Understand common pet health conditions, recognize symptoms early, and learn evidence-based prevention strategies. Covering 68 conditions across 9 species with breed-specific risk data.
Category: Orthopedic | Severity: Moderate to Severe
Hip dysplasia is a genetic skeletal condition where the ball and socket joint of the hip does not develop properly. The joint becomes loose, leading to abnormal wear, inflammation, and eventually degenerative joint disease (osteoarthritis). It is one of the most common orthopedic conditions in dogs, particularly affecting large and giant breeds.
83 breeds affected
Category: Orthopedic | Severity: Mild to Severe
Patellar luxation occurs when the kneecap (patella) dislocates from its normal position in the femoral groove. It can luxate medially (toward the inside of the leg) or laterally (toward the outside). Medial luxation is far more common, especially in small and toy breeds. The condition is graded from I (intermittent) to IV (permanent dislocation).
36 breeds affected
Category: Metabolic/Nutritional | Severity: Moderate
Obesity is defined as an accumulation of excess body fat that impairs health and well-being. In pets, it is typically diagnosed when body weight exceeds the ideal by 15-20% or more. It is the most common nutritional disorder in companion animals, affecting an estimated 25-30% of dogs and cats in developed countries.
33 breeds affected
Category: Orthopedic | Severity: Moderate to Severe
Elbow dysplasia is a complex developmental condition encompassing several abnormalities of the elbow joint, including fragmented medial coronoid process (FCP), osteochondritis dissecans (OCD), ununited anconeal process (UAP), and elbow incongruity. It is the most common cause of forelimb lameness in young large-breed dogs.
29 breeds affected
Category: Parasitic/Infectious | Severity: Moderate to Severe
Ich (Ichthyophthirius multifiliis) is one of the most common and destructive parasitic diseases in freshwater aquarium fish. The protozoan parasite burrows beneath the epithelium of the fish's skin and gills, causing characteristic white spots. Without treatment, ich can rapidly spread through an entire aquarium and cause mass mortality.
26 breeds affected
Category: Ophthalmologic | Severity: Severe
Progressive Retinal Atrophy (PRA) is a group of inherited degenerative diseases affecting the photoreceptor cells (rods and cones) of the retina. The condition leads to progressive vision loss, initially affecting night vision and eventually resulting in complete blindness. Multiple genetic mutations have been identified across different breeds.
26 breeds affected
Category: Dental | Severity: Mild to Severe
Dental disease encompasses a spectrum of conditions affecting the teeth and supporting structures, from mild gingivitis to severe periodontitis with tooth loss. It affects over 80% of dogs and 70% of cats by age three. The disease begins with plaque accumulation, progresses to calculus formation, and leads to gingival inflammation, periodontal pocket formation, and eventual bone loss.
23 breeds affected
Category: Bacterial/Infectious | Severity: Mild to Moderate
Fin rot is a common bacterial infection in aquarium fish that causes progressive deterioration of the fins and tail. It typically begins at the fin edges and works inward. The condition is usually secondary to poor water quality, stress, or physical damage, allowing opportunistic bacteria (Pseudomonas, Aeromonas, Vibrio) to establish infection.
23 breeds affected
Category: Endocrine | Severity: Moderate
Hypothyroidism is the most common endocrine disorder in dogs, resulting from inadequate production of thyroid hormones (T3 and T4). The thyroid gland regulates metabolism, and deficiency affects virtually every organ system. Most cases (95%) result from immune-mediated thyroiditis or idiopathic thyroid gland atrophy.
19 breeds affected
Category: Systemic | Severity: Mild to Severe
Dehydration is a critical and common condition in captive reptiles, amphibians, and small mammals, resulting from inadequate water intake or excessive fluid loss. Reptiles are particularly vulnerable due to their reliance on environmental humidity and behavioral drinking patterns. Chronic low-grade dehydration is one of the most overlooked husbandry issues in exotic pets.
