The Role of Nutrition in the Health of Canine Ears

Publishing Authors : Fausto Quintavalla, Ezio Bianchi, Marco Sperotto, Stefano Guazzetti

Date Published : 2004


The aim of this study is to evaluate the infl uence of nutrition on the ear of the
dog. Twenty-nine dogs were included in the study, divided in two groups. One group
was fed with a dry feed made of fi sh and added with pineapple and ginseng. Starting
at the beginning and every 15 days in the course of the study, all dogs were subjected
to clinical and laboratory evaluations. The overall duration of the study was 60 days.
The results of the study confi rm that diet may infl uence the colour and quantity of
cerumen in ear canal. Furthermore, statistics show that the specifi c diet object of this
study can reduce ear infl ammation.

Canine external ear consists of the pinna, that differs from breed to breed,
and the external ear canal that ends with the tympanic membrane. The skin covering
the external canal is not different from the rest of the skin surface. Several glands
can be found (sebaceous and modifi ed ceruminous apocrine glands) that produce
cerumen. Cerumen is a a mixture of desquamated cheratinocites and hair so rich in
fat that Taishin et al. reported that the fat percentage in the cerumen might be used
in female cattle as an indicator of the fat percentage in milk (as it does not depend
on the milking machine or technique, nor on the nippleʼs health).1 A cromatographic test on lipids in canine cerumen showed its compositon: 100% cholesterol, 93.8%
cholesterol esters, 93.8% free fatty acids, 93.8% fatty acids aldehydes, 93.8% wax,
68.8% triglycerids, 56.3% lecithin, 18.8% sphingomyelin 2
In canine ear several pathogens can be found, that may become virulent and
therefore cause a pathologic state when environment conditions are favourable. An
example is given by Malassezia pachydermatis that represents a reservoir for the
infection of other skin parts and may very easily be a secondary problem during
allergic dermatitis, cheratinization defects, endocrin pathologies, staphylococcus
infections or other primary dermatoses³. In canine auditory canal Malassezia is
attached to cornifi ed epitheliumʼs cells through lipids4
In vitro observations showed that adding fatty acids to the culture medium
does not affect M. pachydermatis coloniesʼ growth, but oleic and linoleic acid do
have mycostatic effects.5
This study aims at evaluating the role of a fi sh based nutrition, added with
pineapple and ginseng, on canine ears.
Animals. 30 female and male dogs of different ages and breeds were included
in this study (Table 1), all apparently healthy; they have been living at Parmaʼs dogs
home for at least 6 months and have been fed dry food. All dogs had pendent ears.
The dogs tested, all lodged in single boxes and correctly vaccinated, were
divided into two groups: group A was fed with dry food, composed of fi sh and fi sh
products, pineapple stalk and ginseng dry extract; group B was fed with former food
and acted as a control group. (Table 2).
Group A changed to the new food gradually, during 4 days.
The dogs involved in this study were fed once a day with a food quantity
corresponding to their weight. Water was at their disposal ad libitum. No antibiotics
or antinfl ammatory substances were given during the study.
Test. Before beginning the test (T0) all animals were accurately visited, with
laboratory and instrumental tests. All dogs underwent a blood test (blood taken from
the forearmʼs cefalic vein) and a videotoscopic evaluation (Video Path™, Welch
Allyn ® – Skaneateles Falls, NY; USA), followed by an ear tampon (Dry Swab, Euro.
Me.D. scrl – Surbo, LE).
The blood sample was put in test-tubes containing CaEDTA and rapidly
handed in at the Animal Health Department, Unit of Internal Medicine, of the
University of Parma. Each blood sample passed a hemocrome test performed with
Medonic camera CA 570 to count blood cells (Delcon, Milan).
