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Veterinary Assisting Certificate Program

Common Diseases and Medical Conditions Affecting Canines

OBJECTIVES:

1. Describe common diseases and medical conditions affecting companion dogs.

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Anal Gland Impaction: The Embarrassing “Personal” Problem

Pet owners often confuse anal sac disease with a worm problem. They call the vet hospital saying they think their dog has worms because he’s scooting his bottom on the carpet. Chances are the dog is having problems with its anal sacs, and is scooting because his perianal region is itchy, irritated, and uncomfortable.

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|The archaic anal sacs are an organ of the past and have no purpose in modern pets. The anal sacs are paired organs located beneath |

|the skin and anal sphincter muscles at about the five and seven o'clock positions surrounding the rectum. Tiny ducts lead to the |

|tissue just inside the rectum. The secretion that comes from these glands is brown in color and about the consistency of water or |

|oil. The secretion has a very disagreeable odor to humans. As the pet defecates, the anal sphincter squeezes the sacs against the |

|hard passing feces and causes the anal secretion to discharge onto the fecal mass. In olden times, this was used to mark a unique |

|scent on the BM. It was like a signpost used to communicate with the other dogs and cats. |

|As explained above, the anal sphincter must squeeze the sac against hard feces to express the contents. Some people believe the |

|reason why modern pets have so many problems is that the feces are just not hard enough.  In ancient times, dogs and cats ate large |

|quantities of meat and bone making their feces hard and dry. Today’s diets for dogs and cats contain vegetable protein as the main |

|ingredient. This produces a much softer stool so there is nothing for the glands to be squeezed against. The secretions build up and |

|the pet has problems. |

Scooting is the most common clinical sign of anal gland impaction. In more severe cases, skin irritation around the anal region and a discharge from the rectum is present. Most affected dogs are sensitive to palpation around the anal region. On rectal examination, the anal glands will be enlarged and hard.

The anal sacs should be regularly checked and, when necessary, expressed (gently squeezed) by a veterinarian or groomer to empty the contents. If the secretion stays in the sacs for very long, it begins to thicken and become like peanut butter in consistency. At this point it is very difficult to be expressed and subject to bacterial invasion and abscess formation.  Once an abscess forms and there is no route of escape for the secretion and pus, it may rupture through the skin causing an unsightly mess and lots of pain for the pet. If caught in the early stages, the veterinarian is able to flush out the anal gland, treat with antibiotics, and clear up the problem. More often than not, however, the problem reoccurs. At this time, surgical correction is the best solution. The anal sacs can be excised in the traditional manner or can be “vaporized” by laser surgery.

Aural Hematoma

An aural hematoma is a blood-filled swelling within the ear flap (pinna). It is usually associated with an ear problem such as an infection, parasites, trauma, or a foreign body in the ear canal. Discomfort or itchiness may stimulate the animal to scratch at the ear or vigorously shake its head. This scratching or shaking can rupture a blood vessel in the pinna causing the inner portion of the ear flap to fill with blood. Aural hematomas can be quite painful and can permanently disfigure the pinna if not treated properly.

Aural hematomas should be treated by a veterinarian. The procedure generally involves anesthetizing the animal, draining the fluid from the ear flap, and then suturing the pinna through and through to keep it from refilling with fluid. The sutures are removed after healing. Determining why the dog was scratching at the ear will be important to avoid a recurrence. (e. g., treat ear infections, remove foreign body, etc.) Leaving an aural hematoma untreated can result in a condition known as “cauliflower ear” where the body slowly reabsorbs the fluid from the pinna, leaving it crinkled, thickened and disfigured.

Addison’s Disease (Named after Sir Thomas Addison who first described this disease in humans.)

Hypoadrenocorticism or Addison’s Disease is an endocrine system disease that is focalized in the cortex of the adrenal gland. With this disease, the adrenal cortex is not producing adequate supplies of the hormones cortisol and aldosterone. Without cortisol or aldosterone, electrolyte (potassium, sodium, chloride) and calcium ratios get out of proportion, making the animal very sick. Addison’s Disease can be caused by tumors, infections, autoimmune problems, or from the over use of corticosteriod drugs (e.g., too many cortisone injections (“itch shots”) for the dog’s skin problems).

