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The role of dietary omega-3 and omega-6 essential fatty acids in the nutrition of dogs and cats: A review

January 2004
Progress in Nutrition 6(2):0-0

Authors:

Giacomo Biagi

University of Bologna

Attilio Mordenti

University of Bologna

Massimo Cocchi

University of Bologna

Omega-3 and omega-6 fatty acids are essential in all mammalians for normal growth and prevention of several diseases. Because of the seed oil production tendencies and the feeding techniques of farm animals, in the Western countries, diets for humans as well as homemade diets for dogs and cats are usually very high in omega-6 and low in omega-3 fatty acids. Several studies have shown that an optimal omega-6/omega-3 fatty acid ratio (about 6 to 1) in the diet of dogs and cats may reduce the incidence of some diseases, such as cancer and sudden cardiac death. Furthermore, the use of fatty acid supplements has proved to be beneficial in the treatment of several pathogenic conditions, such as chronic inflammatory diseases, atopy, chronic renal insufficiency, and some types of cancer. Therefore, particular attention should be paid to the type and quantity of fat sources that are used when diets for dogs and cats are formulated, in order to assure the optimal amount and balance of omega-3 and omega-6 fatty acids in the food.

Metabolic pathways for the production of eicosanoids from AA and EPA

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The role of dietary omega-3 and

omega-6 essential fatty acids in the

nutrition of dogs and cats: a review

1 DIMORFIPA, Università di

Bologna, Ozzano Emilia, Italy

2 Scottish Agricultural College,

Edinburgh, United Kingdom

Indirizzo per la corrispondenza:

Dr. Giacomo Biagi

DIMORFIPA

via Tolara di Sopra 50

40064 – Ozzano Emilia (BO), Italy

Tel: +39-051-2097363

Fax: +39-051-2097373

E-mail: gbiagi@vet.unibo.it

MONOGRAFIA

IAGI

G.1,M

ORDENTI

A.L.1,

OCCHI

M.2,M

ORDENTI

A.1

PROGRESS IN NUTRITION

VOL.6,N.2,000-000,2004

TITOLO

Il ruolo degli acidi

grassi essenziali

omega-3 e omega-6

nell’alimentazione del

cane e del gatto:

una rassegna

KEY WORDS

Dog, cat, essential fatty acids,

omega-3, omega-6

PAROLE CHIAVE

Cane, gatto, acidi grassi essenziali,

omega-3, omega-6

Summary

Omega-3 and omega-6 fatty acids are essential in all mammalians for nor-

mal growth and prevention of several diseases. Because of the seed oil pro-

duction tendencies and the feeding techniques of farm animals, in the

Western countries, diets for humans as well as homemade diets for dogs

and cats are usually very high in omega-6 and low in omega-3 fatty acids.

Several studies have shown that an optimal omega-6/omega-3 fatty acid

ratio (about 6 to 1) in the diet of dogs and cats may reduce the incidence

of some diseases, such as cancer and sudden cardiac death. Furthermore,

the use of fatty acid supplements has proved to be beneficial in the treat-

ment of several pathogenic conditions, such as chronic inflammatory dis-

eases, atopy, chronic renal insufficiency, and some types of cancer. There-

fore, particular attention should be paid to the type and quantity of fat

sources that are used when diets for dogs and cats are formulated, in order

to assure the optimal amount and balance of omega-3 and omega-6 fatty

acids in the food.

Riassunto

L’apporto alimentare di acidi grassi della serie omega-3 e omega-6 è essen-

ziale nei mammiferi al fine di assicurarne il corretto accrescimento e ridur-

re l’incidenza di alcune patologie. A causa delle odierne tendenze produtti-

ve nel settore delle piante oleaginose e delle moderne tecniche di alimenta-

zione degli animali da reddito, nei paesi occidentali, le diete dell’uomo, così

come quelle preparate in casa per cani e gatti, sono generalmente ricche di

acidi grassi omega-6 e povere di omega-3. Numerose ricerche hanno di-

mostrato che un rapporto ottimale tra acidi grassi omega-6 e omega-3 (in-

torno a 6 a 1) nella dieta di cani e gatti può ridurre l’incidenza di alcune

patologie, quali alcuni tumori e la morte cardiaca improvvisa. Inoltre, l’im-

piego di supplementi alimentari contenenti acidi grassi essenziali può risul-

tare di aiuto nel trattamento di diverse condizioni patologiche, quali malat-

tie infiammatorie a decorso cronico, atopia, insufficienza renale cronica ed

alcuni tipi di tumore. È pertanto molto importante tenere conto del tipo e

della quantità delle fonti lipidiche che si impiegano nella formulazione del-

le diete di cani e gatti, al fine di assicurare la giusta quantità ed il corretto

rapporto di acidi grassi essenziali nell’alimento.

