Could Horace have gout?

Gout-aware.com:

Canine Gout can appear as lesions and ulcerations and can also be linked to animal diabetes and kidney disease.

This is also similar to Human Gout in the fact that it can be genetically passed down in the breed.

This form of Gout appears in mainly large breeds of dogs such as : ... Labrador retrievers

Canine Gout appears mainly in the paws and toes, but can also appear in the elbows, the neck area and even on the tongue. It is most common on the hind feet.

Calcinosis Cutis, Calcium Circumscripta, or Canine Gout
by Fred Lanting

The subject ailment is an imbalance in mineral assimilation resulting in abnormal deposits, sometimes between bones, often in layers of the skin or integument. Calcium deposits in the skin can be the result of injury, of metabolic changes, or of unknown factors. Since mineralization (calcium deposits) in skin can occur in a wide variety of unrelated diseases, a common thread among them is not easy to establish. One form of the condition is related to, or could be an early indication of, a canine version of the disorder which in humans is called Cushing's Disease, although many dogs will never develop the distended abdomen, susceptibility to hematomas and bruising, or over-pigmented, sparsely-coated skin. Indeed, that may be a sufficiently different disorder that it should be classified as a separate variety of hyperadrenocorticism or hyperglucocorticoidism.

Journal of Veterinary Medicine Calcinosis Circumscripta in the Dog: A Retrospective Pathological Study

Summary

Calcinosis circumscripta is an uncommon syndrome of ectopic idiopathic, dystrophic, metastatic or iatrogenic mineralization characterized by deposition of calcium salts in soft tissues. This paper is a retrospective study of 77 canine cases. The age of dogs in the study varied from 4 months to 15 .... Several pure and mixed, typically large breed dogs were affected so that 28.6, 13 and 9% were German Shepherd, Rottweiler and Labrador Retriever respectively. The size of lesions varied from 2 mm to 13 cm in diameter but most lesions were between 0.5 cm and 3 cm in diameter. Lesions were solitary in 82% of the affected dogs, and occurred most commonly on the hind feet (50%) and tongue (23%). With multiple lesions there was no apparent body symmetry.