Malignant Histiocytosis in the
Bernese Mountain Dog
Irish perspective
John M. Angles , BVSc, BSc(Vet), DACVIM, DECVIM-CA Nestle Purina Lecturer,
Small Animal Clinical Studies, University College Dublin, Ballsbridge.
A seven-year-old male intact Bernese mountain dog presents to the local veterinarian for 2 weeks of poor appetite and consequent weight loss. On the physical examination there are no obvious abnormalities.
This is a scenario that is all too common in clinical veterinary medicine. The decision to pursue further diagnostics tests or to treat symptomatically is based on a number of criteria, including suspicion for a particular disease, previous disease problems, and owner expectations. In most breeds of dog a conservative approach with daily review would not be inappropriate for the above presentation. However, on further questioning of the owner there are some worrisome aspects to this case, with the dam euthanased for cancer one year previously.
Further blood tests confirm that the liver is involved and the dog is referred to the Veterinary Teaching Hospital at UCD. It is noticed that the dog is panting excessively and chest radiographs confirm a mass involving one of the right lung lobes. Unfortunately, other masses are detected involving the rib cage, liver and spleen. Biopsies confirm a diagnosis of malignant histiocytosis.
Histiocytic sarcoma and malignant histiocytosis is recognised as a familial cancer in the Bernese mountain dog. Histiocytes are a form of white blood cells that occur in tissues and are part of the immune system. In malignant histiocytosis (MH), these histiocytes proliferate abnormally, leading to tumour formation throughout the body in affected dogs. Affected dogs are invariably middle-aged, with males more commonly affected than female Bernese mountain dogs.
Most Bernese mountain dogs with malignant histiocytosis (MH) present with vague signs as above. The actual clinical signs will depend on the tissues involved, with most tumours involving the lung, kidneys, spleen, liver, spinal cord and lymph nodes. Common presenting signs include fever, lethargy, and reduced appetite with weight loss. Most Bernese mountain dogs will eventually develop respiratory signs, manifested as increased breathing effort or rate. The eyes and the skin are rarely affected.
Diagnosis of malignant histiocytosis (MH) requires biopsy and confirmation by an experienced pathologist. Malignant histiocytes can be difficult to identify due to malignant transformation and it is not uncommon for our pathologists to request special stains to confirm a diagnosis of malignant histiocytosis (MH). An accurate diagnosis is critical.
There are currently no successful treatments for malignant histiocytosis (MH). Chemotherapy has been used but responses are transient and side effects from treatment are common. Care is generally at best supportive until euthanasia is indicated based on quality of life considerations.
Systemic histiocytosis (SH) is another syndrome that occurs in the Bernese mountain dog. This is a disease of younger Bernese mountain dogs and typically affects the skin, lymph nodes and eyes. Other tissues may be involved but this is rare. The age of onset and tissue distribution help to differentiate the more benign systemic histiocytosis (SH) from malignant histiocytosis (MH). Treatment is available for systemic histiocytosis (SH) using an immunosuppressive drug called leflunomide (Aravar; Aventis), although cost of the medication has limited its use to insured Bernese mountain dogs.
Recognition of this variant form of histiocytosis is important, as systemic histiocytosis (SH) is rarely fatal by itself. The disease has a fluctuating course and with untreated dogs showing ulceration around the nose and eyes.
Inheritance of histiocytosis in the Bernese mountain dog is confirmed, with the pattern more consistent with a complex mode of inheritance. This suggests that there are multiple genes providing the risk for the disease. Systemic histiocytosis (SH) and malignant histiocytosis (MH) are known to occur in similar lines. Unfortunately many Bernese mountain dogs have already produced litters by the time malignant histiocytosis (MH) expresses itself, as was seen in the case above.
Several groups are investigating the cause for histiocytosis in the Bernese mountain dog. Dr. Peter Moore has a terrific Internet site on histiocytosis in the Bernese mountain dog at www.histiocytosis.ucdavis.edu, which is suitable for both owners and veterinarians. Over recent months we are aware of several Bernese mountain dogs in Ireland being diagnosed with malignant histiocytosis (MH) and all owners should at least be aware of this disease.
The Department of Small Animal Clinical Studies, University College Dublin is collecting information on affected Bernese mountain dogs. Any enquires should be directed to myself either via email at [email protected] or by phone at (01) 668-7988, extension 2632.
References :
Small Animal Clinical Studies, University College Dublin, Ballsbridge.
A seven-year-old male intact Bernese mountain dog presents to the local veterinarian for 2 weeks of poor appetite and consequent weight loss. On the physical examination there are no obvious abnormalities.
