Animalia Life

The Breed History
This breed originates from Tibetan lines of mastiff dogs; progressive development of the modern breed type has occurred since the 16th century, primarily in Germany. A breed club established the first breed standard in Munich in the late 1800s. The breed is a bulldog type, and these trace back to Molossus bloodlines. Other bloodlines bred into the boxer include terrier and perhaps English Bulldogs. The boxer is thought to get his name from the way he used his front paws during fights since it resembled a human boxing action. Others feel the name is a derivative of the Germanic word boxl. The year 1904 marked the first AKC registry.

Breeding for Function
In Germany, the boxer was a top choice for police work. Before fighting and baiting were outlawed, this breed was also used for these old sports. In Germany, the breed was used for hunting large game such as boars or bears and their powerful jaws were used to secure the catch. They were also used in theater and circus. The boxer was also used as a watchdog, assistance dog, and has become a very popular companion and obedience dog.

Physical Characteristics
Height at Withers: female 21-23.5" (53.5-60 cm), male 22.5-25" (57-63.5 cm).
Weight: females 55-65 lb (25-29.5 kg), males 65-80 lb (29.5-36.5 kg). Males are heavier boned.
Coat: The short glossy coat is brindle or fawn. White marking ("flash") is allowed over up to one third of the coat. All-white pups can be born, but are not used for breeding. The mask is usually black. Longevity: 11-13 years.
Points of Conformation: This dog is a medium-built athletic dog with well-developed musculature, and a springy stride. The brachycephalic head is broad and the muzzle is blunt and broad. Eyes are dark brown, and the forehead wrinkles when ears are pricked. Ears are usually cropped and the nose is black, a distinct stop is present, and a slight prognathism is the standard. The topline slopes slightly down towards the back end, they have a deep thorax with a short back and a slight tuck-up is standard. Dewclaws may be removed and tails are generally docked. Feet are compact, with well-knuckled toes.

Recognized Behavior Issues and Traits
Boxer breed characteristics reported include: A dog with high intelligence, independent minded, and possessing excellent strength and stamina. He is a watchdog and a good defender and loves to be around children. This breed is sometimes aloof with strangers, but enjoys close human contact. They are bred for a stable temperament and can be very playful, even boisterous. They are considered high-energy dogs and should be given daily exercise and play sessions to help them keep fit and mentally challenged. Training and socialization should be consistent and start early. These dogs may snore and can drool. They have low grooming needs, and are low shedders. They tolerate temperature extremes poorly. They should not be off-leash because of their well developed chase and fight instincts.

Normal Physiologic Variations
Heart size, based on the vertebral heart scale is normally larger than other breeds.
Boxer dogs may have an increased relative thickness of the LVW and IVS that is independent of aortic size, aortic velocity, or arterial blood pressure, and this morphology should be taken into consideration when screening Boxers by echocardiography.
A natural bob-tail Boxer line has been developed due to the heterozygous dominant expression of the T gene. Homozygous dominant individuals are pre-natally lethal.

Drug Sensitivities
Boxers have reportedly had severe reactions to injectable (IV or IM) acepromazine, including profound hypotension, collapse, respiratory arrest, and profound bradycardia.

