PREGNANCY DIAGNOSIS WITH ULTRASOUND IN THE DOMESTIC CAT

Ultrasonographic examinations of seven pregnant cats with known breeding dates were made on successive days to establish the identifiable characteristics of pregnancy. Subsequent serial examinations were made to sonographically characterize normal feline prenatal development before 30 gestational days. An enlarged uterus, gestational sacs, and fetal poles were recognized as the features of early feline pregnancy and were first seen at 4, 11, and 15 days, respectively. Cardiac activity was detected earliest on gestational day 16, and recognizable feline fetal morphology appeared at day 26. Fetal membranes became apparent at as early as 21 days of gestation. Generalized fetal movements were first noted at day 28. Live and dead fetuses were compared in utero and marked differences were noted, with dead fetuses rapidly losing previously recognizable morphology. Determination of litter size in each cat could not be done accurately by ultrasound examination. It was concluded that the diagnosis and accurate dating of early pregnancy in the domestic feline may be accomplished with serial ultrasound evaluation.     

HELMINTH AND ARTHROPOD PARASITES OF THE DOMESTIC CAT IN PAPUA AND NEW GUINEA

A survey of the parasites found in 117 cats from the Port Moresby area of Papua and New Guinea is reported. The helminth species not previously recorded on the Australian mainland included Joyeuxiella pasquelei, Ancylostoma tubaeformae and Euparadistomum sp. The heart-worm, Dirofilaria immitis, is a relatively common parasite of aged cats in the Territory. Arthropods decorded included two indigenous tick species lxodes confusus and Haemaphysalis noveguineae.     

THE EFFECT OF PREPUBERAL AND POSTPUBERAL GONADECTOMY ON PENILE EXTRUSION AND URETHRAL DIAMETER IN THE DOMESTIC CAT

Male (n = 6/group) and female (n = 6/group) kittens were gonadectomized at 7 weeks or 7 months of age, or left intact. At 22 months of age, complete penile extrusion was possible in all of the intact males, in 3/5 (60%) males castrated at 7 months of age, and in none of the males castrated at 7 weeks of age. Antegrade (voiding) cystourethrograms were performed at 22 months of age. Diameter of the preprostatic (p = 0.13) and penile (p>0.25) urethra of male cats did not vary by group. Diameter of the pre-pelvic urethra of female cats gonadectomized at 7 weeks of age was significantly smaller than that of intact females (p = 0.02).     

MYELOGRAPHY IN THE CAT

Metrizamide myelographic examinations were performed on five normal cats using sequential cisternal and lumbar injections at weekly intervals to determine the dose of contrast medium required, adverse effects, and quality of the myelographic study. The normal myelographic appearance in the cat is described. All spinal cords were examined histopathologically after the termination of the study, and variable mild lesions were found. Doses of 0.2 ml/kg, 0.35 ml/kg, and 0.4 ml/kg metrizantide, respectively, for lumbar, thoracolumbar, and complete spinal studies are recommended when performing lumbar injection. Recommended doses using cisternal injection for cervical, cervicothoracic, and complete spinal studies are 0.2, 0.45, and 0.5 ml/kg, respectively. Subjectively, lumbar injection produced higher-quality thoracolumbar myelograms and cisternal injection produced higher-quality cervical studies. Clinical complications during the study included one seizure following cisternal myelography and mild neurologic deficits in all cats, which resolved within 36–48 hours.     

CHRONIC METHYLMERCURIALISM IN THE CAT

SUMMARY The mercury levels in 69 muscle samples from fish weighing from 0.3 to 200 kg caught in Moreton Bay, Queensland, in the latter half of 1976 ranged from 10 to 2,030 ng/g. Mercury levels in blood samples from 53 humans and 100 dogs in Brisbane almost all contained 10 ng/ml while the level in 162 cats sampled ranged from 10 to 329 ng/ml. Chronic methylmercurialism developed in 2 cats dosed daily with methylmercury, bound to cysteine, at the rate of 0.6 mg/kg body weight for 74 and 77 days respectively. Terminal clinical signs included anorexia, weight loss, knuckling over at the carpus and tarsus. hypermetria initially involving the forelegs and later the hindlegs, sluggish reflexes, paresis involving all limbs, persistent crying, apparent blindness, tonic and clonic convulsions and salivation. Pathological changes were confined to the nervous system and included degeneration of neurones and perivascular cuffing in the cerebrocortical grey matter, focal atrophy of the granular layer, focal sponglosus of the molecular layer and degeneration and loss of Purkinje cells in the cerebellum and demyelination in the fibre tracts of the dorsal funiculus, mainly the fasciculus cuneatus and in the lateral and ventral corticospinal tracts. Terminal blood methylmercury levels were in excess of 18 μg/ml, while brain methylmercury levels ranged from 21.0 to 28.4 μg/g. The liver and kidney contained the highest total levels of mercury of 50 to 80 μg/g, of which 23 to 37% was inorganic.     

DOUBLE CONTRAST GASTROGRAPHY IN THE CAT

Radiographic diagnosis of gastric mucosal disease has not been reported in the cat. This may be due to the difficulty in making these diagnoses with survey or single contrast radiography. Double contrast gastrography (DCG) allows direct visualization of gastric mucosal surfaces. The DCG technique in the cat is described, and the normal radiographic appearance is illustrated.     

TWO-DIMENSIONAL ECHOCARDIOGRAPHY IN THE NORMAL CAT

Two-dimensional echocardiography (2DE) and M-mode echocardiography were used to image the heart of 13 clinically healthy cats. Seven awake cats and six cats tranquilized with a combination of acetylpromazine and ketamine were studied. Six cats were studied by 2DE on 3 consecutive days to assess repeatability of the study. Long-axis and short-axis echocardiographic tomograms were obtained from the right parasternal location, and these images were used to determine internal cardiac dimensions, ventricular and septal wall thicknesses, repeatability of the study, and interobserver variability. Some but not all parameters were significantly (P < 0.05) related to body weight. Significant correlations (P <0.05) were found between measurements obtained by long-axis and by short-axis image planes. Comparison of parameters measured by 2DE and M-mode echocardiography demonstrated minimal differences between mean values. Repeatability of the 2DE study was good with 14 of 16 parameters having a mean percent error less than 10%. Interobserver variability was acceptable for some but not all parameters. The study indicates that repeatable 2DE tomograms can be obtained in the cat and that quantitation of cardiac anatomy is possible with this imaging technique.