16 breeds affected
Category: Cardiovascular | Severity: Severe
Hypertrophic Cardiomyopathy (HCM) is the most common heart disease in cats, characterized by abnormal thickening of the left ventricular wall. This thickening reduces the heart's ability to relax and fill properly (diastolic dysfunction), potentially leading to heart failure, thromboembolism, or sudden death.
15 breeds affected
Category: Systemic/Infectious | Severity: Severe
Dropsy is not a single disease but a symptom complex in fish characterized by severe fluid retention causing the body to swell and scales to protrude outward (pinecone appearance). It indicates kidney failure or severe systemic infection, most commonly caused by Aeromonas bacteria. By the time dropsy is visible, the condition is often advanced.
12 breeds affected
Category: Renal/Urinary | Severity: Severe
Polycystic Kidney Disease (PKD) is an inherited condition characterized by the development of multiple fluid-filled cysts within the kidneys. These cysts progressively enlarge over time, replacing normal kidney tissue and eventually leading to chronic kidney failure. It is most common in Persian cats and related breeds.
12 breeds affected
Category: Dental | Severity: Moderate
Dental malocclusion in small mammals (rabbits, guinea pigs, chinchillas) occurs when continuously growing teeth (hypsodont dentition) fail to wear properly, leading to overgrowth, abnormal angulation, and oral pain. Unlike dogs and cats, these species' teeth grow continuously throughout life and require constant wear through fibrous diet to maintain proper length and alignment.
12 breeds affected
Category: Cardiovascular | Severity: Severe
Dilated Cardiomyopathy (DCM) is a primary myocardial disease characterized by dilation of the heart chambers and impaired systolic (contractile) function. The heart muscle becomes thin and weak, unable to pump blood effectively. It is the second most common heart disease in dogs, predominantly affecting large and giant breeds.
10 breeds affected
Category: Fungal/Infectious | Severity: Moderate to Severe
Aspergillosis is a fungal infection caused by Aspergillus species (primarily A. fumigatus) that primarily affects the respiratory system. In birds, it is one of the most common and serious infectious diseases, affecting the air sacs and lungs. In dogs, it typically presents as nasal aspergillosis (sinonasal infection) or disseminated aspergillosis.
10 breeds affected
Category: Metabolic/Nutritional | Severity: Moderate to Severe
Metabolic Bone Disease (MBD) is a common condition in captive reptiles and amphibians resulting from inadequate calcium metabolism. It encompasses nutritional secondary hyperparathyroidism, osteomalacia, and rickets. The condition leads to progressive weakening of bones due to calcium depletion, often caused by insufficient UVB exposure, dietary calcium deficiency, or improper calcium-to-phosphorus ratios.
10 breeds affected
Category: Ophthalmologic | Severity: Moderate to Severe
Cataracts are opacifications of the crystalline lens that impair vision. They can affect part or all of the lens and one or both eyes. In dogs, hereditary cataracts are common in many breeds, while diabetic cataracts develop rapidly due to osmotic changes in the lens. Cataracts are classified by stage (incipient, immature, mature, hypermature) and age of onset.
9 breeds affected
Category: Gastrointestinal | Severity: Critical/Life-threatening
Gastric Dilatation-Volvulus (GDV) is a life-threatening emergency where the stomach distends with gas (dilatation) and rotates on its axis (volvulus), cutting off blood supply and trapping gas. Without immediate surgical intervention, GDV is fatal within hours. It primarily affects large, deep-chested breeds.
9 breeds affected
Category: Parasitic | Severity: Mild to Moderate
Mite infestations encompass several conditions caused by microscopic arachnids that parasitize the skin. Sarcoptic mange (Sarcoptes scabiei) causes intense itching and is highly contagious. Demodectic mange (Demodex) involves overgrowth of normal skin mites due to immune dysfunction. Other mites include Cheyletiella (walking dandruff) and ear mites (Otodectes).
