Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification

Long-term use of lokivetmab in dogs with atopic dermatitis

BACKGROUND

Lokivetmab, a caninised monoclonal antibody against interleukin (IL)-31, is an effective treatment for the pruritus associated with canine atopic dermatitis (cAD).

OBJECTIVES

To investigate the efficacy and safety of lokivetmab during long-term treatment defined as at least three consecutive lokivetmab injections in atopic dogs under field conditions. To assess individual factors influencing treatment outcome and adverse events.

ANIMALS

150 dogs with cAD.

MATERIALS AND METHODS

Medical records of dogs treated with lokivetmab were reviewed, and owners and/or veterinarians were contacted as needed for follow-up. A decrease of the pruritus Visual Analog Scale (PVAS) score by ≥2 or a PVAS score ≤2 after treatment was considered as treatment success. Logistic regression was used to investigate the influence of a variety of factors on outcome: type of cAD (food versus environment), age at first lokivetmab administration, disease chronicity, dosage and/or secondary infection. Any adverse event that occurred during the study period was recorded.

RESULTS

Lokivetmab reduced the PVAS score with long-term use (p < 0.01); the success rate was 53 of 69 total dogs (77%). The probability of treatment failure decreased with increasing treatment duration. None of the factors investigated influenced the treatment outcome. Twelve dogs of 150 (8%) showed adverse events such as gastrointestinal signs or lethargy.

CONCLUSION AND CLINICAL RELEVANCE

Lokivetmab appears to be an effective and safe long-term anti-itch therapy for dogs with cAD.

Treatment of moderate-to-severe canine atopic dermatitis with modified-release mycophenolate (OKV-1001): A pilot open-label, single-arm multicentric clinical trial

BACKGROUND

Mycophenolate is an immunomodulating agent successfully used for the treatment of moderate-to-severe atopic dermatitis (AD) in people. Mycophenolate is an effective steroid-sparing treatment option for use in dogs with inflammatory skin diseases.

OBJECTIVE

To evaluate whether once-daily modified-release mycophenolate (OKV-1001) is safe and effective for treating moderate-to-severe canine AD.

ANIMALS

Client-owned atopic dogs (n = 9) were enrolled.

MATERIALS AND METHODS

In an open-label multicentre pilot study, OKV-1001 (30 mg/kg every 24 h) was given orally for ≤84 days. Concomitant tapering doses of glucocorticoids were administered up to Day (D)28. Clinicians assessed Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-04) on D0, D14, D28, D56 and D84. Body weight and clinical pathological parameters were measured at baseline and at the end of the study.

RESULTS

Treatment with OKV-1001 combined with glucocorticoids significantly reduced the severity of AD within two weeks in seven of nine (77.8%) dogs. The mean percentage change from baseline in the CADESI-04 score was 29% (p = 0.009) at D14 (n = 9), 39% (p = 0.008) at D28 (n = 9) and 49% (p = 0.03) at D56 (n = 7) at which point glucocorticoids had been withdrawn. In two dogs the improvement in CADESI-04 was 62% and 23% (respectively) on D84. No significant adverse events including clinical pathological findings were reported.

CONCLUSIONS AND CLINICAL RELEVANCE

Modified-release mycophenolate (OKV-1001) may represent a promising alternative treatment option for dogs with moderate-to-severe AD. The safety and efficacy profile of OKV-1001 will need to be established in larger, placebo-controlled clinical trials.

A placebo-controlled, double-blind study evaluating the effect of orally administered polyunsaturated fatty acids on the oclacitinib dose for atopic dogs

BACKGROUND

Supplementation of polyunsaturated fatty acids (PUFA) enables dose reduction of prednisolone and ciclosporin in canine atopic dermatitis (cAD).

OBJECTIVE

To determine if oral administration of PUFA reduces the dose of oclacitinib in cAD.

ANIMALS

Twenty-two client-owned dogs with cAD receiving oclacitinib.

MATERIALS AND METHODS

Dogs received a fish oil product (PUFA) or paraffin oil (placebo) for 16 weeks. Owners adjusted the oclacitinib dose according to daily pruritus assessments. On Day (D)0, D56 and D112, Canine Atopic Dermatitis Extent and Severity Index, fourth iteration (CADESI-04), pruritus Visual Analog Scale (PVAS), quality-of-life score (QoL), Global Assessment (GA), quality-of-coat (QoC) and adverse events were recorded.

RESULTS

Mean daily oclacitinib dose was significantly reduced in the PUFA group from 0.51 ± 0.20 mg/kg/24 h (D0) to 0.19 ± 0.14 mg/kg/24 h (D85-112; p < 0.00001) and not in the placebo group (D0: 0.70 ± 0.33 mg/kg/24 h; D85-112: 0.53 ± 0.35 mg/kg/24 h, p = 0.5422). CADESI-04 did not change over time or differ between groups. PVAS was significantly lower in the PUFA group (2.8 ± 1.5) compared to placebo (4.2 ± 1.6) at D112 (p = 0.0375). QoL and QoC improved only in the PUFA group (QoL: D0: 20 ± 7, D112: 12 ± 5, p = 0.0057; QoC: D0: 0 ± 0.5, D112: 1 ± 0.5, p = 0.0410). GA on D112 was higher in the PUFA group (p = 0.008). No adverse events were observed.

CONCLUSION

Oral supplementation of PUFA allowed dose reduction of oclacitinib and improved PVAS, QoL, QoC and GA. The use of PUFA is recommended and was safe in the atopic study dogs receiving oclacitinib.

Preliminary evaluation of a commercial shampoo and fine bubble bathing in the treatment of canine atopic dermatitis: A single-blinded, randomised, controlled study

BACKGROUND

Fine bubble (FB) bathing has shown benefits on a mouse model of atopic dermatitis (AD). However, its efficacy in dogs with AD remains to be evaluated.

OBJECTIVE

This study aimed to assess the clinical effectiveness of FB bathing in dogs with AD.

ANIMALS

Seventeen dogs with AD whose clinical presentation showed a Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-04) score of <40.

MATERIALS AND METHODS

The dogs were randomly assigned to either the FB bathing group or the shampoo group. The treatments were administered once a week as per the instructions, in a trial totalling 4 weeks. Evaluations were conducted on Day (D)0 and D28 to assess the outcomes of the trial. The severity of AD was measured using the CADESI-04 and the pruritus Visual Analog Scale (PVAS). The skin barrier function parameters, transepidermal water loss (TEWL) and stratum corneum hydration were measured before and after the treatment.

RESULTS

Both treatment groups demonstrated a decreasing trend in CADESI-04 scores, yet the FB group exhibited significant improvement in comparison to the shampoo group after 1 month of trial. There were no significant changes in PVAS scores in either group. No significant difference was found in skin barrier function parameters between the two treatments, although TEWL slightly decreased in the FB group and slightly increased in the shampoo group after treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

These results suggested that FB treatment provides benefits for dogs with AD and offers an alternative topical treatment option with a lesser impact on skin barrier function compared to frequent shampooing.

Evaluation of the correlation of serological and intradermal allergen testing with clinical history in 29 dogs with atopic dermatitis

BACKGROUND

Limited information exists about the correlation between clinical history and positive serum (SAT) and intradermal allergen test (IDAT) results in atopic dogs.

OBJECTIVES

To evaluate the correlation between clinical history and SAT/IDAT results in atopic dogs.

ANIMALS

Twenty-nine client-owned dogs with nonseasonal atopic dermatitis with or without seasonal exacerbation were enrolled.

MATERIALS AND METHODS

IDAT, SAT (immunoglobulin (Ig)M antibody capture enzyme-linked immunosorbent assay [MacELISA] with bromelain CCD inhibitor) and clinical information collected in a questionnaire regarding seasonal variations in pruritus affecting the dogs were performed on the same day. Two independent investigators (Inv A and Inv B) recorded IDAT results.

RESULTS

The kappa coefficients agreement for positive IDAT scores between Inv A and B was substantial. The agreement between IDAT and SAT results at different ELISA absorbance units (EAU) cut-offs (>79 and ≥300) was slight and fair for both investigators, respectively. A higher agreement was observed between IDAT and SAT (≥300 EAU) than between IDAT and SAT (>79 EAU) with the exception of mite and flea allergens. There was a statistically significant association between clinical history and positive IDAT results for seasonal allergens (Inv A and Inv B, p = 0.016). There was no significance between positive SAT results and clinical history. Five (IDAT) and 12 of 13 (SAT) atopic dogs without clinical seasonal exacerbation showed positive results for seasonal allergens.

CONCLUSIONS AND CLINICAL RELEVANCE

The agreement between IDAT and SAT ≥300 EAU results was fair and the agreement between IDAT and SAT >79 EAU results was slight for all allergens. Only positive IDAT results significantly correlated with clinical history.

A prospective study evaluating the correlation between local weather conditions, pollen counts and pruritus of dogs with atopic dermatitis

BACKGROUND

Canine atopic dermatitis (cAD) is a hereditary, generally pruritic and predominantly T-cell-driven inflammatory skin disease, involving an interplay between skin barrier abnormalities, allergen sensitisation and microbial dysbiosis. The individual immunological response is predominantly against environmental allergens, including mite antigens; mould spores; and pollen from grasses, trees and weeds. Airborne pollens show fluctuating patterns during the year.

OBJECTIVE

The aim of this prospective study was to evaluate the influence of local pollen concentrations and weather conditions on the clinical signs of atopic dogs, and to investigate any possible correlations with the results of intradermal testing (IDT).

