Dog Diseases Database
Every hereditary and common canine condition — with tests, affected body regions, and the breeds where each shows up most.
Filters
- SevereHead / nervous systemAutosomal recessive
Lissencephaly and cerebellar hypoplasia, RELN-related(LCH)
This is a severe, inherited brain disorder primarily documented in White Swiss Shepherd Dogs, where the brain does not develop normally. A mutation in the RELN gene causes lissencephaly, which means the surface of the brain remains smooth instead of forming normal folds, and cerebellar hypoplasia, which is an underdeveloped cerebellum (the part of the brain controlling movement). This combination severely disrupts the dog's nervous system and coordination.
Tested via: DNA testView details - ModerateGeneral / metabolicComplex
Litters (dam per year)
This entry represents a breeding management and welfare parameter regarding the number of litters a female dog carries per year, rather than an inherited disease. Producing litters too frequently without adequate rest periods prevents the female's body and reproductive system from fully recovering. This can lead to severe physical depletion, affecting her overall metabolic and immune health.
View details - MildGeneral / metabolicUnknown
Litters (Kennel per year)
This is not a medical condition or genetic disorder, but rather an administrative statistic tracking the number of litters registered to a specific kennel within a calendar year. It is used by breed clubs to monitor breeding activity and ensure responsible breeding practices. Because it is a record-keeping metric, it does not affect any organ system or biological mechanism in the dog.
View details - MildGeneral / metabolicUnknown
Litters (total per dam)
This is a breeding statistic that tracks the total number of litters a female dog produces over her lifetime. It serves as a welfare monitoring tool to protect the female's reproductive system and overall physical health from the strain of excessive pregnancies. Monitoring this metric helps prevent physical exhaustion and long-term wear on the dog's body.
View details - MildSkin & coatAutosomal recessive
Long hair(LH)
This is a natural genetic variation affecting the FGF5 gene, also known as the L-locus, which controls the hair growth cycle in a dog's skin. Instead of signaling the hair follicle to stop growing at a standard length, this variation allows the growth phase to continue, resulting in longer fur. It is inherited in an autosomal-recessive manner, meaning a dog must inherit the variant from both parents, and it is a normal physical characteristic rather than a medical disease.
Tested via: DNA testView details - SevereHeartAutosomal dominant
Long QT syndrome, KCNQ1-related(LQTS)
Long QT syndrome (KCNQ1-related) is an inherited heart condition that affects the cardiac electrical system. It delays the time it takes for the heart muscle to recharge its electrical system after each beat. This delay can disrupt the normal heart rhythm, potentially leading to dangerous, irregular heartbeats.
Tested via: DNA testView details - SevereGeneral / metabolicAutosomal recessive
Lundehund Syndrome (Norwegian Lundehund)(LS)
Lundehund syndrome is an inherited gastrointestinal disease caused by an autosomal-recessive genetic mutation. It leads to chronic inflammation of the intestinal lining, which prevents the body from properly absorbing nutrients. This inflammation causes a condition called protein-losing enteropathy, where essential proteins leak out of the bloodstream and into the digestive tract.
Tested via: DNA testView details - SevereGeneral / metabolicUnknown
Lymphangiosarcoma
Lymphangiosarcoma is a rare, aggressive cancer that develops in the lining of the lymphatic vessels, which are part of the body's immune and fluid-drainage system. These tumor cells multiply rapidly, destroying nearby healthy tissues and frequently spreading to other parts of the body.
View details - SevereGeneral / metabolicAutosomal recessive
Lysosomal storage disease, ARSG related(ARSG)
This is an inherited metabolic disorder, also known as Neuronal ceroid lipofuscinosis 4A (NCL4A), where a deficiency in the enzyme arylsulfatase G prevents cells from breaking down waste products. Over time, these waste materials build up inside lysosomes, which are the recycling centers of the cell, particularly damaging the nerve cells in the brain. This accumulation leads to progressive cell damage and degeneration throughout the nervous system.
Tested via: DNA testView details - SevereGeneral / metabolicAutosomal recessive
Lysosomal storage disease, CNP-related(LSD)
This hereditary metabolic disorder is caused by a genetic defect that prevents cells from properly breaking down cellular waste. This waste builds up inside the cells, particularly in the brain and nervous system, leading to progressive damage. Over time, this accumulation disrupts normal neurological functions.
Tested via: DNA testView details - MildHeartAutosomal dominant
Macrothrombocytopenia(MTC)
Macrothrombocytopenia is a harmless, inherited blood condition where a dog has fewer but much larger blood platelets, also known as thrombocytes. Platelets are specialized cell fragments in the circulatory system that help the blood clot to stop bleeding. Despite the lower overall platelet count, the larger size of these cells compensates for the difference, allowing the blood to clot normally.
Tested via: DNA testView details - HighEyesAutosomal recessive
Macular Corneal Dystrophy(MCD)
Macular corneal dystrophy is an inherited eye disorder where abnormal metabolic byproducts build up within the cornea, which is the clear outer layer of the eye. This accumulation causes progressive, cloudy spots to form on both eyes, gradually reducing their transparency. Over time, this buildup impairs the dog's ability to see clearly.
Tested via: Eye exam, DNA testView details - SevereGeneral / metabolicComplex
Malignant Melanoma(MM)
Malignant melanoma is an aggressive cancer of the pigment-producing cells, called melanocytes, which give color to a dog's skin and tissues. It most commonly develops in the mouth, on the toes, or on the skin, where these cells multiply uncontrollably. This cancer is highly prone to spreading, or metastasizing, to other vital organs like the lungs.
