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Genetic Welfare Problems of Companion Animals
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Dalmatian
Copper-associated Chronic Hepatitis
Related terms: copper storage disease, copper toxicosis; copper storage hepatopathy
VeNom term: copper-associated chronic hepatitis (VeNom code: 584).
Related conditions: liver failure, liver toxicity, inflammation of the liver, hepatic encephalopathy, cirrhosis
Outline: Copper associated chronic hepatitis is a progressive inflammatory disease of the liver which is caused or worsened by high levels of copper in the liver and bloodstream. The condition affects middle-aged to older dogs and Dalmatian are at higher risk than other breeds of developing the disease. Chronic hepatitis is characterised by inflammation, scarring and destruction of the cells and tissue of the liver, which can result in loss of liver function and, if left untreated, liver failure. It is currently not known why the Dalmatian is predisposed to develop the condition, but a genetic defect in copper metabolism in this breed is likely. Early diagnosis of chronic hepatitis is difficult because the clinical signs are non-specific and include weight loss, weakness, fatigue, vomiting, diarrhoea and abdominal pain. Signs of later stages of the condition include abdominal swelling and jaundice, and confusion/altered consciousness may occur when increased copper levels affect brain function.
Summary of Information
(for more information click on the links below)
1. Brief description
Copper-associated chronic hepatitis is an inflammatory condition of the liver which is caused or worsened by excess copper accumulation in the liver and bloodstream. The tissues of the liver become damaged when high levels of copper cause oxidative stress and cell damage. The liver becomes inflamed and its tissues are destroyed and replaced with scar tissue, which reduces the normal function of the liver; which include protein synthesis, detoxification of metabolites and the production of bio-chemicals required for digestion. The damage caused by chronic hepatitis is progressive, and over time the liver stops functioning normally and, if not treated successfully, will result in liver failure and death. In the early stages of chronic hepatitis, dogs will suffer from weight loss, weakness, fatigue, vomiting, diarrhoea and abdominal pain. These signs are vague and non-specific and therefore an early diagnosis of chronic hepatitis is not easy. Treatment is available for early stages of the condition and is focused on reducing and stabilising the levels of copper in the body.
Excess copper in the blood is common in Dalmatians with chronic hepatitis, and relatives of affected dogs also have a high level of copper in their blood and this suggests the condition is likely to be inherited. However, the exact cause of copper accumulation and chronic hepatitis in the breed is not known, due to a lack of research-based evidence.
2. Intensity of welfare impact
Dogs with chronic hepatitis are likely to feel unwell with fatigue, weakness and abdominal pain, and they may be affected for months or years before the condition is diagnosed and/or treatment or death occurs. Medical treatment is available for early stages of the condition, although treatment is not always successful in managing the clinical signs and preventing progression of the condition. As the disease becomes more advanced, the prognosis becomes poorer, and other signs can develop such as yellowing of the skin (jaundice, due to liver failure), or abdominal swelling due to a fluid build-up in the abdomen (ascites). Confusion or altered consciousness (due to hepatic encephalopathy) may also occur as the excess copper in the blood enters the brain, and may cause damage to the nerves and cells in the brain which are involved in the coordination of movement, processing of stimuli and mood regulation. Death can be caused by liver-related complications, pneumonia, or renal failure.
3. Duration of welfare impact
Chronic hepatitis is usually reported in middle aged dogs, but the average age of diagnosis in Dalmatians is younger, at 4 years 7 months (range: 3-12 years). Usually, by the time dogs are diagnosed with this condition, the damage to the liver is enough to cause dysfunction, and therefore the survival time and response to treatment may be poor.
4. Number of animals affected
Dalmatians are at higher risk of developing the condition compared with other breeds. Bitches seem to have a greater risk of developing chronic hepatitis than male dogs.
5. Diagnosis
The clinical signs of chronic hepatitis are non-specific and may only be intermittently presented or not at all, so an early diagnosis is difficult. Most animals are presented late in the course of the disease when they show dramatic weight loss and persistent diarrhoea and vomiting.
Measurement of increased blood serum enzymes will indicate the presence of chronic hepatitis but a liver sample is required to confirm a diagnosis.
6. Genetics
Copper accumulation and symptoms of chronic hepatitis occurs in related Dalmatians (Webb et al 2002) and therefore it is likely that there is a genetic defect which is inherited. However, the exact nature of the defect or how this is passed to offspring is currently unknown.
