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  • Writer's pictureDr Meredith Wall

Case of the month: symmetrical lupoid onychodystrophy in a Giant Schnauzer

Updated: Dec 20, 2023

Recently referred to us was a 4-year-old male entire Giant Schnauzer with symmetrical lupoid onychodystrophy. Symmetrical lupoid onychodystrophy is an unusual disease that affects the dog's claws - it's believed to be immune-mediated, but may also be genetic. It causes painful claw loss, sometimes on all four feet. Claws do grow back, but they are misshapen, brittle, discoloured and friable, and often slough off. It's a horrible disease that more frequently affects German Shepherd dogs, Rottweilers, and Gordon Setters, although any breed can be affected.

Giant Schnauzer portrait

There are a range of medications that may be effective; however, dietary interventions can also help. Some possible strategies include the use of a novel protein or hydrolysed diet, vitamin E supplementation, omega-3 supplementation and biotin supplementation. For this dog, we formulated recipes for a therapeutic diet incorporating all these strategies. After discussion with the owner, goat meat and pearled barley were selected as the novel proteins, as they were affordable and easily available for the owner. As always, we recommended human-grade goat meat only, and no pre-made mince, to reduce the risk of contamination with other proteins. And as always, we made sure that the diet was complete and balanced - the need to feed novel proteins is no excuse for feeding a deficient diet.

Pearled barley for dog food
Pearled barley can be useful for novel protein diets for dogs, as it is sold in most supermarkets, and isn't expensive.

There is some evidence to support the use of novel proteins in these cases. In a study by Mueller et al. (2001), four dogs with symmetrical lupoid onychodystrophy also showed clinical signs of an adverse food reaction. Those dogs were maintained on a novel protein diet for 6-8 weeks; all four showed a partial or complete response to the diet trial and relapsed upon challenge with the original diet. Therefore, an elimination diet appears to be a worthwhile diagnostic test for canine patients with claw disease. The occurrence of an adverse reaction to a food protein depends on a complex interplay between the immune system and the protein itself; unfortunately, there is a lack of understanding with regards to why certain proteins elicit an immunologic response in susceptible dogs.

We also supplemented the dog's diet with a substantial amount of algae oil. Ziener and Nodtvedt (2014) conducted a study to determine whether the addition of fish oil (or cyclosporine) to a diet already rich in omega-3 fatty acids could improve the treatment outcome of symmetrical lupoid onychodystrophy. In that study, dogs were given a daily dose of 2.7 g EPA + DHA from the fish oil supplementation, and 3.3 g EPA + DHA from the diet (Eukanuba Dermatosis Fish and Potato), producing a total daily dose of 6 g EPA + DHA.

The authors saw a statistically significant improvement in the number of healthy claws after six months of treatment, with a median increase of 13.5 claws for both groups; omega-3 fatty acid treatment proved equally effective, when compared with cyclosporine. Omega-3 fatty acid supplementation has also yielded good to excellent to excellent results in other studies by Scott et al (1995), Bergvall (1998), and Mueller et al. (2003). We therefore supplemented the patient's diet with algae oil, to achieve a daily dose of 6 grams EPA + DHA, as per the Ziener and Nodtvedt study. Algae oil was used, rather than fish oil, due to the need to minimise any risk of an adverse reaction to fish-derived proteins.

Biotin is a water-soluble B vitamin that is an essential cofactor for several mitochondrial

enzymes. Studies have demonstrated that supplementation of biotin improves the strength

and hardness of pig claws and equine hoofs, even in animals that are not biotin deficient.

Additionally, for some human patients with brittle fingernails and onychoschizia, therapy

with biotin results in increased thickness of the nail, with firmer and harder nails and

reduced splitting.

Biotin deficiency is very uncommon in dogs, and typically only occurs if the dog is consuming large amounts of raw egg white or is being treated with antimicrobials for a long time period. This is because it is found in many food ingredients, and can also be synthesised by gut microflora. There are no studies to support its use as a treatment for canine symmetrical lupoid onychodystrophy, however, the addition of biotin to the dog's diet was considered unlikely to be harmful. We therefore supplemented the diet with biotin at a dose of 1000 mcg per day, as per recommendations for other species.

There is no specific evidence to demonstrate the efficacy of vitamin E

as a supplement for symmetrical lupoid onychodystrophy (independent of other supplements) however, it is important to minimise peroxidation of omega-3 fatty acids. Vitamin E is an important lipid-soluble antioxidant that is present in cell membranes, where it helps to prevent oxidative damage to polyunsaturated fatty acids. The concentration of vitamin E required in the diet to protect against peroxidation of cell membrane lipids depends on the amount of fat in the diet, the proportion of polyunsaturated fatty acids, and the presence of other antioxidants. Given that we formulated a diet that was very rich in polyunsaturated fatty acids, we supplemented the diet with additional vitamin E.

The owner started the diet immediately, and the referring veterinarian made sure that no changes were made to medication or other factors, so that we could accurately assess the patient's response. We have seen a few cases of symmetrical lupoid onychodystrophy previously, and unfortunately the response to dietary therapy has always been mediocre. In this case, the diet appeared to cause a marked improvement in clinical signs. The number of healthy claws increased substantially, and the dog was able to return to light exercise after 4 months of treatment.

If you would like more information about a home-prepared therapeutic diet for your dog, please don't hesitate to get in touch:

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