Geriatrics or old age is a complex biological process which results in changes in the ability to maintain the living homeostasis. It is a well-established fact that geriatrics is naturally selected and genetically programmed in all species of animals¹. It is a heterogeneous process which ultimately leads to progressive reduction of ability and gradual onset of morbidity. The most common and first sign of ageing is slowing down². Old age is manifested with change in behavioral pattern to different visible changes. Hematological and biochemical alterations accompanied by structural and functional changes at tissue or cellular levels are encountered during old age signaling the disease process. Signs of ageing are inevitable in older dogs with all these alterations indicating certain illness or disease.

Geriatric age chart of different breeds as per Goldston³ is a standard reference protocol for primary screening of geriatric dogs. Most of the times we ignore certain parameters-like external visible changes while determining the old age in dogs. External visible changes include loss of elasticity of skin, rough hair coat, thickening of skin at flank region of hind limb, area around eye and behind the elbow and hock joint, dental wear and tear etc. Along with this different haemato- biochemical alterations also indicate the advent of old age in dogs. Haematological alterations range from anemia to decreased PCV etc. Biochemical changes include decreased serum protein and increased cholesterol etc. in such animals. These haemato-biochemical alterations can directly be correlated with different dysfunctions of heart, liver, kidneys, spleen and musculo-skeletal system etc. Geriatric dogs also encounter certain disease conditions-like arthritis, skin effections fibrosis of kidney and liver, glaucoma, arteriosclerosis, brown pigmentation and haemosiderosis of different internal organs. At times these disease conditions are also associated with tumors. All these changes either at systemic or organ level may lead to loss of functionality in the geriatric animals. The animals also lose their efficacy and agility in the later part of their life. Scanty information is available about age related biomarkers in dogs. Identification of senescent cells through X-gal staining procedure using canine skin tissue collected from dead dogs immediately after death can be correlated with ageing process⁴.

All the age-related alterations are not very specific for age determination. It is always difficult to have an accurate age estimation of dog during live and dead conditions. Many times dogs die due to old age complicated with systemic dysfunctions which becomes difficult to establish. There is scanty literature in relation to tissue alterations in geriatric animals whereas geriatric study is extensive in its human counterpart. Therefore, the present study was carried out to detect the aging process through gross and microscopic changes in various organs of geriatric dogs which can be useful for determination of geriatrics. The knowledge of systemic alterations can be helpful for effective management of geriatric dogs at the critical period of their life.

The present study on clinic-pathological changes in geriatric or old dogs was undertaken in the Department of Veterinary Pathology and Teaching Veterinary Clinic Complex (TVCC) spanning a period of about one year. For screening of geriatric dogs, standard geriatric age chart of different breeds as per Goldston³, viz. external visible changes and age as per record were considered as primary screening parameters. During the study period, 15 old dogs were taken into consideration as geriatric dogs during clinical presentation and died at different times (table 1). History and clinical information along with haemato-biochemical alterations were studied in all the 15 cases. Postmortem examination of 7 was conducted and in rest 8 cases, post mortem could not be conducted due to field limitations. Systemic postmortem examination of all 7 dogs was conducted and special care was taken to record the detailed gross lesion in different organs. For histopathological study, representative tissues from different organs with or without gross lesions were collected in 10% formal saline solution. The formalin-fixed tissues were processed by routine histological techniques⁵. The fixed tissues were washed overnight in running tap water and dehydrated in ascending grades of alcohol and cleared in xylene.

Paraffin blocks were prepared and sections were cut at 5 micron thickness and stained by haematoxylin and eosin method. Stained slides were examined under microscope for histopathological changes.

For screening of geriatric dogs, standard geriatric age chart of different breeds as per Goldston³ was followed. External visible changes and age as per record were considered as primary screening parameters (Table. 1). History and clinical information along with haematobiochemical alterations were studied in all the 15 clinically presented cases (table 2). Clinical findings, hematological and biochemical changes were correlated with the systemic dysfunctions of respective cases associated with old age. Pathomorphology of the respective cases were studied to correlate with systemic dysfunction associated with old age. All the seven cases were grouped into various suspected systemic dysfunctions on the basis of clinical and haemato- biochemical findings as: (1) anemia -2, (2) anemia and dirofilariasis -1, (3) jaundice, hepatitis & nephritis -2, (4) hepatitis and nephritis -1, and (5) chronic enteritis -1.

Most organs were altered morphologically and functionally in old animals⁶. Physiological changes that occur throughout the ageing process reflect the gradual loss of functional activities in various systems⁷ organ. Grossly, skin was thickened at flank region of the hind limb, area around eye, behind elbow and hock joint. However, skin was thinner in other region in geriatric dogs. The pathological changes observed in various organs in present study on geriatric dogs revealed that heart, liver and kidney were found to be the major affected organ during postmortem which are mostly the metabolically demanded organs⁸. One of the common symptoms of liver affection is jaundice, a yellowish tinge to the skin, most often noticed in eyes, gums and even on cut surfaces of internal organs which lead to yellowish appearance. Jaundice and icterus are hallmark of hepatic disorder in aged dogs⁹. Important histopathological findings in kidney were glomerular sclerosis, glomerular atrophy and tubular atrophy. In age related changes of renal histomorphology, tubular atrophy is the common and pronounced findings in aged dogs between 7–14 years old¹⁰. It may also include glomerular lesions-like glomerular sclerosis which is in accordance with the above study. Age related changes are quite evident in kidneys that include decrease in number of glomeruli, decreased tubule size and increased renal fibrosis¹¹. The renal lesions mostly the degenerative and inflammatory changes were associated with old age¹². There is also reports of renal amyloidosis and immune complex deposition in the glomerulus which is not observed in the present study¹². Above kidney changes can be correlated with ageing process.

In all cases the splenic pulp showed severe depletion of lymphoid cells from the Malpighian corpuscles which indicate decreased immune response that further can be correlated with aging. Aging has been associated with decreased function of the immune system in a variety of species¹³. Grossly, spleen was also found to be enlarged which might be immune mediated response. The most evident age related effects in the heart were loss of muscles fibers due to disruption of muscle fibres along with congestion of vasa vassorum¹⁴. Blood vessels were markedly congested in the intestinal sub mucosa in geriatric dogs¹⁴. Geriatric stage is an important aspect of life of a dog during which it encounters different patho-morphological alterations affecting functionality of different vital organs. These pathological alterations must be identitial and addressed in geriatric dogs to augment its quality of living and to enhance the life expectancy of the animal.

N.B.: Units - Hb g%, PCVC%, TEC×10⁶mm³, TLC×10³/mm², Glucose mg/dl, Total Protein mg/dl, Albumin mg/dl, SGPT IU/L, SGOT IU/L, Cre atinine mg/dl & Urea mg/dl

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