Category Archives: Disorders in Dogs

Disorders of the Mammary Glands

1) Are bitches with a history of false pregnancy more likely to suffer from pyometra than bitches that never had false pregnancy? The signs of false pregnancy are a consequence of the normal hormonal changes all dogs undergo when they go through heat. Because all dogs go through these changes, whether or not they show signs of false heat, and because it is these hormonal changes that are associated with development of pyometra, dogs with signs of false pregnancy are not more likely to get pyometra than are bitches that never show signs of false pregnancy. In fact, I like a history of false pregnancy because it gives me historical evidence that hormonal changes occurred as expected in that bitch. 2) Will spaying cure false pregnancy? How about having a litter? No. The clinical signs of false pregnancy are due to a lack of progesterone. Removing the ovaries and uterus will not increase progesterone concentrations in the body. Spaying will, however, keep the bitch from ever having false pregnancy again because she will never go through heat again. Having a litter will not decrease signs of false pregnancy after subsequent heat cycles and may increase mammary development and milk production. 3) Is spaying protective Read more […]

Mammary Neoplasia

Development Several types of mammary tumor have been reported in the dog. The two most common are the benign fibroadenoma, or mixed mammary tumor, and the malignant adenocarcinoma. These occur with about equal frequency. The inflammatory carcinoma is a much less common type of tumor; one study reported inflammatory carcinoma to be 8% of mammary tumors reported. A given bitch may have more than one tumor type. In humans, mammary neoplasia is hormone dependent, with estrogen the most common hormone involved in tumor development. In dogs, hormones play a role in mammary tumor development, but the exact pathogenesis is not clear. Bitches spayed before going through heat have a greatly reduced risk of developing mammary neoplasia when aged. The protective effect gradually declines as the bitch is allowed to cycle. Historically it was thought that once a bitch had cycled four times or had reached 2.5 years of age, all protective effect of OHE was gone. Recent work from Belgium suggests that some protective effect remains, even in bitches as old as 9 years. Receptors for estrogen, progesterone, and other hormones have been identified in mammary tumor tissue, suggesting action of those hormones on the neoplastic tissue. Read more […]

Disorders of the Puerperium

1) What does a normal bitch look like in the days following whelping? When should I worry that something’s wrong? Normal bitches pass an odorless, reddish brown to green vulvar discharge for up to 3 weeks after whelping. Body temperature may be slightly elevated for a couple of days but never should be above 102.5° F. The mammary glands should be full but not painful. It is normal to see milk expressed from several openings at the end of every nipple. Abnormalities include creamy, malodorous vulvar discharge; one or more swollen and painful mammary glands; decreased appetite and thirst; disorientation; and neglect of the pups. 2) My bitch finished whelping in the “wee hours” of the morning. Does she need to go into the veterinarian for a “cleanout” shot? Not if she has live pups that are nursing. The nursing pups stimulate frequent release of small amounts of oxytocin, which causes milk letdown and uterine contractions. This is better for the bitch than our giving her one big shot of oxytocin. The puerperal period is that time from whelping to complete involution and repair of the uterus. This period usually lasts about 12 weeks. By the end of the puerperal period, the pups are weaned, the uterus Read more […]

Disorders of eyes and vision

The neuro-ophthalmological examination combines aspects of the neurological examination with components of the ophthalmic assessment and is an important element of both disciplines. Armed with a basic knowledge of the visual pathways and pupillary light reflex, performing the neuro-ophthalmological examination is simple, quick and requires no expensive or specialized equipment. From a neurological viewpoint, the visual system is both fascinating and unique, in that the retina and optic disc are the only components of the nervous system directly visible in the normal patient. Even in the absence of overt neuro-ophthalmological abnormalities, athorough evaluation of the eyes, including afundic examination, should always be performed in the neurological patient, as the underlying cause of neurological disease may be evident (). Conversely, a full neurological examination should be performed in any animal with neuro-ophthalmological abnormalities. Terms that are commonly used in clinical neuro-ophthalmology are defined in Definitions of terms commonly used in clinical neuro-ophthalmology. Definitions of terms commonly used in clinical neuro-ophthalmology Term Definition Anisocoria Pupils of unequal or Read more […]

Decreased vision with pupillary light reflex deficits

Concurrent impaired vision and pupillary light reflex deficits are suggestive of a lesion affecting the proximal portion of the visual pathway, from the retina to just prior to the lateral geniculate nucleus, which is common to both the visual pathways and the pupillary light reflex pathway. Retinal, optic disc and optic nerve lesions Unilateral lesions will usually result in impaired vision in the affected eye and loss of the direct and consensual pupillary light reflex on stimulating the affected eye. Both the direct and consensual pupillary light reflex should still be present on stimulating the normal eye. Bilateral lesions will usually result in impaired vision, mydriasis and loss of the pupillary light reflex (both the direct and consensual reflexes) in both eyes. Sudden acquired retinal degeneration: SARD is characterized by an acute loss of vision (although in some cases this may develop over a few days), and occurs occasionally in dogs in the UK (). Affected dogs are typically adult (middle-aged), can be of pedigree or mixed breed descent, and present bilaterally blind with dilated unresponsive pupils. In the acute stages no abnormalities are evident on ophthalmoscopic examination, but overtime (weeks Read more […]