Inherited Diseases
Boxer Cardiomyopathy (Arrhythmogenic Right Ventricular Cardiomyopathy, ARVC): Autosomal dominant disorder with incomplete penetrance, characterized by sudden death, ventricular premature complexes (VPCs), ventricular tachycardia, syncope, dilated cardiomyopathy, and heart failure. The primary disease process is ventricular arrhythmia, which is reported in over 30% of all Boxers. Diagnose with 24 hour Holter ECG. Greater than 100 VPCs in 24 hours is abnormal for this breed. VPCs are generally positive in Lead II, suggesting a right ventricular origin. Echocardiogram is generally normal until heart failure/ cardiomyopathy develops. Treat with anti-arrhythmic drugs. One study showed that fish oils (omega 3 fatty acids) reduced arrhythmias in affected Boxers. A direct genetic test is available showing homozygous affected dogs more severely affected than heterozygotes. Genetic testing shows 41% heterozygotes and 6% homozygous for the gene.
Hip Dysplasia: Polygenically inherited trait causing degenerative joint disease and hip arthritis. OFA reports 11.1% affected.
Elbow Dysplasia: Polygenically inherited trait causing elbow arthritis. One study found Boxers to be one of the most commonly affected breeds with the fragmented medial coronoid process form of elbow dysplasia. OFA reports 0.7% affected.
Patella Luxation: Polygenically inherited laxity of patellar ligaments, causing luxation, lameness, and later degenerative joint disease. Treat surgically if causing clinical signs. Too few Boxers have been screened by OFA to determine an accurate frequency.
Progressive Axonopathy (Boxer Axonopathy): Rare, autosomal recessive disorder presenting with a slowly progressive weakness and incoordination of the hind limbs. Age of onset 2-3 months. Progresses to all four limbs, eventually causing severe paresis and ataxia. No genetic test is available.

