Chihuahua Genetics

Chihuahua:

This is not intended to frighten you but to educate on some of the genetic predispositions that your pup may have based on his/her breed.  Your Chihuahua may have one, some, or none of these conditions.  However, it is best to be aware so you know what to look out for.  Most of the conditions listed below can be avoided with good care and management and early intervention by your veterinarian.  At Meadowlands Veterinary Hospital we know the importance of individual care and will take precautions if your pup presents any indications they may be carrying one of these genes.

Genetic Predispositions:

Eye Problems

Glaucoma, an eye condition that affects Chihuahuas and people too, is an extremely painful disease that rapidly leads to blindness if left untreated. Symptoms include squinting, watery eyes, bluing of the cornea (the clear front part of the eye), and redness in the whites of the eyes. Pain is rarely noticed by pet owners though it is frequently there and can be severe. In advanced cases, the eye may look enlarged or swollen like it’s bulging.

Dry eye, also known as keratoconjunctivitis sicca or KCS, is common in  Chihuahuas. The tear glands no longer produce enough tears to keep the eye moist, which results in sore, itchy eyes and infections. Symptoms include a thick discharge, squinting, pawing at the eye, or a dull, dry appearance of the eye. This is a painful condition as well.

Cataracts are a common cause of blindness in older Chihuahuas. The lenses of their eyes to become more opaque—meaning they look cloudy instead of clear. Many dogs adjust well to losing their vision and get along just fine. Surgery to remove cataracts and restore sight may also be an option.

 

Heart Disease

Heart failure is a leading cause of death among Chihuahuas in their golden years. Most heart disease in dogs is caused by weakening of a valve. A heart valve slowly becomes deformed so that it no longer closes tightly. Blood then leaks back around this valve and strains the heart. Pets with heart valve disease (sometimes called mitral valve disease) have a heart murmur.  If heart valve disease is diagnosed early, we may be able to prescribe medications that could prolong his life for many years. Veterinary dental care and fatty acid supplementation can help prevent heart disease and weight control can help diminish symptoms.

Chihuahuas are susceptible to a condition called Patent Ductus Arteriosis, in which a small vessel that carries blood between two parts of the heart does not close shortly after birth as it should. This results in too much blood being carried to the lungs, fluid build-up, and strain on the heart. Outward signs may be mild or you may see coughing, fatigue during exercise, weight loss, shortness of breath, or weakness in the hind limbs.

Knee Problems

Sometimes your Chihuahua’s kneecap (patella) may slip out of place (called patellar luxation). You might notice that he runs along and suddenly picks up a back leg and skips or hops for a few strides. Then he kicks his leg out sideways to pop the kneecap back in place, and he’s fine again. If the problem is mild and involves only one leg, your pup may not require much treatment beyond arthritis medication. When symptoms are severe, surgery may be needed to realign the kneecap to keep it from popping out of place.

Tracheal Collapse

The trachea, or windpipe, is made up of rings of cartilage, making it look something like a vacuum cleaner’s ridged hose. Just as in the hose, this structure provides flexibility and strength. In Longhaired Chihuahuas, the cartilage rings are sometimes weak or have formed incorrectly. The trachea can collapse and become too narrow, which leads to coughing and difficulty breathing. Most cases of tracheal collapse are mild and are treated symptomatically with medication. When symptoms are severe, surgery may be an option.

Hip Necrosis

Young Chihuahuas may be prone to a painful degenerative hip condition called Legg-Calve-Perthes Disease. The exact cause of this condition is still not completely understood, but it is thought to be a problem with blood supply to the hip, which causes the femoral head (the top of the thigh bone) to become brittle and easily fracture. Usually occurring between six and nine months of age, it causes pain and lameness in one or both rear legs and often requires surgery.

Bleeding Disorders

Your Chihuahua is prone to a bleeding disorder called hemophilia.

Liver Problems

Your Chihuahua is more likely than other dogs to have a liver disorder called portosystemic shunt (PSS). Some of the blood supply that should go to the liver goes around it instead, depriving the liver of the blood flow it needs to grow and function properly. If your pup has PSS, their liver cannot remove toxins from his bloodstream effectively.  If they develop symptoms such as stunted growth or seizures, we’ll test his blood and possibly conduct an ultrasound scan of his liver. Surgery may be needed, but in some cases, we can treat with a special diet and medication

Bladder or Kidney Stones

There are a few different types of stones that can form in the kidney or in the bladder, and  Chihuahuas are more likely to develop them than other breeds.  Stones can form in the urinary bladder resulting in irritation and potentially obstruction.

Reproductive Difficulties

Breeds with a large head and small pelvis are more prone to difficulties during the birthing process. Her pelvis is just too small to pass puppies and a C-section is often required for her health and that of her puppies.

 

Retained Puppy Teeth

Dogs normally begin to lose their primary (“puppy”) teeth at around 4 months of age. When the primary teeth don’t fall out as the adult teeth come in, infection or damage to the adult teeth may develop. Retained teeth are common in small breeds like Chihuahuas. The retained puppy teeth trap food and hair between the normal adult tooth and the primary tooth. Painful gums, bad breath, and adult tooth loss can result if untreated. 

Neurologic Problems

Several neurologic diseases can afflict Chihuahuas. Symptoms of neurological problems can include seizures, imbalance, tremors, weakness, or excess sleeping.

Low Blood Sugar

Hypoglycemia, also known as low blood sugar, is a common condition in young, small-breed dogs, including Chihuahuas. It can be caused by many conditions. The physical signs include weakness, collapse, and seizures. These signs may occur after exercise, excitement, or after missing a meal.

Allergies

In humans, an allergy to pollen, mold, or dust makes people sneeze and their eyes itch. In dogs, rather than a sneeze, allergies make their skin itchy. We call this skin allergy “atopy”, and Chihuahuas often have it. Commonly, the feet, belly, folds of the skin, and ears are most affected. Symptoms typically start between the ages of one and three and can get worse every year. Licking the paws, rubbing the face, and frequent ear infections are the most common signs.

Spinal Cord Injuries

Chihuahuas are more likely than other breeds to have instability in the first two neck vertebrae (called the atlantal and the axial vertebrae). This can cause a sudden spinal-cord injury in the neck. If your dog is suddenly unable or unwilling to jump up or go upstairs, cries for no apparent reason, or tries to turn or lower their head when you pick them up, they are in pain.  As with so many other diseases, weight control helps to prevent it. With this breed, it’s important to use ramps or steps from the time your dog is a puppy so that he doesn’t spend a lifetime stressing his neck by jumping on and off of the furniture.

 

Mange

Demodex is a microscopic mite that lives in the hair follicles of dogs. All dogs have them. Normally a dog’s immune system keeps the mites in check, but some breeds, like your Chihuahua, develop an overabundance of these mites. In mild cases, pet owners may notice a few dry, irritated, hairless lesions. These often occur on the face or feet and may or may not be itchy. Secondary skin infections may occur.  Many pets seem to outgrow the problem, while others require lifelong management.

Water on the Brain

Hydrocephalus occurs when fluid builds up inside the skull and puts pressure on the brain. This condition is most common in breeds with dome-shaped heads, like the Chihuahua. It is often present when the skull bones don’t fuse properly. Signs include seizures, difficulty training the puppy, dulled mental function, circling, and a spastic gait. It is usually diagnosed early in life, but occasionally we diagnose it in adult dogs.

By |May 25th, 2018|

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