.02*#
9% MCT diet (n= 11) 2.07 ±0.33* 1.73 ±0.33*# 3.81 ±0.63*# 14.12 ±1.35 5.80 ±0.80*# 38.77 ±1.86 0.146 ±0.02*#
*Significantly (p <0.05) different from control. #Significantly (p <0.05) different between 6.5% MCTs and 9% MCT diets.
TABLE 3 | Effects of the diets on fasting blood glucose, BHB, cholesterol, and triglycerides in dogs.
Glucose (mmol/l) Beta-hydroxybutyrate (µmol/l)
Control 5.16 ±0.14 5.07 ±0.14 0.600 82.76 ±8.20 78.72 ±8.20 0.686
6.5% MCT 5.12 ±0.14 5.26 ±0.14 0.400 74.50 ±8.05 61.96 ±8.05 0.204
9% MCT 4.91 ±0.17 5.11 ±0.14 0.300 76.43 ±8.55 97.43 ±8.55 0.047
Cholesterol (mmol/l) Triglycerides (mmol/l)
Baseline End of Study P-value Baseline End of Study P-value
Control 6.71 ±0.31 6.86 ±0.31 0.500 1.53 ±0.16 1.56 ±0.16 0.900
6.5% MCT 6.57 ±0.30 6.57 ±0.30 0.999 1.48 ±0.15 1.30 ±0.16 0.300
9% MCT 6.82 ±0.31 7.75 ±0.33 0.0002 1.38 ±0.18 1.43 ±0.19 0.800
function in healthy senior dogs (13,22). In those two studies,
we used a single breed (Beagle) and established cognition-
evaluating protocols to determine whether a MCT diet or BPB
diet enhanced learning, memory, and executive function in
senior dogs. Responses to the protocols were mostly dependent
on dogs’ cognitive ability. This clinical study reflected the clinical
population with a wide range of breeds and breed mixes.
However, previous studies have shown that breeds are not a
risk factor for CDS (28,41). Since it was not possible to use
established cognition-evaluating protocols in a clinical study, we
used a questionnaire to evaluate any improvement in each of
the six CDS signs. The questionnaire was entirely dependent
on pet owners’ input of their pets’ status, which could be
subjective. The 6.5% MCT diet significantly improved all three
CDS signs (disorientation, altered social interaction, housing
training, learning, and memory) related to cognitive function,
while the control diet significantly improved only one of these
CDS signs. These data suggest that a diet containing both MCT
and BPB was able to improve CDS signs by enhancing cognition
in dogs with CDS.
The following factors may contribute to the significant effect
of the control diet. First, the control diet contained most
of the BPB ingredients at levels several times the minimum
requirements for adult dogs based on AAFCO profiles, except
for DHA, EPA, vitamin C, and vitamin E (Table 1). Therefore,
the control diet may have delivered some of the BPB benefits
in control-fed dogs. Secondly, a placebo effect is commonly
observed in clinical studies and placebo treatments can enhance
physical processes of disease more easily and effectively than
biochemical processes (42). Because of the potential placebo
effects in clinical studies, we initially confirmed the efficacy of
MCT and BPB in colony dogs with validated cognition tests,
which minimized placebo effects and eliminated any subjective
owner evaluation (13,22). It has been proposed that the placebo
effect may be due to a person’s expectations of clinical benefits
(43). Since all pet owners were blind to the treatments of the
study, pet owners in the control group may have thought that
their dogs were in the treatment groups, and expected some
beneficial changes in their pets.
Since most cases of cognitive dysfunction presenting with
mild signs go unreported, and a majority (87%) of cases go
undiagnosed, veterinarians must actively screen for behavioral
signs at each senior pet visit (27,41). As 13 of the 100 dogs
with signs of cognitive dysfunction in this study were excluded
because of underlying medical problems, this also supports the
need for blood and urine tests as an essential part of senior pet
screening. In fact, considering that 42% of dogs over 9 years of
age with no signs of impairment progressed to mild impairment
over 6 months (27), health care screening in the senior pet should
be scheduled twice a year.
CONCLUSION
In summary, the results of this clinical study showed that the
6.5% MCT diet was able to significantly improve all six categories
of the CDS signs in dogs with CDS at the end of the 90-day
study. Most of the significant benefits in the dogs fed 6.5% MCT
diet were observed at day 30. For some dogs, the 9% MCT diet
may have had some acceptance issues, diminishing the overall
response in dogs with CDS. Dogs that did not have any issues
with consumption did show significant improvements in their
CDS signs after 90 days. The observed benefits of the control diet
may be due to both partial BPB benefits and a placebo effect. The
results from this dog study confirm the benefits of MCT and BPB
in managing clinical signs of CDS in dogs. The results support
Frontiers in Nutrition | www.frontiersin.org 8December 2018 | Volume 5 | Article 127
Pan et al. A Therapeutic Diet for CDS in Dogs
our hypothesis that targeting known risk factors associated with
brain aging and AD is able to improve symptoms of CDS in
dogs. These data provide pre-clinical data to support clinical
studies testing similar nutrient blend in subjects with MCI
or AD.
AUTHOR CONTRIBUTIONS
GL, NM, and YP designed the study, interpreted the results,
and prepared the manuscript. GL and IM visited participating
clinics and taught veterinarians how to evaluate clinical signs
of CDS in dogs. GL, IM, and SK coordinated the clinical study.
HX formulated the diets and SB scheduled and supervised the
production of the diets. CG, HX, SB, and YP are employees
of Nestlé Purina Research and have not been involved in dog
recruitments, randomization, data and sample handling, data
analysis, and storage except that CG analyzed the data of
blood lipid profiles, Complete Blood Count, and blood chemical
parameters.
FUNDING
The study was entirely funded by Nestlé Purina Research.
ACKNOWLEDGMENTS
We thank Nestlé Purina Pilot Plant for manufacturing the diets
used in this study.
SUPPLEMENTARY MATERIAL
The Supplementary Material for this article can be found
online at: https://www.frontiersin.org/articles/10.3389/fnut.2018.
00127/full#supplementary-material
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Conflict of Interest Statement: YP is one of the inventors for EP2194781B1-
Compositions and methods for enhancing cognitive function. CG, HX, SB, and
YP are employees of Nestlé Purina Research. The authors have no other relevant
affiliations or financial involvement with any organization or entity with a financial
interest in or financial conflict with the subject matter or materials discussed in the
manuscript apart from those disclosed. IM is the President and CEO of CanCog
Technologies. NM is the Chief Technology Officer of Cancog Technologies. GL
is the Vice President of Clinical Affairs at Cancog Technologies and served as
scientific director of the clinical study. SK is a study coordinator of Vivocore Inc.
GL, IM, NM, and SK have no other financial involvement with Nestlé Purina or
financial interest in the subject matter and materials discussed in the manuscript.
Copyright © 2018 Pan, Landsberg, Mougeot, Kelly, Xu, Bhatnagar, Gardner and
Milgram. This is an open-access article distributed under the terms of the Creative
Commons Attribution License (CC BY). The use, distribution or reproduction in
other forums is permitted, provided the original author(s) and the copyright owner(s)
are credited and that the original publication in this journal is cited, in accordance
with accepted academic practice. No use, distribution or reproduction is permitted
which does not comply with these terms.
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