Disease Predispositions
Dystocia (Difficult Whelpings): Dystocia presents more commonly in Boxers than other breeds. In a Swedish study, 27.7% of whelpings developed dystocia, with the majority requiring caesarian section. The most common reasons for dystocia were primary uterine inertia (60%) and malpresentation of the fetus (26%).
Hypothyroidism: Inherited autoimmune thyroiditis. 18.0% positive for thyroid auto-antibodies based on testing at Michigan State University. (Ave. for all breeds is 7.5%).
Distichiasis: Abnormally placed eyelashes that irritate the cornea and conjunctiva. Can cause secondary corneal ulceration. Identified in 12.90% of Boxers CERF examined by veterinary ophthalmologists between 2000-2005. Because the condition causes significant corneal disease in the Boxer, CERF discourages breeding affected dogs.
Aortic Stenosis (Subaortic Stenosis, SAS): Affected dogs present with a left heart base murmur, and aortic velocities greater than 1.5 m/second on Doppler echocardiography, aortic regurgitation, and mitral regurgitation. Can cause exercise intolerance, syncope, and progress to heart failure. Occurring in 10% of Boxers screened in one study. Identified in 8.50% of screened Boxers in Italy. Reported at a frequency of 8.1% in Switzerland. Odds ratio of 8.6x versus other breeds. Unknown mode of inheritance - considered polygenic.
Cryptorchidism (Retained Testicles): Can be unilateral or bilateral. Boxers have an increased prevalence of the disorder. Found to be moderately (24%) heritable in the breed in a Danish study. Identified in 9.8% of male pups in a Swedish study. Reported at a frequency of 10.7% with a heritability of 0.24 in a Dutch study.
Persistent Corneal Erosion/Corneal Dystrophy (Ulcerative Keratitis, Indolent Ulcer, Boxer Ulcer): Inherited breed prevalence. Treat with topical medications, keratectomy, flap +/- contact lens. Reported in 9.05% of Boxers CERF examined by veterinary ophthalmologists between 2000-2005.
Cancer/Neoplasia: A Danish study shows a higher standard morbidity rate (SMR) for both malignant and benign cancers in Boxers versus other breeds.
Mast Cell Tumor (MCT): Boxers are a predisposed breed for developing cutaneous mast cell tumors. Mast cell tumors produce histamine, and can cause inflammation and ulceration. These are typically more benign in Boxers, but they are at higher risk to develop additional MCTs at distant sites (outside the surgical margins).
Histiocytic Ulcerative Colitis (Boxer Colitis): Inflammatory bowel disease (IBD) that occurs predominantly in Boxers. The lesions are characterized by mucosal ulceration and a mixed inflammatory cell infiltrate. Treatment is with medication and diet. Enrofloxacin therapy against intramucosal E. coli improves clinical signs in some cases, reflecting an infectious role in the pathogenesis. Some severe cases cannot be controlled. Unknown mode of inheritance.
Gingival Hypertrophy: Older Boxers can develop a proliferative gingival hypertrophy affecting all gum surfaces. Treat with gingivectomy.
Atopic Dermatitis/Inhalant Allergies: Presents with pruritis, pyotraumatic dermatitis (hot spots), and often hives. Reported at an increased frequency in the breed versus other breeds. White Boxers have a higher risk.
Cranial Cruciate Ligament Rupture (ACL): Traumatic tearing of the anterior cruciate ligament. The breed is found to have an increased incidence versus other breeds. Treatment is surgery. Found to be moderately (28%) heritable, with a frequency of 5.7% in the breed in a Danish study.
Stifle Osteochondritis Dessicans (OCD): Polygenically inherited cartilage defect. Causes stifle joint pain and lameness in young growing dogs. Mild cases can resolve with rest, while more severe cases require surgery. Reported 56.3x odds ratio versus other breeds.12 Ectropion: Rolling out of eyelids, often with a medial canthal pocket. Can also cause conjunctivitis. Dorn reports a 7.97X odds ratio in Boxers versus other breeds. Ectropion is reported in 4.52% of Boxers CERF-examined by veterinary ophthalmologists between 2000-2005.
Pulmonic Stenosis (PS): Congenital cardiac disorder of restricted pulmonic outflow. Echocardiogram findings of restriction of right ventricular outflow tract, pulmonic valve and/or main pulmonary artery on transthoracic imaging from the right parasternal and left cranial parasternal short-axis views. Identified in 3.12% of screened Boxers in Italy. Reported at a frequency of 3.3% in Switzerland. Unknown mode of inheritance.
Cataracts: Anterior cortex intermediate and nuclear punctate cataracts predominate in the breed. Identified in 2.71% of Boxers CERF examined by veterinary ophthalmologists between 2000-2005. CERF does not recommend breeding any Boxer with a cataract.17 Epilepsy: Inherited seizures. Can be generalized or partial. Treat with anticonvulsants. Dorn reports a 7.17x odds ratio in Boxers versus other breeds. Found to be moderately (36%) heritable in a Danish study, with a frequency of 2.4%.
Chronic Pancreatitis: Often subclinical inflammation of the pancreas that can cause intermittent discomfort and gastrointestinal upsets. Can possibly lead to pancreatic insufficiency or diabetes mellitus. Boxers have a 3.0x relative risk versus other breeds.
Demodicosis: Dorn reports a 2.66x odds ratio of developing demodectic mange versus other breeds. This disorder has an underlying immunodeficiency in its pathogenesis. One study shows that a DLA haplotype imparts a 5x odds ratio for the disorder.
Follicular Dysplasia: Alopecia primarily to the flank region, beginning at 2-4 years of age. Melatonin may help alleviate clinical signs. Unknown mode of inheritance.
Osteosarcoma (Bone Cancer): Boxers have an increased incidence of developing malignant osteosarcoma versus other breeds. Occurs primarily in the extremities.
Inflammatory Myopathies: Boxers are a breed at increased risk of developing inflammatory myopathies, including polymyositis, masticatory muscle myositis, dermatomyositis-like myopathy, and extraocular myositis. A high proportion of affected Boxers have muscle-specific circulating autoantibodies against sarcolemma antigens. A serum antigen assay can be used as a diagnostic test.
Seasonal Flank Alopecia: Bilateral, symmetrical alopecia affecting the flank, dorsum and tail. Affects primarily spayed females in the Spring or Autumn. Mean age of onset is 3.6 years.
Spondylosis Deformans: A study of spondylosis deformans and osteophyte development in Boxers showed that it is a heritable condition, especially at specific vertebral sites. Spondylosis deformans does not usually cause spinal problems for the dog.
Atrial Septal Defect (ASD): Congenital cardiac disorder of the wall between the left and right atria. Causes a left heart base systolic murmur that must be differentiated from subaortic stenosis by echocardiography. Affected dogs show exercise intolerance, syncope, dyspnea, and/or a cough. Reported at a frequency of 0.16% in a Swedish study, but identified at a much higher frequency in a French study.
Degenerative Myelopathy: Degenerative condition of the spinal cord in older Boxers presenting with progressive weakness and incoordination of the hind limbs. No treatments have been found to be effective. Unknown mode of inheritance. A direct genetic test for an autosomal recessive DM susceptibility gene is available. All affected dogs are homozygous for the gene, however, only a small percentage of homozygous dogs develop DM. OFA reports DM susceptibility gene frequencies of 38% carrier and 45% homozygous "at risk".
Cleft Lip/Palate: Congenital disorder of facial formation. Found to be moderately (27%) heritable, with a frequency of 2.3% in the breed in a Danish study.
Juvenile Nephropathy: Rare disorder in young Boxers presenting with severe polyuria and polydipsia, and progressing to chronic renal failure. Histopathology includes immature glomeruli and/or tubules, and persistent mesenchyme. A reflux nephropathy may be involved in the disease process.
T-Cell Lymphoma (Mycosis Fungoides): Boxers have an increased incidence of developing this more malignant form of cutaneous lymphoma versus other breeds.
Oral Cancer: One study found that Boxers were a breed with a significantly higher risk of developing oral and pharyngeal tumors, as compared with all breeds combined.
Intracranial Meningioma: One study found that Boxers are overrepresented compared to other breeds for intracranial meningiomas. These are the most common brain tumor in dogs, and can be benign, or malignant.
Juvenile Necrotizing Vasculitis/Sterile Meningitis: Affected Boxers are all under 2 years of age, presenting with apathy, fever, delayed proprioception, ataxia, and increased head and cervical pain. Histopathology shows necrotizing vasculitis in the CNS, with perivascular granulomatous inflammation. 40% of all dogs with this diagnosis are Boxers. Treat with steroids. Unknown mode of inheritance.
Calcinosis Circumspecta, Central PRA, Cervical Vertebral Instability, Cutaneous Asthenia, Cystinuria, Deafness, Dermoid Sinus, Elongated Soft Palate, Factor II Deficiency, Factor VII Deficiency, Gastric Dilatation-Volvulus, Hyperadrenocorticism, Hypoplastic Trachea, Lupoid Onychopathy, Nodular Dermatofibrosis, Polydontia, Progressive Retinal Atrophy, Prolapsed Gland of Nictitans, Pyloric Stenosis, Sphingomyelinosis, Spina Bifida, Supernumerary Teeth, Tricuspid Valve Dysplasia, and von Willebrand's Disease are reported.

