News from research 14

Anxiety

Ability of Royal Canin Calm diet to limit anxiety in fearful cats

The effect of a diet supplemented with L-tryptophan and alpha-casozepine, a milk-protein hydrolysate, was assessed in cats identified as fearful.

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This study included 24 colony cats identified as fearful of humans.

At baseline, compared to non-fearful cats, these fearful cats were significantly more inactive in both open field and human interaction trials; inactivity was thus considered as a sign of anxiety. The 24 cats were divided into two equivalent groups that were fed either the Royal Canin Calm feline diet or a control diet for 4 weeks. At weeks 2 and 4, cats were reassessed in both open field and human interaction tests. Data were analysed using repeated measures (ANOVA and the Fisher exact test) for group comparison.

Baseline

Intro

After 2 weeks

* Distance traveled (Mean)

Open-Field behavioural assays are commonly used to test both locomotor activity and emotionality in mammals. The standard open field trial in the feline species entails placing the cat in an open field arena and allowing the subject to freely explore the room over a fixed period of time. Movement is recorded using a video tracking system and trained personnel record behaviours of interest.

#14 - May 2015

Evolution of distance traveled in fearful cats fed Royal Canin Calm or control

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Providing the best evidence through adapted study design

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Evidence-based medicine first emerged in the 70’s, and can be defined as a systematic approach to clinical problem solving; it enables the best research evidence available to be integrated with clinical expertise and patient values. Within this concept, study design is essential to weigh different levels of evidence and to place the results into perspective. For the identification of causative factors while minimising potential biases, the best study design remains that of long-term prospective cohort studies; these are currently lacking for a good understanding of the aetiology of feline hyperthyroidism. This 14th issue of “News from research” presents a recent review that gathers the best available data on the subject and discusses the strength of evidence that supports reported risk factors for feline hyperthyroidism.

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0 Control

Calm Diet

Marie-Anne Hours (Scientific Support- R&D)

Group

In the open field trial, for distance traveled, cats fed the control diet showed a statistically significant decrease in activity at 2 weeks (p=0.023) and a marginally significant decrease at 4 weeks (p=0.052). For inactivity duration, this group showed a statistically significant increase at 2 weeks. By contrast, the group fed the test diet (Royal Canin Calm feline) showed a statistically significant decrease in inactivity duration at 2 weeks (p=0.0397), a marginally significant decrease at 4 weeks (p=0.0675) and a global numerical increase in movement. No group differences were observed in the human interaction test.

Dermatology

Compared to cats fed the control diet, cats fed the test diet showed an increase in activity and a decrease in the duration of inactivity. These results support the interest of Royal Canin Calm Feline diet in reducing signs of anxiety in cats identified as fearful.

Landsberg GM, de Rivera C, Mougeot I, Kelly S, Drewczynski D, Milgram NW. Anxiety-reducing effectiveness of a therapeutic calming diet using a model of fear and anxiety in cats. Proceedingsof the 2014 ACVB/ABSAB Veterinary Behavior Symposium, Denver, Colorado (USA) July 25, 2014, p19

Available articles: Fieten H, Biourge VC, Watson AL, Leegwater PA, van den Ingh TS, Rothuizen J. Dietary Management of Labrador Retrievers with Subclinical Hepatic Copper Accumulation.

J Vet Intern Med. 2015 Mar 16. doi: 10.1111/jvim.12574.

German AJ, Luxmore J, Holden SL, Morris PJ, Biourge V. Feeding obese dogs during weight loss is on average cost-neutral.

J Small Anim Pract. 2015 Feb 12. doi: 10.1111/jsap.12338.

© ROYAL CANIN® SAS 2015. All Rights Reserved.

Hot off the press!

Clinical improvement of pruritus in dogs fed Royal Canin Hypoallergenic

This prospective study performed by the Veterinary University of Vienna investigated the efficacy of Royal Canin Hypoallergenic Canine in 80 pruritic dogs.

These findings show a positive effect on clinical signs in pruritic dogs fed Royal Canin Hypoallergenic, confirming that both AFR and CAD dogs can improve on this diet. This diet may also be used to make a diagnosis, by distinguishing dogs with atopic dermatitis from dogs suffering from cAFR, keeping in mind that it is mandatory to perform a re-challenge.