Introduction

Over the past 30 years, many stud-

ies have been conducted to investi-

gate the metabolism of polyunsatu-

rated fatty acids (PUFA) in hu-

mans and animals. Today, it is well

known that both omega-3 and

omega-6 fatty acids are essential in

mammalians for normal growth

and prevention of several diseases,

such as cardiovascular diseases, dia-

betes, hypertension, chronic in-

flammatory and autoimmune dis-

orders, and cancer.

The recommendations to increase

omega-6 fatty acids uptake to re-

duce plasma concentration of cho-

lesterol in humans have strongly

influenced seed oil production and

feeding techniques of farm animals.

The large use of grains and oils rich

in omega-6 fatty acids as feedstuffs

for farm animals has led to the pro-

duction of meat and eggs rich in

omega-6 and poor in omega-3 fatty

acids. Furthermore, modern aqua-

culture produces fish containing

less omega-3 fatty acids than wild

fish (1). As a consequence, diets for

humans as well as homemade diets

for dogs and cats are very likely to

be high in omega-6 and low in

omega-3 fatty acids.

The metabolism of omega-3 and

omega-6 essential fatty acids

The omega-3 and omega-6 fami-

lies consist of several fatty acids de-

rived from two precursors, linoleic

acid (LA, C18:2 n-6) and α-

linolenic acid (LNA, C18:3 n-3).

These two fatty acids can not be

synthesized by animals and must be

obtained from the diet. Once in-

gested, LA and LNA undergo the

action of two enzymic systems,

known as desaturase and elongase,

and are metabolised in other acids

of the same series. The desaturases

act by replacing a saturated bond

with a double one, the elongases

exert their action adding carbon

atoms to the acid in order to extend

the chain. The metabolic pathway

of the omega-3 and omega-6 fatty

acids is shown in figure 1.

Omega-3 and omega-6 fatty acids

compete for the same desaturase

enzymes (2). As a result, the pro-

portions of omega-6 and omega-3

VOLUME 6

Figure 1 - Metabolic pathway of the omega-3 and omega-6 fatty acids

AA = arachidonic acid; EPA = eicosapentaenoic acid; DHA = docosa-

hexaenoic acid

fatty acids that are available to

these enzymes directly affect the

quantity and proportions of arachi-

donic acid (AA, C20:4 n-6), eicos-

apentaenoic (EPA, C20:5 n-3) and

docosahexaenoic acid (DHA,

C22:6 n-3) that are formed.

Like other obligate carnivores, cats

show only little d-6 desaturase ac-

tivity and require foods of animal

origin as a source of AA, EPA and

DHA (3). Conversely, dogs are able

to convert LA and LNA to the

long-chain PUFA by desaturase

and elongase systems (4, 5).

The biological role of omega-3 and

omega-6 fatty acids

Long chain PUFA can have both a

functional and a structural role.

Arachidonic acid is found in fairly

high proportions in the membranes

of most cells, where it is bound as a

component of phospholipids. Upon

cellular stimulation AA is released

and becomes the substrate for the

synthesis of eicosanoids. Eicosa-

noids are polyunsaturated metabo-

lites of fatty acids which include

prostaglandins, thromboxanes,

leukotrienes, and hydroxylated

eicosatetraenoic acids (lipoxins).

DHA is an essential component of

cell membranes. DHA is particu-

larly present in the phospholipids

of retina, cerebral synaptosomes,

and sodium intra-membranous

channels (6). DHA seems to play a

very important role in:

1) brain development and growth

2) reproductive apparatus develop-

ment and growth

3) retinal tissue development and

growth

EPA is mainly a precursor of

eicosanoids. When the diet is rich

in omega-6 and poor in omega-3

fatty acids, eicosanoids are mainly

produced from AA, but when ani-

mals ingest enough omega-3 fatty

acids, EPA and DHA partially re-

place the omega-6 fatty acids (es-

pecially AA) in cell membranes.

When the cell is injured, EPA and

AA are released from the mem-

brane by a phospholipase and

metabolised to eicosanoids by two

main enzymatic systems, ciclooxi-

genase and lipoxygenase. The

metabolic pathways for the produc-

tion of eicosanoids from AA and

EPA are shown in figure 2.

Eicosanoids that are derived from

AA are pro-inflammatory and pro-

aggregatory, and act as potent me-

diators of inflammation in type I

hypersensitivity reactions. Eicosa-

noids from EPA are less inflamma-

tory, vasodilatory, anti-aggregatory,

and prevent cardiac arrhythmia (6).

These actions resist those produced

by the eicosanoids from AA. The

main actions of EPA and AA are

summarized in table 1.

Dihomo-γ-linolenic acid (DGLA,

C20:3 n-6) is produced through

elongation from γ-linolenic acid

(GLA, C18:3 n-6). The eicosa-

noids (group 1 prostaglandins and

group 3 leukotrienes) that derive

from DGLA suppress the synthesis

of tumor necrosis factor-a which is

a strong proinflammatory cytokine.