Isolated Case Studies
Neuroblastoma: A 2 year old Boxer presenting renal disease and a palpable abdominal mass was diagnosed with a peripheral neuroblastoma.
Polyglandular Syndrome: An 8-year-old spayed female boxer dog, presented because of progressive symmetrical truncal alopecia, lethargy, and intolerance to cold. Pathological findings were immune thyroiditis and lymphocytic adrenalitis.
Type C Niemann-Pick Disease (Lipid Storage Disease): A 9-month-old boxer dog was presented with progressive neurological deterioration. The brain showed increased levels of lactosylceramide and two gangliosides, GM3 and GM2.
Neuronal Vacuolation: Two 6-month-old Boxer littermates presented with progressive pelvic limb paresis and ataxia, upper airway stridor, and visual deficits. Pathology revealed neuronal vacuolation and spinocerebellar degeneration, analogous to the syndrome reported in Rottweilers.

Genetic Tests
Tests of Genotype: Direct test for ARVC is available from North Carolina State University - Meurs Lab.
A direct genetic test for an autosomal recessive DM susceptibility gene is available from the OFA.
Direct test for coat color alleles is available from VetGen. Tests of Phenotype: Recommend hip and elbow radiographs, CERF eye examination, cardiac evaluation (echocardiogram +/- 24 hour Holter ECG), patella evaluation, and thyroid profile including autoantibodies.

Miscellaneous
- Breed name synonyms: Bullenbeisser (historical)
- Registries: CKC, AKC, UKC, KCGB (Kennel Club of Great Britain), ANKC(Australian National Kennel Club), NKC (National Kennel Club.
- AKC rank (year 2008): 6 (29,705 dogs registered)
- Internet resources: The American Boxer Club: americanboxerclub.org
Boxer Club of Canada: boxerclubofcanada.com
The British Boxer Club: thebritishboxerclub.co.uk