Australian Shepherds of the miniature variety suffer from relatively few genetic disorders. However, defects recognized in the Australian Shepherd can also occur in its smaller counterpart. The Miniature Australian Shepherd Club of America is working to preserve the health of the mini Aussie and strongly encourages breeders to clear eyes and hips on all breeding stock.
Look for the Blue Ribbon Breeder symbol for breeders that do so!
Eye defects of varying severity are the most common disorder in Australian Shepherds of all size varieties. An AVCO (American College of Veterinary Ophthalmologists) Certified diplomate should examine the eyes of all breeding stock less than one year before breeding as well as puppies between the age of 6 and 9 weeks (at which time certain anomalies can be identified which do not appear again for several years). Results may be submitted to the Canine Eye Registration Foundation (CERF) for database reference. A photocopy of the certificate can be submitted to MASCA toward a reduced cost litter registration.
The following have been recognized in the Australian Shepherd of all sizes:
Iris Colobomas (IC) are a cleft in the iris of the eye and will impair vision if large. A dog with a small IC may be sensitive to bright light. While the exact mode of inheritance is unknown, it is probably polygenetic. They may also be the result of abnormal development in puppies from merle to merle breedings.
Juvenile Cataracts are a congenital opacity of the lens of the eye due to abnormal early degeneration of the lens tissue. They cause gradual, painless deterioration of sight, resulting in partial or complete blindness by 2 to 5 years of age.
Offset or Oval Shaped Pupils are usually due to multiple small iris colobomas. Impairment varies from mild light sensitivity to moderate vision loss.
Persistent Pupilary Membrane (PPM) although rare in the mini Aussie, has been diagnosed. During normal development, a puppy’s eyes are enveloped by a membrane which stretches and breaks away by 8 weeks of age. In an affected dog, the membranes fail to break free, whether on the frontal part of the eye or behind it, causing varying degrees of vision impairment depending on placement and concentration of the strands. Diagnosis can be mild to severe. If strands have not broken free by 8 weeks, the dog is inclined to carry them for the rest of its life. Mode of inheritance is as yet undetermined in Aussies, but this congenital fault is passed on in Basenjis as an autosomal dominant with a range of expression.
The following are either recognized in the Australian Shepherd, or related to merle to merle breedings, and therefore should be screened for:
Anophthalmia is the total absence of the eye and is a more severe developmental version of “small eye”.
Collie Eye Anomaly (CEA) is a blanket term used to describe a variety of eye disorders, including Iris Colobomas, detached retinas, “small eye” and optic disk colobomas. These tend to appear together and are common to the Collie, but also exist in Australian Shepherds and other collie breeds. It is believed to be controlled by a genetic cluster, or large group of genes, and ranges in severity from mild impairment to total blindness.
Detached Retinas are the separation of the retina from its vascular base and cause a partial loss of vision. Hereditability appears to be polygenetic.
Progressive Retinal Atrophy (PRA) is common in many breeds of dogs and has been identified in Australian Shepherds. It affects the entire retina and is the canine equivalent of retinitis pigmentosa. Typically, the clinical disease is recognized first in early adolescence or early adulthood. Puppies may be blind by six to eight months. An ophthalmologic examination by an ACVO-certified vet should be able to identify cases of PRA.
All dogs affected with PRA eventually go blind. Carriers show no clinical symptoms. Symptoms are subtle, starting with night blindness, some eye dilation, progressing to complete blindness. It is quite common not to notice anything wrong until the dog is nearly completely blind.
There is a genetic test to identify normal/clear, carrier, and affected dogs. This disease is thought to be a simple autosomal recessive gene, thus two recessive genes are needed for a dog to be affected and an affected dog’s parents are either carriers or also affected. Optigen is currently doing the testing for PRA.
“Small Eye” (Microphthalmia), literally, the eye or eyes are smaller than normal and is believed to be controlled by a genetic cluster, or large group of genes. Small eye ranges in severity and is usually accompanied by one or more of a series of associated lesions (see “Collie Eye Anomaly”).
Microphthalmia with colobomas in this breed is hereditary, but the genetics are not well understood. The defects appear to be linked to the dominant merle gene, since severely affected dogs are homozygous merles and often have excessive white in their coats. A similar syndrome has been seen in merle Shelties, merle Collies and harlequin Great Danes. (Affected dogs are also often deaf in one or both ears.)
Canine Hip Dysplasia (CHD) is the dislocation of the hip joint; it occurs when the head of the femur (thighbone) does not properly fit into a too shallow acetabulum, the cup-socket at the base of the hipbone. CHD can either be congenital or caused by contusion. The poor fit eventually results in the deterioration of the joint, with painful and possibly crippling results. CHD has been identified in certain lines of the Australian Shepherd.
A Licensed Veterinarian should radiograph (x-ray) hips on all breeding stock and submit the results to the Orthopedic Foundation for Animals (OFA), PennHIP or the nationally accepted registry (if outside the USA). A photocopy of the certificate can be submitted to MASCA for a reduced cost litter registration.
It is safest and also best for OFA results to NOT anesthetize your dog. Please seek out a veterinarian experienced in providing x-rays for this purpose. OFA radiographs require that the dog be at least 2 years old to receive permanent certification, whereas PennHIP may be performed on puppies as young as 4 months but MUST be completed by a PennHIP trained orthopedic veterinarian.