The purpose of this study was to determine the clinical response of dogs showing signs of atopic dermatitis, and suffering from nonseasonal pruritus to a 60-day hydrolysed protein-based elimination diet (Royal Canin Hypoallergenic Canine). Over a two-year period, 80 pruritic dogs with a history and clinical appearance that were compatible with Canine Atopic Dermatitis (CAD) or with cutaneous Adverse Food Reactions (cAFR) were enrolled, and 67 dogs completed the 60-day study. Skin lesions and pruritus were scored at inclusion, and 30 and 60 days after implementing the diet. Data were analysed using Wilcoxon tests for pruritus and ANOVA for repeated measures (GLM) for skin lesions to compare differences between time points.

Horvath-Ungerboeck C, Tichy A, Tran JL, Litschauer B. Efficacy of a hydrolysed diet in 80 pruritic dogs: a prospective study. Proceedings of the 27th annual ESVD-ECVD congress, Salzburg (Austria), 11-13 September 2014, p18

Pruritus improved significantly from day 0 to 30 (p<0.001), day 0 to 60 (p<0.001) and day 30 to 60 (p=0.008). Skin lesions also improved significantly from day 0 to day 30 and from day 0 to day 60 (p<0.001).

After 60 days, owners were asked to feed their previous diet as a re-challenge to confirm the diagnosis for cAFR (i.e. improvement of symptoms after being fed the Hypoallergenic diet, and flare-up in clinical signs when back on previous diet). 21 dogs were diagnosed with cutaneous AFR, 19 with CAD (confirmed through adapted skin tests) and 5 with both CAD and cAFR. For 22 dogs a definitive diagnosis could not be made as owners refused to re-challenge.

Mean values of pruritus in dogs that were finally diagnosed with atopic dermatitis, cutaneous adverse food reactions and without diagnosis, respectively No diagnosis CAD Cutaneous AFR 3 2,5 2 1,5 1 0,5 0 Day 0

Day 30

Day 60

Endocrinology

What are the real food-associated risk factors for feline hyperthyroidism?

Over the past two decades, several epidemiological studies have investigated possible dietary risk factors for feline hyperthyroidism (HT). The purpose of this review was to provide an objective evaluation of the information available on the aetiology of feline HT. Two types of studies can be performed to assess risk factors: retrospective case-control studies (with data collection generally performed through questionnaires) and prospective cohort studies, which are the only studies allowing an evaluation of the cause and effect relationship between risk factors and the development of disease. Scientific literature comprises 9 publications investigating food-associated factors in HT, but to date, no prospective study has been performed in cats. Therefore, no true causative factor has been identified. Various epidemiologic studies have suggested a multifactorial aetiology of feline HT: non-dietary factors identified include increasing age, indoor housing, the use of fertilisers, herbicides, flea powder and sprays, as well as the presence of cat litter. Dietary factors have also been suggested, including canned food consumption, dietary flavonoids, selenium and iodine.

Canned food and associated constituents Quantitatively, feeding canned food was not found to be a significant risk factor for feline HT in one study, while it was found to be a risk factor in five retrospective studies. However, all of the studies suggesting this association have strong limitations in their materials and methods, such as insufficient recording for dietary history, poor age-matching between cases and controls, or lack of information about the health status of the control cats. From the available publications there is insufficient evidence to conclude that a canned diet is a food-associated factor in the aetiology of HT. Nonetheless, this has led to several hypotheses to explain a potential role of constituents such as PBA and PBDEs. Bisphenol A (BPA) is a monomere that is used to make polycarbonates in plastics. BADGE is the diglycidyl ether of BPA. BADGE epoxy resins are used in epoxy lacquer-coated food cans. BPA has structural similarities to thyroid hormones and can act as a thyroid hormone receptor antagonist. To date, no study has been carried out to show BPA

in the blood or tissue of HT cats. BPA has been detected in canned cat food in Japan and in the USA at a concentration ranging from below the detection limit to well below the current EU maximum. Polybrominated diphenyl ethers (PBDE’s) are flame retardants and known endocrine disruptors due to the structural similarities of various PBDE isomers with thyroid hormone. No case-control studies have been carried out to show an association between PBDE exposure and HT. It is suggested that ingestion of household dust is the primary source for cats. Dust PBDE, and not serum PBDE, was significantly correlated to serum T4.

Flavonoids In vitro studies demonstrated that soy isoflavones can act as an alternative substrate for iodination. To date, there is only one shortterm study in healthy cats evaluating the effect of dietary soy on the thyroid function. A diet containing soybean meal caused increased total T4 and free T4 concentrations, but in this diet isoflavone concentration was much higher than levels reported in commercial feline diets and the iodine content was higher than the legal maximum concentration.

When purified sources of soy, such as soy isolates and soy hydrolysates are used, they contain naturally limited levels of isoflavones.

