Tag Archives: Basenji

Congenital and Hereditary Disorders of the Kidney

Structural Anomalies of the Kidney RENAL AGENESIS Renal agenesis is the complete absence of one or both kidneys. Bilateral renal agenesis is fatal and is a cause of early death in puppies and kittens (). Unilateral renal agenesis is more frequendy observed in puppies and kittens than is bilateral agenesis (). Unilateral renal agenesis may affect either kidney and is usually accompanied by ipsilateral ureteral agenesis. The etiopathogenesis of renal agenesis in dogs and cats is uncertain. A familial predisposition for renal agenesis in beagles, Shetland sheepdogs, and Doberman pinschers supports a genetic basis for the anomaly (Table 17-1). Unilateral renal agenesis may remain clinically silent, provided the contralateral kidney undergoes sufficient compensatory change to maintain normal hemostasis. Clinical findings may include an inability to palpate both kidneys or to detect a kidney by ultrasonography or contrast urography. Because of close associations in the development of the urogenital system, findings of abnormal or absent vas deferens, epididymal tails, or uterine horns at the time of castration or ovariohysterectomy should arouse suspicion of concurrent unilateral renal agenesis. Because unilateral renal Read more […]

Hypertrophic gastritis

This is a condition characterized by gross thickening of the gastric mucosa occurring as a diffuse or focal form involving the fundus, body or pylorus of the stomach (). It appears to be similar to a condition seen in man termed ‘Menetrier’s Disease’. The condition has been described in the cat () as well as the dog (). The focal form often involves the antrum and pylorus causing outflow obstruction or may appear like a polyp. In the diffuse form the majority of the mucosa is involved with macroscopic thickening of the mucosa and large rugal folds (3 and Plate 1). This is due histologically to glandular hyperplasia and cystic dilation of mucus glands with cellular infiltration of plasma cells and lymphocytes. Metaplastic changes lead to a loss of differentiation between the parietal and chief cells. Occasionally there is ulceration and hypertrophy of the muscle layer as well as the mucosa. The aetiology is not known but may include autoimmune disease, genetic predisposition in Boxers and Basenjis, hormonal influence especially through excessive levels of acetylchoiine, gastrin or histamine which have a trophic effect on the mucosa (). It may also occur where there is renal disease with failure to metabolize gastrin Read more […]

The Anterior Uvea

The irides of the puppy and kitten are often a different color than those of the adult. The blue-gray iris of puppies and kittens usually changes to the adult coloration within a few weeks. Iris color is ultimately related to the degree of stromal pigmentation and is influenced by coat color. Congenital Abnormalities Persistent Pupillary Membranes. Persistent pupillary membranes are strands of tissue that arise from the anterior iris surface and represent remnants of an embryonic vascular system. The persistent pupillary membranes may be confined to the iris surface or may extend from the iris to the cornea or lens (). Persistent pupillary membranes are inherited in the basenji. Iris Cysts. Iris cysts are floating, fluid-filled vesicles that arise from the posterior iris epithelium and are usually found in the anterior chamber. Iris cysts may be unilateral or bilateral and singular or multiple in number. Pupillary Abnormalities. A notch-like defect (coloboma) is occasionally seen in the ventronasal pupillary border of young dogs and cats, resulting in a keyhole-shaped pupil. An eccentric pupil (corectopia) may accompany multiple ocular defects, as occurs in the Australian shepherd. Eccentric pupils are usually Read more […]

The Lens and Vitreous

The lens develops rapidly in the early stages of embryogenesis, during which time it is nourished by the hyaloid vessel. The fully developed lens is avascular; by the second week of life, no remnants of the hyaloid system should remain. The normal lens often exhibits minor imperfections that can be easily detected with magnification in dogs and cats younger than 1 year. These include prominent anterior and posterior Y sutures and minute granules in its nucleus and cortex. A mosaic of brown pigment spots is occasionally seen on the anterior lens capsule near the center of the pupil, representing remnants of embryonic mesoderm. Disease of the vitreous would be expected to influence the lens or retina because of its attachments at the posterior lens surface and the optic disc. Congenital Abnormalities Congenital lens abnormalities include alterations in size or shape. Congenital absence of the lens (aphakia) is uncommon. In microphakia, the margin of the abnormally small lens along with elongated ciliary processes may be observed after pupillary dilation. Microphakia occurs along with other ocular defects in the Saint Bernard and beagle and in cats. Luxation of the microphakic lens may cause glaucoma. Lenticonus is a Read more […]

The Retina and Optic Nerve

Tapetal coloration of the fundus of the puppy and kitten is usually gray or blue at 6 to 8 weeks of age, gradually acquiring its adult coloration by 4 to 7 months of age when the tapetum matures. Myelination of the optic disc may also be incomplete in the puppy and kitten, giving the impression of a small, well-defined nerve head that takes on a more fluffy appearance as adult myelination occurs.Both congenital and acquired disorders of the retina and optic nerve are recognized in the young dog and cat. These may be inherited, as with collie eye anomaly, or secondary to postnatal influences, as occurs with canine distemper-induced retinitis. Congenital abnormalities can be diagnosed as early as 6 weeks of age, when the posterior segment is clearly observed. The more common congenital abnormalities of the canine fundus are summarized in Table Congenital Abnormalities of the Canine Fundus. Acquired abnormalities develop with advancing age and in this discussion are limited to those in dogs and cats younger than 6 months of age. Table Congenital Abnormalities of the Canine Fundus (diagnosed as early as 6-8 wk of age). DISORDER BREED CHARACTERISTIC FEATURES Collie eye anomaly Collie, Shetland sheepdog, Read more […]