The clinical signs of this disease include anorexia, muscle weakness, and vomiting, and in severe cases, cardiac problems. It is most commonly seen in female dogs ages 5-7 years. A veterinarian can diagnose this condition with a blood test. This condition can, most generally, be managed with medication.

Carnassial Tooth Abscess

The carnassial tooth is the fourth upper premolar in a dog’s mouth. A carnassial abscess in an infection of the roots of this tooth. The inflammatory reaction caused by the infected tooth can cause a fistula, or abscessed opening, on the face below the eye. Facial swelling and the presence of a draining wound below the eye are common signs of a carnassial tooth abscess. Treatment involves surgical removal of the infected tooth, wound flushing with antiseptics, and antibiotic treatment.

Cherry Eye

The third eyelid of dogs contain a gland that can become inflamed and swollen, causing it to protrude or prolapse out of its normal position. It appears as a very swollen, red structure that resembles a cherry on the medial canthus.. Several breeds seem to be more prone to cherry eye than others. These include the American Cocker Spaniel, Boston Terriers, English Bulldogs, Lhasa Apso, Pekingese, and the Beagle.

Dogs suffering with Cherry Eye need the assistance of a veterinarian. Surgery is generally performed during which the gland is placed back behind the third eyelid and sutured into a new pocket made near its original position. Previous surgical procedures involved excising the gland, but this method has been found to predispose the dog to a condition known as Dry Eye. Occasionally a small portion of the gland must be removed, but care must be taken to retain as much as possible due to the gland’s important role in tear production that helps to bathe and protect the eye.

Collapsing Trachea

Collapsing trachea is a congenital problem often associated with small or miniature breeds of dogs like Chihuahuas, Toy Poodles, Boston Terriers, and Yorkshire Terriers. During normal respiration the rigid cartilage rings on the trachea keep the lumen from narrowing or closing. Collapsing trachea occurs when weakened cartilage rings flatten out and collapse inward, causing a narrowing or closing of the airway.

The most common symptom of collapsing trachea is a chronic, dry, hacking (honking) cough. In severe cases there may be exercise intolerance, cyanosis, asphysia, and death. Clinical signs are often worse in hot and humid weather and are exacerbated by obesity and other airway problems. Diagnosis is made based on physical examination, radiographs (x-rays), and patient history. Only the most severe cases are treated surgically. Most patients respond to treatments involving weight loss, cough suppressants, cortisone drugs, and a low stress life style.

Anterior Cruciate Ligament Rupture

The anterior cruciate ligament (ACL) is located in the stifle joint where it functions to help stabilize the knee joint. When the ACL is torn or stretched, instead of moving like a hinge, the knee joint begins to make a sliding motion. This painful motion and the joint instability it creates can lead to abnormal wearing of the cartilage and subsequent inflammation. Rupture of this important ligament causes lameness, joint instability, and chronic arthritis.

ACL injuries are most commonly seen in overweight large breeds but can occur in any dog that turns the stifle joint just the “right” way. The clinical signs of ACL include sudden hind leg lameness, holding up of the affected leg, and painfulness. This condition is diagnosed by physical examination of the joint where the veterinarian will test the sedated dog’s stifle for “drawer action” to see if the joint makes a sliding motion from side to side. Surgical repair is the accepted treatment and involves replacement of the now useless ligament with an artificial material (heavy nylon suture) that takes over the function of the ACL.

Cushing’s Disease (Named after Dr. Harvey Cushing in 1932)

Cushing’s Disease, or hyperadrenocorticism, is the most common endocrine disease occurring in dogs. Unlike Addison’s Disease that is caused by a lack of cortisol in the body, Cushing’s Disease is caused by an overproduction of cortisol by the adrenal gland. In most cases, it develops because the pituitary gland produces too much ACTH, a hormone that cause the adrenal glands to enlarge. Tumors on the adrenal glands can also cause Cushing’s Disease, but are less common than the pituitary-dependent form of the disease. The clinical signs of Cushing’s Disease include polyphagia, polydipsia, polyuria, muscle weakness, lethargy, abdominal distention, alopecia, and reproductive problems. The high levels of steroids in the body suppress the dog’s own immune system making them more susceptible to secondary bacterial infections.