MATERIALS AND METHODS

Thirty-seven privately owned atopic dogs in Bavaria were surveyed from 1 April to 30 November 2021. Owners were asked to record pruritus using a validated Visual Analog Scale (PVAS) score and the weekly medication of their dog. Furthermore, weather data, including pollen count, rainfall, relative humidity, hours of sunshine and temperature from the dog's location were collected daily.

RESULTS

Of the evaluated parameters, only humidity and medication scores correlated positively with the PVAS scores of the atopic dogs. There was no correlation between specific pollen counts and PVAS scores of dogs with positive IDT reactions to that pollen.

CONCLUSION AND CLINICAL RELEVANCE

The outcome of this study highlights the importance of a careful interpretation of positive IDT results in dogs with cAD and questions the validity of airborne pollen trap methodology in representing pollen exposure for dogs at ground level.

Effects of a Protocol Combining a Non-Irritating Shampoo and an Adelmidrol-Based Adsorbent Mousse on Seborrhoea and Other Signs and Symptoms Secondary to Canine Atopic Dermatitis: A Multicenter, Open-Label Uncontrolled Clinical Trial

The present study aimed at evaluating the effect of a gentle shampoo and a mousse containing Adelmidrol, tapioca starch and a non-prescription antimicrobial complex on seborrhoea and other clinical signs secondary to canine atopic dermatitis (cAD). Forty-six dogs with cAD-associated seborrhoea and/or pruritus > 4 cm on the pruritus visual analogue scale (P-VAS) and/or bacterial/Malassezia overgrowth were enrolled. The mousse was applied twice daily, and dogs were evaluated at days (D)0, 7, 14 and optionally 28, by means of a skin seborrheic index (SSI), P-VAS, cAD lesion index (CADLI), and a semiquantitative cytological score. The mean SSI value improved during the first two weeks (4.1 ± 0.37 to 1.9 ± 0.30; p < 0.0001). The mean P-VAS score (cm) decreased from 6.6 ± 0.19 at D0 to 3.8 ± 0.31 at D14 (p < 0.0001). The mean CADLI score dropped from 13.7 ± 1.24 to 8.5 ± 1.14 at D14 (p < 0.001). The cytological score for bacteria and Malassezia decreased from 3.2 ± 0.10 and 3.2 ± 0.11, respectively, to 1.2 ± 0.19 and 1.2 ± 0.24 (p < 0.0001). All the investigated signs further improved at D28. Altogether, these observations suggest that the tested protocol might be useful in managing cAD-associated signs.

PDE4D and miR-203 are promising biomarkers for canine atopic dermatitis

BACKGROUND

Canine atopic dermatitis (CAD) is a common genetically predisposed, inflammatory, and pruritic skin disorder that affects dogs globally. To date, there are no specific biomarkers available to diagnose CAD, and the current diagnosis is based on a combination of criteria including patient history, clinical signs, and exclusion of other relevant differential diagnoses.

METHODS AND RESULTS

We examined the gene expression of phosphodiesterase 4D (PDE4D) in peripheral blood mononuclear cells (PBMCs), as well as miR-203 and miR-483 in plasma, in three groups: healthy dogs, CAD dogs, and other inflammatory pruritic skin diseases (OIPSD) such as pemphigus foliaceus, scabies, cutaneous lymphoma, and dermatophytosis. Our results showed that PDE4D gene expression in the CAD group is statistically higher compared to those in the healthy and OIPSD groups, suggesting PDE4D may be a specific marker for CAD. Nevertheless, no correlation was found between PDE4D gene expression levels and the lesion severity gauged by CAD severity index-4 (CADESI-4). We also showed that miR-203 is a generic marker for clinical dermatitis and differentiates both CAD and OIPSD inflammatory conditions from healthy controls.

CONCLUSIONS

We show that PDE4D is a potential marker to differentiate CAD from non-atopic healthy and OIPSD while miR-203 may be a potential marker for general dermatologic inflammation. Future study of PDE4D and miR-203 on a larger scale is warranted.

Investigation of the relationship between atopic dermatitis of dogs and intestinal epithelial damage

BACKGROUND

A significant association between atopic dermatitis and leaky gut syndrome has been demonstrated in humans. No studies have been conducted to determine whether there is an association between atopic dermatitis and intestinal damage in dogs.

OBJECTIVES

This study aimed to determine whether there is an association between canine atopic dermatitis and intestinal damage using selected intestinal-related biomarkers.

METHODS

Twenty-six dogs with atopic dermatitis and 10 healthy dogs were included. Moderate-to-severe pruritus, erythema, erosion and alopecia on different parts of the body were sought in dogs to suspect atopic dermatitis. The presence of atopic dermatitis was confirmed by an allergic skin test. Serum biomarkers including intestinal fatty acid binding protein (I-FABP), intestinal alkaline phosphatase (IAP), trefoil factor-3 (TFF-3), immunoglobulin E (IgE), interleukin-4 (IL-4) and interleukin-13 (IL-13) concentrations were measured from venous blood samples.

RESULTS

Of the 26 dogs tested for allergens, 16 were found to be sensitive to mould mites, 10 to vernal grass, eight to house dust mites, five to wheat dust and five to grass pollen mix allergens. Significant increases in serum IAP, TFF-3, IgE, IL-4 and IL-13 concentrations were determined.

CONCLUSION

It was thought that the increase in TFF-3 and IAP concentrations may be due to the presence of intestinal epithelial damage and the repair of this damage. In addition, the development of atopic dermatitis may be predisposed to the entry of allergens into the body through sites of intestinal damage.

A randomized double-blind clinical trial: Comparison of oclacitinib with a traditional Chinese herbal medicine product (Dihuang Guiqin capsule) in the treatment of canine atopic dermatitis

Canine atopic dermatitis (cAD) is a common chronic inflammatory skin disease, which seriously affects the quality of life for both dogs and their owners. Currently, the common therapeutic drugs in the clinic have disadvantages such as obvious adverse effects and high prices. Traditional Chinese herbal medicine (TCHM) has great potential for the treatment of cAD. The aim of this study is to compare the effects of different doses of the TCHM product (Dihuang Guiqin capsule) and oclacitinib in the treatment of cAD through a randomized, double-blind trial. Sixty dogs diagnosed with AD were randomly and evenly divided into four groups (n = 15). The TCHM treatment group consisted of three subgroups that received three different oral doses (20, 40, and 60 mg/kg BW), while the control group received 0.5 mg/kg BW of oclacitinib. Each group was administered twice daily for 14 consecutive days. The results showed that both TCHM and oclacitinib significantly improved cAD-induced itching (evaluated by pVAS) and skin lesions (evaluated by CADESI-04), while interleukin 31 (IL-31) concentrations decreased significantly (P < 0.05) and serum biochemical indicators returned to normal. In particular, The therapeutic effects of TCHM medium- and high-dose groups were similar to those of oclacitinib (P > 0.05). The preliminary recommended dose of Dihuang Guiqin capsule for the treatment of cAD has been determined to be 40-60 mg/kg BW twice daily for 14 consecutive days, which can be reduced to once daily as appropriate. Dihuang Guiqin capsule was safe and well tolerated, which may be a new option for the treatment of cAD.

Influence of a single oral dose of trazodone on intradermal histamine reactivity in clinically healthy dogs

BACKGROUND

Drug interactions are significant considerations for intradermal testing (IDT). Trazodone (TRZ) is an anxiolytic and selective histaminergic (H1 ) antagonist with no interaction in human prick tests; however, interaction in canine IDT is unknown.

HYPOTHESIS/OBJECTIVES

Trazodone will not adversely affect intradermal histamine reactions in dogs.

ANIMALS

Fourteen nonanxious, nonatopic, healthy client-owned dogs were enrolled in this randomised, blinded, cross-over study.

MATERIALS AND METHODS

Dogs were randomised to receive low-dose TRZ (4 mg/kg) (Teva Pharmaceuticals), high-dose TRZ (8 mg/kg) or no TRZ per os two hours before intravenous sedation with dexmedetomidine (5 mcg/kg) (Dexdomitor; Zoetis). Intradermal testing was performed with five quadrupling dilutions of histamine (1:100,000 to 1:25,600,000 w/v; Greer) and 0.9% saline (Hospira), observing a minimum two weeks washout period between treatments. Two observers, who were blinded to treatment and the identity of the injections, evaluated each test using previously established subjective and objective methods.

RESULTS

The mean wheal diameter of histamine 1:1,600,000 w/v was significantly smaller with low-dose TRZ (4 mg/kg) compared to the control group (p = 0.048; repeated measures ANOVA with post hoc Tukey's test). For all other histamine dilutions and saline, mean wheal diameter was not significantly different among groups. There were no significant differences in the subjective scores of all histamine dilutions and saline (p > 0.05; Friedman test).

CONCLUSION AND CLINICAL RELEVANCE

A single oral dose of TRZ does not adversely affect intradermal histamine reactions in dogs.

Suppressive effect of Yokukansan on glutamate released from canine keratinocytes

Background

Canine atopic dermatitis (CAD) is caused by skin barrier dysfunction due to allergen exposure. Excessive glutamate release in the skin is associated with delayed skin barrier function recovery and epidermal thickening and lichenification. Treatment with Yokukansan (YKS), a traditional Japanese medicine, reduces dermatitis severity and scratching behavior in NC/Nga mice by decreasing epidermal glutamate levels. However, the association between canine keratinocytes and glutamate and the mechanism by which YKS inhibits glutamate release from keratinocytes remains unknown.