7. How do you know if an animal is a carrier or likely to become affected?
Since the genetic defect in this breed has not been identified, there is currently no way of knowing which animals are more at risk of developing the condition. We do know that the condition is more prevalent in Dalmatians than is expected.
8. Methods and prospects for elimination of the problem
Research is required to identify the exact mechanisms involved in copper-associated chronic hepatitis, and the mode of inheritance are identified. It is not advisable to avoid breeding between affected individuals or from dogs with affected relatives, including grandparents, siblings, previous offspring and siblings of parents.
For further details about this condition, please click on the following:
(these link to items down this page)
- Clinical and pathological effects
- Intensity of welfare impact
- Duration of welfare impact
- Number of animals affected
- Diagnosis
- Genetics
- How do you know if an animal is a carrier or likely to become affected?
- Methods and prospects for elimination of the problem
- Acknowledgements
- References
1. Clinical and pathological effects
Chronic hepatitis is a term given to a group of inflammatory liver diseases which arise for a variety of different causes, including metabolic, infectious, toxic and autoimmune factors. Chronic hepatitis is the term used regardless of the cause of the disease because the diseases are similar in diagnosis, clinical signs and management, but there is a hereditary form of the disease affecting Dalmatians which is likely to be caused by an inherited defect that affects the way the liver metabolises copper. Little is known about the exact causes of chronic hepatitis, its treatment and prognosis, and there is a need for greater research (Watson 2004).
Chronic hepatitis is characterised by destruction of the cells and tissue of the liver, inflammation mediated by immune cells (mononuclear cells such as monocytes and lymphocytes) and regeneration, thickening and scarring (fibrosis) of the connective tissues in the liver. In a healthy liver, liver enzymes, such as alkaline phosphatase (ALP) and alanine aminotransferase (ALT) drive chemical reactions for metabolism, detoxification and other vital functions, and these enzymes are mostly contained within the liver. When the liver becomes damaged, these enzymes leak out into the blood, and tests for ALP and ALT enzymes in the blood can identify liver damage. The liver has a remarkable ability to repair itself and can continue to function even when there is significant cell and tissue damage. Over time, however, the progressive damage and scarring caused by chronic hepatitis means that the liver cannot function adequately and may eventually fail to function at all. Cirrhosis, which is where normal cells are replaced by poor or non- functioning scar tissue, causes an abnormal liver structure which can be identified from samples of the liver. Cirrhosis may occur at the end stage of the condition and this damage is irreversible.
Clinical signs of the early stages of chronic hepatitis vary widely and include anorexia, depression, weakness, fatigue, weight loss, vomiting, diarrhoea, excessive drinking (polydipsia) and excessive urination (polyuria). Some dogs may present with abdominal pain. These signs are vague and non-specific and therefore an early diagnosis of chronic hepatitis is not easy.
The causes of breed-specific chronic hepatitis in the Dalmatian is unknown, but excess copper is widely implicated as the likely cause. Copper is an essential micronutrient for all living organisms, since the metal is required for the generation and function of several enzymes, electron transport proteins and antioxidant molecules. Absorption of copper occurs in the stomach and small intestine, and the copper is carried by transporter proteins (metallothionein, ceruloplasmin) to the liver via the hepatic portal vein. Enzymes produced by the liver are responsible for binding copper to these transporter proteins, and also for removing excess copper by secreting it into bile. When these mechanisms are damaged or defective, copper accumulates in the liver because it cannot be transported to the blood, or excreted into bile. Excessive copper concentrations lead to oxidative stress in the liver cells due to an increased concentration of very reactive free radicals, which cause cellular damage. In the inherited form of chronic hepatitis, copper accumulation is localised to the central lobular region (centrilobular) region of the liver, as opposed to other forms of hepatitis (eg viral) which usually affect the outer regions of the tissue. The cells in the centrilobular region of the liver are near to the portal vein, which takes blood from the gastrointestinal tract rich in nutrients to the liver, and are important for glycolysis, lipogenesis and drug detoxification.
