Positive Cat Research Articles

Cross-Reactivity of Cat and Dog Allergen Extracts

The commercial cat and dog allergen extracts are traditionally prepared from pelt, fur or dander. However, there is increased evidence of the allergenicity of saliva and urine of the animals. We have investigated 25 asthmatic children with a positive cat and/or dog RAST result. All 20 subjects with a positive cat RAST gave a positive skin prick test result to cat saliva, cat urine and cat hair. Analogously, all 20 subjects with a positive dog RAST had a positive skin reaction to dog saliva, urine and dander. In RAST inhibition experiments with dog and cat allergen discs, dog saliva appeared to be at least as potent as a commercial dog dander and hair extract, while cat saliva was less potent than the respective commercial extract. Both dog and cat salivas were clearly more potent than the respective urine. Significant cross-reactivity was observed between cat hair and dog dander in the RAST inhibition, whereas saliva and urine were shown to be more species-specific. An experimental dog dander preparation had about the same specificity as, and even higher allergenic activity than, that of dog saliva or urine. Our results suggest that saliva actually may be the best source of cat and dog allergen preparations. The importance of urine warrants further investigation.

The control of lymphosarcoma/leukaemia and feline leukaemia virus

ABSTRACTThis article discusses a removal programme designed especially for catteries and so–called multiple–cat households in an effort to control lymphosarcoma/leukaemia in cats and transmission of FeLV (feline leukaemia virus).The removal programme calls for: annual testing of all stud cats; testing of all contacts of a FeLV–positive cat during the previous 2 years; testing of imported cats; and isolation of FeLV–positive cats or, if this is impossible, euthanasia. The FeLV antigen can be demonstrated in cats by the indirect immunofluorescence antibody (IFA) test.The results of a removal programme carried out over a 4–year period in a large Dutch cat club are discussed. The percentage of FeLV–positive catteries decreased from 11 –5% during the first half of 1974 to 21% during the latter half of 1977; during the same period the percentage of FeLV–positive cats and stud cats decreased from 4–9% and 5–9%, respectively, to 1–2% and 1–0%, respectively.It is concluded that the recommended removal programme can be carried out without difficulty and produces good results.

CAT SCRATCH DISEASE: NONBACTERIAL REGIONAL LYMPHADENITIS

Of 145 patients with nonbacterial lymphadenitis observed over a period of 10 years, 115 had clinical cat scratch disease (CSD) with a positive cat scratch antigen skin test. In this group 86% had a typical benign course of CSD; the remaining 16 (14%) had an atypical form. These unusual forms were: Parinaud's oculoglandular syndrome in 7, encephalopathy in 3, atypical pneumonia in 2, and recurrent suppurative lymphadenopathy in 1. Two typical cases occurred after a dog scratch or bite, and one after a monkey scratch. The disease was most prevalent in late fall and early winter; 80% of patients were under age 20 years. Primary lesions were detected in 55%, node suppuration occurred in 26%, and lymphadenopathy lasted 2 weeks to 2 months in most patients. Symptoms were absent in 35% of cases. Fever occurred in 26%, and exanthem was present in 4%. Lymphadenopathy was most common in the extremities (57%), and head and neck (43%). Cat scratch antigen was found to be a reliable diagnostic skin test. A negative test was found in 98% of control patients; a positive test was found in 94% of patients who were clinically suspected to have CSD and a history of cat scratch. Management consisted of reassurance, symptomatic therapy, and closed aspiration of enlarged nodes if suppuration occurred. Antibiotics were not effective. The disease is self-limited and has an excellent prognosis in the majority of patients. An etiologic agent could not be isolated in this study. Until the causative agent is known, it will be difficult to carry out preventive measures.

The nematode transmission of Toxoplasma gondii

A cat infected with the nematode, Toxocara cati, and another which was nematode-negative, were both fed with the cystic forms of Toxoplasma gondii. The cat infected with Toxocara cati produced faeces capable of infecting mice with Toxoplasma; the Toxocara-negative cat did not. The Toxocara-negative cat was then infected with this nematode and the positive cat was treated with an anthelmintic to remove the worms. Both cats were again fed with Toxoplasma cysts; once again, the faeces containing the Toxocara cati ova infected mice with Toxoplasma, while those negative for Toxocara did not. These experiments support the idea that Toxoplasma gondii can be transmitted within Toxocara cati ova. Additional support has been provided by the fact that the toxoplasm infections can be filtered from a positive inoculum by using a sieve whose mesh size is small enough to retain the nematode ova. Evidence is given that this transmission mechanism could be responsible for avian infections.

TRIPLOID-DIPLOID CHIMERISM IN A MALE TORTOISESHELL CAT.

Chromosome analysis was made on somatic cells in culture derived by necropsy from the ear and the peritoneum of a sex-chromatin positive male tortoiseshell domestic cat. A mixture of triploid (57, XXY) and normal diploid female (38 XX) cells was found in cultures of both tissue origins. The chimerism † probably existed in the cat and did not arise during in vitro cultivation. Several mechanisms for the origin of this particular chimera are suggested, including double fertilization and fusion of various types of fertilized or unfertilized meiotic products. It is postulated that the sex-linked allelic genes for the black and yellow coat color in cats follow Mendelian inheritance and that the tortoiseshell phenotype possibly is due to genetic inactivation of either X-chromosome in a heterozygous female. It is further suggested that a male tortoiseshell cat can possess an XXY sex chromosome constitution and be heterozygous for the sex-linked coat-color genes, but other types of sex chromosome anomalies and mosaicism can give rise to the same phenotype in males. The karyotype of the normal domestic cat (Felts domestica) is presented. Most, if not all, of the chromosomes can be identified. Certain similarities of karyotypes among members of Felidae are noted.