Tag archives: canine blindness

One of the goals at Paw Print Genetics (PPG) is to add to our large menu of tests whenever we can. New genetic changes found in the dog genome for diseases and traits are published periodically in the medical literature. These publications guide us in developing new tests for our customers.

Among the new tests launched this month are three tests for traits. Two of the tests will identify whether a dog carries for polydactyly, which results in having hind dewclaws. One of the polydactyly variants in the LMBR1 gene will cause hind dewclaws in many different breeds, while the mutation in ALX4 only causes polydactyly in the Great Pyrenees. Both variants are dominant, meaning that one or two copies will result in polydactyly. Interestingly, the mutation for the Great Pyrenees causes double dewclaws, whereas the mutation in LMBR1 causes just single dewclaws.

The third trait launched is for another E locus variant. PPG offers several E locus variants, so it is important to read the description of each before choosing your test. Most breeds will produce a yellow or red coat color when there are two copies of the ‘e’ allele from the common E locus variant.  However ...

Canine progressive retinal atrophy (PRA) is a group of inherited eye diseases which are among the most common causes of inherited blindness in domestic dogs. Extensive study and characterization of the various PRAs have led to the discovery of well over a dozen different genetic mutations in many different genes which can now be identified to help prevent, predict, or diagnose PRA in many breeds. However, complicated PRA naming schemes and the breed-specific nature of the PRA tests can make it challenging for dog breeders or veterinarians to select the correct test for the dog in front of them.  

Multiple Genes, Similar Clinical Findings

The known underlying mutations associated with the various forms of PRA are found in a wide variety of different genes. Thus, highlighting the complexity of the biological pathways involved in the development and ongoing maintenance of the eyes. PRAs are marked by the abnormal development and/or the gradual degeneration of rod and cone photoreceptor cells of the retina. Each type of PRA may display variation in the age of onset, speed of disease progression, and the relative rates at which each of the two photoreceptor types are destroyed. However, when it comes to clinical ...

The discovery of various disease-associated genetic mutations has greatly changed the way some inherited canine diseases are categorized and perceived by the veterinary community. Through the use of genetic testing developed to identify these discovered mutations, various diseases which were once assumed to have a single underlying molecular cause (due to similarity between disease states) have been found in some cases to actually be caused by many different mutations, often in different genes. This phenomenon, known as genetic heterogeneity, elucidates the way genes work together in pathways and how a disruption in different genes of a pathway may result in similar or nearly identical disease states despite seemingly disparate underlying molecular etiologies. Understanding that there may be one of many different genetic mutations responsible for a dog’s clinical signs can help plot a better course for veterinarians to obtain an accurate, definitive diagnosis and in some cases, may alter treatment strategies.

Pet Owner vs Breeder

The accuracy and specificity of an inherited disease diagnosis are particularly important in the world of dog breeding where every potential health issue must be considered prior to breeding. Unlike general pet owners who may not need to know the specific underlying molecular mechanisms of ...

Paw Print Genetics is celebrating the Australian Cattle Dog this week. Although generally considered a relatively healthy breed, like other purebred dogs, the Australian Cattle Dog is known to inherit several genetic diseases. Testing your dog prior to breeding prevents the disease through avoidance of producing puppies at-risk. This brief article describes a few of the diseases that can currently be tested for in Australian Cattle Dogs.  You can find a complete list and more information at  https://www.pawprintgenetics.com/products/breeds/91/.  All of these tests performed by Paw Print Genetics are accepted by the Orthopedic Foundation For Animals. 

Cystinuria is an inherited disease that is known to affect amino acid absorption by the kidneys. This abnormality leads to cysteine crystals and/or stones in the bladder that can block the ureters or urethra and stop the normal flow of urine. If not treated, urinary stones can cause urinary tract infections, kidney failure and even death.

Degenerative Myelopathy (DM) is a late-onset neurological disease found in over 100 breeds of dog.  Known as amyotrophic lateral sclerosis (ALS or Lou Gehrig’s Disease) in humans, affected dogs typically begin to show signs of neurological weakness in ...

With depictions in artwork from as early as the 8^th century, the ancient Briard is a French dog breed that has been employed in diverse roles throughout its history, but is most commonly recognized as a herding breed or as a guard dog for flocks of sheep. Though documentation of its early history is sparse, the first breed standard for the Briard was written in the late 19^th century and the breed was accepted for registration by the AKC in 1922 after being brought to North America from Europe (including Briards imported by Thomas Jefferson). Praised for their intelligence and memory, the Briard is a naturally protective dog that can benefit from early and extensive socialization in order to establish proper boundaries and temperament toward strangers. They are often regarded as extremely loyal and bonded to their owners and appreciate significant time with their human “pack”. Though the breed is regarded as relatively healthy, as with most purebred dogs, the Briard has developed some inherited disease concerns during its path to the modern state of the breed. One of the best known Briard inherited disease concerns, unique to the breed, is a disease known as congenital stationary night ...