Dietary sources of PUFA

Omega-6 fatty acids are widely dis-

tributed in food of vegetable and

animal origin. Most oils consumed

in the Western countries (particu-

larly corn, peanut, and sunflower

oil) are very rich in LA and contain

only little LNA. Among vegetable

oils, flaxseed oil is the one showing

the highest content in LNA; signif-

icant amounts of LNA are present

also in rapeseed and soybean oil,

and in walnuts. A major source of

EPA and DHA is oily fish, such as

sardine, salmon, mackerel, and

fresh tuna. The fatty acid composi-

tion of some foodstuffs is reported

in table 2.

Deficiency of PUFA in dogs and

cats

Deficiencies of PUFA are not very

common in dogs and cats. Com-

mercial diets usually contain ade-

quate PUFA; nevertheless, products

that contain significant amounts of

PUFA must be protected from oxi-

dation with the inclusion of natural

or synthetic antioxidants and

avoiding all the factors that may

activate lipids oxidation during

production and storage, such as

light, high temperature, and hu-

midity. Deficiencies of PUFA may

PROGRESS IN NUTRITION 2/2004

occur when animals are fed for a

prolonged time inadequate home-

made diets or diets that have un-

dergone oxidation of lipids.

A PUFA deficiency in dogs is char-

acterized by dull dry hair, hair loss,

and skin lesions (7). Hansen and

Wiese (8) reported cases of external

otitis in PUFA-deficient dogs.

Because of their inability to convert

LA into AA (as well as LNA into

EPA and DHA), cats are more

likely to develop a PUFA deficien-

cy.When cats are fed a diet lacking

LA, they show signs of deficiency,

such as poor growth, skin lesions,

increased loss of water through the

skin, reduced platelet aggregation,

reproductive failure, and fatty liver.

These signs of deficiency may be

prevented by including LA into the

diet. Nevertheless, cats fed diets

containing adequate LA but lack-

ing AA showed reproductive failure

and impaired platelet aggregation

(9-11). Interestingly, male cats fed

LA-adequate AA-deficient diets

show normal reproduction func-

tions. This finding suggests that

some conversion of LA into AA

may take place (11). The existence

of some δ-6 desaturase activity in

cats was later confirmed by

Pawlosky et al. (12).

In rats, δ-6 desaturase activity in

the liver decreases at a rate propor-

VOLUME 6

Figure 2 - Metabolic pathways for the production of eicosanoids from AA and EPA

AA = arachidonic acid; EPA = eicosapentaenoic acid; DGLA = Dihomo-g-linolenic acid

tional to the animal age (13). Even

if there are no specific studies in

the dog, it seems reasonable that

also in old dogs the liver δ-6 desat-

urase activity may be lower and, as

a consequence, the conversion of

LA and LNA to their derivatives

may be decreased. Therefore,

adding a source of AA, EPA and

DHA to the diet of old dogs may

be helpful in preventing a deficien-

cy of these PUFA.

Excessive intake of PUFA in dogs

and cats

Cases of vitamin E deficiency in

cats receiving diets very high in

PUFA have been reported. Diets

with a very high fish content may

cause steatitis (“yellow fat disease”)

in cats if they are deficient in vita-

min E (14, 15). Momoi et al. (16)

observed that healthy cats receiving

a raw fish diet had a significant in-

crease of plasma lipid peroxide lev-

el. When a cat diet is very rich in

PUFA, the NRC (17) suggests a 3-

4 fold increase of vitamin E inclu-

sion in the food. Feeding dogs with

a diet with a very low omega-

6/omega-3 fatty acid ratio (1.6:1)

reduced plasma concentration of α-

tocopherol and increased lipid per-

oxidation (18).

The role of PUFA in the

development of the nervous system

of dogs and cats

The mammalian brain is very rich

in PUFA, especially DHA and AA

(19). In the retina, the rod outer

segment membranes of the pho-

toreceptors are very rich in DHA

(20). Essential fatty acid deficiency

during early brain development

may produce permanent and dele-

terious effects (21). Therefore, ade-

quate PUFA dietary levels in the

mother are very important both

during foetal and early postnatal

period. Ward et al (20) observed

that dietary supplementation with

different levels of DHA and/or AA

in neonatal rats increased deposi-

tion of PUFA in the brain but also

affected tissue levels of the other

acid.

In dogs, the retinal tissue is able to

synthesize DHA from docosapen-

taenoic acid (DPA, C22:5 n-3)

which can be obtained from LNA

(4). However, because the quantity

of LNA that is needed to optimise

neural tissue development is not

known, feeding bitches and puppies

with a source of dietary DHA is

the best approach to provide the

puppies with this nutrient.