Poodles, Boston Terriers, Boxers, Golden Retrievers, and Dachshunds seem to be more prone to develop Cushing’s Disease. Treatment depends on the cause of the disease. Pituitary-dependent Cushing’s Disease can be managed with medications. Adrenal tumors should be surgically removed and treated accordingly. The prognosis for treated patients is fairly good. Untreated, it is a fatal condition.

Diabetes Mellitus

The pancreas has two primary functions: the production of digestive enzymes to breakdown food for absorption, and the production of two hormones: insulin and glucagon. A deficiency in insulin production by the pancreas causes the disease known as Diabetes mellitus.

In the body, insulin binds to glucose molecules to facilitate their movement from the bloodstream into tissue cells. Low production of insulin impedes this movement, causing glucose to build up in the bloodstream. When blood-glucose levels rise to a certain point, the glucose “spills” into the urine. Simultaneously, the body attempts to compensate for the lack of energy-producing glucose in tissue cells by drawing upon stored fats and proteins in the body. This process precipitates the following clinical signs: weight loss, lethargy, polyphagia, polydipsia, and polyuria. Untreated diabetes mellitus causes an accumulation of ketones (fat metabolites from the liver). Ketosis, as it is commonly referred, can lead to vomiting, extreme weakness, inappetence, diabetic coma, and eventually death.

The cause of diabetes is generally unknown, but is often associated with other diseases and conditions affecting dogs. Diabetes mellitus is a frequent sequela to Cushing’s Disease and pancreatitis. Diabetes occurs most often in older, unspayed bitches and is very common in poodles. Diagnosis is made by testing blood and urine glucose levels. It is treated with dietary changes and insulin administration. Managing an insulin-dependent pet is a time consuming undertaking. It requires a dedicated owner to check blood and urine glucose levels and administer injectable insulin on a daily basis. Regular feedings and insulin administration are critical to the management of these patients. The owner must have the time and patience to provide this intensive care. Hypoglycemia and cataract formation (cloudy eye lens) are the most common complications of diabetes mellitus.

Distichiasis

This eye condition occurs when tiny hairs emerge from the Melbomian gland, found in the eyelids, and rub on the surface of the eye causing irritation. It is a heritable condition most commonly found in spaniels, retrievers, and poodles. Some dogs may have only a few distichia (abnormal hairs) on a single eyelid, while others may have more severe cases. The clinical signs of distichiasis include redness, discharge, squinting, eye rubbing, and in severe cases corneal ulcers. Treatment is based on the severity of the condition. Mild cases may require little or no intervention. More severe cases may require removal of the offending hair(s) by plucking or surgical removal by cryosurgery or cauterization. Very often the hairs grow back after removal, or emerge in new areas on the eyelid.

Entropion

A common congenital problem in Chow Chows, Shar Pei, English Bulldogs, Poodles, and Rottweillers is entropion. Entropion is an ophthalmic condition in which the eyelids roll inward allowing the lashes to irritate the surface of the eye. The clinical signs of entropion include excessive tearing, squinting, red eyes, and constant rubbing of the eyes. Dogs suffering from this congenital condition should be spayed or neutered to prevent offspring from inheriting it. Entropion should be surgically treated by a veterinarian. The procedure involves removal of a small section of skin just below the upper or lower eyelid (whichever is causing the problem, and maybe both), then suturing up the incision, causing the lid to roll away or evert from the eye.

Ectropion

Ectropion is the exact opposite of entropion. It is the outward rolling of an eyelid, causing abnormal exposure of the eye and conjunctiva (lining of the eye). Dogs with ectropion are more prone to bacterial and allergic conjunctivitis. The occurrence of eye infections are often the result of dirt particles and debris collecting in the loose tissue surrounding the eye. Several breeds seem to be predisposed to this inheritable condition including Bloodhounds, Cocker Spaniels, St. Bernards, Labrador Retrievers, Springer Spaniels, and Shih Tzu.