Instrumental auditory canal evaluation showed that all dogs had integral
tympanic membranes. While evaluating the ears, the operator paid special attention
to possible infl ammations of the pinna and the canal, crusts, hypercheratosis,
cerumen/exudates (quantity), tissue proliferations, evaluating the subjects tested
in a corresponding clinical chart according to the scale shown (Table 3). Each ear
Ann. Fac. Medic. Vet. di Parma (Vol. XXIV, 2004) – pag. 53 – pag. 67
canal was photographed in its horizontal section and identifi ed through a progressive
The ear tampon was performed to take a sample of the material present in the
horizontal duct of each ear and analysed with a cytologic and micro
Ann. Fac. Medic. Vet. di Parma (Vol. XXIV, 2004) – pag. 53 – pag. 67
day food average score
1 0 GROUP A 0.03571429
2 15 GROUP A 0.03333333
3 30 GROUP A 0.00000000
4 45 GROUP A 0.00000000
5 60 GROUP A 0.00000000
6 0 GROUP B 0.10000000
7 15 GROUP B 0.11666667
8 30 GROUP B 0.00000000
9 45 GROUP B 0.00000000
10 60 GROUP B 0.00000000
day food average score
1 0 GROUP A 0.6428571
2 15 GROUP A 0.5000000
3 30 GROUP A 0.2321429
4 45 GROUP A 0.1785714
5 60 GROUP A 0.2142857
6 0 GROUP B 0.6166667
7 15 GROUP B 0.4833333
8 30 GROUP B 0.3666667
9 45 GROUP B 0.5333333
10 60 GROUP B 0.4833333
External canal infl ammation
day food average score
1 0 GROUP A 1.1428571
2 15 GROUP A 0.7500000
3 30 GROUP A 0.7857143
4 45 GROUP A 0.4464286
5 60 GROUP A 0.5714286
6 0 GROUP B 1.0666667
7 15 GROUP B 1.1000000
8 30 GROUP B 0.9166667
9 45 GROUP B 0.8166667
10 60 GROUP B 0.8833333
Ann. Fac. Medic. Vet. di Parma (Vol. XXIV, 2004) – pag. 53 – pag. 67
day food average score
1 0 GROUP A 1.464286
2 15 GROUP A 1.216667
3 30 GROUP A 1.250000
4 45 GROUP A 1.142857
5 60 GROUP A 1.285714
6 0 GROUP B 1.550000
7 15 GROUP B 1.550000
8 30 GROUP B 1.416667
9 45 GROUP B 1.516667
10 60 GROUP B 1.600000
Phlogosis global score
day food average score
1 0 GROUP A 3.183333
2 15 GROUP A 2.550000
3 30 GROUP A 2.116667
4 45 GROUP A 1.650000
5 60 GROUP A 1.966667
6 0 GROUP B 3.633333
7 15 GROUP B 3.450000
8 30 GROUP B 2.850000
9 45 GROUP B 2.866667
10 60 GROUP B 2.966667
In order to have more statistic date, an infl ammation global score was created
by adding the individual phlogosis scores (pinnal infl ammation, crusts, otalgia,
external canal infl ammation, exudates) in a clinical global score.
The analysis of this variableʼs trend was performed with random effects
models6 (to avoid the codependancy of ear/dog/time observations) subject to the
following transformation [log(score+1)=logscore].
This analysis (Table 4) shows that, considering the correlation among
measures repeated on the same dog and the same ear at different times, the difference
in clinical score is signifi cant when the p level is slightly superior to the nominal
level (0.05).
Ann. Fac. Medic. Vet. di Parma (Vol. XXIV, 2004) – pag. 53 – pag. 67
A graphic presentation of the global and individual scores is shown in
graphic 1-3. Figure 1 shows some signifi cant examples of cerumen and auditory
canal infl ammation reduction.
No relevant difference has been observed in the ematochemical parameters
tested together with clinical parameters: blood parameters have always remained in a
physiological range during the whole test.
A microscope and cytological cerumen analysis showed no difference
between the two groups and no variation in time.
External otitis represent an important part of a veterinarianʼs clinical activity,
both for their incidence (ranging from 5 and 20% of the dogs) and the diffi culties in
the therapy and in handling the patients7
The most comon problem that may cause otitis are allergic pathologies
and particularly food intollerance8
. In certain cases, recurring otitis might be the
only clinical sign of an allergic pathology.9
External otitis, associated with itching
and compatible with a food allergy, responds quickly when patients are fed with
hypoallergenic food, particularly if essential fatty acids are correctly added.10
Every time an infl ammatory stimulus appears, cerumen production grows; it
does not seem to have antibacterial effects in patients with recurring otitis as opposed
to healthy patients.11 No relation between the cerumenʼs colour and microorganisms
isolated from the external auditory canal seems to exist12. It is certain, though, that
average fats contained in the cerumen of dogs with ear diseases are signifi cantly lower
than in healthy dogs2 (average: 24.4%, range 4.3-69.9%). Nonetheless, although M.
pachydermatis prefers the auditory canal of dogs with a cerumen high in fats, its
growth depends on the canine breed13.
We share Watsonʼs opinion that diet has a main infl uence on skin and coat
health and plays an important role in etiology and therapy of certain skin diseases.14
External otitis with cerumen, for example, is often associated with zinc defi cit15. In
particular, certain types of food play an important role in allergic pathologies and world
bibliography becomes fuller and fuller of information on that subject, and especially
on the protective function of certain elements, such as fats, vitamins and minerals.
For example, in industrialized countries asthma is increasing and at the same time
a reduction of fi sh consumption (rich in polyunsatured fatty acids omega-3) and an
increased use of seed oil (rich in fatty acids omega-6) can be observed16. Eicosanoids
deriving from membrane cellsʼ metabolism together with arachidonic acid (a fatty
acid omega-6) are strong mediators of phlogosis and itch17. In these cases, variations
in membraneʼs fat composition, due to diet changes in the consumption of fats, may
be involved in the infl ammatory reaction. A diet balanced in fats and micronutrients
seems to be the right condition to maintain an ideal health of canine skin and ears.