Aim

We aimed to investigate glutamate release from canine progenitor epidermal keratinocytes (CPEKs) and the inhibitory effect of YKS on this release. We also explored the underlying mechanism of YKS to enable its application in CAD treatment.

Methods

Glutamate produced from CPEKs in the medium at 24 hours was measured. The measurement conditions varied in terms of cell density and YKS concentration. CPEKs were treated with a glutamate receptor antagonist (MK-801), a glutamate transporter antagonist (THA), and a glutamate dehydrogenase inhibitor (epigallocatechin gallate; EGCG), and the inhibitory effect of YKS, YKS + THA, MK-801, and EGCG on this release was determined. MK-801 and glutamate dehydrogenase inhibitor were tested alone, and THA was tested in combination with YKS. Finally, glutamine incorporated into CPEKs at 24 hours was measured using radioisotope labeling.

Results

CPEKs released glutamate in a cell density-dependent manner, inhibited by YKS in a concentration-dependent manner. Moreover, YKS reduced the intracellular uptake of radioisotope-labeled glutamine in a concentration-dependent manner. No involvement of glutamate receptor antagonism or activation of glutamate transporters was found, as suggested by previous studies. In addition, EGCG could inhibit glutamate release from CPEKs.

Conclusion

Our findings indicated that glutamate release from CPEKs could be effectively inhibited by YKS, suggesting the utility of YKS in maintaining skin barrier function during CAD. In addition, CPEKs are appropriate for analyzing the mechanism of YKS. However, we found that the mechanism of action of YKS differs from that reported in previous studies, suggesting that it may have had a similar effect to EGCG in this study. Further research is warranted to understand the exact mechanism and clinical efficacy in treating CAD.

Update on the skin barrier, cutaneous microbiome and host defence peptides in canine atopic dermatitis

BACKGROUND

Canine atopic dermatitis (AD) is a complex inflammatory skin disease associated with cutaneous microbiome, immunological and skin barrier alterations. This review summarises the current evidence on skin barrier defects and on cutaneous microbiome dysfunction in canine AD.

OBJECTIVE

To this aim, online citation databases, abstracts and proceedings from international meetings on skin barrier and cutaneous microbiome published between 2015 and 2023 were reviewed.

RESULTS

Since the last update on the pathogenesis of canine AD, published by the International Committee on Allergic Diseases of Animals in 2015, 49 articles have been published on skin barrier function, cutaneous/aural innate immunity and the cutaneous/aural microbiome in atopic dogs. Skin barrier dysfunction and cutaneous microbial dysbiosis are essential players in the pathogenesis of canine AD. It is still unclear if such alterations are primary or secondary to cutaneous inflammation, although some evidence supports their primary involvement in the pathogenesis of canine AD.

CONCLUSION AND CLINICAL RELEVANCE

Although many studies have been published since 2015, the understanding of the cutaneous host-microbe interaction is still unclear, as is the role that cutaneous dysbiosis plays in the development and/or worsening of canine AD. More studies are needed aiming to design new therapeutic approaches to restore the skin barrier, to increase and optimise the cutaneous natural defences, and to rebalance the cutaneous microbiome.

A Randomized Controlled Trial to Evaluate the Impact of a Novel Probiotic and Nutraceutical Supplement on Pruritic Dermatitis and the Gut Microbiota in Privately Owned Dogs

Pruritic dermatitis (PD) is a common presentation of canine allergic skin diseases, with diversity in severity and treatment response due to complex etiopathogenesis. Evidence suggests the gut microbiota (GM) may contribute to the development of canine allergies. A 10-week double-blind randomized controlled trial evaluated a novel probiotic and nutraceutical blend (PNB) on clinical signs of skin allergy, health measures, and the GM of privately owned self-reported pruritic dogs. A total of 105 dogs were enrolled, with 62 included in pruritus and health analysis and 50 in microbiome analysis. The PNB supported greater improvement of owner-assessed clinical signs of PD at week 2 than the placebo (PBO). More dogs that received the PNB shifted to normal pruritus (digital PVAS10-N: <2) by week 4, compared to week 7 for the PBO. While a placebo effect was identified, clinical differences were supported by changes in the GM. The PNB enriched three probiotic bacteria and reduced abundances of species associated with negative effects. The PBO group demonstrated increased abundances of pathogenic species and reduced abundances of several beneficial species. This trial supports the potential of the PNB as a supplemental intervention in the treatment of PD; however, further investigation is warranted, with stricter diagnostic criteria, disease biomarkers and direct veterinary examination.

Establishment of an experimental model of ovalbumin-induced atopic dermatitis in canines

Introduction

A reliable standard model is required to evaluate the efficacy of new drugs for companion animals, especially dogs. Canine atopic dermatitis (cAD), also known as allergic inflammatory skin disease, is a common condition. Currently, the house dust mite animal model is used in the research of cAD; however, this model exhibits significant individual variation and is difficult to standardize. In this study, we used ovalbumin as an antigen to sensitize and stimulate dogs, thereby establishing a stable model mimicking the T-helper 2 (Th2) response seen in cAD. Our objective was to create a cAD model that could be employed to evaluate the efficacy of novel drugs and mimic the Th2 dominant allergic response observed in the pathogenesis of atopic dermatitis of dogs.

Methods

In this study, six beagles were used. Normal saline was applied to two animals, and ovalbumin to four, on their dorsal skin.

Results

The ovalbumin-treated groups exhibited clinical cAD symptoms, such as pruritus and erythema. Moreover, plasma levels of the cAD markers immunoglobulin E and CCL17 chemokine were higher in the ovalbumin-treated group than in the vehicle control group. The skin thickness of the epidermis was significantly increased in the ovalbumin-treated group, with infiltration of inflammatory cells observed in the thickened dermis region. In conclusion, treatment of canine skin with an optimal concentration of ovalbumin induced typical cAD-like symptoms, and histological and molecular analyses confirmed an enhanced Th2-related immune response.

Conclusion

Therefore, we successfully established a suitable Th2-dominant response mimicking cAD, which will facilitate targeted research of atopic dermatitis in dogs.

Canine amniotic membrane-derived mesenchymal stem cells ameliorate atopic dermatitis through regeneration and immunomodulation

Mesenchymal stem cells (MSCs) are a promising tool for treating immune disorders. However, the immunomodulatory effects of canine MSCs compared with other commercialized biologics for treating immune disorders have not been well studied. In this study we investigated the characteristics and immunomodulatory effects of canine amnion membrane (cAM)-MSCs. We examined gene expression of immune modulation and T lymphocytes from activated canine peripheral blood mononuclear cell (PBMC) proliferation. As a result, we confirmed that cAM-MSCs upregulated immune modulation genes (TGF-β1, IDO1 and PTGES2) and suppressed the proliferation capacity of T cells. Moreover, we confirmed the therapeutic effect of cAM-MSCs compared with oclacitinib (OCL), the most commonly used Janus kinase (JAK) inhibitor, as a treatment for canine atopic dermatitis (AD) using a mouse AD model. As a result, we confirmed that cAM-MSCs with PBS treatment groups (passage 4, 6 and 8) compared with PBS only (PBS) though scores of dermatologic signs, tissue pathologic changes and inflammatory cytokines were significantly reduced. In particular, cAM-MSCs were more effective than OCL in the recovery of wound dysfunction, regulation of mast cell activity and expression level of immune modulation protein. Interestingly, subcutaneous injection of cAM-MSCs induced weight recovery, but oral administration of oclacitinib induced weight loss as a side effect. In conclusion, this study suggests that cAM-MSCs can be developed as a safe canine treatment for atopic dermatitis without side effects through effective regeneration and immunomodulation.

Pilot study to determine the concordance between skin prick and intradermal test (IDT) reactivity to environmental allergens in atopic dogs using IDT as the gold standard

BACKGROUND

Prick testing is widely used as the first-line in vivo test for environmental allergens in people owing to its noninvasive nature and speed of performance.

OBJECTIVES

To determine concordance between skin prick testing (SPT) and intradermal testing (IDT) reactivity to environmental allergen mixes in dogs with atopic dermatitis (cAD).

ANIMALS

Forty client-owned dogs with cAD.

MATERIALS AND METHODS

Skin prick testing (GREER Pick System; Stallergenes Greer) and IDT were performed on 40 dogs using seven glycerinated and aqueous environmental allergen mixes, respectively (tree, grass and weed pollens, house dust mites and three mould mixes). Reactions for IDT and SPT were evaluated both subjectively and objectively (mean wheal diameter; MWD) and compared to saline and histamine controls.

RESULTS

Using IDT as the gold standard, with subjective scoring, SPT was 47.0% sensitive [95% confidence interval (CI) 36.0%-58.7%], 92.1% specific (95% CI 87.6%-95.3%) and agreement was moderate (79%, Cohen's kappa = 0.424). The positive predictive value of SPT was 36% and negative predictive value was 95%. Objective and subjective scores had only fair agreement.

CONCLUSIONS AND CLINICAL RELEVANCE

Skin prick testing with allergen mixes was specific yet poorly sensitive as compared to IDT. For both IDT and SPT, 95% (38 of 40) dogs failed to react to an allergen mix, despite showing a positive reaction to at least one component. Future studies comparing SPT and IDT should test individual allergens rather than mixes to prevent the dilution of individual components, which may have resulted in false negatives.