The exact cause of copper accumulation and chronic hepatitis in Dalmatians is currently unknown due to a lack of research-based evidence, but it is thought to be due to an inherited defect in the way that the liver metabolises copper (Webb et al 2002). The cause may be similar to that in Bedlington terriers where a hereditary defect inhibits the excretion of copper into bile (Forman et al 2005; see also the bedlington-terrier-copper-storage-hepatopathy condition on this UFAW site), resulting in a harmful accumulation of copper in the cells of the liver (called Wilson’s disease in humans). There is a wide range for normal hepatic copper levels in dogs, and liver copper concentrations less than 2,000 parts per million on a dry weight basis (ppm dw) is considered to have no adverse effect on the dog’s health. In a study of liver copper concentrations of 9 Dalmatian dogs with chronic hepatitis, 5 of the 9 dogs have copper levels which exceeded this safe level, and the highest concentration was 8,390 ppm dw (Webb et al 2002). The storage of copper in its nontoxic form may occur in dogs, and exhaustion of cellular systems which protect against oxidative damage, or an additional stressor that affects protective mechanisms may be necessary for copper accumulation to cause symptoms of hepatitis.
There are a range of stages and severity of chronic hepatitis, and this is scored on the extent of scar tissue in the liver (none, mild, moderate, severe or cirrhosis) and on the severity of liver cell death and inflammation (minimal, mild, moderate, severe), respectively (Sterczer et al 2001).
2. Intensity of welfare impact
Dogs with chronic hepatitis are likely to show signs of malaise and their welfare may be affected for months or years before diagnosis and/or treatment are required or death occurs. In the early stages, dogs may feel unwell, nauseous and weak. As the disease advances, dogs may show extreme discomfort and pain. Medical treatment is available for the early stages of the condition, although treatment is not always successful in managing the clinical signs and preventing disease progression. Treatment is focused on removing the excess copper; termed chelation therapy. A drug, Penicillamine, binds to copper and leads to the excretion of copper in the urine. Once the levels of copper have stabilised, as seen through the results of blood and urine tests, dogs can be given zinc to maintain stable copper levels in the body; zinc stimulates a protein in the cells of the gut which binds copper and prevents its absorption into the blood and transport to the liver. Dogs may be restricted to low-copper diets. Due to various side-effects, such as nausea, vomiting or fever, treatment may not improve the quality of life of the dog in the short-term but may improve the life expectancy.
As the disease becomes more advanced, the prognosis becomes poor and other signs can develop such as yellowing of the skin (jaundice) due to a failure of the liver to remove toxins, or painful or uncomfortable abdominal swelling (ascites) due to a fluid build-up in the abdomen. Confusion or altered consciousness (hepatic encephalopathy) may also occur since the excess copper in the blood enters the brain, and may cause damage to the nerves and cells in the brain which are involved in the coordination of movement, processing of stimuli and mood regulation.
In dogs in which the disease has progressed, death can be caused by liver-related complications, pneumonia, or renal failure. Dogs with enlarged livers are prone to develop difficulties with normal blood clotting due to abnormally low levels of blood thickening agents (thromboplastin) and platelets (thrombocytopenia), and these dogs are considered to be at a higher risk of death..
3. Duration of welfare impact
Bexfield et al (2012) reported that Dalmatians were significantly younger when first diagnosed with chronic hepatitis than is found in other affected breeds eg Labrador retrievers, and the average age for diagnosis in Dalmatians was 4 years 7 months (range: 3-12 years). Unfortunately, the clincial signs associated with liver disease are often only detected when the damage is severe enough to cause dsyfunction. Therefore the prognosis of dogs reaching this stage is poor, since the condition has already progressed to a severe stage. In one study, the average (median) survival time of dogs after diagnosis was 1 year (range: 1 day to 7.2 years; Shih et al 2007).
4. Number of animals affected
In the UK, when comparing the breeds found within a population of dogs with chronic hepatitis against a control group from a microchipping database, Dalmatians were found to have increased risk of chronic hepatitis (odds ratio: 4.1, 95% confidence interval: 2.2-7.7) and this risk was increased from 2001 to 2008 (Bexfield et al 2012). Bitches seem to have a greater risk of developing chronic hepatitis than male dogs in this breed, suggesting that sex-related hormones may be involved in the cause or the exacerbation of symptoms of the condition.
5. Diagnosis
Since the clinical signs are non-specific and may only be intermittently presented, an early diagnosis is difficult, and therefore most animals are presented late in the course of the disease, when it has progressed. Furthermore, some dogs may be asymptomatic, ie do not show any outward signs, and these dogs may only be diagnosed following abnormalities shown in routine blood and stool sample tests.