The clinical signs of ectropion can include conjunctivitis and a mucopurulent discharge from the eye. Mild cases can be managed by gently flushing the eyes with a saline solution to keep foreign debris out of the eye, lubricant medications, and by treating secondary conjunctivitis with antibiotic ointments. Severe cases may require surgical correction.

Flea-Allergy Dermatitis (FAD)

In addition to the irritation and itchiness associated with flea bites, some dogs are actually allergic to the proteins in the saliva of fleas. Hypersensitive dogs can develop widespread clinical signs from a single flea bite with moderate to severe itchiness, hair loss, especially along the back near the tail and hind legs, secondary bacterial infections, and an unpleasant odor. Constant itchiness, and the resultant licking and chewing, is exhausting for the dog and often, irritating to the owner. Some allergic dogs harbor a staphylococcal bacteria not found on healthy dogs that can add to the syndrome by causing skin infections that make the dog itch even more. Managing FAD requires the assistance of a veterinarian and a dedicated owner. Treatment generally involves the use of insect growth regulators and adulticide-type flea products, as well as medicated shampoos, anti-inflammatory/anti-itch medications and antibiotics. Treating the animal’s environment (indoors and outdoors) is critical to the successful treatment of FAD.

Gastric Dilatation & Volvulus

Acute gastric dilatation & volvulus (GDV) is a life-threatening condition in which the dog’s stomach becomes distended with gas or fluid (bloat). In some cases, the stomach twists in a clockwise direction, cutting off the blood supply and preventing the passage of gas or fluid from the stomach. GDV is generally associated with large, deep-chested breeds, such as Great Danes, Doberman Pinchers, German Shepherd Dogs, and Standard Poodles. The clinical signs of GDV can include restlessness, respiratory distress, nausea (hypersalivation, retching, dry heaves), and bloating of the abdomen. It is an EXTREMELY painful condition for the dog. Signs of shock are common in GDV and are often responsible for the high mortality rates. Diagnosis is made by observation of the clinical signs, inability to pass a stomach tube, and radiographs (x-rays). Rapid treatment is imperative. Twisting of the stomach cuts off the blood supply to the stomach tissues, and sometimes the adjacent spleen, causing necrosis of the tissue. Mortality rates are extremely high under these conditions.

Early detection with shock therapy (I. V. fluids, antibiotics, steroids, etc.), pain management, and surgical intervention can increase a dog’s prognosis, but reoccurrence is common and the patient can become difficult for many owners to manage.

Hip Displasia

This condition affects dogs of all sizes and breeds, but is most prevalent in large, fast-growing dogs, such as German Shepherd Dogs, Rottweilers, Golden Retrievers, Labrador Retrievers, and many others. Hip displasia is a inheritable disease involving the hip joints. Several dynamics can contribute to its progression, including diet and environmental factors.

Joint looseness (laxity), shallow joints, dislocation of the hips, cartilage breakdown, remodeling of the bony joint surfaces, and secondary joint degeneration are the defining characteristics of hip displasia. The observable clinical signs include, changes in gait, joint stiffness, hindquarter lameness and painfulness, especially following any type of exercise. Over time, friction from the constant rubbing of bone on bone (ball & socket), can lead to degenerative arthritis, further adding to the tremendous pain associated with this condition. Anti-inflammatory drugs, pain medications, and exercise restriction can ease some of the discomfort. Several types of surgical interventions are designed to alleviate joint pain or provide artificial hip replacement. Dogs diagnosed with hip displasia should be spayed or neutered. Breeding animals should be OFA certified to prevent the further spread of this highly heritable and extremely debilitating disease.

Pancreatitis

Inflammation of the pancreas, or pancreatitis, is a painful condition caused by the overproduction of pancreatic enzymes. It is most commonly seen in middle-aged, overweight female dogs. It is also seen in dogs that consume large quantities of high fat foods like the whole Christmas turkey, or the drippings from a large quantity of cooked bacon. High fat diets can stimulate over production of pancreatic enzymes. This overproduction can lead to inflammation in the pancreas. In severe cases these enzymes can actually begin “digesting” the pancreatic tissues, worsening the inflammatory response, and making the animal extremely ill and painful.