A randomised, double-blinded, controlled trial to determine the efficacy of combined therapy of oclacitinib and marine oil extract PCSO-524 in dogs with atopic dermatitis

BACKGROUND

Polyunsaturated fatty acids (PUFA) can be beneficial in the management of canine atopic dermatitis (cAD). A commercial product PCSO-524 containing PUFA has demonstrated anti-inflammatory effects in dogs.

HYPOTHESIS/OBJECTIVES

To evaluate the efficacy of PCSO-524, in combination with oclacitinib in dogs with cAD.

ANIMALS

Seventeen client-owned dogs with cAD.

MATERIALS AND METHODS

A randomised, double-blinded, controlled trial. All dogs were treated with oclacitinib (0.4-0.6 mg/kg) twice a day for 14 days, then once a day until Day (D)42. They were randomly divided into two groups: PCSO-524 (n = 9) and sunflower oil (n = 8). Clinical status was assessed by Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-04) and pruritus Visual Analog Scale (pVAS) at baseline (D0), D14, D28 and D42. Trans epidermal water loss (TEWL) was measured at the same time points.

RESULTS

CADESI scores decreased significantly after treatment and there was a significant difference between the PCSO-524 and the control group at D28 (p = 0.04) and D42 (p = 0.03). The PCSO-524 group also demonstrated a significantly decreased pVAS on D28 and D42 (p < 0.001 and p < 0.001) compared to D0, while significant differences were observed in the control group at D14 and D28 (p < 0.01 and p = 0.04) and not at D42 (p = 0.12). The mean TEWL showed a significant decrease at D28 and D42 in the PCSO-524 group, compared to the control group (p = 0.002 and p < 0.001).

CONCLUSIONS AND CLINICAL RELEVANCE

The combination of PCSO-524 and oclacitinib may help to alleviate the rebound effect that occurs when tapering down the dosage of oclacitinib, as compared to using oclacitinib alone for the management of cAD.

A retrospective study of treatment, outcome, recurrence and concurrent diseases in 190 dogs with anal sacculitis

BACKGROUND

Few studies report the treatment and recurrence rate in anal sacculitis (AS).

OBJECTIVES

Retrospective study reporting the management, recurrence and concurrent diseases in dogs with AS in a primary care practice.

ANIMALS

One hundred and ninety privately owned dogs in Sweden.

MATERIALS AND METHODS

Clinical records of dogs diagnosed with AS between 2018 and 2021 were reviewed, and management, time until clinical resolution, number of recurrent episodes and comorbidites were recorded.

RESULTS

The 190 dogs developed 290 episodes of AS. The most common management, in 235 of 290 (81.0%) episodes, was flushing ± infusion of an antimicrobial product into the sacs ± prescription of a nonsteroidal anti-inflammatory drug (NSAID), providing resolution in 213 of 235 (90.6%) episodes. Median time to resolution was one week (range 1-16 weeks), with resolution seen within one week in 205 of 290 (70.7%) episodes. A single episode of AS developed in 126 of 190 (66.3%) dogs. Dogs with concurrent cutaneous allergic disease were more likely (p < 0.001) to have recurrence of AS when compared to dogs with other comorbidities. Cutaneous allergic disease occurred more often (p < 0.001) in dogs with AS than in the practice population.

CONCLUSIONS AND CLINICAL RELEVANCE

Local treatment of the anal sacs ± systemic NSAID was the most common treatment, inducing clinical resolution in the majority of dogs. Cutaneous allergic disease was the most common concurrent diagnosis, with higher recurrence rate of AS compared to other diseases and occurring in higher prevalence than in the practice population. Further studies are needed to determine if management of cutaneous allergic disease would reduce the risk of AS.

Cross-reactive carbohydrate determinants in atopic and healthy dogs and their influence on allergy test specificity

BACKGROUND

The selection of allergens for immunotherapy in atopic dogs is often based on serum allergy testing. Cross-reactive carbohydrate determinants (CCDs) are common structures in plant and insect allergens that reportedly induce polysensitisation, reduce agreement between intradermal and serum tests and complicate allergen selection.

METHODS

Thirty-four dogs with diagnosed atopic dermatitis and 10 healthy dogs were included in the study. An intradermal test was conducted in atopic dogs, and serum samples from allergic and healthy dogs were analysed for allergen-specific immunoglobulin E (IgE) before and after inhibition of detectable anti-CCD-IgE antibodies.

RESULTS

Anti-CCD-IgE antibodies were not found in any of the healthy dogs and no polysensitisation to plant and insect allergens was detected. The agreement between intradermal and serum allergy test results in the atopic dogs with anti-CCD-IgE antibodies improved from slight to fair after blocking the anti-CCD-IgE antibodies. In addition, blocking clearly reduced polysensitisation to plant allergens but not to acarid allergens.

LIMITATIONS

Only a limited number of healthy dogs were tested in this study. A gold standard for determining the clinical relevance of IgE sensitisation does not exist.

CONCLUSION

Inhibition of anti-CCD-IgE antibodies seems to be of importance to improve serum test specificity for allergen-specific IgE in atopic dogs in relation to intradermal allergy testing.

Primary Prevention of Canine Atopic Dermatitis: Breaking the Cycle-A Narrative Review

Canine atopic dermatitis (cAD) is a common and distressing skin condition in dogs, affecting up to 30% of the canine population. It not only impacts their quality of life but also that of their owners. Like human atopic dermatitis (hAD), cAD has a complex pathogenesis, including genetic and environmental factors. Current treatments focus on managing clinical signs, but they can be costly and have limitations. This article emphasizes the importance of preventing cAD from developing in the first place. Understanding the role of the skin's protective barrier is crucial, as its dysfunction plays a vital role in both hAD and cAD. hAD prevention studies have shown promising results in enhancing the skin barrier, but more research is needed to support more robust conclusions. While hAD primary prevention is currently a focal point of intensive investigation in human medicine, research on cAD primary prevention remains under-researched and almost non-existent. Pioneering effective prevention strategies for cAD holds immense potential to enhance the quality of life for both dogs and their owners. Additionally, it bears the promise of a translational impact on human research. Hence, further exploration of this crucial topic is not only relevant but also timely and imperative, warranting support and encouragement.

Survey of Sensitization to Common Fungi in an Allergic Dog Population: The Need for Further Focus on Sensitization and Allergy to Fungi in Veterinary Medicine

Most fungal species are commensals and non-pathogenic to plants, humans, or animals. However, several species of the Alternaria, Aspergillus, Trichophyton, and Microsporum genera are common causes of disease, even for immunocompetent individuals. Besides mucosal damage, fungi may contribute to a skin barrier impairment, favoring sensitization and allergy development. A total of 68 allergic dogs were selected from a veterinary dermatology and allergy outpatient consultation for conditions related to both Malassezia overgrowth and other fungal complications. The allergy diagnosis was made through anamnesis and current clinical criteria, with the involved allergenic species being identified by intradermal tests (IDTs) and allergen-specific immunoglobulin E (sIgE) determination in serum. Dermatophagoides farinae, Dactylis glomerata, and Malassezia pachydermatis showed as the higher sensitization species from house dust mites, grass pollen, and fungi, respectively. Significant correlations at p < 0.05 were found between sensitization to Dactylis glomerata and Phleum pratense grass pollens, Dermatophagoides farinae and Dermatophagoides pteronyssinus, Acarus siro, Tyrophagus putrescentiae, and Lepidoglyphus destructor dust/storage mites, and between fungi like Aspergillus mix and Penicillium or Alternaria alternata. A significant correlation was also found between sensitization to the Aspergillus mix and D. farinae, D. pteronyssinus, or A. siro. Rather severe dermatitis was observed when a positive IDT to Malassezia pachydermatis was found, regardless of the detection of circulating sIgE, allowing us to consider the usefulness of both the IDT and the sIgE for a systematic diagnosis of allergy to fungi.

A review of cutaneous hypersensitivity reactions in dogs: A diagnostician's guide to allergy

Allergic dermatoses are common in people and domestic animals. Resultant lesions are routinely biopsied and submitted for histological examination to confirm a diagnosis or rule out diseases with overlapping or atypical clinical features. Diagnostic pathologists and clinicians are often faced with the difficult task of determining whether an allergic reaction pattern is present on both the microscopic and macroscopic levels and correlating histopathologic findings with clinical and historical data to achieve a precise clinical diagnosis. The bulk of the current veterinary literature on allergic dermatoses focuses on atopic dermatitis in dogs, distantly followed by cats, horses, and other animals. The objectives of this review are to demonstrate the key histopathologic and clinical diagnostic features of the various allergy-mediated reaction patterns, and to provide diagnosticians with a practical guide for clinicopathological correlations. Current concepts in the pathophysiology of immediate hypersensitivity reactions, with a focus on atopic dermatitis, are discussed. Points of potential histopathologic overlap between the "classic" allergic reaction pattern and less common inflammatory, predominately eosinophilic, conditions that may mimic this pattern will be discussed with the goal of highlighting the critical need for collaboration between pathologists and clinicians in furthering patient care.

Dermatological evaluation in dogs with atopic dermatitis treated with full-spectrum high cannabidiol oil: a pre study part 1

Introduction

Dermatological consultations represent a great part of the small animal medical clinic routine. Canine atopic dermatitis (CAD) is a common skin disease that affects a significant amount of dogs, making it a relevant consideration in clinical practice. The role of the endocannabinoid system on skin homeostasis has been described and its deregulation contributes to dermatopathies. Its function in specialized skin cells reveals an expressive therapeutic potential. Due to the difficulties and the growing scientific evidence of the therapeutic benefits of cannabis on animals, this work aimed to evaluate the anti-inflammatory effects of cannabis-derived oil in the treatment of CAD.