8 breeds affected
Category: Dermatologic/Infectious | Severity: Mild to Moderate
Otitis externa (inflammation of the external ear canal) is one of the most common reasons for veterinary visits in dogs. It can progress to otitis media (middle ear) and otitis interna (inner ear). Predisposing factors include ear conformation, allergies, moisture, and foreign bodies. Chronic cases lead to canal stenosis and require surgical intervention.
8 breeds affected
Category: Systemic | Severity: Mild to Moderate
Swim bladder disease encompasses conditions affecting the swim bladder's ability to regulate buoyancy. Affected fish cannot maintain normal position in the water column, floating at the surface, sinking to the bottom, or swimming at abnormal angles. It is particularly common in fancy goldfish and bettas due to their compressed body shapes.
7 breeds affected
Category: Respiratory/Infectious | Severity: Moderate to Severe
Respiratory infections in small mammals, reptiles, and birds encompass a range of bacterial, viral, and fungal pathogens affecting the upper and lower respiratory tract. In guinea pigs, Bordetella and Streptococcus are common. In reptiles, bacterial pneumonia is often secondary to husbandry issues. In birds, respiratory infections can rapidly become life-threatening.
7 breeds affected
Category: Neurological | Severity: Moderate to Severe
Epilepsy is a chronic neurological disorder characterized by recurrent, unprovoked seizures. Idiopathic (genetic) epilepsy is the most common cause of seizures in dogs aged 1-5 years. Seizures result from abnormal, excessive electrical activity in the brain and can range from focal (partial) to generalized (grand mal) events.
7 breeds affected
Category: Neurological | Severity: Severe/Fatal
Degenerative Myelopathy (DM) is a progressive, fatal neurodegenerative disease affecting the spinal cord of dogs. It is analogous to Amyotrophic Lateral Sclerosis (ALS) in humans. The disease causes progressive loss of coordination and strength in the hind limbs, eventually leading to complete paralysis. A mutation in the SOD1 gene is associated with the condition.
6 breeds affected
Category: Neurological/Sensory | Severity: Moderate
Congenital sensorineural deafness is associated with white coat color and blue eyes in dogs and cats. It results from degeneration of the stria vascularis in the cochlea during the first few weeks of life. The condition is linked to the piebald (S) and merle (M) genes in dogs and the white (W) gene in cats. It can be unilateral or bilateral.
6 breeds affected
Category: Gastrointestinal | Severity: Moderate to Severe
Gastrointestinal stasis is a potentially life-threatening condition in rabbits and other hindgut fermenters where normal gut motility slows or stops. The condition disrupts the delicate balance of cecal microflora, leading to gas accumulation, bacterial overgrowth, toxin production, and hepatic lipidosis. It is one of the most common emergencies in pet rabbits.
5 breeds affected
Category: Respiratory | Severity: Moderate to Severe
Brachycephalic Airway Syndrome (BAS) is a set of upper airway abnormalities found in short-nosed (brachycephalic) breeds. The syndrome includes stenotic nares (narrowed nostrils), elongated soft palate, hypoplastic trachea, and everted laryngeal saccules. These anatomical abnormalities create increased airway resistance and respiratory compromise.
5 breeds affected
Category: Ophthalmologic | Severity: Moderate
Entropion is a condition where the eyelid rolls inward, causing the eyelashes and fur-covered skin to rub against the corneal surface. This chronic irritation leads to corneal ulceration, scarring, and potentially vision loss. It most commonly affects the lower eyelid and is particularly prevalent in breeds with loose facial skin or prominent skin folds.
5 breeds affected
Category: Ophthalmologic | Severity: Severe
Glaucoma is a group of diseases characterized by elevated intraocular pressure (IOP) that damages the optic nerve and retina, leading to vision loss. Primary glaucoma is inherited and involves abnormal drainage angle anatomy. Secondary glaucoma results from other ocular diseases. It is a painful condition requiring emergency treatment.