This is a scenario that is all too common in clinical veterinary medicine. The decision to pursue further diagnostics tests or to treat symptomatically is based on a number of criteria, including suspicion for a particular disease, previous disease problems, and owner expectations. In most breeds of dog a conservative approach with daily review would not be inappropriate for the above presentation. However, on further questioning of the owner there are some worrisome aspects to this case, with the dam euthanased for cancer one year previously.
Further blood tests confirm that the liver is involved and the dog is referred to the Veterinary Teaching Hospital at UCD. It is noticed that the dog is panting excessively and chest radiographs confirm a mass involving one of the right lung lobes. Unfortunately, other masses are detected involving the rib cage, liver and spleen. Biopsies confirm a diagnosis of malignant histiocytosis.
Histiocytic sarcoma and malignant histiocytosis is recognised as a familial cancer in the Bernese mountain dog. Histiocytes are a form of white blood cells that occur in tissues and are part of the immune system. In malignant histiocytosis (MH), these histiocytes proliferate abnormally, leading to tumour formation throughout the body in affected dogs. Affected dogs are invariably middle-aged, with males more commonly affected than female Bernese mountain dogs.
Most Bernese mountain dogs with malignant histiocytosis (MH) present with vague signs as above. The actual clinical signs will depend on the tissues involved, with most tumours involving the lung, kidneys, spleen, liver, spinal cord and lymph nodes. Common presenting signs include fever, lethargy, and reduced appetite with weight loss. Most Bernese mountain dogs will eventually develop respiratory signs, manifested as increased breathing effort or rate. The eyes and the skin are rarely affected.
Diagnosis of malignant histiocytosis (MH) requires biopsy and confirmation by an experienced pathologist. Malignant histiocytes can be difficult to identify due to malignant transformation and it is not uncommon for our pathologists to request special stains to confirm a diagnosis of malignant histiocytosis (MH). An accurate diagnosis is critical.
There are currently no successful treatments for malignant histiocytosis (MH). Chemotherapy has been used but responses are transient and side effects from treatment are common. Care is generally at best supportive until euthanasia is indicated based on quality of life considerations.
Systemic histiocytosis (SH) is another syndrome that occurs in the Bernese mountain dog. This is a disease of younger Bernese mountain dogs and typically affects the skin, lymph nodes and eyes. Other tissues may be involved but this is rare. The age of onset and tissue distribution help to differentiate the more benign systemic histiocytosis (SH) from malignant histiocytosis (MH). Treatment is available for systemic histiocytosis (SH) using an immunosuppressive drug called leflunomide (Aravar; Aventis), although cost of the medication has limited its use to insured Bernese mountain dogs.
Recognition of this variant form of histiocytosis is important, as systemic histiocytosis (SH) is rarely fatal by itself. The disease has a fluctuating course and with untreated dogs showing ulceration around the nose and eyes.
Inheritance of histiocytosis in the Bernese mountain dog is confirmed, with the pattern more consistent with a complex mode of inheritance. This suggests that there are multiple genes providing the risk for the disease. Systemic histiocytosis (SH) and malignant histiocytosis (MH) are known to occur in similar lines. Unfortunately many Bernese mountain dogs have already produced litters by the time malignant histiocytosis (MH) expresses itself, as was seen in the case above.
Several groups are investigating the cause for histiocytosis in the Bernese mountain dog. Dr. Peter Moore has a terrific Internet site on histiocytosis in the Bernese mountain dog at www.histiocytosis.ucdavis.edu, which is suitable for both owners and veterinarians. Over recent months we are aware of several Bernese mountain dogs in Ireland being diagnosed with malignant histiocytosis (MH) and all owners should at least be aware of this disease.
The Department of Small Animal Clinical Studies, University College Dublin is collecting information on affected Bernese mountain dogs. Any enquires should be directed to myself either via email at [email protected] or by phone at (01) 668-7988, extension 2632.
References :
- Brearley, M.J., Dunn, K.A., Smith, K.C. and Blunden, A.S. (1994) Systemic histiocytosis in a Bernese mountain dog. JSAP, 35: 271-274
- Moore , P.F. (1984) Systemic histiocytosis of Bernese Mountain Dogs. Vet Pahol., 21: 554-563
- Moore , P.F. and Rosin, A. (1986) Malignant Histiocytosis of Bernese Mountain Dogs. Vet Pathol., 23: 1-10
- Padgett, G.A., Madewell, B.R., Keller, E.T., Jodar, L. and Packard, M. (1995) Inheritance of histiocytosis in Bernese Mountain dogs. JSAP, 36: 93-98
- Paterson, S., Boydell, P. and Pike, R. (1995) Systemic histiocytosis in the Bernese mountain dog. JSAP, 36: 233-236
- Ramsey, I.K., McKay, J.S., Rudorf, H. and Dobson, J.M. (1996) Malignant histiocytosis in three Bernese mountain dogs. Vet Record, 138: 440-444