Clinical signs of pancreatitis include vomiting, anorexia, depression, hyper-salivation, diarrhea, and severe abdominal pain. Withholding of food and water is critical to treatment, along with I. V. fluid therapy, pain medication, antibiotics, and other treatments. Reoccurrence is prevalent in animals recovering from initial episodes. In some cases, shock and death can occur if the inflammation and pain are not aggressively managed. Diabetes mellitus can be a sequela to pancreatitis.

Patellar Luxation

Patellar luxation, or dislocation of the kneecaps, is a common orthopedic problem that causes the kneecap to slip to one side of the joint, causing discomfort and lameness. Small breed female dogs seem to experience patellar luxation most frequently. Medial luxation (slippage toward the inside) is the most prevalent form noted in toy breeds, but lateral (toward the outside) luxation or slippage from side to side may also occur. Yorkshire Terriers, Pomeranians, and miniature Poodles are several of the breeds commonly associated with this congenital condition. Injuries to the stifle joint can also result in patellar luxation.

Clinical signs of patellar luxation consist of intermittent lameness with a reluctance to stand on the affected hind leg. The dog may appear fine one minute and be yelping in pain the next. It is not uncommon for the patella to slip back into place of its own accord. Untreated, dogs suffering with this condition have a predilection for stifle joint arthritis as they age. Diagnosis is made by physical examination of the stifle joints and radiographs (x-rays). Surgical repair is generally quite successful.

Retained Deciduous Teeth

Deciduous teeth or “baby teeth” that don’t fall out when they should are referred to as a supernumerary tooth. Normally, a dog’s deciduous teeth should all be gone by the age of 6-7 months. Occasionally, one or more of these teeth will be retained in the mouth. The canine teeth are the most commonly affected. Small breed dogs like Yorkshire Terriers and miniature Poodles tend to have a greater incidence of retained deciduous teeth. Retained baby teeth can crowd permanent teeth, making the adult teeth come in crooked. Dental crowding from retained deciduous teeth can create an environment where dental tartar builds up and subsequent gingival infections occur.

Veterinarians often recommend removal of retained deciduous teeth while the animal is undergoing anesthesia for another procedure such as spaying or neutering.

Undescended Testicles

A cryptorchid animal has one, or on rare occasion, both testes retained in either the abdominal cavity or the groin region. It can be diagnosed by palpating the scrotum for testicles. Undescended testicles have a tendency to develop tumors. Testes retained in the abdomen usually do not produce testosterone, the male hormone responsible for secondary male sex characteristics. Those retained in the groin region may produce testosterone but are incapable of producing spermatozoa. Dogs with an undescended testicle should have a complete physical examination and blood work to determine if tumor formation and bone-marrow suppression is occurring. Otherwise healthy dogs should be neutered immediately to prevent tumor formation on the retained testicle. Dogs with malignant testicular tumors or bone marrow suppression should receive blood transfusions and other medical support before undergoing castration.

Pyometra

Pyometra is a secondary infection that occurs as a result of hormonal changes in the female's reproductive tract. Following estrus (heat), the hormone progesterone remains elevated for up to two months and causes the lining of the uterus to thicken in preparation for pregnancy. During estrus, white blood cells, which would normally protect against infection by eliminating bacteria, are inhibited from entering the uterus. This normal occurrence allows sperm to safely enter the female's reproductive tract without being damaged or destroyed by these immune system cells.

Pyometra may occur in any sexually intact young to middle-aged dog; however, it is most common in older dogs. Pyometra generally happens 2-8 weeks after the last estrus.

The clinical signs depend on whether or not the cervix remains open. If it is open (Open Pyo), pus will drain from the uterus through the vagina to the outside. High fever, polydipsia, lethargy, anorexia, and depression are common signs of open and closed pyometra.

If the cervix is closed (Closed Pyo), pus that forms in the uterus is not able to drain to the outside. The bacteria release toxins that are absorbed into the bloodstream. Dogs with closed pyometra become severely ill very rapidly. They are anorectic and very depressed. Vomiting or diarrhea may also be present.

The preferred treatment is to surgically remove the infected uterus and ovaries by performing an ovariohysterectomy (spay).

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