5 breeds affected
Category: Endocrine | Severity: Moderate to Severe
Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia due to insufficient insulin production (Type 1, common in dogs) or insulin resistance (Type 2, common in cats). Without adequate insulin action, cells cannot utilize glucose, leading to metabolic derangements affecting multiple organ systems.
5 breeds affected
Category: Oncologic | Severity: Severe/Fatal
Osteosarcoma is the most common primary bone tumor in dogs, accounting for approximately 85% of skeletal tumors. It is a highly aggressive malignant neoplasm that typically affects the appendicular skeleton (limbs) of large and giant breed dogs. The tumor is locally invasive and has a high metastatic rate, with >90% of dogs having micrometastases at diagnosis.
5 breeds affected
Category: Orthopedic | Severity: Moderate
Legg-Calve-Perthes Disease is a condition where the blood supply to the femoral head (ball of the hip joint) is disrupted, leading to avascular necrosis (bone death), collapse, and secondary osteoarthritis. It primarily affects young small-breed dogs between 4-12 months of age and is typically unilateral.
4 breeds affected
Category: Cardiovascular | Severity: Moderate to Severe
Subaortic stenosis (SAS) is a congenital heart defect where a fibrous ridge or ring develops below the aortic valve, creating obstruction to blood flow from the left ventricle. It is the most common congenital heart defect in large-breed dogs. The obstruction creates turbulent flow (murmur) and forces the heart to work harder, leading to left ventricular hypertrophy.
4 breeds affected
Category: Behavioral/Dermatologic | Severity: Moderate
Feather Destructive Behavior (FDB) is a complex condition where parrots damage or remove their own feathers through plucking, barbering, or chewing. It affects up to 10% of captive parrots and is one of the most challenging behavioral problems to treat. The behavior can have medical, environmental, or psychological origins and often becomes self-reinforcing.
4 breeds affected
Category: Bacterial/Infectious | Severity: Moderate to Severe
Columnaris is a common and highly contagious bacterial infection in freshwater fish caused by Flavobacterium columnare. Despite its common name 'mouth fungus,' it is bacterial, not fungal. The disease can affect the skin, fins, gills, and mouth, progressing rapidly in warm water conditions. It is one of the leading causes of fish mortality in aquaculture and aquariums.
4 breeds affected
Category: Neurological/Orthopedic | Severity: Moderate to Critical
Intervertebral Disc Disease (IVDD) occurs when the cushioning discs between vertebrae degenerate, bulge, or rupture into the spinal canal. This causes compression of the spinal cord or nerve roots, resulting in pain, nerve damage, and potentially paralysis. Type I (acute extrusion) is common in chondrodystrophic breeds; Type II (chronic protrusion) affects larger breeds.
3 breeds affected
Category: Hematologic | Severity: Mild to Severe
Von Willebrand Disease (vWD) is the most common inherited bleeding disorder in dogs, caused by deficiency or dysfunction of von Willebrand factor (vWF), a protein essential for platelet adhesion and blood clot formation. Three types exist: Type 1 (most common, partial quantitative deficiency), Type 2 (qualitative deficiency), and Type 3 (complete absence, most severe).
3 breeds affected
Category: Dermatologic | Severity: Mild to Moderate
Allergic dermatitis (atopy) is a genetically predisposed inflammatory skin condition caused by hypersensitivity to environmental allergens (pollen, dust mites, mold spores). It is the second most common allergic skin disease in dogs after flea allergy dermatitis. The condition is chronic, requiring lifelong management.
2 breeds affected
Category: Environmental/Emergency | Severity: Severe/Life-threatening
Heatstroke is a life-threatening condition where body temperature rises above the thermoregulatory capacity of the animal, causing cellular damage, organ failure, and potentially death. Dogs are particularly susceptible due to limited cooling mechanisms (panting only). Brachycephalic breeds, obese animals, and those with thick coats are at highest risk.