Methods

Fourteen canines diagnosed with CAD were divided into two groups: T: full spectrum high cannabidiol (CBD) cannabis oil, 2,5 mg/kg; and C: control group (treated with olive oil alone). The effectiveness was evaluated based on the degree of pruritus, dermatological evaluation (CADESI-4) and histopathological evaluation of the skin including mast cell count.

Results

Despite the theoretical basis, there were no significant results obtained between the compared treatments.

Discussion

Thus, it can be concluded that although full spectrum high cannabinoids therapy presents a promising approach to immunological diseases, further research is required in order to establish the actual effective cannabinoid ratio within the myriad possible combinations and for multi-target therapy of CAD.

A comprehensive analysis of gut and skin microbiota in canine atopic dermatitis in Shiba Inu dogs

BACKGROUND

Like its human counterpart, canine atopic dermatitis (cAD) is a chronic relapsing condition; thus, most cAD-affected dogs will require lifelong treatment to maintain an acceptable quality of life. A potential intervention is modulation of the composition of gut microbiota, and in fact, probiotic treatment has been proposed and tried in human atopic dermatitis (AD) patients. Since dogs are currently receiving intensive medical care, this will be the same option for dogs, while evidence of gut dysbiosis in cAD is still missing, although skin microbial profiling in cAD has been conducted in several studies. Therefore, we conducted a comprehensive analysis of both gut and skin microbiota in cAD in one specific cAD-predisposed breed, Shiba Inu. Additionally, we evaluated the impact of commonly used medical management on cAD (Janus kinase; JAK inhibitor, oclacitinib) on the gut and skin microbiota. Furthermore, we genotyped the Shiba Inu dogs according to the mitochondrial DNA haplogroup and assessed its association with the composition of the gut microbiota.

RESULTS

Staphylococcus was the most predominant bacterial genus observed in the skin; Escherichia/Shigella and Clostridium sensu stricto were highly abundant in the gut of cAD-affected dogs. In the gut microbiota, Fusobacteria and Megamonas were highly abundant in healthy dogs but significantly reduced in cAD-affected dogs. The abundance of these bacterial taxa was positively correlated with the effect of the treatment and state of the disease. Oclacitinib treatment on cAD-affected dogs shifted the composition of microbiota towards that in healthy dogs, and the latter brought it much closer to healthy microbiota, particularly in the gut. Additionally, even within the same dog breed, the mtDNA haplogroup varied, and there was an association between the mtDNA haplogroup and microbial composition in the gut and skin.

CONCLUSIONS

Dysbiosis of both the skin and the gut was observed in cAD in Shiba Inu dogs. Our findings provide a basis for the potential treatment of cAD by manipulating the gut microbiota as well as the skin microbiota. Video Abstract.

The safety of rush immunotherapy in the management of canine atopic dermatitis-230 cases

BACKGROUND

The duration of the induction phase of allergen-specific immunotherapy conventionally is a period of several weeks, during which the volume of an allergen solution, administered by injection, is gradually increased until the maintenance dose is reached. In rush immunotherapy (RIT), the induction period is abbreviated to achieve a faster improvement in clinical signs of atopic dermatitis (AD) compared to conventional immunotherapy.

OBJECTIVE

The aim of this retrospective study was to evaluate the safety of RIT in 230 dogs with AD and report any adverse effects (AE).

ANIMALS

Two hundred thirty client-owned dogs.

MATERIALS AND METHODS

Medical records of dogs receiving RIT between 2012 and 2021 were analysed and observed AE were investigated. All dogs underwent RIT following a protocol of subcutaneous allergen extract injections, given hourly with an incrementally increasing volume from 0.1 to 1.0 mL.

RESULTS

Adverse effects were documented in 6 of 230 (2.6%) dogs. Five of these dogs (2.2%) showed mild gastrointestinal signs (1 of 5 vomiting, 4 of 5 diarrhoea) and one patient an increase in body temperature by 1.5°C. These occurred at different stages of the RIT protocol. All AE were graded as mild and self-limiting.

CONCLUSIONS AND CLINICAL RELEVANCE

Based on these data, supervised RIT in dogs appears to be a safe procedure to achieve the maintenance dose of allergen immunotherapy earlier with infrequent and mild AE.

Comparison of the quantity and antimicrobial activity of host defence peptides in ear canals between healthy and atopic dogs: A preliminary study

BACKGROUND

Host defence peptides (HDPs) are involved in cutaneous immune defence. The secretion of HDPs in the ears of healthy normal and noninfected atopic dogs has not been measured.

HYPOTHESES/OBJECTIVES

The aim of this study was to quantify the concentrations of β-defensins (cBD3)-like and cathelicidin (cCath) HDPs in ears of healthy and atopic dogs without infectious otitis, additionally to evaluate the antimicrobial effect of the HDPs obtained.

ANIMALS

Ten healthy and 20 atopic dogs with mild inflammatory, noninfectious otitis were included.

MATERIALS AND METHODS

Absence of infection was determined by cytological evaluation, and the severity of clinical signs, if present, was assessed by a previously validated score (Otitis Externa Scoring System for Clinical Study, OTIS-3). The left ear canal of each dog was rinsed with 2 mL of sodium phosphate buffer. The solution obtained was analysed by enzyme-linked immunosorbent assay to quantify HDPs. Additionally, aural secretions were incubated with two concentrations (5 × 105 and 5 × 104 colony-forming units/mL) of Staphylococcus pseudintermedius and the bacterial density measured after 24 h of incubation. Data were statistically analysed. Significance was set as p ≤ 0.05.

RESULTS

There was a significantly lower concentration of HDPs from atopic ears when compared with those from normal healthy dogs (cBD3-like: p = 0.0007; cCath: p = 0.049). There was minimal to variable antimicrobial activity in the aural secretions of both groups.

CONCLUSIONS AND CLINICAL RELEVANCE

This study showed, for the first time, that the ear canals of atopic dogs with mild noninfectious otitis contain a lower concentration of cBD3-like and cCath HDPs than those of healthy dogs with normal ears. A consistent antimicrobial activity was not present in the aural secretions from either group.

High-frequency ultrasound biomicroscopy findings of the skin of dogs with atopic dermatitis

BACKGROUND

The high-frequency ultrasonographic appearance of skin of dogs with atopic dermatitis (cAD) has not been described.

OBJECTIVES

To compare high-frequency ultrasonographic findings among lesional, macroscopically nonlesional skin of dogs with cAD, and the macroscopically nonlesional skin of healthy dogs. Additionally, to determine whether there is any correlation between the ultrasonographic findings in lesional skin and local Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-04) or its domains (erythema, lichenification, excoriations/alopecia). As a secondary aim, six cAD dogs were re-evaluated after management intervention.

ANIMALS

Twenty dogs with cAD (six were re-examined after treatment) and six healthy dogs.

MATERIALS AND METHODS

In all dogs, ultrasonographic examination was performed on the same 10 skin sites, using a 50 MHz transducer. Wrinkling of skin surface, presence/width of subepidermal low echogenic band, hypoechogenicity of dermis and thickness of the skin were evaluated and scored/measured blindly.

RESULTS

Dermal hypoechogenicity was more common and severe in lesional compared to macroscopically nonlesional skin of dogs with cAD. In lesional skin, presence/severity of wrinkling of skin surface and of dermal hypoechogenicity were positively correlated with presence/severity of lichenification, while severity of dermal hypoechogenicity was positively correlated with local CADESI-04. A positive correlation between the change in skin thickness and the change in the severity of erythema during treatment was noted.

CONCLUSIONS AND CLINICAL RELEVANCE

High-frequency ultrasound biomicroscopy may be useful for the evaluation of skin of dogs with cAD and for evaluating the progression of skin lesions during treatment.

Hymenoptera Venom Immunotherapy in Dogs: Safety and Clinical Efficacy

Hymenoptera allergens are the main triggers for anaphylaxis in susceptible dogs and humans. Hymenoptera venom specific immunotherapy (VIT), the only disease-modifying treatment, has the potential to prevent future life-threatening reactions in human patients. Prospective clinical data on VIT efficacy in dogs are currently lacking. Therefore, the aim of this study was to show that VIT is not only safe but also efficacious in preventing anaphylaxis in dogs allergic to Hymenoptera. This uncontrolled prospective clinical trial included 10 client-owned dogs with a history of anaphylaxis following repeated Hymenoptera stings. The sensitization to bee and wasp allergens was demonstrated by intradermal testing (IDT) and allergen-specific IgE serology. For VIT induction (induction phase), dogs received a shortened rush immunotherapy protocol with aqueous allergens, which was then followed by monthly injections of 100 µg of alum-precipitated allergen (maintenance phase). VIT efficacy was determined by observing patients' clinical reactions to re-stings. No systemic adverse events were seen during the induction and maintenance phases. From the seven re-stung dogs, only one developed a mild angioedema at the site of the sting; the remaining dogs were asymptomatic. These results show that VIT represents a safe and effective treatment option for Hymenoptera-allergic dogs.

