Several significant disease syndromes affect the Weimaraner breed (Table 1). Many of these diseases are part of a broader hyper-inflammatory syndrome seen in Weimaraners of similar bloodlines. A common underlying cause has been postulated, and the most appropriate treatment will be determined by the age of onset, clinical signs and overall prognosis.

Hypertrophic osteodystrophy (HOD) is a major manifestation of the hyper-inflammatory syndrome, and causes high fever, pain and lameness associated with swelling of the growth plates in the femur and humerus. This is typically seen in one or two puppies in a genetically susceptible litter, soon after they receive multivalent vaccination, although it also can occur after monovalent vaccination. Other recognized disease syndromes include a post-vaccinal reaction with high fever and nodular skin disease; humoral antibody immunodeficiency syndrome with recurrent infections involving the bowel, skin, and urinary tract; and aseptic meningitis.

Diagnosis of HOD relies not only on the typical history and clinical signs, but also on the characteristic radiographic findings of changes at the growth plate of long bones. Clinical signs include swollen, painful metaphyses, fever, lameness and reduced appetite. Many dogs have self-limiting small bowel diarrhea prior to onset of the fever and joint pain. Males and females are equally affected, and the age of onset is typically 8-16 weeks.

The cause of HOD remains unknown, as earlier speculations of vitamin C deficiency or over-nutrition have not been substantiated. A link between HOD and humoral antibody immunodeficiency disease has not been established. Low levels of serum IgA, IgM, or IgG are found inconsistently in HOD-affected dogs. The high heritability of HOD within certain families suggests a significant genetic effect, and a DNA marker analysis is ongoing at the Veterinary Genetics Laboratory at UC-Davis.

Treatment of HOD in breeds other than the Weimaraner has traditionally relied on rest, non-steroidal anti-inflammatory drugs (such as carprofen or meloxicam), and opiate analgesics (such as butorphanol, tramadol, or fentanyl) as needed. In most cases, the disease is self-limiting, and most dogs recover in several weeks. However, the disease in Weimaraners is different, as these dogs are prone to a severe multi-organ inflammatory form of the disease, which commonly becomes fatal without appropriate treatment. Prompt recognition of the disease, and treatment with high doses of corticosteroids are key to a good outcome in this disease.

While the mode of inheritance of HOD has not been determined, an obvious breed predisposition exists such that genetic factors play an important role. Research from the Dublin group has found a high heritability for Weimaraner HOD (0.68; 95% confidence interval of 0.65 - 0.71). This is important both for genetic counselling and for potential development of a genetic marker test. Until then, the only way to detect dogs carrying HOD-susceptibility genes has been by test matings.