Because CHD is inherited polygenically, the best prevention is to continue to breed only those dogs that have been certified free of CHD. The PennHIP team was able to eliminate CHD from their closed dog population when selecting only for this trait.
Feeding regimens can possibly effect the expression of CHD in genetically predisposed dogs, but diet should have no effect on non-affected stock.
Luxating Patella. The patella, or kneecap, is part of the stifle joint (knee). In patellar luxation, the kneecap luxates, or pops out of place, either in a medial or lateral position. Although the luxation may not be present at birth, the anatomical deformities that cause these luxations are present at that time and are responsible for subsequent recurrent patellar luxation. Patellar luxation should be considered an inherited disease.
Chronic Flea Allergies and excessively dry skin have appeared in certain lines. Inheritance is simple co-dominant and breeders are advised to use caution to avoid perpetuating the problem. For flea allergy suffering dogs, consider using Program® combined with a topical flea preventive.
Ivermectin Sensitivity. Some Australian Shepherds and mini Aussies are highly sensitive to Ivermectin, available both as a single worming treatment and in a lower dosage as a heartworm preventive under the brand name Heartguard®. Ivermectin affects the central nervous system in individuals to which it is toxic. Symptoms of vermectin toxicity include depression, excitability, seizures, loss of muscle control, drooling, coma or even death.
NEVER PRESCRIBE IVERMECTIN TO AN AUSTRALIAN SHEPHERDS OF THE MINIATURE VARIETY
Interceptor® is a non-Ivermectin based heartworm treatment safer for most mini Aussies. Sentinel® combines Interceptor® and Program® into one pill.
Brucellosis, or more specifically Brucella Canis, is a bacteria that was first isolated in the mid-1960′s.
It is suspected that one in ten dogs in this country carries Brucellosis. In addition, it is transmissible to humans who may develop a serious liver impairment or arthritis. Medical advancements in controlling this disease have been few and far between and it remains a very difficult disorder to treat and in most cases, treatment is a failure. If “successful”, the individual will probably be sterile or a poor breeding specimen. Do not breed an individual that is said to be treated and cured. “Cured” patients often begin shedding the bacteria months to years after treatments. Do not knowingly take a chance.
Brucellosis in the female dog lives in the vaginal and uterine tissue and secretions. Litters are commonly aborted, usually in the last two weeks of gestation, or the puppies may die shortly after birth. She can spread the bacteria to other animals through her urine, aborted fetuses, or most commonly through the act of breeding. In males, the brucella bacteria live in the testicles and seminal fluids. An infected male is just as dangerous as the female as he can spread it via his urine or semen. Oftentimes, there are no signs except in advanced cases when the testicles may be uneven in size.
Since Brucella Canis is mainly spread by the act of breeding, it is paramount to test all canines, male and female, prior to breeding. Test between every breeding of different animals. In other words, if a male (or female) was tested one year ago but has bred since, it must be tested again. In the case of a male, if he serviced a female since his last test, then he must be retested even if his last test was as recent as four weeks ago. Testing is the only sure way to detect carriers.
Breeding Merle to Merle
Inheritance of Color in the Australian Shepherd
I am receiving some mail that requests information on breeding dogs that are blue tris. This is a dilution factored dog and should not be bred or registered.
DNA testing is a valid source in identifying structure of gene protocol. A few hairs from a follicle or a light scrape of skin from inside the cheek can reveal the genetic codes of an animal, thus verifying if the dog is indeed a purebred Australian Shepherd of the miniature variety in circumstances of disputed parentage. Samples are taken by the breeder, sealed in a special container and forwarded to the lab. Results are usually available within two weeks.
This method of verification is resourceful evidence when a bitch is bred by a dog of unknown source, such as in an accidental breeding, or a litter is suspected to have multiple sires. It will also preserve the integrity of the stud book.
MASCA strongly encourages that all breeding stock be DNA tested in order to better track ancestry of the mini Aussie. DNA typing will one day soon enable us to track the above listed health issues. When this occurs, puppies will be able to be tested at 6 weeks to determine future soundness. DNA will not only benefit the furtherance of the breed healthwise, but can also aid a breeder in evaluating their stock. Imagine a breed virtually free of health defects! And since we are a breed still small in number, DNA testing and gene mapping is a realistic goal.
If DNA becomes necessary, the applicant will be required to have all dogs/puppies DNA’d by the same lab.
your “one-stop shopping” site for information about
genetics & hereditary disease in Australian Shepherds
Australian Shepherd Genetic Epilepsy Network and Education Service
Read Buster’s story and get an extended drug list for MDR1
Canine Eye Registration Foundation (CERF)
W. Lafayette, IN 47907
(317) 494-9981 (FAX)
Canine Health Information Center
Orthopedic Foundation for Animals (OFA)
2300 E. Nifong Boulevard
Columbia, MO 65201-3856
(573) 875-5073 (FAX)
Puppy Puzzleby Pat Hastings
International Canine Genetics
271 Great Valley Parkway
Malvern, PA 19355
Washington State University
Multidrug Sensitivity (MDR1)
this test is highly recommended – find out if your Aussie is drug sensitive.
It could save his/her life one day!