In cats, brain DHA levels increase

during the last weeks of pregnancy

PROGRESS IN NUTRITION 2/2004

Arachidonic acid Effect EPA Effect

↑PGE2↑Platelet aggregation ↑PGI3↓Platelet aggregation,

↑vasodilation

↑LTB4↑Inflammation ↑LT B 5↓Inflammation

↑TXA2↑Platelet aggregation, ↑TXA3↓Platelet aggregation

↑vasoconstriction ↓vasoconstriction

↑TNF-α↑Inflammation ↑IL-2b

↑IL-1β↑Inflammation ↑Nitric Oxide ↑Vasodilation

↑PAF ↑Platelet aggregation

PAF = Platelet activating factor

Table 1 - Main actions of arachidonic and eicosapentaenoic acid (EPA)

and keep increasing during early

life. Sources of DHA and AA must

be present in the diet of the queen

to assure the correct development

of brain and retina of the kittens

(22).

The influence of PUFA on the

immune system of dogs and cats

As previously mentioned, dietary

lipids may modulate the immune

system influencing eicosanoids pro-

duction. Kearns et al. (23) showed

that, despite the antiinflammatory

properties of omega-3 PUFA, re-

ducing the omega-6/omega-3 fatty

acid ratio in the diet of dogs to 5:1

did not negatively affect the im-

mune function of old animals and

had some positive effect on the im-

mune system of young animals.

Feeding dogs with a diet rich in fish

oil reduced the production of

leukotriene B4,a strong proinflam-

matory eicosanoid derived from

AA, by neutrophiles (24, 25). In

another study (26), when dogs were

fed a diet with an omega-6/omega-

3 fatty acid ratio of 1.4:1, CD4+ T

lymphocyte count after vaccination

was lower than in control animals,

showing that a very low omega-

6/omega-3 fatty acid ratio reduced

immune response to vaccination. A

diet with an omega-6/omega-3 fat-

ty acid ratio of 1.4:1 reduced cell-

mediated immune response and

PGE2production in aged dogs (18).

VOLUME 6

Foodstuff Total Saturated Monouns. Polyunsaturated FA

FatFAFAC18:2 C18:3 C20:4 C20:5 C22:6 TOT

Beef, rib 6.1 2.03 1.99 0.57 0.11 0.16 0.14 0.07 1.21

Chicken, breast 0.9 0.29 0.23 0.11 0 0.07 0 0.02 0.25

Lamb, leg 2.5 1.01 0.86 0.24 0.01 0.09 0 0 0.35

Pork, loin 7.0 2.23 2.38 1.68 0 0.03 0 0 1.82

Mackerel 11.1 2.61 4.13 0.16 0.15 0.16 0.73 1.26 2.46

Salmon, fresh 12.0 2.97 4.60 0.15 0.09 0.05 0.89 1.19 3.05

Sardine 15.4 4.71 2.89 0.18 0.69 1.05 1.73 2.35 6.29

Tuna, fresh 8.1 3.35 1.51 0.15 0.09 tr. 0.80 2.15 3.20

Egg, whole 8.7 3.17 2.58 1.06 0.04 0.16 0 0 1.26

Butter 83.4 48.78 23.72 1.57 1.18 0002.75

Margarine 84.0 26.43 36.78 16.62 1.02 0 0 0 17.64

Corn oil 99.9 14.96 30.66 49.83 0.60 0 0 0 50.43

Flaxseed oil 99.9 9.40 20.20 12.70 53.30 0 0 0 66.00

Olive oil 99.9 16.16 74.45 7.85 0.99 0008.84

Peanut oil 99.9 19.39 52.52 27.87 000027.87

Rapeseed oil 99.9 6.31 61.52 20.54 9.08 0 0 0 29.62

Soybean oil 99.9 14.02 22.76 51.36 7.60 0 0 0 58.96

Sunflower oil 99.9 11.24 33.37 49.89 0.33 0 0 0 50.22

Walnuts 68.1 5.57 9.54 34.02 6.64 0 0 0 40.66

*Data from Marletta L, Carnovale E: Composizione degli alimenti. Aggiornamento 2000. Istituto Nazionale di Ricer-

ca per gli Alimenti e la Nutrizione. 2000. CDROM.

FA = fatty acids

Table 2 - Fatty acid composition of some foodstuffs (g per 100 g of edible portion)*

Because of the antiinflammatory

properties of the omega-3 PUFA,

many studies have been conducted

in animals and humans to investi-

gate the influence of dietary PUFA

on chronic diseases, such as arthro-

sis, dermatitis, and autoimmune

diseases.

In human patients with rheuma-

toid arthritis, clinical improvement

is achieved with the consumption

of fish oil (27). Simopoulos (28)

has reviewed the beneficial effects

of omega-3 PUFA in human pa-

tients with inflammatory and au-

toimmune diseases.

In dogs with experimental and in-

fectious arthritis, leukotriene B4is

increased in synovial fluid (29, 30),

as it is in human patients with

rheumatoid arthritis (31). The re-

duction of the omega-6/omega-3

acid ratio in the diet of dogs with

osteoarthrosis of the elbow joint did

not reduce lameness during a 12

week study (32). At the present

time, considering the lack of litera-

ture, it is not possible to assess the

effects of dietary omega-3 PUFA on

chronic arthritis of dogs and cats.