Diminished antimicrobial drug use in dogs with allergic dermatitis treated with oclacitinib

Introduction

Dogs with allergic dermatitis often suffer concurrent skin and ear infections. The objective of this study was to retrospectively quantify the number of systemic and topical antimicrobial transactions in dogs with allergic dermatitis, following administration of oclacitinib or a glucocorticoid, compared to dogs that did not receive a pruritus therapy when there is an initial diagnosis of pyoderma. A secondary objective was to demonstrate that dogs on oclacitinib use fewer antimicrobials and concomitant therapies over time and have improved quality of life.

Materials and methods

This was a retrospective case-control study using a large, centralized database to identify canine patients receiving pruritus therapy along with a concurrent diagnosis of pyoderma. For the second objective, 58 client-owned dogs diagnosed with allergic dermatitis were enrolled in a prospective owner and dog quality of life and treatment satisfaction (QoL&TS) study that also evaluated concomitant therapy use over time. In Part A, data consisted of anonymous transaction records from 1,134 hospitals across the United States, representing pyoderma visits between December 2018 and December 2019. Odds ratios comparing the relative odds of having additional antimicrobial agent transactions were calculated, given initial pruritus therapy compared to dogs that did not receive pruritus therapy. Parametric bootstrapping was used to calculate goodness-of-fit statistics. In part B, dogs entered the study on Day 0 and returned for examination on Days 14, 21, 30, and 60. Owner determination of QoL&TS was performed on Days 0, 1, 3, 14, 21, 30, and 60. On Days 0, 14, 21, and 60, a veterinarian assessed concomitant therapies and dermatitis severity scoring. Least Squares Means and Standard Errors for QoL&TS, and Dermatitis Vet VAS (Visual Analog Scale) Scores were calculated using a Linear Mixed Model Approach for Repeated Measures (α = 0.05). The percent reduction in therapies was also calculated.

Results

Dogs that received oclacitinib (n = 5,132) or a glucocorticoid (n = 7,024) had reduced odds (OR: 0.8091; p = 0.0002 and OR: 0.7095; p < 0.0001, respectively) of having a follow up antimicrobial drug transaction after initial antimicrobial therapy compared to dogs with no pruritus therapy at the initial visit (n = 12,997). In part B, oclacitinib demonstrated a statistically significant improvement in QoL&TS scores over time QoL (p < 0.05). Veterinarian assessment showed a 70% reduction in dermatitis severity over time (p < 0.05), supporting oclacitinib's anti-inflammatory effects. Oclacitinib therapy was also associated with an 83% reduction in concomitant treatments, including a 100% reduction in systemic antimicrobial therapy over eight weeks.

Discussion

Dogs receiving oclacitinib showed no increase in antimicrobial therapy transactions compared to glucocorticoid recipients at the initial pyoderma diagnosis. Having a pruritus therapy at the index pyoderma visit reduced the odds of subsequent antimicrobial transactions. In addition to reducing concomitant therapy usage, oclacitinib improved owner and pet QoL, suggesting a paradigm shift in treatment success that could reshape allergic pruritus therapy recommendations. The study provides empirical evidence of oclacitinib's reduction in antibacterial therapy, supporting its therapeutic value and antimicrobial stewardship.

Effect of Allergen-Specific Immunotherapy on Transcriptomic Changes in Canine Atopic Dermatitis

Canine atopic dermatitis (cAD) is a genetic, chronic, and recurrent inflammatory and pruritic skin disorder. Allergen-specific immunotherapy (ASIT) is presently recognized as the only clinically effective disease-modifying treatment for allergies. The aim of our study was to analyze the changes in gene expression observed in the peripheral blood nuclear cells of cAD patients subjected to ASIT. Blood samples designated for transcriptomic analyses were collected from AD dogs twice, before and six months after ASIT, and also from healthy dogs. Statistical analysis revealed 521 differentially expressed transcripts, among which 241 transcripts represented genes with well-described functions. Based on the available literature, we chose nine differentially expressed genes (RARRES2, DPP10, SLPI, PLSCR4, MMP9, NTSR1, CBD103, DEFB122, and IL36G) which may be important in the context of the dysregulated immune response observed in cAD patients. The expressions of five out of the nine described genes (DPP10, PLSCR4, NTSR1, DEFB122, and IL36G) changed after the application of ASIT. The expressions of three of these genes returned to the level observed in the healthy control group. The genes listed above need further investigation to determine details of their role in the molecular mechanism of immune tolerance induction in response to allergen-specific immunotherapy.

Part 1: Understanding the role of Malassezia spp. in skin disorders: Malassezia yeasts as commensal or pathogenic organisms of human and animal skin

INTRODUCTION

Malassezia spp. are a group of lipid-dependent basidiomycetes yeasts acting as commensal organisms of the human and animal skin. However, under some not well-defined circumstances, these yeasts may switch to opportunistic pathogens triggering a number of skin disorders with different clinical presentations. The genus comprises of 18 lipid-dependent species with a variable distribution in the hosts and pathologies thus suggesting a host- and microbe-specific interactions.

AREA COVERED

This review highlighted and discussed the most recent literature regarding the genus Malassezia as a commensal or pathogenic organisms highlighting Malassezia-associated skin disorders in humans and animals and their antifungal susceptibility profile. A literature search of Malassezia associated skin disorders was performed via PubMed and Google scholar (up to May 2023), using the different keywords mainly associated with Malassezia skin disorders and Malassezia antifungal resistance.

EXPERT OPINION

Malassezia yeasts are part of the skin mycobiota and their life cycle is strictly associated with the environment in which they live. The biochemical, physiological, or immunological condition of the host skin selects Malassezia spp. or genotypes able to survive in a specific environment by changing their metabolisms, thus producing virulence factors or metabolites which can cause skin disorders with different clinical presentations.

A 40-YEAR (1980-2019) RETROSPECTIVE REVIEW OF MORBIDITY AND MORTALITY OF FENNEC FOXES (VULPES ZERDA) AT THE BRONX AND PROSPECT PARK ZOOS

The Wildlife Conservation Society (WCS) has housed fennec foxes (Vulpes zerda) at its facilities since the early 1900s and currently has one of the largest populations managed by the fennec fox Species Survival Plan. Of the 83 foxes held by WCS institutions between 1980 and 2019, 52 medical records and 48 postmortem reports were available for review. Common causes of morbidity included trauma and dermatologic disease, especially atopic dermatitis. Average age at death for animals surviving past 10 wk was 9.76 yr. Common causes of death or euthanasia were neoplasia (15/48, 31%) and infectious disease (14/48, 29%), with neoplastic processes incidentally identified in an additional seven animals. Significant antemortem cardiac changes were identified in 22 animals. Hepatocellular carcinoma (HCC) was diagnosed in nine animals, consistent with previous documentation of HCC as one of the most common neoplasms in this species. Four animals were suspected to have succumbed to vaccine-induced canine distemper virus after receiving a modified live vaccine. No canine distemper infections have been documented after 1981 in this population and since the use of a canarypox-vectored recombinant vaccine. Recommendations for management of this species include routine screening for hepatic neoplasia in adult animals, regular cardiac evaluations including electrocardiogram, echocardiogram, and dermatologic examination as described by the current consensus statement on canine atopic dermatitis. This descriptive morbidity and mortality report is the first for the fennec fox.

A Review of Clinical Outcomes, Owner Understanding and Satisfaction following Medial Canthoplasty in Brachycephalic Dogs in a UK Referral Setting (2016-2021)

Brachycephalic breeds have increased in popularity despite growing awareness of their predisposition to a wide range of conformation-related diseases. The extreme facial conformation of many popular brachycephalic breeds compromises their ocular surface health, increasing the risk of painful corneal ulceration. Medial canthoplasty (MC) is a surgical procedure to address ocular abnormalities in brachycephalic dogs, which are collectively referred to as brachycephalic ocular syndrome (BOS). This study retrospectively reviewed the records of dogs recommended MC at a referral hospital between 2016 and 2021. A questionnaire was designed to identify owners' perceptions pre- and post-operatively. From 271 brachycephalic dogs recommended MC, 43.5% (118/271) underwent surgery and 72.0% (85/118) were Pugs. The majority of dogs (73.7%, 87/118) that underwent surgery had current or historical corneal ulceration. Follow-up was available in 104 dogs, of which 5.7% (6/104) had corneal ulceration post-operatively. Sixty-four owners completed the questionnaire and reported post-operative corneal ulceration in 12.5% of dogs (8/64), reduced ocular discharge (70.8%, 34/48), reduced ocular irritation (67.7%, 21/31) and less periocular cleaning (52.5%, 32/61). Owners were satisfied with the clinical (85.9%, 55/64) and cosmetic (87.5%, 56/64) outcome. In conclusion, MC has high clinical relevance for the surgical management of BOS, restoring functional conformation and improving the quality of life of affected dogs.

First identification of Tyrophagus curvipenis (Acari: Acaridae) and pathogen detection in Apis mellifera colonies in the Republic of Korea

Mites of the genus Tyrophagus (Acari: Acaridae) are among the most widely distributed mites. The species in this genus cause damage to stored products and crops, and pose a threat to human health. However, the influence of Tyrophagus spp. in apiculture remains unknown. In 2022, a study focusing on the identification of Tyrophagus species within five apiaries was conducted in Chungcheongnam Province, Republic of Korea. Its specific objective was to investigate the presence of Tyrophagus mites in response to the reported high mortality of honey bee colonies in this area. Morphological identification and phylogenetic analysis using the mitochondrial gene cytochrome-c oxidase subunit 1 (CO1) confirmed for the first time the presence of the mite species Tyrophagus curvipenis in a honey bee colony in the Republic of Korea. Two honey bee pathogens were detected in the mite, a viral pathogen (deformed wing virus, DWV) and a protozoal pathogen (Trypanosoma spp.). The presence of the two honey bee pathogens in the mite suggests that this mite could contribute to the spread of related honey bee diseases. However, the direct influence of the mite T. curvipenis on honey bee health remains unknown and should be further investigated.