Disorders of pupil size and function

Pupil abnormalities, usually evident as alterations in pupil size, in the absence of visual loss may affect one or both pupils (Causes of alterations in pupil size and function that are not usually associated with loss of vision (with the exception of raised intracranial pressure)). Anisocoria results when only one pupil is affected. In this instance, evaluation of the PLRs is necessary in order to determine which pupil is abnormal. Before any neuro-ophthalmology assessment is performed it is essential first to ascertain whether the pupil abnormalities could be explained by non-neurological abnormalities of the iris (including iris atrophy, iris hypoplasia, uveitis and trauma) or globe (including lens luxation and glaucoma). Painful conditions of the cornea and conjunctiva may also cause miosis. Brief oscillations of pupillary size, referred to as hippus, may occur as a normal feature in response to light exposure. Very exaggerated hippus may be an indication of CNS disease, particularly if it occurs in conjunction with other neuro-ophthalmological abnormalities. Causes of alterations in pupil size and function that are not usually associated with loss of vision (with the exception of raised intracranial pressure). Condition Miosis Read more […]

Disorders of eyeball position and movement

As discussed previously, there is an intimate functional association between the innervation to the extraocular muscles and the vestibular system. The extraocular muscles are innervated by cranial nerve III (oculomotor), cranial nerve IV (trochlear) and cranial nerve VI (abducent) (). Any strabismus due to a lesion in one or more of these cranial nerves must be differentiated from lesions affecting the extraocular muscles (including traumatic rupture and extraocular myositis). • Lesions simultaneously affecting CNs III, IV and VI result in external ophthalmoplegia, and internal ophthalmoplegia if the pupillary constrictor (CN III) is affected. • Lesions with only cranial nerve III involvement may present with a ventrolateral strabismus; more rarely lesions may only affect single muscle groups, resulting in a strabismus opposite to the normal function of the denervated muscle. • Lesions affecting the trochlear nerve in isolation are extremely rare but, where they do occur, will result in loss of function of the ipsilateral dorsal oblique muscle (brainstem lesions may result in loss of function, ipsilateral or contralateral). The dorsal oblique muscle functions to rotate the dorsal portion of the globe nasally Read more […]

Disorders of blink

Abnormalities of the blink are usually the result of lesions affecting cranial nerve V (trigeminal) or cranial nerve VII (facial). The integrity of the blink pathway is evaluated by performing the palpebral reflex (afferent touch sensation via the trigeminal nerve and efferent motor function via the facial nerve) and the menace response (afferent visual stimulus via the optic nerve and efferent motor function via the facial nerve). Abnormalities of blink due to a sensory (CN V or trigeminal nerve) lesion Lesions of the ophthalmic branch of the trigeminal nerve will result in loss of sensation to the cornea and medial canthus of the eye (as well as the nasal cavity). The consequence of this is loss of the corneal and palpebral reflexes. The menace response should still be intact if vision and the facial nerve are not involved. Exposure keratopathy, with rapid progression from neuroparalytic keratitis to ulcerative keratitis (), is a frequent complication of ophthalmic branch lesions but is infrequently seen following facial nerve (motor) lesions. Although basal tear secretion should be normal, reflex tear production in response to stimulation of the cornea or nasal mucosa is lost as this is mediated through the ophthalmic Read more […]

Disorders of lacrimation

The normal production of tears can be subdivided into two components: basal tear production (evaluated by a Schirmer II test, where tear production following anaesthesia of the cornea is measured); and induced tear production (evaluated by a Schirmer I test, where the cornea is not anaesthetized and as a consequence the corneal stimulation from placing the test strip in the eye induces reflex tear production). Induced tear production occurs following stimulation of the ophthalmic branch of the trigeminal nerve (which innervates the surface of the cornea and the nasal mucosa) and in response to high light intensities. Loss of induced tear production most commonly occurs due to lesions of the ophthalmic branch of the trigeminal nerve (), but the decreased tear production is less importantthan the loss of corneal sensation with consequent decreased blink frequency and development of neuroparalytic keratitis. Lesions resulting in decreased tear production The lacrimal gland is innervated by the parasympathetic portion of the facial nerve, a branch of which also innervates the lateral nasal gland (a serous-secreting gland that functions to keep the nose moist). Lesions affecting the parasympathetic portion of the facial Read more […]