In dogs, omega-3 PUFA have been

successfully used to treat a claw

disorder called symmetrical lupoid

onychodystrophy, usually charac-

terised by pain and lameness (33,

34).

The role of PUFA in the treatment

of allergic dermatitis in dogs and

cats will be discussed in the next

paragraph.

The role of PUFA in the treatment

of atopy in dogs and cats

Many studies have investigated the

efficacy of PUFA in the manage-

ment of canine and feline atopy (al-

lergic inhalant dermatitis). It has

been estimated that 10-15% of the

canine population is affected by

atopy (35). Other types of allergies

that may be responsible for an al-

lergic dermatitis are flea bites and

food ingredients. The main clinical

sign of allergic dermatitis is pruri-

tus with secondary skin lesions

mainly resulting from self-trauma.

Depending on the presence of the

responsible allergens, pruritus may

or may not be seasonal. Otitis ex-

terna is noted in about 55% of the

dogs with atopic dermatitis (36).

Scott et al. (37) observed that a

commercial diet with an omega-

6/omega-3 fatty acid ratio of 5.5:1

reduced pruritus in almost 50% of

the atopic dogs used for the trial.

The favourable response was ob-

served after 7 to 21 days on the di-

et, and was lost 3 to 14 days after

the diet was withdrawn. During

another study with atopic dogs,

Harvey (38) observed that skin

condition was improved in animals

receiving a combination of fish oil

(rich in EPA and DHA) and bor-

age seed oil (rich in GLA) com-

pared to the control animals receiv-

ing olive oil as a placebo. During

another study, skin condition im-

provement was observed in 19 of

26 atopic dogs receiving a mixture

of fish oil and evening primrose oil

(also rich in GLA; 39). Another

source of GLA is blackcurrant seed

oil. When fed to atopic dogs,

blackcurrant seed oil reduced pruri-

tus, erythema and skin lesions (40).

Conversely, other researchers did

not notice any significant benefits

from feeding fish oil and evening

primrose oil to atopic dogs (41,

42). In another trial (43), changing

the dose of omega-3 PUFA and

the omega-6/omega-3 ratio did not

produce any benefit on clinical

signs in dogs with pruritus.

In cats with crusting dermatosis,

Harvey (44) observed that a mix-

ture of evening primrose oil and

fish oil was more effective than fish

oil alone in improving skin condi-

tion. During a precedent study

(45), six of eight cats with pruritus

showed some benefit from dietary

supplementation with PUFA.

Feeding an omega-3 fatty acid sup-

plement to non-pruritic cats with

miliary dermatitis lead to the com-

plete disappearance of clinical signs

in three animals of five (46). Con-

versely, in another study, feeding

primrose oil to 15 pruritic cats did

not improve their skin condition

(47). When used together with an

antihistamine, an omega-3/omega-

6 fatty acid supplement was effec-

tive in reducing pruritus in 6 cats of

11 (48). Interestingly, no benefit

was observed when the antihista-

mine or the fatty acid supplement

PROGRESS IN NUTRITION 2/2004

were used alone, suggesting a syn-

ergistic action of the two antiin-

flammatory agents tested.

The lack of clear benefits from

feeding PUFA to dogs and cats

with dermatitis and the sometimes

controversial results obtained may

be due to different causes, such as

inadequate duration of treatment,

lack of a control diet, different

composition of diets and supple-

ments used in the experiments, dif-

ferent doses of PUFA fed to the

animals, and different etiology of

disease.

Cardiovascular effects of PUFA in

dogs

The beneficial effects of omega-3

fatty acids on coronary heart dis-

ease have been shown in hundreds

of experiments in animals and hu-

mans (49). Dietary omega-3 fatty

acids prevent heart disease through

several actions, such as prevention

of arrhythmias, production of

prostaglandins and leukotrienes

with antiinflammatory properties

and inhibition of the synthesis of

cytokines and mitogens that aug-

ment inflammation, stimulation of

nitric oxide release, antithrombotic

properties, reduction of plasmatic

triacylglycerols and VLDL, and in-

hibition of atherosclerosis (50).

Despite the fact that atherosclerosis

is not a major clinical problem in

dogs and cats, it is known that sled

dogs like trained human athletes

may develop pathological alter-

ations of the heart conduction sys-

tem (fibrosis and fat infiltration)

that can eventually lead to sudden

death (51). Billman et al. (52, 53)

showed that omega-3 PUFA have

antiarrhythmic effects also in dogs

and can prevent sudden cardiac

death. Kang and Leaf (54) ob-

served that omega-3 PUFA stabi-

lize electrically every myocyte in

the heart of dogs by increasing by

approximately 50% the electrical

stimulus required to elicit an action

potential and prolonging the rela-

tive refractory time by approxi-

mately 150%.

