Dog Diseases Database
Every hereditary and common canine condition — with tests, affected body regions, and the breeds where each shows up most.
Filters
- 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.
View details - HighGeneral / metabolicComplex
Mast cell tumor(MCT)
A mast cell tumor is a type of cancer that arises from mast cells, which are specialized white blood cells involved in the body's immune and allergic responses. These tumors most commonly develop in the skin and the tissues just beneath it, though they can occasionally affect internal organs. Because mast cells contain chemical messengers like histamine, the tumors can cause localized inflammation, swelling, or redness.
View 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' (or 'Lanzenzahn'), this abnormal positioning causes the misplaced teeth to rub or press painfully against the lips, gums, or other teeth.
View 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.
View 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.
View 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.
View 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.
View 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.
View 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.
View details - ModerateGeneral / metabolicAutosomal recessive
Methaemoglobinaemia, CYB5R3-related
This is an inherited blood disorder where a deficiency in a specific enzyme, cytochrome b5 reductase, impairs the red blood cells' ability to carry oxygen. Without this enzyme, an abnormal form of hemoglobin—the protein responsible for transporting oxygen—builds up in the bloodstream, reducing the amount of oxygen delivered to the body's tissues.
View details - SevereEyesAutosomal recessive
Microphthalmia with haematopoietic defects, DNAJC21-related
This severe inherited disorder affects eye development and the blood-producing system in the bone marrow, caused by a genetic mutation in the DNAJC1 gene. Because the bone marrow cannot produce enough vital blood cells, affected dogs suffer from a lack of oxygen-carrying red blood cells (anemia) and a severely weakened immune system. This condition is genetically similar to bone marrow failure syndromes seen in humans.
View details - HighEyesAutosomal recessive
Microphthalmia, isolated, with coloboma
This is a congenital developmental disorder of the eyes where the eyeball does not grow to its normal size, a condition known as microphthalmia. It is accompanied by coloboma, which refers to structural gaps or missing tissue in parts of the eye such as the iris or retina. Because these structures fail to fuse properly during embryonic development, the eye's ability to function is severely compromised.
View details - MildEyesUnknown
Miosis
Miosis is an eye condition characterized by abnormally small, constricted pupils that do not dilate, or widen, properly. This occurs due to a dysfunction in the muscles of the iris or the nervous system pathways that control pupil movement. It can be congenital, meaning a puppy is born with it, and is routinely assessed during official veterinary eye examinations.
View details - ModerateMouth & teethComplex
Mislocated polydontic maxillary incisor teeth
This is a congenital dental condition where extra, or supernumerary, front teeth (incisors) grow in the upper jaw in abnormal positions. This misalignment affects the mouth and dental structure, often causing crowding and improper contact between the upper and lower teeth. Over time, this crowding can lead to painful rubbing against the gums and surrounding soft tissues.
View details - SevereHead / nervous systemAutosomal recessive
Mitochondrial fission encephalopathy(MFE)
Mitochondrial fission encephalopathy, also known as MFF-related encephalopathy, is a severe inherited brain disorder where the normal division of mitochondria (the energy-producing parts of a cell) is impaired. Without this division, nerve cells in the brain suffer a severe energy deficit and progressively die. This condition is historically referred to as familial cerebellar ataxia with hydrocephalus.
View details - HighHeartComplex
Mitral stenosis(MS)
Mitral stenosis is a congenital heart defect where the mitral valve, which controls blood flow between the left upper and lower chambers of the heart, is abnormally narrowed. This narrowing restricts normal blood flow through the heart, causing blood to back up into the blood vessels of the lungs. Over time, this fluid buildup puts significant strain on the cardiovascular system.
View details - MildGeneral / metabolicX-linked
Modifier of copper toxicosis, ATP7A-related
This genetic variant in the ATP7A gene acts as a modifier for copper toxicosis, which is a metabolic disorder affecting the liver. It influences how copper is absorbed and stored in the body, potentially reducing the severity of copper accumulation in the liver. Because it is a modifier, it does not cause disease on its own but instead alters how another genetic condition behaves.
Tested via: DNA testView details - ModerateGeneral / metabolicComplex
Modifier of copper toxicosis, RETN-related
This genetic variant in the RETN gene acts as a modifier for copper toxicosis, a metabolic condition affecting the liver. It does not cause the disease on its own, but it influences how severely copper accumulates in the liver tissue. This accumulation can lead to progressive liver damage and inflammation.
Tested via: DNA testView details - SevereGeneral / metabolicX-linked
Mucopolysaccharidosis II(MPS II)
Mucopolysaccharidosis II (MPS II) is a severe, inherited metabolic disorder caused by a deficiency in an enzyme needed to break down complex sugar molecules. Without this enzyme, these sugars build up inside cells, causing progressive damage to multiple organ systems, including the skeleton and the nervous system. This condition is inherited in an X-linked manner, meaning it primarily affects male dogs.
View details - SevereGeneral / metabolicAutosomal recessive
Mucopolysaccharidosis IIIA(MPS IIIA)
Mucopolysaccharidosis IIIA is an inherited metabolic disorder where the body lacks a specific enzyme needed to break down complex sugar molecules. Without this enzyme, these sugars build up to toxic levels inside cells, causing progressive and irreversible damage to the central nervous system, particularly the brain.
Tested via: DNA testView details
Why HonestDog?
What makes HonestDog different from other platforms
Full transparency
We lay everything out clearly: who the breeder is, how they work, health checks, and genetic test results. So you can decide with full confidence.
Responsible breeding, assured
Every breeder on HonestDog meets strict standards, including health checks and genetic testing for both parents. So you never have to worry about puppy mills or bad actors.
Trust and verification
We verify breeders and buyers alike, so every conversation happens on solid ground. It's a new standard of trust in dog breeding.
Less hassle, more time
We've already vetted the breeders and gathered the details, so you can skip the endless research and focus on finding the right puppy for your family.
Our Mission
We connect dog lovers with responsible breeders and shelters to ensure every dog finds the perfect home.
Founded by dog enthusiasts, our platform focuses on ethical dog breeding and adoption.
Why HonestDog?
We connect you with vetted breeders and shelters so you can find your — your new companion — with confidence.
Vetted Partners
Only verified breeders and shelters — for a safe start.
Highest Standards
Every animal's health and wellbeing is our top priority.
Guides & Resources
Guides, checklists, and breed profiles — so you can make a well-informed decision.