Selenium Selenium is known to be implicated in the functioning of the thyroid gland, acting as a cofactor for the thyroid hormone deiodinase. To date, only two studies have investigated the effects of selenium intake on the thyroid function in cats. One study showed that in kittens a low selenium diet led to an increase in serum total T4 and a decrease in serum total T3. The second study compared plasma selenium concentrations in 43 euthyroid and 7 HT cats from different regions, with a different incidence in HT, and found no significant difference between cats from different regions or between euthyroid and HT cats. Thus, as for flavonoids, the role of selenium in the etiopathology of feline HT remains unclear.

Iodine intake Dietary iodine has been proposed as a causal factor of HT in a variety of ways: fluctuant iodine intake, but also insufficient or excessive iodine intake have been hypothesised to contribute to the development of thyroid disorders. Iodine recommendations have varied over the years.

Recently, FEDIAF increased the minimum recommended concentration to levels equal to the NRC recommendations. No safe upper limit of iodine has been defined by the NRC, but European authorities established a legal maximum when supplemented. A recent retrospective case-control study showed that cats fed commercial diets, without iodine supplementation, were more likely to develop HT compared to cats eating iodine-supplemented cat foods. High iodine ingestion has also been suggested as a cause of HT, from extrapolation in humans. When healthy cats were fed diets with different levels of iodine for 2 weeks, serum thryoid hormone concentrations responded inversely to dietary iodine; however, when diets with low and high iodine contents were fed for 5 months, no significant difference in serum free T4 was noted.

Current knowledge based on available epidemiologic indicates that feline HT is a complex and multifactorial disease. Some dietary factors have been suggested, but none of these have yet been confirmed as inducing feline HT. Lifelong prospective longitudinal studies based on the strongest epidemiological evidence will be required to identify the true causative factors of this disease. van Hoek I, Hesta M, Biourge V.A critical review of food-associated factors proposed in the aetiology of feline hyperthyroidism. J Feline Med Surg 2014 nov 3 Notes: PBDE: Polybrominated diphenyl ethers BPA: Bisphenol A FEDIAF: Federation Europeenne de l’Industrie des Aliments pour Animaux Familiers NRC: National Research Council. Nutrient Requirements of dogs and cats.

Paediatrics

An optimal passive immune transfer lengthens the protection against Canine Parvovirus

This study involving 79 puppies, followed from birth to 2 months of age, established a clear link between the absorption of maternally derived antibodies and the length of the protection period against parvovirus infection in puppies.

% of puppies protected from CPV2 infection % of puppies protected from CPV2 infection (HI≥1:80) depending on maternally derived antibodies at 2 days of age 100

Canine parvovirus type 2 (CPV2) is a ubiquitous enteropathogen, responsible for outbreaks of acute gastroenteritis, with a high prevalence in diarrheic puppies. Systemic CPV2 maternally derived antibodies decrease with age, and no longer seem to protect against CPV2 when the serological titre has fallen below 1:80. The aim of this study was to analyse the kinetics of systemic maternally derived antibodies in puppies maintained in field conditions.

Seventy-nine puppies from various breeds were included and followed from birth until 56 days of age. All puppies were housed with their dam in heated whelping boxes and were allowed to suckle freely. Titres of antibodies against CPV2 were evaluated at days 2 and 7, and every week until day 56. Faecal excretion of CPV2 was determined at day 17 and every week until day 52.

At 2 days of age, 43% of puppies (designed as group A) had maternally derived antibodies ≤1:160 and 57% (designed as group B) had greater titres. In all cases, the maternally derived antibodies declined with age.

However, the proportion of puppies with an antibody level considered to protect against CPV2 infection (1:80) was significantly higher in group B, as compared with A, from day 2 until 42. Among all puppies surviving until 56 d of age, 67 out of 70 (95·7 %) underwent CPV2 infection, but puppies from group A excreted CPV2 significantly earlier than puppies from group B. The early consumption of a sufficient amount of maternal colostrum to maximise passive immune transfer increases the length of the protective period against CPV2 infection. Consequently, breeders should be encouraged to pay full attention to early suckling within the first 12 hours after birth.

Mila H, Grellet A, Desario C, Feugier A, Decaro N, Buonavoglia C, Chastant-Maillard S. Protection against canine parvovirus type 2 infection in puppies by colostrum derived antibodies. Journal of Nutritional Science.

2014; 3, e54 doi:10.1017/jns.2014.57

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HI = Haemagglutination Inhibition titre Group A (HI≤1:160 at day 2) Group B (HI>1:160 at day 2)

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Age of puppies in days