Raised levels of serum enzymes, such as alkaline phosphatase (ALP) and alanine aminotransferase (ALT), are the best initial screening tool for the presence of chronic hepatitis (Shih et al 2007), since these enzymes are not usually found in high levels in the blood. A liver sample is usually required to confirm diagnosis of chronic hepatitis, taken via a laparoscope. Typical changes which can be seen in the liver tissue include inflammation, fatty deposition, fibrosis or cell death. It is suggested that a diagnosis of chronic hepatitis should be made after a documented increase in alanine aminotransferase (ALT) levels for a minimum of 4 months, with concomitant histological evidence of the characteristic liver damage described above during this period. Many chronic liver diseases, however, only become apparent in the end stages.
6. Genetics
Chronic hepatitis is likely to be a complex inherited disorder, involving multiple genes. This suggests an inherited defect in hepatic copper metabolism, although the exact nature of the defect or mode of inheritance is unknown in this breed.
7. How do you know if an animal is a carrier or likely to become affected?
The condition is more prevalent in Dalmatians than is expected but the mode of inheritance of copper-associated chronic hepatitis has not yet been determined for the breed, and therefore there is no way to tell specifically which animals are likely to be affected by the condition.
8. Methods and prospects for elimination of the problem
Research is required to identify the exact mechanisms involved in copper-associated chronic hepatitis and the mode of inheritance. Affected dogs should not be bred from, but unfortunately the condition is unlikely to show until after breeding age has been reached, and often it only occurs after the dog has been retired from breeding. This makes it particularly important that the genetics of the disease are elucidated and a predictive test developed.
Since hepatitis is likely to involve multiple genes, of which very little is known, the advice that can be given to eliminate the problem is limited (Meyers-Wallen 2003). For such complex inherited disorders, a multi-approach strategy using health screening schemes, pedigree breed information and genome-wide estimated breeding values is recommended to reduce the problem (Farrell et al 2015). With the current state of knowledge on the causal factors of hepatitis, the best advice that can be offered to prospective breeders is to avoid breeding between affected dogs or from dogs with affected relatives, including grandparents, siblings, previous offspring and siblings of parents.
9. Acknowledgements
UFAW thanks Dr Emma Buckland (BSc, PhD), Dr David Brodbelt (MA VetMB PhD DVA DipECVAA MRCVS) and Dr Dan O’Neill (MVB BSc, MSc, PhD, MRCVS) for their work in compiling this section.
10. References
Bexfield NH, Buxton RJ, Vicek T, Day MJ, Bailey SM, Haugland SP, Morrison LR, Else RW, Constantino-Casas F and Watson PJ (2012) Breed, age and gender distribution of dogs with chronic hepatitis in the United Kingdom. Veterinary Journal 193: 124–8. doi:10.1016/j.tvjl.2011.11.024
Farrell LL, Schoenebeck JJ, Wiener P, Clements DN and Summers KM (2015). The challenges of pedigree dog health: approaches to combating inherited disease. Canine Genetics and Epidemiology 2: 3. doi:10.1186/s40575-015-0014-9
Forman OP, Boursnell MEG, Dunmore BJ, Stendall N, van den Sluis B, Fretwell N, Jones C, Wijmenga C, Rothuizen J, van Oost BA, Holmes NG, Binns MM and Jones P (2005) Characterization of the COMMD1 (MURR1) mutation causing copper toxicosis in Bedlington terriers. Animal Genetics 3:, 497–501. doi:10.1111/j.1365-2052.2005.01360.x
Meyers-Wallen VN (2003) Ethics and genetic selection in purebred dogs. Reproduction in Domestic Animals 38: 73–6
Shih JL, Keating JH, Freeman LM and Webster CRL (2007) Chronic hepatitis in Labrador Retrievers: Clinical presentation and prognostic factors. Journal of Veterinary Internal Medicine 21: 33–39. doi:10.1111/j.1939-1676.2007.tb02925.x
Sterczer A, Gaál T, Perge E and Rothuizen J (2001) Chronic hepatitis in the dog - a review. The Veterinary Quarterly 23: 148–52. doi:10.1080/01652176.2001.9695104
Watson PJ (2004) Chronic hepatitis in dogs: A review of current understanding of the aetiology, progression, and treatment. Veterinary Journal 167: 228–41. doi:10.1016/S1090-0233(03)00118-7
Webb CB, Twedt DC and Meyer DJ (2002) Copper-associated liver disease in dalmatians: A review of 10 dogs (1998-2001). Journal of Veterinary Internal Medicine 16: 665–668. doi:10.1111/j.1939-1676.2002.tb02405.x
© UFAW 2015
Credit for main photo above:
By Mark Berbezier (Daisy the Dalmatian) [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0) or CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons
