Toy Fox Terrier Diseases and Problems
All purebred dogs are prone to specific types of genetic diseases, but contrary to popular belief, most breeds of dogs are not more prone to disease in general than are mixed breeds. Mixed breed dogs are also prone to genetic diseases at a similar rate to purebreds, but their diseases are not tracked from generation to generation to know which ones are most likely to occur in the lines. Responsible breeders know their breed's common genetic diseases and do everything they can to breed away from them. For any diseases with tests available, breeders should test. For those without tests, breeders should look back through the pedigrees to see genetic health histories of their dog's ancestors and try to avoid breeding together lines with the same problems.
Patellar Luxation
Patellar luxation is a condition where the kneecaps (patellas) pop out of place. This can result in discomfort and loss of function and is, therefore, a health condition of concern. Ethical breeders of breeds prone to this condition (primarily small breeds, but some large breeds also suffer from it) should test all of their breeding dogs for this condition and have normal scores. Patellar luxation is due to complex abnormalities of the skeleton which change the overall alignment and positioning of the limb. Hip dysplasia, malformation of the femur or tibia, deviation of the tibial crest, tightness or atrophy of the quadricep muscles, or overly long patellar ligament can all contribute to patellar luxation. [MORE INFORMATION]
Elbow dysplasia is similar to hip dysplasia but instead affects the elbows. There is no normal grade for elbows. Elbows with any grade mean they have dysplasia of some level. Testing for elbow dysplasia is an optional test in Caridgan Welsh corigs, as it has not historically been a major problem in the breed. [MORE INFORMATION]
Primary Lens Luxation (PLL)
Work in progress. [MORE INFORMATION]
Degenerative Myelopathy (DM)
While this disease typically does not affect dogs until they are 8-14 years of age, it can be quite devastating when it does hit. It causes gradual paralysis in dogs and eventually death (if the dog does not die of other causes first) when the lungs become paralyzed, making it so the dog can no longer breathe. There is no "sure fire" test for DM, but there is a test which can identify dogs that are "at risk" of developing the disease so they can be not used in a breeding program. "At risk" dogs may or many not develop DM. "DM carrier" means the dog has the genetics to produce "at risk" puppies if it is bred to an "At risk" or "DM carrier" dog, but "DM carriers" will not develop DM themselves. They can be used in breeding so long as they are bred to a "DM clear" dog. If a dog is "DM clear by pedigree", it means neither parent was a DM carrier, so the offspring will also not have DM. Take this with a grain of salt, as sometimes mistakes in record keeping are made. I personally prefer to test all of my dogs, even if they are clear by pedigree. This is NOT a required test for Toy Fox Terriers, but since it is common in many breeds, some breeders still test for it even in breeds it is not required in. [MORE INFORMATION]
Congenital Hypothyroidism with Goiter (CHG)
Work in progress. [MORE INFORMATION]
Spinocerebellar Ataxia (SCA)
Work in progress. [MORE INFORMATON]
Other Problems
The following are not necessarily genetic diseases, but they should be taken into consideration when breeding or owning Toy Fox Terriers.
Size
Toy Fox Terriers are very small dogs. Before a year old, their joints are still very delicate. They should not be allowed to jump off furniture or other high areas. Broken bones and joint problems can occur from letting young dogs jump off of tall areas. Pick your pup up or train them to use a ramp or doggy stairs.
Whitehead
Whitehead is an unknown allele or alleles* currently being [RESEARCHED]. As the name suggests, it causes white on the head. When the white spreads across much of the head, it increases the risk of deafness in one or both ears. Whitehead is not the same as piebald nor Irish white. Piebald is currently the only one of the three with a genetic test available.
(*Alleles are variants of genes) The video to the right compares the spread of white in piebald versus whitehead. Spread of white does not mean that an individual dog will progressively get more white. Rather, it means that through the generations, as more white appears (usually from breeding similar levels of white to each other), it typically follows these patterns. A piebald that is heavily white on the head is also likely to be nearly or completely white on the body. A whitehead that is heavily white on the head may still have quite a bit of color on the body. Notice that both piebald and whitehead can mimic Irish white pattern. It will be interesting to follow the research and see whether Irish white interacts with whitehead. Whitehead type pattern exists in Toy Fox Terriers, though piebald is the primary white spotting in this breed. |
So far it seems that breeding a dog with any whitehead characteristics to another with any whitehead characteristics risks a more extreme whitehead pattern. This would suggest incomplete dominance mode of inheritance (plus likely interaction with other alleles). Below are examples of a "double whitehead" or "extreme whitehead" where the entire head is white.
|
Single whitehead traits are as follows:
- Split face (one half of the face predominantly white, sometimes with a blue eye on the same side of the face)
- All white muzzle
- White face that connects to a white neck
- Irregular/asymmetrical wide blaze
- Sometimes also a wide blaze (wider than the width of an eye)