2 breeds affected
Category: Oncologic | Severity: Severe
Lymphoma is one of the most common cancers in dogs and cats, arising from malignant transformation of lymphocytes. It can affect virtually any organ but most commonly involves lymph nodes (multicentric), gastrointestinal tract (alimentary), chest (mediastinal), or skin (cutaneous). It accounts for 7-24% of all canine neoplasms.
2 breeds affected
Category: Respiratory | Severity: Moderate
Tracheal collapse is a progressive condition where the cartilage rings of the trachea weaken and flatten, causing the airway to narrow during breathing. It primarily affects small and toy breed dogs. The condition can involve the cervical trachea, intrathoracic trachea, or mainstem bronchi. It is a common cause of chronic cough in small dogs.
2 breeds affected
Category: Cardiovascular | Severity: Moderate to Severe
Myxomatous Mitral Valve Disease (MMVD) is the most common acquired heart disease in dogs, accounting for approximately 75% of all canine heart disease. The mitral valve leaflets undergo progressive myxomatous degeneration, becoming thickened and distorted, leading to valve incompetence (regurgitation) and eventually congestive heart failure.
2 breeds affected
Category: Gastrointestinal | Severity: Moderate to Severe
Pancreatitis is inflammation of the pancreas that can range from mild edematous to severe necrotizing forms. Acute pancreatitis involves sudden onset of pancreatic inflammation, while chronic pancreatitis involves ongoing low-grade inflammation with progressive fibrosis. It is a common and potentially life-threatening condition in both dogs and cats.
2 breeds affected
Category: Endocrine | Severity: Moderate to Severe
Addison's disease (hypoadrenocorticism) results from insufficient production of corticosteroids (cortisol and aldosterone) by the adrenal glands. It is often called 'the great pretender' due to its vague, waxing-and-waning clinical signs that mimic many other diseases. Acute adrenal crisis (Addisonian crisis) is a life-threatening emergency.
2 breeds affected
Category: Hepatic | Severity: Severe/Life-threatening
Hepatic lipidosis is the most common liver disease in cats, characterized by excessive accumulation of triglycerides within hepatocytes. It typically develops when an overweight or obese cat stops eating for as few as 2-7 days. The liver becomes overwhelmed by mobilized fat, leading to liver failure. It can be primary (idiopathic) or secondary to another disease.
1 breeds affected
Category: Renal/Urinary | Severity: Moderate to Critical
Feline Lower Urinary Tract Disease (FLUTD) is an umbrella term for conditions affecting the bladder and urethra of cats. The most common form is Feline Idiopathic Cystitis (FIC), a stress-related inflammatory condition. Urethral obstruction ('blocked cat') is a life-threatening emergency, primarily affecting male cats due to their narrow urethra.
1 breeds affected
Category: Endocrine | Severity: Moderate
Hyperthyroidism is the most common endocrine disorder in middle-aged to senior cats, caused by excessive production of thyroid hormones (T3 and T4) from a benign thyroid adenoma (97-99% of cases). The resulting hypermetabolic state affects virtually every organ system and, if untreated, leads to heart disease, hypertension, and kidney damage.
1 breeds affected
Category: Renal/Urinary | Severity: Moderate to Severe
Chronic Kidney Disease (CKD) is a progressive, irreversible loss of kidney function over months to years. It is one of the most common diseases in senior cats, affecting up to 30% of cats over 15 years. The kidneys lose ability to concentrate urine, excrete waste products, and maintain electrolyte balance. CKD is staged I-IV based on creatinine and SDMA levels.
1 breeds affected
Category: Viral/Infectious | Severity: Severe/Fatal
Psittacine Beak and Feather Disease (PBFD) is caused by a circovirus that attacks rapidly dividing cells in the feather follicles, beak, and immune system of parrots. It is one of the most significant viral diseases of psittacine birds worldwide. The virus causes progressive feather dystrophy, beak deformities, and immunosuppression.
1 breeds affected