Pilot evaluation of a single oral fecal microbiota transplantation for canine atopic dermatitis

The gut microbiota has been suggested to be involved in the pathogenesis of canine atopic dermatitis (cAD). However, the gut microbiota has not been well characterized in dogs with atopic dermatitis (AD). In addition, the efficacy of fecal microbiota transplantation (FMT) in dogs with AD remains unclear. This research, therefore, aimed to characterize the gut microbiota of dogs with AD and conduct pilot evaluation of the efficacy of a single oral FMT on clinical signs and the gut microbiota of dogs with AD. For these purposes, we used 12 dogs with AD and 20 healthy dogs. The 16S rRNA analysis of the fecal microbiota revealed significant differences between 12 dogs with AD and 20 healthy dogs. Next, a single oral FMT was performed in 12 dogs with AD as a single-arm, open-label clinical trial for 56 days. A single oral FMT significantly decreased Canine Atopic Dermatitis Extent and Severity Index (CADESI)-04 scores from day 0 (median score, 16.5) to day 56 (8) and Pruritus Visual Analog Scale (PVAS) scores from days 0 (median score, 3) to day 56 (1). Furthermore, a single oral FMT changed the composition of the fecal microbiota of dogs with AD at the phylum and genus levels. The number of common amplicon sequence variants in the fecal microbiota between donor dogs and dogs with AD was positively correlated with CADESI-04 and PVAS reduction ratios 56 days after FMT. Our findings suggest that the gut microbiota plays a pivotal role in the pathogenesis of cAD, and that oral FMT could be a new therapeutic approach targeting the gut microbiota in cAD.

Canine dermatitis on contacting grass leaf: A case series

BACKGROUND

Pruritus is a common clinical sign in dogs for which owners seek veterinary attention. Its diagnosis and treatment are often a source of frustration for the owner and veterinarian. Contact dermatitis is rarely considered, even when lesions are located only on the skin. This report describes the immediate reaction to grass leaf material after skin exposure, with similarities to human protein contact dermatitis.

HYPOTHESIS/OBJECTIVE

To describe the history, clinical findings, diagnostic methods, and characteristics of an undescribed canine pruritic dermatitis that is clinically distinct from canine atopic dermatitis and contact dermatitis.

ANIMALS

Eighteen pet dogs living in Australia were referred for unresolved pruritic dermatitis.

MATERIALS AND METHODS

Retrospective analysis of clinical records from patients with pruritic dermatitis after contacting grass leaves. Findings on skin testing, isolation, challenge, and description of skin lesions are described.

RESULTS

Dogs had an inflammatory and pruritic dermatitis affecting the ventral chest, anterior-medial thighs and distal limb, areas that had been in contact with grass, which dogs instinctively avoided. Erythema and erythematous macules and papules were characteristic in the affected skin, inducing coat loss, and thickened pigmented skin. Isolating the dogs from grass resolved their clinical signs and pruritus returned within hours of contact with causative grass.

CONCLUSION AND CLINICAL IMPORTANCE

A literature review revealed that this canine dermatitis was similar to human protein contact dermatitis. The impact may be enormous for the treatment of dogs having this disease because the treatment path differs from the therapeutic options of common canine pruritic skin disorders, including the possibility of cure by avoidance.

A randomised controlled trial testing the rebound-preventing benefit of four days of prednisolone during the induction of oclacitinib therapy in dogs with atopic dermatitis

BACKGROUND

A rebound of pruritus occasionally occurs after oclacitinib dose reduction in dogs with atopic dermatitis (AD).

OBJECTIVES

To determine whether an initial 4-day course of prednisolone decreases the probability of a pruritus rebound after reducing the frequency of oclacitinib administration.

ANIMALS

Forty dogs with mild-to-moderate AD lesions and moderate-to-severe pruritus.

MATERIALS AND METHODS

Dogs were randomised to receive oclacitinib at 0.4-0.6 mg/kg twice daily for 14 days then once daily, alone or with prednisolone at 0.5 mg/kg, orally, twice daily for the first 4 days. Clinicians graded the Canine Atopic Dermatitis Extent and Severity Index (CADESI)4 and 2D-investigator global assessment (IGA) before and after 28 days; owners assessed the pruritis Visual Analog Scale (PVAS)10 and Owner Global Assessment of Treatment Efficacy (OGATE) on Day (D)0, D4, D14, D21 and D28. We considered a rebound any increase greater than one PVAS10 grade at D21 compared to D14.

RESULTS

On D21, there were significantly fewer rebounds in the dogs receiving prednisolone (three of 20, 15%) compared to those given oclacitinib alone (nine of 20, 45%; Fisher's test, p = 0.041). Compared to oclacitinib monotherapy, the concurrent administration of prednisolone for the first 4 days led to significantly lower PVAS10 on D4 and D28, CADESI4 and 2D-IGA on D28, and OGATE on D21 and D28 (Wilcoxon-Mann-Whitney U-tests). Adverse effects of therapy were minor, intermittent and self-resolving.

CONCLUSIONS AND CLINICAL RELEVANCE

The initial addition of 4 days of prednisolone significantly decreased the probability of a rebound of pruritus 1 week after oclacitinib dose reduction. This short concomitant glucocorticoid administration led to a higher skin lesion improvement and improved perception of treatment efficacy with minimal adverse effects.

Long-term effects of ciclosporin and oclacitinib on mediators of tolerance, regulatory T-cells, IL-10 and TGF-β, in dogs with atopic dermatitis

BACKGROUND

Atopic dogs often are managed with allergen-specific immunotherapy (AIT) and concurrent dosages of ciclosporin (CSA) or oclacitinib to alleviate their clinical signs. Both drugs might affect proper tolerance induction by inhibiting regulatory T-cell (Treg) induction.

HYPOTHESIS/OBJECTIVES

We evaluated Treg cell numbers and serum interleukin (IL)-10 and transforming growth factor-beta (TGF-β)1 levels in dogs diagnosed with atopic dermatitis (AD) and successfully treated with either CSA or oclacitinib for nine or more months.

ANIMALS

We included 15 dogs receiving oclacitinib, 14 dogs treated with CSA, 15 healthy dogs, 13 dogs with untreated moderate-to-severe AD and 15 atopic dogs controlled with AIT.

MATERIALS AND METHODS

Peripheral blood CD4+CD25+FOXP3+ T-cell percentages were determined using flow cytometry. Serum concentrations of IL-10 and TGF-β1 were measured by enzyme-linked immunosorbent assay.

RESULTS

The percentage of Treg cells in the CSA group was significantly lower in comparison with the healthy group (p = 0.0003), the nontreated AD group (p = 0.0056) or the AIT group (p = 0.0186). There was no significant difference in Treg cell percentages between the CSA and oclacitinib groups, nor between the oclacitinib and the healthy, nontreated AD or AIT-treated dogs. No significant differences were detected in IL-10 and TGF-β1 serum concentrations between the five groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Lower Treg cell percentages in the CSA-treated dogs suggest an impact of this drug on this cell population; however, it does not necessarily mean that it diminishes tolerance. Functionality and cytokine production may be more important than the number of Treg cells. Further studies evaluating the treatment outcome of dogs receiving AIT and concurrent drugs are needed to show clinical relevance.

Nasal microbiota profiles in shelter dogs with dermatological conditions carrying methicillin-resistant and methicillin-sensitive Staphylococcus species

Dermatological conditions may be complicated by Staphylococcus spp. infections influencing skin and nasal microbiota. We investigated the associations between the resident nasal microbiota of shelter dogs with and without dermatological conditions carrying methicillin-resistant and -sensitive Staphylococcus spp. Nasal sampling of 16 dogs with and 52 without dermatological conditions were performed upon shelter admission (baseline), and then bi-weekly until discharge (follow-up). All samples were cultured for Staphylococcus spp., while 52 samples underwent microbiota analysis. Two elastic net logistic regression (ENR) models (Model 1-baseline samples; Model 2-follow-up samples) were developed to identify predictive associations between dermatological conditions and the variables: signalment, antimicrobial treatment, and nasal microbial genera. Follow-up nasal samples of dogs with dermatological conditions had decreased microbiota diversity and abundance compared to dogs without dermatological conditions. Our ENR models identified predictive differences in signalment and nasal microbial genera between baseline and follow-up samples. Co-occurrence networks showed nasal microbial genera were more dissimilar when comparing dogs with and without dermatological conditions at follow-up. Overall, this study is the first to investigate Staphylococcus spp. carriage effects on nasal microbial genera in a canine animal shelter population, and ultimately reveals the importance of investigating decolonisation and probiotic therapies for restoring nasal microbiota.

Phosphorylation of Janus kinase 1 and signal transducer and activator of transcription 3 and 6 in keratinocytes of canine atopic dermatitis

BACKGROUND

Canine atopic dermatitis (cAD) is a disease associated with Type 2 helper T (Th2) immune responses in the acute phase of the disease. In humans, keratinocytes are activated by Th2 cytokines via the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. However, the activation of keratinocytes by Th2 cytokines in cAD has not yet been demonstrated.

HYPOTHESIS/OBJECTIVES

To evaluate keratinocyte activation based on the phosphorylation (p) of JAK1, STAT3 and STAT6.