Freeman et al. (55) showed that

fish oil supplementation can im-

prove the health status of dogs with

heart failure, reducing Interleukin-

1β(IL1) production and improving

the cachexia that is often associated

with heart failure. IL1 is correlated

with higher mortality rates and this

may be the consequence of the

negative inotropic effect of IL1 or

of the fact that IL1 increases skele-

tal muscle protein turnover and re-

duces cardiac myocyte protein syn-

thesis (56).

The role of PUFA in the treatment

of chronic renal disease in dogs and

cats

Despite the fact that renal disease

is a very common cause of death in

dogs and cats, the causes of renal

disease and its progression are only

poorly understood. In dogs and

cats with renal insufficiency,

glomerular hypertension and hy-

pertrophy are observed (57, 58).

These findings are supposed to

represent the adaptive renal re-

sponse to the injury. Frequently, re-

nal failure with glomerular hyper-

tension is associated with elevation

of systemic arterial pressure of dogs

and cats (59, 60). In dogs with re-

nal failure, preglomerular vessels

are dilated and even transient ele-

vations of systemic pressure are

transmitted to the susceptible

glomerular capillary bed causing

further progression of the disease

(61).

Intrarenal hemodynamics are influ-

enced by vasoactive renal eicosa-

noids, such as Prostaglandin E2and

I2and Thromboxane A2(62, 63),

both deriving from AA. While

PGE2and PGI2are powerful va-

sodilators and help maintain renal

blood flow and glomerular filtra-

tion, TXA2reduces renal blood

flow and glomerular filtration and

induces aggregation of platelets

(64). Intrarenal platelet aggregation

may lead to proteinuria due to

higher capillary permeability and to

intraglomerular coagulation with

subsequent fibrosis and sclerosis

(65). Conversely, TXA3,which is

derived from EPA, does not cause

platelet aggregation (66).

Brown et al. (67) fed dogs with re-

nal insufficiency different sources

of fat. Feeding the animals with

VOLUME 6

safflower oil (rich in omega-6 fatty

acids) enhanced renal injury while

feeding fish oil prevented deterio-

ration of renal function. Dietary

supplementation with beef tallow

(a source of saturated fatty acids)

also produced a progressive decre-

ment of renal function but the rate

of function decline was slower than

in animals receiving safflower oil.

During another study (68), dogs

with early renal insufficiency were

fed safflower oil, fish oil or beef tal-

low. Compared to feeding beef tal-

low, feeding fish oil decreased

serum cholesterol concentration

and PGE2and TXA2excretion,

while dietary supplementation with

safflower oil increased eicosanoids

excretion, glomerular capillary

pressure and glomerular enlarge-

ment.

The role of PUFA in the

prevention and treatment of

neoplastic disorders in dogs and

cats

In humans, there is evidence that

omega-3 fatty acids may have some

beneficial effect on some neoplastic

diseases, such as breast, colorectal,

and prostatic cancer, preventing de-

velopment and growth of tumors

and reducing the incidence of

metastatic disease (69-72).

Cachexia is a very common conse-

quence of malignancy and it is

caused by a number of derange-

ments in carbohydrate, lipid and

protein metabolism that are ob-

served in humans (73, 74) as well

as in dogs (75, 76). Since TNF and

interleukin-6 are supposed to play a

role in the pathogenesis of cancer

cachexia (77), feeding fish oil to

cancer patients may reduce the pro-

duction of these eicosanoids and

consequently the incidence of

cachexia (78, 79).

In dogs with lymphoma, dietary

omega-3 fatty acids significantly

increased disease free interval and

survival time (80).

Conclusions

There is evidence from the litera-

ture that the omega-6/omega-3

fatty acid ratio of the diet influ-

ences growth and health status of

dogs and cats. Essential fatty acids

are very important for the develop-

ment of the nervous system and an

optimal dietary omega-6/omega-3

fatty acid ratio (about 6 to 1) re-

duces the incidence of some dis-

eases, such as cancer and sudden

cardiac death. Furthermore, the use

of fatty acid supplements has

proved to be beneficial in the treat-

ment of several pathogenic condi-

tions, such as chronic inflammatory

diseases, atopy, chronic renal dis-

ease, and some types of cancer.

Therefore, particular attention

should be paid to the type and

quantity of fat sources that are used

when diets for dogs and cats are

formulated, in order to assure the

optimal amount and balance of

omega-3 and omega-6 fatty acids

in the food.

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Fatty acid profiling in animal feeds and related food matrixes using a fast GC/MS method and in situ derivatization

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Full-text available

Nov 2021

The purpose of the present study was to characterize lipid fraction extracted from five self-prepared and seven commercial cat foods using gas chromatography (GC) and pressurized differential scanning calorimetry (PDSC) techniques. Self-prepared food recipes were composed using BARFny kalkulator, software dedicated for balancing cat diets, and prepared on the basis of fresh raw meat and offal. Extracted fat fractions were compared qualitatively and quantitatively with literature data for the fat of whole prey items to check the main assumptions of the software used. The fatty acid (FA) composition and distribution were determined using GC. The PDSC method was used for the determination of the oxidative stability of extracted fats. The obtained results indicate that self-prepared cat foods contained a high level of essential fatty acids (EFA) but low oxidative stability, especially for those with significant amounts of polyunsaturated FA. The FA profile and oxidative stability were examined for four dry and three wet commercial cat foods. It was found that their omega-6 to omega-3 ratio was beneficial reaching 5.3:1 to 10.1:1, despite the low amount of EFA. The longer induction time was determined for fats extracted from commercial cat foods than for self-prepared ones, which indicate their higher oxidative stability.