View details - SevereGeneral / metabolicComplex
Mammary tumor
Mammary tumors, often abbreviated as CMT, are abnormal growths of tissue in the milk glands of dogs. These tumors can be either benign, meaning non-cancerous, or malignant, meaning cancerous and capable of spreading. The development of these growths is heavily influenced by hormones, which is why unspayed female dogs are at the highest risk.
View details - SevereGeneral / metabolicAutosomal dominant
Marfan syndrome(MFS)
Marfan syndrome is a rare connective tissue disorder that weakens the body's structural support systems, particularly affecting the skeleton, eyes, and major blood vessels. In dogs, this condition is still poorly defined, and the exact genetic cause remains unknown, meaning no genetic test is currently available. The lack of proper tissue support leads to structural instability throughout the body.
Tested via: DNA testView details - ModerateMouth & teethComplex
Maxillary canine-tooth mesioversion(MCM)
This is a congenital dental condition affecting the mouth and teeth, where the upper canine teeth grow forward at an abnormal angle instead of pointing downward. Often referred to as 'lance teeth', this abnormal positioning causes the misplaced teeth to rub or press painfully against the lips, gums, or other teeth.
Tested via: Clinical examView details - MildHeartAutosomal dominant
May-Hegglin anomaly(MHA)
May-Hegglin Anomaly is an inherited blood disorder affecting platelets, which are the cells responsible for clotting, and white blood cells. It causes the body to produce abnormally large platelets, often accompanied by a lower overall platelet count. This genetic condition is mild and primarily impacts the blood-forming system rather than other major organs.
Tested via: DNA testView details - SevereHead / nervous systemAutosomal recessive
MECR-related polioencephalopathy(MEP)
This condition is an inherited brain disorder caused by a genetic mutation that disrupts the mitochondria, which act as the energy-producing powerhouses within cells. Without adequate energy, nerve tissues in the brain and central nervous system progressively degenerate and die. This leads to severe, irreversible damage to the dog's neurological function.
Tested via: DNA testView details - HighGeneral / metabolicAutosomal recessive
Medium-chain acyl-CoA dehydrogenase deficiency (MCADD)(MCADD)
This is an inherited metabolic disorder where the body is unable to properly break down medium-chain fatty acids, which are specific types of fats used for energy. Because of a genetic variant in the ACADM gene, the metabolic system cannot convert these fats into fuel, leading to a severe energy deficit. This shortage of energy primarily impacts the liver and cellular function, especially during periods of fasting.
Tested via: DNA testView details - SevereGeneral / metabolicUnknown
Megakaryoblastic leukemia(AMKL)
Megakaryoblastic leukaemia is a rare, severe cancer of the bone marrow where abnormal, immature cells that normally produce blood platelets (megakaryoblasts) multiply uncontrollably. This rapid growth crowds out healthy blood cells, disrupting normal blood production. A definitive diagnosis requires specialized veterinary testing, specifically a bone marrow biopsy and immunophenotyping.
Tested via: Clinical examView details - SevereGeneral / metabolicAutosomal recessive
Megaoesophagus, MCHR2-related(ME)
This is a hereditary condition of the digestive system where the esophagus, the muscular tube connecting the throat to the stomach, becomes abnormally stretched and loses its muscle tone. Because the esophagus cannot contract properly, it is unable to push food and liquids down into the stomach. This specific genetic form of the condition is associated with German Shepherds.
Tested via: DNA testView details - SevereGeneral / metabolicComplex
Meningioma
A meningioma is a slow-growing tumor that arises from the meninges, which are the protective membranes surrounding the brain and spinal cord. As the tumor grows, it creates physical pressure on these delicate nervous system structures, leading to progressive nerve damage. Although these tumors are typically non-cancerous (benign) and do not spread to other organs, their location makes them highly serious.
View details - SevereHead / nervous systemComplex
Meningoencephalitis(MUO)
Meningoencephalitis is a severe inflammatory condition affecting the brain and its protective outer membranes, known as the meninges. In dogs, this is most commonly caused by an abnormal immune system response where the body mistakenly attacks its own central nervous system tissue. Diagnosis typically relies on advanced imaging like an MRI and analysis of the cerebrospinal fluid surrounding the brain and spinal cord.
Tested via: Clinical examView details - SevereGeneral / metabolicX-linked
Menkes disease
In dogs, this genetic variant involving the ATP7A gene is a benign genetic modifier rather than a severe disease. Instead of causing a harmful copper deficiency, it acts as a protective factor in regulating copper levels in the body. It does not cause any harmful effects on the dog's organs or overall health.
View details - ModerateHeartAutosomal recessive
Methaemoglobinaemia, CYB5A-related
This is a rare hereditary blood disorder caused by a deficiency in the cytochrome b5 enzyme. This deficiency prevents red blood cells from properly converting methemoglobin—a non-functional form of hemoglobin—back into normal, oxygen-carrying hemoglobin. As a result, the blood cannot efficiently deliver oxygen to the body's tissues and organs.
Tested via: DNA testView details
Frequently asked questions
What is the HonestDog dog diseases database?
Our database brings together hereditary and common canine conditions with symptoms, inheritance patterns, testing methods, and the breeds where each matters most.
How do I find the right test for a condition?
Search by disease name, abbreviation or symptom, then filter by test type, body region or severity. Each detail page lists recommended tests and affected breeds.
Why do health tests matter for breeders?
Health tests help catch hereditary conditions early and support responsible breeding. Many breed clubs require or recommend specific tests as part of their screening.
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