Dogs fed with food A showed a relevant reduction of clinical score, which was
confi rmed by a statistic analysis (p= 0.0578). This might prove the antiinfl ammatory
effect of the nutritional elements of food A.
Ann. Fac. Medic. Vet. di Parma (Vol. XXIV, 2004) – pag. 53 – pag. 67
Fish, main component of diet A, represents an excellent source of food, rich
in Vitamin B12, phosphorus, selenium, and PUFA omega-3. Essential fatty acids are
crucial for cell membranes and to maintain the skinʼs structure and function and act
as precursors for eicosanoids, like leucotriens and prostaglandins.
Linoleic acid (omega-6), contained in many types of seeds oil, as a precursor
of arachidonic acid, enhances E-prostaglandinsʼ synthesis, while EPA contained
in fat fi sh oil (pilchard, mackerel, tuna, salmon), and partly DHA too, inhibits it.
The enhanced synthesis of PGE2
seems to aid IgE production and enhance allergic
tendencies in metabolism.18
Other than fats, vitamin C, E and selenium have drawn the attention of
researchers studying the antioxidantsʼ capacity of affecting some allergic pathologies18.
These elements are well represented in two components of food A: pineapple and
Pineapple contains fl avonoids and vitamin C, used for their antioxidant
properties. 19 Many pathologies present oxidative stress as a secondary phenomenon.
Examples are abundant. The oxidative damage of blood vessels walls caused by the
fats seems to play an important role in developing human arteriosclerosis. If the
oxidative damage affects DNA, tumours may develop and the aging process can be
accelerated. An excessive production of free radicals probably contributes to damage
tissues in rheumatoid arthritis and in the intestineʼs infl ammatory diseases (such as
Crohnʼs disease and ulcerative colitis)20.
Ascorbic acid (vitamin C) is considered the most important antioxidant in
cell fl uids, while α-tocopherol is the predominant liposoluble antioxidant in tissues,
plasma and low density lipoproteins (LDL). Vitamin C is a hydrosoluble element
with several well defi ned biological activities: it works as a co-substratum in the
biosynthesis of protocollagen, carnicin and catecholamines, as a co-factor in some
hydroxilasis, and it contributes to the activity of hepatic microsomial systems, and so
on.20 Flavoinoids are contained in virtually every type of food of vegetable origin. They
perform several different biological activities and have vasodilatative, antitumoural,
antiinfl ammatory, antibacterial, antiallergic, antiviral and estrogenic effects; they also
stimulate the immune system. In particular, they can restrain the activity of prooxidant
enzymes such as lipoxygenase and cycloxygenase, phospholipase A2 (whose function
in the infl ammatory process is well known), glutation reductase and xanthin oxydase,
proteinchinase, succinoxydase, mitochondrial NADH-oxydase.20
Ginseng, orally given in powder, has always been empirically used to
prevent cerebrovascular diseases. Recently Lim et al. have proved that the main
ingredient of ginseng, ginsenosyde Rb 1, has most pharmacological properties. 21
If infused after prosencephalonʼs ischemia, it protects CA1 hippocampusʼ neurons
from lethal ischemic damage due to an overproduction of free radicals in situ. This
protection function has been observed in canine myocardium, too. 22 Ginseng, given
orally, seems to accelerate hepatic regeneration and to improve hepatic damage due
to hepatectomy in dogs. As Kwon et al. state, three day after the operation all blood
parameters are normal, except for leucocytes, and the levels of hepatic enzymes (AST
and ALT) were signifi cantly reduced in comparison with the control group.23
Data we have collected are preliminary, but they show some evidence that
Ann. Fac. Medic. Vet. di Parma (Vol. XXIV, 2004) – pag. 53 – pag. 67
diet may affect the cerumenʼs colour and quantity, similarly to what Dunstan et al.
stated about dogʼs diet that affect cholesterolʼs eters and triglycerids. 24
Canine otitis prevention does not depend on hygiene and cleaning products
only, but also on a correct diet that allows to control ear cerumen production and to
inhibit an infl ammatory reaction and therefore a change in the ear environment that
may help develop yeasts and pathogenic bacteria.
Feeding the animals food which contains a correct balance of essential fatty
acids, vitamin A and antioxydants, such as food A, seems very useful. Not only: many
pets owners donʼt fi nd it easy to adopt a restrictive diet for their pet that suffer from
allergies. Therefore it is very important to contribute to the prevention of allergic
phenomena, which are stressful for the pets, their owners and veterinarians too,
through a specifi cally formulated food with antiallergic properties.
Key words
Ear, nutrition, food, dog
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