Influence of marine algae ( Schizochytrium spp.) dietary supplementation on doe performance and progeny meat quality

Article

Full-text available

Mar 2010
LIVEST SCI

A study was conducted on a total of 240 primiparous does and their 1184 kits. Does were divided into two experimental groups of 120 each and their kits into four groups. Does were all submitted to artificial insemination on the same day; both groups were fed commercial diets supplemented respectively with coconut oil (2g/kg) and dehydrated alfalfa (2g/kg) (Group D−) or cultivated single-cell marine algae (4g/kg) characterized by a high content of long-chain polyunsaturated fatty acids (LCPUFA) (primarily docosahexaenoic acid, DHA) (Group D+). Kits born from the 200 does that became pregnant (100 in the first group and 100 in the second) were assigned to 4 experimental groups (2 treated and 2 controls) and received, like their mothers, commercial diets with or without LCPUFA supplementation. Results showed a substantial similarity in the reproductive efficiency of does and zootechnical and slaughtering performances of growing–fattening rabbits. The quality of loin and thigh lipids also were influenced not only by the presence of algae in the feeds administered to weaned and finishing rabbits, but also by n-3 LCPUFA supplementation in the mothers' diet.

Can diet composition affect behaviour in dogs? : food for thought

Article

Full-text available

Jan 2009

Guido Bosch

Impact of nutrition on canine behaviour: Current status and possible mechanisms

Article

Full-text available

Jan 2008
NUTR RES REV

Each year, millions of dogs worldwide are abandoned by their owners, relinquished to animal shelters, and euthanised because of behaviour problems. Nutrition is rarely considered as one of the possible contributing factors of problem behaviour. This contribution presents an overview of current knowledge on the influence of nutrition on canine behaviour and explores the underlying mechanisms by which diet may affect behaviour in animals. Behaviour is regulated by neurotransmitters and hormones, and changes in the availability of their precursors may influence behaviour. Tryptophan, the precursor of serotonin, may affect the incidence of aggression, self-mutilation and stress resistance. The latter may also be influenced by dietary tyrosine, a precursor to catecholamines. As diet composition, nutrient availability and nutrient interactions affect the availability of these precursors in the brain, behaviour or stress resistance may be affected. PUFA, especially DHA, have an important role as structural constituents in brain development, and dietary supply of n-3 and n-6 PUFA could modify aspects of the dopaminergic and serotonergic system and, consequently, cognitive performance and behaviour. Finally, persistent feeding motivation between meals can increase stereotyped behaviour and aggression and decrease resting time. This feeding motivation may be altered by dietary fibre content and source. At present, few studies have been conducted to evaluate the role of nutrition in canine (problem) behaviour through the above mentioned mechanisms. Studies that explore this relationship may help to improve the welfare of dogs and their owners.

Dietary (n-3)/(n-6) Fatty Acid Ratio: Possible Relationship to Premenopausal but Not Postmenopausal Breast Cancer Risk in U.S. Women

Article

May 2003

Recent research has suggested that an increased (n-3) fatty acid intake and/or increased (n-3)/(n-6) polyunsaturated fatty acid (PUFA) ratio in the diet is associated with a lower breast cancer risk. This case-control study investigated the association between intake of (n-3) and other fatty acids and the (n-3)/(n-6) PUFA ratio and breast cancer risk. After combining data from two related case-control studies in Connecticut, we had information available on a total of 1119 women (565 cases and 554 controls). Cases were all histologically confirmed, incident breast carcinoma patients. Controls were hospital-based (Yale-New Haven Hospital study site) and population-based (Tolland County study site). Information on dietary intake was obtained through a validated food-frequency questionnaire. Standard multivariate methods were used to address the independent effects of specific fatty acids, fat classes and macronutrients on breast cancer risk. In the full study population, there were no significant trends for any macronutrient/fatty acid when comparing the highest to the lowest quartile of intake. When the analysis was restricted to premenopausal women, consumption of the highest compared with the lowest quartile of the (n-3)/(n-6) PUFA ratio was associated with a nonsignificant 41% lower risk of breast cancer [odds ratio (OR) = 0.59, 95% confidence interval (CI) 0.29, 1.19, P for trend = 0.09]. A higher (n-3)/(n-6) PUFA ratio was significantly associated with a lower risk of breast cancer when the data were restricted to the Tolland County (population-based) study site; OR = 0.50, 95% CI 0.27, 0.95, P for trend = 0.02. These results are consistent with the hypothesis that a higher (n-3)/(n-6) PUFA ratio may reduce the risk of breast cancer, especially in premenopausal women.

