Nutraceutical Diet Improves Treatment Response in Dogs with Keratoconjunctivitis Sicca

A nutraceutical diet combined with topical drug treatment improved clinical signs in dogs with keratoconjunctivitis sicca (KCS) that was poorly responsive to drug treatment alone, according to the results of a study recently published in BMC Veterinary Research. The study was performed in collaboration with (but was not funded by) the manufacturer of a canine nutraceutical diet.

The randomized, controlled study included 50 client-owned dogs with immune-mediated KCS, or dry eye, that had not responded to standard pharmacologic treatment. Dogs with toxic, traumatic, or neurogenic KCS were excluded, as were dogs with systemic or neurologic disease and those with an intolerance to ingredients of the tested diet. All dogs included in the study had baseline Schirmer tear test values of less than 10 mm/min; blepharospasm; conjunctival inflammation; and corneal pigmentation, keratinization, and neovascularization. Their median age was 6.5 ± 0.7 years.

The dogs were randomly divided into two groups of 25. One group was fed a diet supplemented with botanical nutraceuticals (Forza10; SANYpet, Bagnoli di Sopra, Italy) and one was fed a standard canine diet. The two diets had similar ingredients and nutrient composition. According to the authors, the main difference in the diets was the inclusion of botanicals in the nutraceutical diet. Dogs in both groups received topical tacrolimus 0.03% twice a day and artificial tears containing hyaluronic acid five times a day. Dog owners fed and medicated the dogs according to investigators’ instructions.

The dogs were assessed on days 0, 15, 30, and 60 by independent observers and received eye examinations by veterinary ophthalmologists. Notable results included the following:

• At 60 days, mean Schirmer tear test values had significantly increased (from 4.7 ± 0.4 mm/min to 10.7 ± 0.6 mm/min) in dogs fed the nutraceutical diet. The change in Schirmer tear test values in dogs fed the standard diet was not significant (from 4.3 ± 0.5 mm/min to 5.1 ± 0.5 mm/min).
• Conjunctival inflammation, corneal pigment density, mucus discharge, and corneal keratinization scores decreased significantly after 60 days in the nutraceutical diet group but not in the standard diet group.
• Subjective assessments of blepharospasm, hyperemia, ocular discharge, and periocular swelling indicated clinical improvement after 60 days in the nutraceutical diet group but not in the standard diet group.

After the 60-day evaluation, the nutraceutical diet was discontinued for 30 days (although topical treatment continued). The authors report that KCS symptoms relapsed in these dogs after 15 days. Thirty days after the nutraceutical diet was reinstated, KCS symptoms had again improved.

The nutraceutical diet included hydrolyzed fish proteins, muskmelon (Cucumis melo), a type of seaweed (Ascophyllum nodosum), Aloe vera, papaya (Carica papaya), pomegranate (Punica granatum), tea (Camellia sinensis), turmeric (Curcuma longa), black pepper (Piper nigrum), zinc, and other ingredients. Its omega 3 to omega 6 fatty acid ratio was 1 to 0.8. According to the authors, these ingredients have antioxidant and anti-inflammatory properties that most likely work by modulating T cell activity and cytokine production. Other studies performed in collaboration with the diet manufacturer have indicated that nutraceutical diets have anti-inflammatory effects in dogs with otitis externa and positive effects on neuroendocrine parameters in dogs with behavior disorders.

“Our results suggest that association of classical drug therapy with a nutraceutical diet with potential antioxidant/antiinflammatory and immune-modulating activities induce a significant amelioration of clinical signs and symptoms in keratoconjunctivitis sicca,” write the authors. “It is reasonable to hypothesize that metabolic changes could affect immune response orchestration in a model of immune-mediated ocular disease, as represented by keratoconjunctivitis sicca, in dogs and, in a translational perspective, by Sjögren’s syndrome in humans.”

The investigators write that a limitation of the study is that they did not assess inflammatory cytokines or regulatory T cells in blood samples of dogs with KCS. However, they note that metabolic changes that occur in the eye may be difficult to detect in the blood.

The study was performed in collaboration with employees of the research and development division of SANYpet SpA but was not financed by SANYpet. The authors report no competing interests or biases.

Dr. Laurie Anne Walden received her doctorate in veterinary medicine from North Carolina State University. After an internship in small animal medicine and surgery at Auburn University, she returned to North Carolina, where she has been in small animal primary care practice for over 20 years. Dr. Walden is also a board-certified editor in the life sciences and owner of Walden Medical Writing, LLC. She works as a full-time freelance medical writer and editor and continues to see patients a few days each month.