Animalia Life

The Breed History
In South Africa, native Hottentot tribe dogs were crossed with imported European breeds such as Danes, Mastiffs and others. The native dogs had the unique breed signature "ridge" which is a patch of hair growing in reverse to the normal direction of hair on the topline. They were imported to the USA in the mid 1900s, and first AKC registration occurred in 1955.

Breeding for Function
The harsh environment of arid temperature extremes and rough bush required a dog that was hardy and could both hunt and protect. This loyal dog was used for lion hunting in Rhodesia starting in the late 1800s, and the standard breed arose from this Zimbabwe breeder group in 1922. These dogs have also been used for other large game such as bear and bobcat, and are now shown in obedience and conformation and are popular for hunting, watchdog, and companionship.

Physical Characteristics
Height at Withers: female 24-26" (61-66 cm), male 25-27" (63.5-68.5 cm)
Weight: females 70 lb (32 kg), males 85 lb (38.5 kg).
Coat: The sleek short coat is wheaten; a range of shades is permissible, with only very small white patches on chest or toes allowed.
Longevity: 10-12 years.
Points of Conformation: A lean, muscular athletic dog with excellent endurance, this breed is slightly longer than they are tall. The stop is defined, and eyes are round. Ears are wide at the base, tapering to a point and nose is black, brown or liver. Chest is deeper than wide, and the topline is slightly arched. Limbs are straight and strong but not coarse, and dewclaws may be removed. The signature characteristic, the ridge, should be symmetrical and start at the level of the shoulder, then taper as it reaches the wing of the ileum level. Exactly two whorls should be present and are placed opposite each other at the anterior end of the ridge.

Recognized Behavior Issues and Traits
This dog is protective, gentle and loyal. He is easily trained, even-tempered and enjoys a family with children. They are known to be wary with strangers, and only rarely bark. Gentle obedience training should be combined with socialization to people and other pets when the dog is young. They need regular exercise and stimulation to prevent boredom. Average shedders, they require minimal grooming. They are not ideal city dogs, unless they get vigorous exercise.

Normal Physiologic Variations
Ridgelessness: The distinct dorsal ridge is inherited as an autosomal dominant trait. Ridgelessness is reported at a frequency of 10.6% in the RRCUS Health Survey 2001 Update. It is reported at a frequency of 5.6% in a study of Swedish Rhodesian Ridgebacks. The gene has been identified, but a commercial genetic test is not available.

Drug Sensitivities
None reported

Inherited Diseases
Elbow Dysplasia: Polygenically inherited trait causing elbow arthritis. OFA reports 6.4% affected.
Hip Dysplasia: Polygenically inherited trait causing degenerative joint disease and hip arthritis. OFA reports 5.1% affected.
Patella Luxation: Polygenically inherited laxity of patellar ligaments, causing luxation, lameness, and later degenerative joint disease. Treat surgically if causing clinical signs. OFA reports 1.3% affected.
Deafness: Rhodesian Ridgebacks have a rare, autosomal recessive form of deafness that develops after 8 weeks of age, and causes bilateral deafness by 1 year of age. Diagnosed by BAER testing. The gene has been identified, but a commercial genetic test is not available.
Hemophilia B: An X-linked severe form of hemophilia B occurs in the breed due to a mutation in the Factor IX gene. Most affected Rhodesian Ridgebacks are male, with non-clinical carrier mothers. The frequency of the mutation in the breed is not known, but is thought to be low. A commercial genetic test is not available.