The role of essential fatty acids in neural development: implications for perinatal nutrition

Article

May 1993

M A Crawford

The brain is 60% structural lipid, which universally uses arachidonic acid (AA; 20:4n−6) and docosahexaenoic acid (DHA; 22:6n−3) for growth, function, and integrity. Both acids are consistent components of human milk. Experimental evidence in animals has demonstrated that the effect of essential fatty acid deficiency during early brain development is deleterious and permanent. The risk of neurodevelopmental disorder is highest in the very-low-birth-weight babies. Babies born of low birth weight or prematurely are most likely to have been born to mothers who were inadequately nourished, and the babies tend to be born with AA and DHA deficits. Because disorders of brain development can be permanent, proper provision should be made to protect the AA and DHA status of both term and preterm infants to ensure optimum conditions for the development of membrane-rich systems such as the brain, nervous, and vascular systems.

Conversion of essential fatty acids by delta 6-desaturase in dog liver microsomes

Conference Paper

Jun 2002

A prospective study of intake of fish and marine fatty acids and prostate cancer in us men.

Article

Jun 2001
AM J EPIDEMIOL

Agents that interfere with arachidonic acid metabolism

Article

Jan 1988

Goldstein I.M.

Arachidonic acid metabolites

Article

Jan 1989

Observations on canine atopy

Article

Jan 1981
J AM ANIM HOSP ASSOC

Danny Scott

Evaluation of effects of dietary n-6 to n-3 fatty acid ratios on leukotriene B synthesis in dog skin and neutrophils

Article

Jan 1994

Essential fatty acid requirements of cats: Pathology of essential fatty acid deficiency

Article

Jul 1984

The pathologic changes of essential fatty acid (EFA) deficiency were studied in specific-pathogen-free, domestic shorthair cats which were fed purified diets for 1.5 to 2.5 years. Cats fed an EFA-deficient diet exhibited signs of deficiency: severe fatty degeneration of the liver, excessive fat in the kidneys, dystrophic mineralization of the adrenal glands, degeneration of the testes, and hyperkeratosis of the skin. Minor clinical pathologic changes were consistent with liver damage. Fatty acid analyses of plasma lipids revealed low concentrations of linoleate and other n6-fatty acids, and high concentrations of n7- and n9-fatty acids, consistent with EFA deficiency. These signs of deficiency were prevented by including safflower seed oil in the diet at a concentration to supply linoleate at 6.7% of dietary energy. Therefore, linoleate is an EFA for the cat, despite negligible conversion of linoleate to arachidonate in cat liver. However, in cats fed a diet containing linoleate, but lacking arachidonate, there was mild mineralization of the kidneys, and the neutral fat content of the liver was slightly higher than that of cats fed a diet containing arachidonate and other long-chain polyunsaturated fatty acids. Also, 2 of the 19 cats fed arachidonate-deficient diets developed unusual inflammatory skin lesions. In cats fed a diet containing hydrogenated coconut oil, safflower seed oil, and chicken fat, fatty livers developed despite the presence of high levels of linoleate. The fatty livers appeared to result from a specific deleterious effect of the medium-chain triglycerides in hydrogenated coconut oil. Most of the organ pathologic changes of EFA deficiency in the cat can be prevented by feeding dietary linoleate. Linoleate meets the EFA requirement for functions which depend on proper membrane structure: growth, lipid transport, normal skin and coat condition, and maintenance of the epidermal permeability barrier. However, dietary arachidonate is required by the cat for functions which depend on eicosanoid formation, such as reproduction and blood platelet aggregation.

The effects of dietary n‐3 vs. n‐6 fatty acids on ex‐vivo LTB4 generation by canine neutrophils

Article

Dec 2001
VET DERMATOL

Dietary n-3 polyunsaturated fatty acids are widely used for amelioration of inflammatory skin disease in dogs. In this study, a diet containing two different sources of n-3 polyunsaturated fatty acid–triglyceride (from menhaden oil) and concentrated ethyl esters–was fed to one group of six purpose-bred dogs, while an isocaloric isonitrogenous diet with corn oil (n-6 polyunsaturated fatty acids) was fed to another group of eight purpose-bred dogs for six weeks. Peripheral blood neutrophils, isolated at week–1 (baseline), week 2 and week 6, were stimulated with calcium ionophore A23187 and the amount of leukotriene B4 produced was determined via reversed-phase high performance liquid chromatography. Analysis of variance of log-transformed data revealed a significant effect for diet (P = 0.005) at six weeks, with dogs fed the high n-3 polyunsaturated fatty acid diet having significantly less mean ex vivo neutrophil leukotriene B4 production than dogs fed the high n-6 polyunsaturated fatty acid diet. Further studies on the clinical usefulness of n-3 polyunsaturated fatty acid ethyl esters are warranted.