ANIMALS

Seven dogs with cAD and three healthy dogs.

MATERIALS AND METHODS

Immunohistochemical analysis was performed to detect pJAK1, pSTAT3 and pSTAT6 in keratinocytes in normal canine skin, and the skin of atopic dogs. In the latter group samples were collected from both primary and secondary lesions, and nonaffected skin.

RESULTS

The percentage of pJAK1-positive keratinocytes was significantly higher in primary cAD lesions than in healthy skin (p < 0.05). No significant differences were observed in pSTAT3-positive keratinocytes among the groups. The percentage of pSTAT6-positive keratinocytes was significantly higher in primary and secondary lesions than in healthy skin (p < 0.05, respectively).

CONCLUSIONS AND CLINICAL RELEVANCE

The novel finding in this study was the activation of keratinocytes as demonstrated by the phosphorylation of JAK1/STATs in lesional and nonlesional cAD skin. These results suggest the potential of not only JAK1, but also of STAT6 as therapeutic targets for cAD.

Lack of Interference of Oclacitinib with the results of intradermal testing or allergen-specific IgE serology in Dermatophagoides farinae-sensitized beagle dogs

Canine atopic dermatitis (AD) is associated with increased levels of allergen-specific IgE due to hyper-sensitization to environmental allergens. Intradermal testing (IDT) and allergen-specific IgE serology testing are often used to determine the allergens which elicit an IgE response in animals with a diagnosis of AD. The objective of this study was to determine the effects of oclacitinib on IDT and allergen-specific IgE serology testing using a laboratory model of house-dust mite sensitized Beagle dogs. Twenty-four (24) normal, healthy purpose-bred Beagle dogs were sensitized to house dust mites (HDM, Dermatophagoides farinae) and randomly assigned to placebo-, oclacitinib- (0.4 mg/kg/dose PO), or prednisolone-treated (0.5 mg/kg/dose PO) groups. After 14 days of twice daily dosing, the effects of prednisolone and oclacitinib were compared to placebo using baseline and post-dose IDT and allergen-specific IgE serum measurements. Sensitized dogs had increased circulating HDM-specific IgE for at least two weeks post-sensitization. Prednisolone significantly inhibited the measurable sensitivity of IDT, while oclacitinib did not. Neither prednisolone nor oclacitinib imposed significant effects on allergen-specific IgE serum levels, suggesting oclacitinib may have potential to be used in dogs concurrently undergoing intradermal skin testing and/or allergen-specific IgE serology testing without interference with test results.

Investigation of the diagnostic performance of prick test with two environmental allergens in dogs with atopic dermatitis: A study using intradermal test as the gold standard

BACKGROUND

There are no studies investigating the correlation between prick test (PT) and intradermal test (IDT) with environmental allergens in dogs with atopic dermatitis (AD).

OBJECTIVES

To investigate the correlation between PT and IDT for two environmental allergens, and to calculate the sensitivity, specificity and Youden index of PT, using IDT as the gold standard.

MATERIALS AND METHODS

Twenty-two dogs with AD were selected. PT was performed with glycerinated allergen extracts, along with negative and positive controls, using the Greer Prick System. Reactions were interpreted (positive/negative) subjectively and by using seven objective criteria, by an examiner blinded to the IDT results. IDT reactions to the same allergens were interpreted, subjectively and objectively, by another masked investigator. The agreement between PT and IDT, the sensitivity, specificity and Youden index of PT, using IDT as gold standard, were calculated.

RESULTS

On subjective evaluation, the correlation between PT and IDT was poor and sensitivity of PT was 0%. Of the seven criteria for the objective evaluation of PT, the best diagnostic performance was attained when allergen-induced wheals were considered positive if their longest diameter was ≥8.5 mm. However, even then, the correlation with IDT was moderate, and the sensitivity of PT, albeit based on few positive IDT reactions, was low.

CONCLUSION AND CLINICAL RELEVANCE

At least as performed herein, PT has a poor-to-moderate correlation with IDT, mainly as a consequence of the lack of positive PT reactions. Further studies are needed to improve PT technique, yet, meanwhile, it cannot be recommended as a substitute for IDT.

Performance and Tolerance of a Protocol for Idiopathic Chronic Greasy Seborrhea in 18 Dogs Using a Shampoo and Mousse Containing Plant Extracts

The study aimed to evaluate the tolerance, performance and effect on hair lipids and skin hydration of a protocol combining applications of one shampoo and subsequent mousses containing plant extracts (Ophytrium and Seboliance) in dogs with an undiagnosed chronic greasy keratinisation disorder. Six dogs were washed with plain water on day (D)0. Twelve dogs were shampooed on D0 and received eight mousse applications at 48-72 h intervals from D2 to D18. Clinical score (CS), Natural Moisturizing Factors (NMF) and hair lipids (HL) were evaluated on D0, D0 + 4 h, D7, D14 and D24. At baseline, no significant differences were observed in CS, NMF and HL between groups. In the control group, CS and HL remained stable throughout the study while a slight decrease in NMF was observed at D0 + 4 h. CS was significantly reduced in the test group between D0 and D7 (-53%) which reached 91% at D24 (p < 0.05), with no side effects. NMF levels decreased in the test group at D0 + 4 h (-73%, p < 0.0001) and returned to baseline from D14. In conclusion, one shampoo and subsequent mousse applications rapidly and safely improved coat quality in dogs with an undiagnosed keratinisation disorder without affecting NMF and HL contents over the study period.

Induction of autophagy improves skin and hair conditions in dogs with underlying diseases

Background

Autophagy was reported to play a crucial role in maintaining general and skin health.

Methods

The study used a synthesized autophagy inducer (AI) (Aquatide™ cospharm Inc.; Daejeon, Korea), for evaluating the effects of autophagy on skin and hair in dogs. Twenty-two dogs with poor skin and hair which were diagnosed with canine atopic dermatitis (CAD) or pituitary-dependent hyperadrenocorticism (PDH) were included. Clinical scores using Canine Atopic Dermatitis Extent and Severity Index-04 (CADESI-04), Pruritus Visual Analog Scale (PVAS) and skin barrier function using measurement of transepidermal water loss (TEWL) were evaluated and canine keratinocytes were also used in vitro investigation of pro-inflammatory cytokines after AI treatment.

Results

In the AI group, clinical scores and skin barrier function were improved at week 8 significantly compared to in the other groups. In particular, the AI significantly improved the hair surface damage at 8 weeks compared to the baseline. In vitro, the AI reduced pro-inflammatory cytokines by activating the 78-kDa glucose-regulated protein (GRP78).

Conclusion

AI improve skin barrier function and hair damage and reduce pro-inflammatory cytokines by inhibiting reactive oxygen species (ROS) production in dogs.

Quality of Life of Allergic Dogs Treated with Allergen-Specific Immunotherapy-A Retrospective Study

BACKGROUND

The quality of life (QoL) of dogs with canine atopic dermatitis (CAD) treated with allergen-specific immunotherapy (ASIT) was studied to determine whether the QoL of dogs treated with ASIT (AG) improved compared with dogs not treated with ASIT (CG).

METHODS

The power of the study was calculated in advance assuming that the AG would assess QoL 20% better than the CG. The CG consisted of 21 dogs with CAD and the AG of 46 dogs with CAD. Validated QoL1 (pre-treatment) and QoL2 (post-treatment) questionnaires were emailed to owners.

RESULTS

AG dogs were significantly less disturbed during mealtimes (i.e., had better appetites and scratched less during mealtimes) and caused significantly less physical discomfort to their owners (due to unpleasant odor, the impression of a dirty apartment) than CG dogs. Owners of dogs treated with ASIT were able to significantly improve their daily activities (leisure, vacation, walks, work, hunting), significantly reduce their expenses (treatment costs, veterinary costs), feel significantly less emotional distress (less guilt, powerlessness, sadness, regret, fear, anger, disgust, rage, frustration), and experience less influence on relationships with family members and friends compared to owners of dogs not treated with ASIT.

CONCLUSIONS

According to our results, the quality of life of dogs treated with ASIT and their owners seemed to improve significantly.

Is Vitamin D3 a Worthy Supplement Protecting against Secondary Infections in Dogs with Atopic Dermatitis?

Canine atopic dermatitis (CAD) is a common, chronic, inflammatory skin disease in dogs worldwide. This disease often predisposes for secondary organisms overgrowth and skin infections with pathogens, such as Staphylococcus pseudintermedius and Malassezia pachydermatis. Unfortunately, the causes of this disease in both humans and animals are not fully understood; therefore, the only possible option is a lifelong, symptomatic treatment. The management of CAD is mainly based on limiting contact with allergens and antipruritic therapy, most often with glucocorticoids and antihistamines. A serious problem in this situation is the fact, that long-term administration of glucocorticoids leads to side effects like polyuria, alopecia, increased susceptibility to infection, muscle atrophy, and many others. For this reason, great emphasis is placed on the development of replacement and supportive therapies. It is a well-documented fact that reduced concentrations of serum vitamin D3 contribute to the severity of atopic dermatitis symptoms in humans. Moreover, unlike the most commonly used therapeutic methods, of which the main goal is to ameliorate inflammation and pruritus, namely the symptoms of AD, vitamin D3 supplementation affects some underlying factors of this disease. Therefore, in this review, we summarize the current state of knowledge regarding the role of vitamin D3 in CAD, its protective effect against secondary bacterial and fungal infections, and the potential of its supplementation in dogs.