Lymphocytic-plasmacytic enteritis

This is a chronic inflammatory condition of the small intestine characterized by infiltration of the lamina propria by plasma cells and lymphocytes (). Middle-aged dogs of either sex are most susceptible and it appears more common in the German Shepherd dog although any breed can be affected. Similar infiltrations have been observed in other conditions such as bacterial overgrowth and giardiasis. In the Basenji a complex disease entity exists, characterized by anorexia, occasional vomiting and chronic diarrhoea. Histological changes to the small intestine resemble lymphocytic—plasmacytic enteritis. The condition is thought to have a hereditary basis and may be precipitated by stress. Hypoalhuminaemia and hypergammaglobulinaemia are other hallmarks of the condition (). The condition has also been diagnosed in cats which usually only develop a mild form of the condition, and certainly are never as severely affected as the Basenji. The aetiology of the condition is not understood but may simply reflect a normal intestinal response to antigen such as bacteria, virus or allergen (). This is further substantiated by a resolution of the problem when a hypoallergen diet is fed or where corticosteroids are administered Read more […]

Aggressive Behavior

Characteristics of Dogs That Bite: Age and Sex The etiology of aggressive behavior presents considerable variation from dog to dog. Aggressive behavior is most frequently exhibited by socially mature and intact male dogs (), but young puppies can have serious precocious aggression problems, as well. Mugford (1984) reported that among 50 English cocker spaniels the mean average age of dogs with dominance-related aggression was 7.4 months (range, 3 to 24 months). In another group of golden retrievers treated by Mugford (1987), 24 with aggression problems averaged 2.9 years of age (range, 0.7 to 8.0 years). Of the 24 dogs treated by Mugford, 19 were males, two of which had been castrated. Beaver (1983) found that of 120 dogs with aggression problems (various diagnoses) the mean age was 3 years (range, 9 weeks to 11 years). She reported that 60.1% of the dogs were intact males (14% castrated), with 15.4% intact females (10.5% spayed). Wright (1985) found that the average age of dogs involved in severe attacks was 3 years (range, 0.67 to 10.5 years). All 16 dogs were males. These statistics suggest that considerable variation exists with respect to the time of onset associated with aggression problems. Although most dogs Read more […]

The Eye

The eye (organum visus) develops as a neuroectodermal outgrowth of the embryonic prosencephalon that contacts surface ectoderm and is enveloped by induced mesodermal and neural crest mesenchyme. The definitive eye and its adnexa are contained within an orbit that is only partly bony. Associated with the bulb of the eye are extraocular muscles that move it; periorbital fascia and fat that surround and cushion it; eyelids and conjunctivae that protect it; and a lacrimal apparatus that keeps its surface moist, provides the first barrier to infection, and helps to nourish the cornea. As a consequence of its dual origin, the eye has both central and peripheral neural elements. The optic nerve is a central nervous system structure with myelin formed by oligodendroglial cells, whereas the nerves of the extraocular muscles and iris are peripheral nervous system structures with lemmocyte (Schwann cell) sheaths for myelin. The vascular and fibrous tunics surrounding the optic nerve are homologous to the meninges surrounding the brain and spinal cord. The intervaginal space of the optic nerve is continuous with the subarachnoid space of the brain and contains cerebrospinal fluid. There is considerable variation between breeds Read more […]

The Eyeball: Vascular Tunic

The vascular tunic (tunica vasculosa bulbi) is the thick middle coat of the eye, interposed between the retina and the sclera. It is commonly referred to as the uvea or uveal tract. The vascular tunic includes three contiguous parts, which, from posterior to anterior, are the choroid, the ciliary body, and the iris. Its functions are numerous and include regulating the amount of light entering the eye through the pupil; producing the aqueous humor, which maintains the intraocular pressure and bathes the structures of the anterior segment; suspending the lens via zonula fibers; changing the visual focus via the ciliary body muscle; limiting the amount of scattered light within the eye (inner pigmented portion of uvea); increasing the photic stimulation of the retina under low light levels (tapetum lucidum of the choroid); and providing nutrition to structures within the eye (ciliary body and choroid). Choroid The choroid is a pigmented vascular layer. It is continuous with the ciliary body anteriorly and completely envelops the posterior hemisphere of the eyeball, except in the region of the area cribrosa (region of the optic nerve head), where it is absent. The choroid is further divided into layers, which, from Read more […]

Sensitivity to Human Attentional States

One might expect that under circumstances in which deictic signals result in interference or exploitation by an observer that a dog might employ gaze amd directional cues to turn the others attention away from the location or object of interest. The results of a study by Call and colleagues () might be interpreted as evidence of tactical behavior organized to evade interference by adjusting risky ventures to changes in human orientation, proximity, and attention. In their study, dogs were exposed to training in which a piece of food was placed on the floor, whereupon the experimenter looked at the dog and said “Aus!” (Out!), followed by a second event in which the dog’s name was called and followed by “Aus!” again. The dogs were subsequently exposed to a series of test trials that continued until the dog either took the food or 3 minutes had elapsed. If the dog took the food without permission, it was not punished, nor was it rewarded if it refrained from taking the food. As such, the procedure appears to asymmetrically favor approach over avoidance, since dogs that took the forbidden food were merely ignored, just as those that obeyed the prohibition were ignored. With only one exception, all of the dogs took the food Read more […]