Despite being one of the most recognizable dog breeds in existence due to their unique physical attributes, the early history of the Chinese crested is a bit mysterious due to a lack of adequate written records. Though early hairless dogs have been documented in Africa, Central and South America, and Asia, the relationship between these dogs is not well understood. Evidence to suggest that they may be related is found in the fact that at least 3 hairless breeds originating from different continents (Mexican hairless, Peruvian hairless, and Chinese crested) are all known to inherit the same FOXI3 gene mutation responsible for their hairlessness. It is most likely that a common ancestor to the hairless breeds developed a spontaneous FOXI3 mutation that was later passed to the individual breeds as they were developed. It is theorized that early hairless dogs travelling on shipping routes with their human companions played a role in the spread of the trait to numerous locations in the world.

In addition to genetic mutations responsible for particular physical traits, like other purebred dogs, Chinese cresteds are known to inherit some genetic mutations responsible for causing inherited disease. Inherited diseases of the eyes are of particular concern ...

In 1953, a prevalent inherited eye condition of collies was first described by W.G. Magrane in a journal article entitled, “Congenital anomaly of the optic nerve in collies”¹. Later termed choroidal hypoplasia by scientists, the disease now known to the general public as collie eye anomaly (CEA) has significantly troubled collie breeders for over 50 years. In 2007, a paper describing a specific genetic mutation of the NHEJ1 gene associated with CEA was published. Identification of this mutation, has made it possible for scientists to develop tests that predictably identify the mutation and subsequently help breeders avoid producing puppies with CEA. Despite its breed specific name, testing has since identified the same CEA associated mutation in several other dog breeds including the Australian shepherd and the Shetland sheepdog.

Though there is significant variability in terms of ocular defects seen in affected dogs, the fundamental characteristics of CEA stem from the malformation of an important structure of the eye known as the choroid. The choroid is a thin layer of tissue containing the blood vessels responsible for supplying blood and nutrients to the retina and other structures of the eye. While mildly affected dogs may maintain normal vision with ...

The intelligent, prey-driven English springer spaniel (ESS) has forged its path as a popular, hardworking companion for bird hunters while maintaining a loyal and affectionate personality suitable to family life. Until the early 1900’s, springer spaniels were produced in the same litters as cocker spaniels; springers were chosen from the largest puppies of the litter and were trained for flushing or “springing” game while the smaller littermates were labeled cocker spaniels and were trained for hunting the elusive woodcock. Since then, springer spaniels have been further split into the generally leaner, shorter haired field (hunting) variety and the denser boned, densely haired show (“bench”) line. Unfortunately, like other purebred dogs, English springer spaniels are known to inherit genetic diseases that can keep some individuals from reaching the great potentials for which the breed is capable. One such inherited condition is an eye disease known as progressive retinal atrophy, cone-rod dystrophy 4 (PRA-crd4) caused by a mutation in the RPGRIP1 gene.

Progressive retinal atrophy (PRA) is not a single disease, but rather a group of inherited diseases each caused by different genetic mutations in different genes. The various forms of PRA affect over 100 different dog breeds. Though there are variations ...

Just like people, blindness or an otherwise significant reduction in vision is a relatively common occurrence in our canine friends. Whether your puppy loses his sight in bright light or your old faithful companion’s eyes are looking a little "cloudy", the profound impact it can have on the life of both pet and owner, makes preventing or treating eye disease a major concern for veterinarians.

Though there are hundreds of possible biological processes responsible for blindness, these processes can be grouped into two major categories: Non-genetic (acquired disease) and genetically inherited disease caused by mutations in a dog’s DNA (the genetic material found in all cells). Though mutations in DNA are present at birth, disease can present in a variable timeframe from puppy to older dog, depending on the specific mutation present.

Though not all eye diseases have an inflammatory component to them, some of the most commonly acquired, non-genetic eye diseases involve chronic inflammation of the eye’s internal and external structures. External chronic eye inflammation gradually damages the structure of the cornea and can eventually lead to difficulty seeing. Most of the cases involve physiological abnormalities (i.e. eyelashes rubbing on the eye) or trauma resulting ...