Disease Predispositions
Hypothyroidism: Inherited autoimmune thyroiditis. 16.8% positive for thyroid autoantibodies based on testing at Michigan State University. (Ave. for all breeds is 7.5%).
Dermoid Sinus (DS): A dermoid sinus is a congenital, dorsal midline tube extending from the skin to the dorsal spinous ligament or dura matter. They usually occur in the neck area, but can be located anywhere over the spine. The sinus is lined with epithelial cells, and may contain hair follicles, sebaceous glands and sweat glands. A DS can be palpated as a cord running between the skin and the spine, and most form a small external opening which can be readily seen once the hair has been shaved. A dog can have multiple DS. Dermoid sinuses become infected over time, which can spread into the CNS. All affected dogs should have the DS removed surgically, which often requires a partial dorsal laminectomy. The frequency in the Swedish Rhodesian ridgeback population is estimated to be between 8 and 10 per cent. DS is reported at a frequency of 4.8% in the RRCUS Health Survey 2001 Update. Undetermined mode of inheritance, but highly correlated to the presence of the dominantly inherited dorsal ridge. It is suggested that dogs homozygous for the dominant ridge gene may be more susceptible than heterozygous dogs. Difficulty in determining heredity pattern may be caused by undetected DS.
Persistent Pupillary Membranes: Strands of fetal remnant connecting; iris to iris, cornea, lens, or involving sheets of tissue. The later three forms can impair vision, and dogs affected with these forms should not be bred. Identified in 5.26% of Rhodesian Ridgebacks CERF examined by veterinary ophthalmologists between 2000-2005.
Allergic Dermatitis (Atopy): Inhalant or food allergy. Presents with pruritis and pyotraumatic dermatitis (hot spots). Reported at a frequency of 4.6% in the RRCUS Health Survey 2001 Update.
Mast Cell Tumor (MCT): Skin tumors that produce histamine and cause inflammation and ulceration. Can reoccur locally or with distant metastasis. Reported at a frequency of 4.1% in the RRCUS Health Survey 2001 Update.
Cataracts: Posterior cortex intermediate and punctate cataracts predominate in the breed. Age of onset 3 years. Identified in 3.41% of Rhodesian Ridgebacks CERF examined by veterinary ophthalmologists between 2000-2005. CERF does not recommend breeding any Rhodesian Ridgeback with a cataract.
Distichiasis: Abnormally placed eyelashes that irritate the cornea and conjunctiva. Can cause secondary corneal ulceration. Identified in 2.73% of Rhodesian Ridgebacks CERF examined by veterinary ophthalmologists between 2000-2005.
Soft Tissue Sarcoma: The Rhodesian Ridgeback is a breed at increased risk for developing soft tissue sarcomas, with 5.7% of all STS cases in one study occurring in Rhodesian Ridgebacks. Aggressive surgical management is associated with a low incidence of local recurrence.
Secondary Glaucoma: Rhodesian Ridgebacks are listed as having a 4.1x risk for developing secondary glaucoma versus other breeds. Causes of secondary glaucoma include anterior uveitis, lens luxation, and cataract.
Degenerative Myelopathy (DM): Affected dogs show an insidious onset of upper motor neuron (UMN) paraparesis at an average age of 11.4 years. The disease eventually progresses to severe tetraparesis. Affected dogs have normal results on myelography, MRI, and CSF analysis. Necropsy confirms the condition. Reported at a frequency of 0.74% in Rhodesian Ridgebacks. Unknown mode of inheritance. A direct genetic test for an autosomal recessive DM susceptibility gene is available, showing 41% carrier and 7% homozygous gene "at risk". All affected dogs are homozygous for the gene, however, only a small percentage of homozygous dogs develop DM.
Cervical Vertebral Instability, Entropion, and Hemivertebra are reported.

Isolated Case Studies
Renal Dysplasia: A six-month-old Rhodesian ridgeback dog was presented in chronic renal failure, with facial swelling due to fibrous osteodystrophy. Post mortem examination revealed renal dysplasia.
Cerebellar Degeneration and Coat Color Dilution: Rhodesian Ridgebacks from two related litters presented with growth retardation, diluted coat color, and ataxia that progressed to lateral recumbency with tremors. Histopathology showed cerebellar Purkinje cell degeneration, and uneven distribution of macromelanosomes within hair shafts. Pedigree analysis suggested an autosomal recessive mode of inheritance.
Acute Nonlymphocytic Leukemia: Diagnosed in a 1-year-old Rhodesian Ridgeback. Clinical signs of disease included weight loss, anorexia, lethargy, lymphadenopathy, splenomegaly, and hepatomegaly.
Myotonic Dystrophy: A mature female Rhodesian Ridgeback had a progressive degenerative myopathy, associated with myotonia, dysphagia, and marked muscle wasting. Clinical findings revealed percussion dimpling, creatine kinase elevation, and a paroxysmal atrial tachycardia.
Renal Adenocarcinoma: Concurrent renal adenocarcinoma and polycythemia were diagnosed in a 19-month-old, female Rhodesian ridgeback. Clinical signs included brick-red mucous membranes, lethargy, a periodic systolic heart murmur, and engorged retinal vessels. A large retroperitoneal mass and pulmonary metastatic nodules were found. Polycythemia was the result of excessive erythropoietin production.
Osteochondrosarcoma of the Hard Palate: A 14-year-old castrated male Rhodesian Ridgeback was presented with a history of sneezing and epistaxis. A multilobular osteochondrosarcoma of the hard palate with pulmonary metastases was diagnosed.
Spinal Meningioma: A 5-month-old male Rhodesian Ridgeback was diagnosed with a meningothelial meningioma with focal mineralization that extended from the cervical to the lumbosacral spine. There was a concurrent hydrocephalus.

Genetic Tests
Tests of Genotype: Direct test for an autosomal recessive DM susceptibility gene is available from the OFA.
The genes for ridgelessness, deafness, and hemophilin B have been identified, however, commercial tests have not yet been developed.
Tests of Phenotype: CHIC certification: Required testing includes hip and elbow radiographs, CERF eye examination (annually to age 9), and thyroid profile including autoantibodies (at age 2, 3, 4, 5, 6 and 8). Optional recommended tests include cardiac evaluation, and BAER testing for deafness (minimum age of 12 months). (See CHIC website; caninehealthinfo.org).
Recommend patella evaluation.

Miscellaneous
- Breed name synonyms: African Lion Hound, Ridgeback - Registries: AKC, CKC, UKC, KCGB (Kennel Club of Great Britain),
ANKC (Australian National Kennel Club), NKC (National Kennel Club) - AKC rank (year 2008): 50 (2,199 dogs registered)
- Internet resources: Rhodesian Ridgeback Club of the United States: rrcus.org
RRCUS Health Website: rhodesianridgebackhealth.org
Rhodesian Ridgeback Club of Canada: rrclubofcanada.org
Rhodesian Ridgeback Club of Great Britain: rhodesianridgebacks.org